Anatomy and Physiology PDF

Anatomy & Physiology Anatomy is the study of form and structure (what they look like and where) Physiology is the study of functions (how it works) There are also four approaches to studying anatomy: Microscopic: (seen with a microscope) Macroscopic: (seen with our eyes) Regional: (examines all str...

Anatomy & Physiology Anatomy is the study of form and structure (what they look like and where) Physiology is the study of functions (how it works) There are also four approaches to studying anatomy: Microscopic: (seen with a microscope) Macroscopic: (seen with our eyes) Regional: (examines all structures in specific part of body) Systemic: (examines each system of the body as a separate topic) Anatomical Planes of Reference Used to describe the location of structures in the body. Some of these include: Saggital Plane: A length-wise plane that divides the body into left and right parts Median Plane: divides the body into equal left and right halves Transverse Plane: A cross-wise plane that divides the body into cranial and caudal parts Dorsal Plane: A cross-wise plane that divides the body into dorsal and ventral parts. Only used for body, not limbs Towards head Towards taily  Directional Terms Used to describe the relative position of one structure to another. Some of these are: 1. Cranial: closer to the head 8. Deep (Internal): closer to the center of the body 2. Caudal: closer to the tail 9. Superficial (External): near or towards the body surface 3. Dorsal: closer to the top or back 10. Proximal: nearer to the attachment of the limb to the 4. Ventral: closer to the bottom or body belly 11. Distal: farther away from the attachment of the limb 5. Rostral: on the head, closer to to the body the nose 12. Palmar: backside of the forelimbs below the carpus (wrist) 6. Medial: closer to the midline/ 13. Plantar: backside of the hind limb below the tarsus inside of body (ankle) 7. Lateral: away from midline/ 14. Dorsal: front side of the forelimbs or hind limb below the inside of the body carpus or tarsus 7 6 9 Superficial (External) 1 g Beep (Internal) 5 3 2 4 18 13 14 12 11 Common Regional Terms: Equine 1. Muzzle: nose and mouth area 11. Cannon: long bone below the knee on the 2. Poll: top of the head, between its ears front leg 3. Withers: highest part of the back, where the 12. Fetlock: joint above the hoof. Like an neck connects ankle 4. Barrel: middle part of the body, think of 13. Hoof: hard part of the foot tummy 14. Stifle: joint high up on hind leg 5. Point of hip: bony part on the side of the 15. Hock: joint lower down on hind leg rump 16. Flank: side of the belly, behind the ribs 6. Tailhead: where the tail begins 17. Thigh: muscular upper part of the hind 7. Shoulder: top part of the front leg leg 8. Brisket: chest part, between the front legs 9. Elbow: joint in the front leg 10. Knee: joint in the front leg that looks like a backwards knee 2 3 5 6 4 1 17 7 16 g 14 9 15 18 11 12 Common Regional Terms: Bovine 1. Fore flank: long part of front leg under the 7. Heart girth: measure how big around it knee is. Goes around their chest, behind their 2. Dewclaw: tiny hoof on the back of the leg front legs 3. Rump: back part of the body where the tail 8. Rear flank: side of the belly, near back begins legs 4. Pin bones: pointy bones on the side of the 9. Switch: fluffy part at the end of tail rump 10. Udder: milk comes from here 5. Hook: bony part that sticks out on hip 11. Underline: underside of belly 6. Loin: lower back 12. Navel: belly button 36 4 7 5 g 18 9 1 11 12 2 Bilateral Symmetry Can be divided into two main cavities: The dorsal body cavity is smaller and contains the central nervous system The ventral body cavity is larger and contains most of the soft organs (viscera) of the body This is then further divided by the diaphragm into the: Cranial = thoracic cavity Cranial Cardal Caudal = abdominal cavity · Thorax Organs are covered by a thin membrane called pleura Visceral pleura Membrane that covers the lungs Parietal pleura Lines the thoracic cavity  Seven Characteristics of living things: Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition The body is organized into different levels of complexity: Cells: the basic functional units of animal life Tissues: groups of specialized cells There are four types of tissues Epithelial: forms linings, coverings and glands Connective: holds the body together and provides support Muscle: moves the body Nervous: transmits information around the body and controls body functions Organs Groups of tissues that work together for a common purpose Systems The most complex level of the body organization and are groups of organs involved in a common set of activities 1. Integumentary 2. Skeletal 3. Muscular 4. Digestive 5. Cardiovascular 6. Respiratory 7. Urinary 8. Lymphatic 9. Endocrine 10. Reproductive 11. Nervous Homeostasis is the maintenance of a dynamic equilibrium in the body, meaning a balance of activity, energy and work  Tiues- Chapter Five Histology: study of tissues/organs structures at the microscopic levels Arranged in groups that perform the same function There are four main types of tissues: Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue Epithelial Tissue Epithelial Tissue: covers and lines organs or tubes in the body Think about building different structures with LEGO blocks! ↳ Each LEGO block is a cell, and when we put many cells together that do the same job, we get a tissue! Different LEGO structures can be built with these blocks, just like the different organs in our body are made up of different types of tissues Epithelial tissue is like the outer layer of LEGO blocks it covers and lines different parts of our body It’s like a protective shield that protects other tissues, just like the outer layer of LEGO blocks protect the blocks inside It can also filter things, like when you use a strainer to separate pasta from water It can absorb things, just like a sponge absorbs water  It helps us feel things, like when you touch something hot or cold There are different shapes of epithelial cells, just like there are different shapes of LEGO blocks: o Squamous: Like a flat, thin LEGO block Cuboidal: Like a cube-shaped LEGO block Columnar: Like a tall, rectangular LEGO block ~ Sometimes LEGO blocks have special tools on their surface to help them do their job even better! These tools are called surface specializations One type of surface specialization is smooth, like the surface of blood vessels. This smooth surface helps blood flow easily without sticking. It’s like a water slide for your blood cells! Another type is called Microvilli. These are tiny little hairs on the surface of some cells. They aren’t as long or noticeable as cilia. Microvilli are found in the intestines and urinary tract, and they help these organs absorb nutrients from food and liquids. Imagine them like tiny fingers grabbing onto all the good stuff. Cilia are longer and move back and forth like tiny oars, moving things along. They are found in the respiratory and urogenital tracts. They help move mucus and other fluids along the surface of the cells. Imagine them like little brooms sweeping things clean! Finally, keratin is a special, tough protein found on the surface of our skin. Keratin helps make our skin waterproof and protects us from germs and injuries. It’s like wearing a raincoat and armour at the same time. Simple Squamous Like a single layer of thin, flat LEGO blocks It’s found where things need to pass through quickly and easily, like in our lungs where air goes in and out Simple Cuboidal Made up of LEGO cubes all in one layer It’s found in “sheltered” areas like glands, where it helps with secretion and absorption Simple Columnar Like a single layer of tall, rectangular LEGO blocks It lines our digestive system and helps us absorb nutrients from the food we eat Stratified Squamous Has many layers of flat cells stacked on top of each other It’s found in places that need extra protection from friction and abrasion, like our skin and mouth Stratified Cuboidal Has two layers of cube-shaped cells It’s found in large ducts, which are like tubes that carry things in our body Stratified Columnar This type is rare and is also in charge of secretion and protection Pseudostratified Columnar This one looks like it has multiple layers, but its actually just one layer of cells that are different heights, so their nuclei is at different levels It’s found in our respiratory system, helping to move mucus and dirt out of our airways Transitional This type is extra stretchy because it has to be able to expand and contract It’s found in our bladder, which needs to stretch when it’s full of urine Glands Glands are like tiny factories in our bodies that make special substances called secretions We can group glands in different ways: Whether they have ducts or not? Exocrine glands: have ducts. These ducts are like tiny tubes that carry the secretions directly to a specific place. Think of it like a factory with a delivery pipe that takes the product straight to where it’s needed Endocrine glands: DON’T HAVE DUCTS! Their secretions, called hormones, are released directly into the bloodstream and travel throughout the body. It’s like a factory that sends its products out on tiny boats in the bloodstream to reach different parts of the body What kind of secretions do they make? Some glands make serous secretions, which are watery Others make mucous secretions, which are thick and slimy like mucous Connective Tissue Connective tissue is like the LEGO blocks that connect and support other LEGO structures It’s the most abundant type of tissue in our body It helps connect different parts of our body It supports our body, just like the base of a LEGO structure supports the blocks above It’s like a transportation system that helps transport things around the body It protects our organs, like wrapping bubble wrap around a fragile LEGO structure it helps us keep warm by acting as an insulation, just like wearing a jacket on a cold day It can also store energy, like keeping extra batteries for your Xbox controller Just like there are different types of LEGO blocks for connecting things, there are different types of connective tissues Connective Tissue Proper 2 Subclasses- Loose Connective Tissue: Areolar Tissue: most common type, think of it like a soft, fluffy blanket that surrounds and supports other tissues and organs in your body. It also provides nutrients NO cartilage, bones, or blood Sometimes, our blanket can get too full of water and make the area puff up. That puffiness is called edema There are a couple of reasons why edema might happen. Sometimes, its because we get hurt and our body sends extra fluid to the area to help it heal, or it can be a sign that something else is going on in our bodies Pitting edema is like poking your finger into playdough- it leaves a little pit. This is what happens when we press on the swollen area, and a little dent stays there for a bit before slowly disappearing Adipose Tissue: This is FAT, which is found throughout our body. Energy Storehouse- like a piggy bank for our body’s energy. When we eat too much food, our body stores some of the energy as fat in the adipose tissue Thermal Insulator: It helps keep us warm. Wearing a coat on a cold day Mechanical Shock Absorber: acts like a cushion for our body, helping to protect our organs from bumps and shocks. It’s like having built-in padding Types of Adipose Tissue White Adipose Tissue: white or yellowish in Color and is what we normally think of when we think about body fat Brown Adipose Tissue: less common and is found in smaller amounts. It’s Color comes from the fact of having more blood vessels than white fat Normally found on newborns or animals that hibernate Reticular Tissue: Acts like a strong, stretchy spiderweb inside some of our organs Reticular tissue forms a framework called the stroma The stroma helps keep all the cells in these organs organized and in place You can find in organs like your liver, spleen, lymph nodes, and bone marrow Specialized Connective Tissue 2 Subdivisions: Supportive Connective Tissue: Imagine the strong beams and pillars that hold up a house. It provides a strong framework to support us and help us move There are two main types: Cartilage: Cartilage is very tough and acts like a shock absorber in our joints. It’s found in our ears, nose, vocal cords Avascular (no direct blood supply) Types of Cartilage 1. Hyaline: Most common type of cartilage in our bodies and the most rigid. It’s found in my places, like: Articular Cartilage: covers the ends of our bones in joints, acting like a shock absorber and helping our bones move smoothly against each other without grinding Tracheal Rings: help keep our trachea (windpipe) open so we can breathe easily Growth Plates: found in the long bones of growing children and help their bones grow longer Embryonic Skeleton: before we are born, most of our skeleton is made of hyaline cartilage. As we grow, this cartilage is replaced by bone 2. Elastic Cartilage: super flexible because it contains elastic fibers. Imagine bending your ear and having it spring right back into place You can find elastic cartilage in: Epiglottis: flap of tissue that covers our windpipe when we swallow, making sure that food goes down our esophagus and not into our lungs Pinnae: gives our ears their shape and helps them bounce back after being folded Fibrocartilage: strongest of the three cartilages! Usually found merged with hyaline and dense connective tissue Designed to handle a lot of pressure and is found in places like: Between Vertebrae (spine): discs between the bones in our spine are made of fibrocartilage, cushioning the bones and allowing us to bend and twist Between Bones in Pelvis: helps hold the bones in our pelvis together, especially during movements like walking and running Knee Joint: the menisci in our knees act like shock absorbers 3. Bone: Bone is the hardest and most rigid type It protects our vital organs like a suit of armour and store calcium Houses bone marrow Vascular Connective Tissue Like a busy highway system that transports important things throughout our body Blood: blood is made up of cells that float in a liquid called plasma. This liquid plasma acts like the “stuffing” in this specialized connective tissue. blood carries oxygen, nutrients and even cells that fight off germs to every corner of our body Dense Connective Tissue Dense Regular: Imagine a bunch of strong ropes all lined up neatly next to each other. The fibers in this tissue all run in the same direction, making it super strong Tissue is avascular Can be found in: Tendons: these connect your muscles to your bones, allowing you to run,jump, and play Ligaments: connect bones to each other Tendons Ligaments Dense Irregular: Imagine a bunch of ropes all tangled up every which way. The fibers in this tissue go in all sorts of directions, making it tough and able to stretch in any direction Can be found in: Skin: helps make our skin strong and flexible Elastic: extra stretchy because it’s made up of elastic fibers rather than just collagen These fibers allow the tissue to stretch and recoil back to its original shape, just like a rubber band Think of the bladder and how it needs to expand to hold urine Membranes Membranes are like special walls and coverings that help keep everything organized and protected epithelial and connective tissue linking together Thin protective layers often tissue that Line body cavities Seperate organs Cover surfaces 4 common types of membranes are: Mucous Membranes: also known as mucosae like slippery slides inside our body. Important in monitoring and controlling what enters the body found in places like our mouth, nose, and tummy They make large amounts of a gooey stuff called mucus that helps moves things smoothly and keeps germs from getting in Mucous membranes can be a key to diagnosis! By using Capillary Refill Time (CRT) we can use the Color of the gums to determine the state of the respiratory system Serous Membranes: also known as serosae · like soft, wet blankets that wrap around your organs. Lines body walls and covers organs make sure your organs can move without rubbing against each other Membranes have two layers: Visceral layer: part touching the organ Parietal layer: part touching the body wall Imagine putting your hands between the layers of a blanket- that’s how your organs sit between the layers of serous membranes. Mesenteries are formed when two layers of a serous membrane, called the visceral layers, come together. Think of it like folding a blanket in half These folded blankets attach your intestines and other organs in your tummy to the wall of your abdomen, kind of like how seatbelts keep you safe in a car There are different names for mesenteries depending on where they are in your tummy Omentum: large mesentery that connects your stomach to your abdominal wall Broad Ligament: connects the uterus to the abdominal wall Fluid in Serosae= transudate like an oil that helps things slide past each other easily Pleural fluid= thorax Peritoneal fluid= abdomen Pericardial fluid= around heart - - ↳ - = peritoneal fluid Damage to these membranes can lead to adhesions Cutaneous Membrane It’s like the outside wall of your house, protecting you from the weather and anything else that might be outside organ always exposed to the outside environment Synovial Membrane Like the special cushions inside your knees and elbows. They make a slippery liquid called synoviaal lquid that helps your bones move without hurting Line the cavities of joints Muscle Tissue Muscle tissue is designed to help your body move by contracting. Imagine muscle tissue like strong ropes inside your body. These ropes are made of special proteins called actin and myosin that work together to make the ropes shorter or longer There are three types of muscle tissue: Skeletal Muscle: It’s attached to your bones and helps you move your arms and legs Skeletal muscles are voluntary and striated (looks striped under microscope) are responsible for pumping blood throughout your body Smooth Muscle Smooth muscle is found in the walls of hollow organs in your body (blood vessels, urinary bladder, uterus) Smooth muscle is involuntary (move without having to think about it) Responsible for Peristalsis ( think of squeezing a tube of toothpaste, the only way it comes out is “out”) constriction of blood vessels emptying of bladder Smooth muscle cells are non-striated Small spindle-like cells Cardiac muscle ONLY found in your heart! Involuntary and is responsible for pumping blood throughout the body Striated (has stripes under miscroscope) Has special cells called pacemaker cells (cells act like tiny clocks, making sure your heart beats at the right speed) Muscle cells in cardiac muscle are connected at an intercalated disc Nervous Tissue Like your body’s messaging system. Made up of special cells that send and receive electrical and chemical signals, just like how you use a phone to talk to people Tissue is found in our brain, spinal cord, and the nerves that run throughout your body Imagine the brain as the control Center, and your spinal cord and nerves as the cables that carry the messages There are two main types of cells in nervous tissue: Neurons: the messengers. They have 3 main parts: perikaryon, dendrites, and an axon Perikaryon: cell body Dendrites: receive messages from other cells Axon: sends messages to other cells Neuroglial cells are like helpers. There are more of them than neurons they support the neurons and help them do their job but don’t transmit the messages themselves Tissue healing & Repair Process 1. Injury 2. Inflammation 3. Organization 4. Regeneration Sometimes our bodies get hurt, like when we fall and scrape our knee. When this happens,our bodies are really good at healing the hurt (injury) all by themselves! 1. Inflammation: the body tries to stop the hurt from getting worse. Area might get a little red, puffy, and warm. That’s because our body sends special helper cells to the hurt area to clean things up and start the healing process 5 steps to inflammation: 1. Vasoconstriction followed by vasodilation: Imagine you’re playing with a hose- and you accidentally spray yourself in the face. What’s the first thing you do? You probably close your eyes really tight for a few seconds. That’s kind of like vasoconstriction, the blood vessels near your boo boo close up really tight for a few minutes to stop the bleeding But then, just like you open your eyes again, those blood vessels open up even wider than before- that’s vasodilation. This allows more blood and helper cells to get to the hurt area to start fixing it 2. Edema: Remember how the hurt area gets puffy? That’s edema. It happens when fluid, like the water in your bathtub, leaks out of your blood vessels and into the hurt area. 3 Clot Formation: Have you ever noticed that when you get a cut, it doesn’t bleed forever? That’s because your body forms a clot to stop the bleeding. Tiny cells in your blood called platelets get sticky and clump together to form a plug. Then something called fibrin comes along and weaves around the clot, making it even stronger 4. Phagocytosis: Just a fancy way of saying that special helper cells called white blood cells come in and eat up any germs or yucky stuff hat might be in the wound 5. Dispersion of histamine and heparin: Now that the cleanup crew is done, it’s time for the inflammation to calm down. Histamine and heparin are little signals that told your body to send help. Once the hurt area is cleaned up and starting to heal, those signals go away, and the redness, puffiness, and warmth starts to go down (think of someone calling an ambulance) 2. Organization: When your body really starts to fix the injury During organization, your body forms something called granulation tissue. Granulation tissue is like a special patch that covers up the boo boo while new skin grows underneath Granulation tissue has lots of tiny blood vessels in it, which bring important nutrients and oxygen to the hurt area, so it can heal quickly Sometimes though, granulation tissue can grow too much, and that’s called proud flesh Proud flesh can look a little bumpy, but nothing to worry about 3. Regeneration: The fixing process after you fall down and scrape your knee is called regeneration Here’s how it works: Epithelialization: First your skin needs to cover up the scrape. It does this by making new skin cells that spread over the boo-boo like a little blanket Pushing away the scab: Remember that hard, dry part that forms over your scrape? That’s the scab and your body pushes it off once the ne waking underneath is ready Making a scar: Sometimes, when your body fixes a big bo- boo, it makes a fibrous scar. It’s like a tough patch that helps hold everything together Classifications of Wound Healing First Intenton Healing (Primary Union) Second Intention Healing (Granulation) Third Intention healing (delayed primary closure) First Intention Healing Imagine your teddy bear ripped a little, and you can sew it back together neatly. The wound is clean, meaning there are no germs, and the edges are close together This healing happens quickly because there’s not that much damage Golden period = 6 hours Second Intention Healing Imagine your toy truck broke into many pieces and some are even missing. You might need extra glue and some time to fill those gaps this healing happens when the wound is bigger, the edges are far apart, or the cutis jagged your body needs to create new tissue to fill in those gaps. That takes bit longer to heal Third Intention Healing Sometimes a toy breaks, and it’s really dirty. You need to clean it up first and then fix it later This happens when the wound is contaminated, like if there’s dirt in it,or if a long time has passed since the injury Your body needs to fight off any infections first, and then it can focus on closing the wound The Integument & Related Structures Integumentary System Imagine your skin is like a house, and your skin is the roof,walls, and doors that protect everything inside! This amazing protective layer is called the integumentary system, and it does more than just keeping your insides in Functions: 1. Covers and protects Just like a sturdy roof keeps the rain out, your skin acts as a barrier against nasty germs 2. Prevents desiccation Keeps our bodies from drying out. Think of our skin as a raincoat, that prevents the body from losing all of its water and shrivelling up like a prune 3. Prevents infection Our skin acts like a physical barrier against infection 4.. Assists in maintenance of normal body temperature This is done through insulation, sweating, etc 5. Excretes water, salt,organic wastes Skin helps your body get rid of waste products, such as water, salt, and organic wastes, through sweating 6. Receives and conveys sensory information Our skin is like a giant sensor, covered in tiny feelers that let us experience the world. These sensors can tell our brain if something is hot or cold, smooth or rough, and even if something hurts 7. Synthesizes vitamin D When you play outside in the sunshine, your skin helps your body make vitamin D. This special vitamin is like a superhero for your bones, making them strong and healthy 8. Stores nutrients Epidermis This is the outermost part of your skin that you can see and touch It’s like the tough outer shell of your suit that’s waterproof It’s also what makes your skin color the way it is Cells of the Epidermis There are four cells that make up the epidermis Keratinocyte: Keratin gives skin resiliency and strength These cells are like the main ingredient in your skins fabric. They make a tough material called keratin, which makes your skin strong and able to resist scratches and scrapes Melanocytes: produces melanin pigment These cells are like tiny artists. They produce a pigment called melanin, which gives your skin its color. Just like crayons come in different colors, melanin comes in different shades, making peoples skin different colors Langerhans Cells: phagocytizes micro invaders These cells are like tiny guards protecting your skin. They are part of your immune system and work hard to capture and destroy any bad germs that try to sneak past your skins defences. They’re like tiny superheroes fighting to keep you healthy Merkel Cells: associated with sensory nerve endings These cells are like tiny sensors that help you feel the world around you. They work closely with your nerves to send signals to your brain, telling you if something is hot, cold, soft, or rough Dermis Think of the dermis as the padding and special features hidden beneath the superhero suit that help it do its job even better. It’s also the middle layer of the skin. Greatest portion Contains hair follicles, sweat glands, blood vessels, and nerve endings. Highly fibrous (dense irregular connective tissue) The dermis is also the largest portion of the integument and is composed of dense, irregular connective tissue This layer also contains: Meissner’s corpuscles: sensory receptors that detect light touch They are like tiny little antennas hidden in the dermis, especially in areas where your skin is extra sensitive to touch, like your fingertips They have super sensitive touch sensors that are designed to pick up on light touches and vibrations. They help you feel things like a gentle breeze on your skin or the soft fur of a kitten They also send signals to your brain, when you touch something, these corpuscles get activated and send super fast messages along your nerves to your brain. Your brain then figures out what you’re touching and how it feels. Mange You know how sometimes you get itchy bug bites? Well, mange is kind of like that, but it’s caused by tiny mites instead of bugs. These mites are so small that you can’t even see them without a microscope, but they can cause big problems for your pets skin. Mange is the inflammation of the epidermis and dermis which is caused by tiny mites that live on or in the skin The mites can cause: irritation Itchiness (pruritis) Hair loss (alopecia) Types of mange can be identified by skin scrapings Demodex Sarcoptes Notoedres Hypodermis This is the deepest and very thick layer of skin, which is made up of fat and connective tissue The hypodermis is like a cozy blanket underneath it all, providing insulation and cushioning The hypodermis is made up of loose areolar tissue, which is a fancy way of saying it’s made of soft and squishy stuff. Its like a comfy cushion that protects your bones and muscles from bumps and jolts This layer also contains special sensors called Pacinian Corpuscles: like tiny pressure gauges. They help you feel when something is pressing against your skin, like when your hugging a teddy bear or sitting in a chair Special Features of The Integument Pigmentation: Presence or absence of melanin granules in extensions of melanocytes If the melanin granules are too close to the nucleus of the melanocyte, there’s no pigmentation. But if those granules are in the cellular arms of the melanocyte and surrounding tissue, then you get pigmentation Paw Pads: Tough, thick layers of fat and connective tissue These pads are like built-in shoes that help them walk on rough surfaces without getting hurt Paw pads even have conical papillae, which are tiny bumps that cover the entire paw pad and give it extra grip, like the tread on your sneakers. Paw pads can also be pigmented too Planum Nasale: the top of a dogs nose (makes a dogs nose wet all the time) Usually pigmented and has lots of glands Those glands produce moisture that helps with their sense of smell In horses and cows, this part is called the muzzle Ergots and chestnuts: Horse have these cool things called ergots and chestnuts on their legs. They’re made of a tough material called horn, which is kind of like your fingernails but much harder Ergots are buried in the caudal hairs of the fetlock (like the back of their ankle) Chestnuts are found on the inside of each leg at the carpus (like their wrist) and tarsus (like their ankle) usually dark brown Cutaneous Pouches in Sheep: folds of the skin. These pouches are found in three places: Infraorbital: below there eyes, its like a tiny pocket under there eye Interdigital: between their toes, tiny pocket between their toes Inguinal: in their groin area Related Structures of The Integument Hair: Hair is essential for survival because it helps to keep the body at the right temperature, like a built in thermostat, and protects the skin from harm. It does this by helping to trap a layer of air close to the skin, which helps to insulate the body. Hair is made of three layers: Medulla: it’s the innermost part of the hair and is usually soft. Sometimes even hollow Medulla is like the caramel inside a caramilk chocolate bar, the medulla is in the very middle of the hair strand Cortex: This gives the hair its strength and shape just like the hard chocolate part of the caramilk bar and gives it its shape This layer also gives your hair its color. That’s because the cortex contains pigment, which is like the colouring they put in candy Cuticle: made of scales that overlap each other, making a strong, protective layer around the cortex Think of it as the wrapper that keeps the caramilk bar from melting and getting sticky Growth cycles of Hair Hair grows in cycles with different stages Anagen: growing stage Catagen: short transition stage after hair has finished growing Telogen: resting stage, hair is no longer growing and will eventually fall out Think of the stages of plants Hair Color Pigment in the cortex and medulla of hair strand Melanin production decreases with age Types of Hair Primary Hairs/Guard Hairs: these are the longest and coarsest hairs, and they act like body guards for the skin They help protect the skin from getting hurt and also help to keep the animal warm or cool. They’re like the tough outer layer of a winter coat Secondary/Wool Type Hairs: these hairs are shorter and softer than primary hairs, and they help to keep the animal extra warm by trapping air close to their skin This is like the soft, fluffy lining of a winter coat Tactile Hairs: these hairs are super sensitive and act like feelers, helping animals sense the world around them Whiskers are a great example of this Cats or dogs use their whiskers to figure out if they can fit through a small space. There whiskers help them to see in the dark. Arrector Pili Muscles When its cold, tiny muscles attached to the hair follicles, called arrector pili muscles, can contract and make the hairs stand up, trapping even more air for warmth Arrector Pili Muscles are small and smooth and they are attached to each hair follicle, which is like a tiny pocket in your skin where the hair grows When you get cold or scared, your brain sends a signal to the arrector pili muscles, telling them to contract. When these muscles contract, they pull on the hair follicle, making the hair stand up straight. This is what causes goosebumps! Glands of the Skin Imagine your skin had tiny factories working inside it. These factories are called glands, and they make special substances that help keep your skin and body healthy Sebaceous Glands: These glands make an oily liquid called sebum. Sebum is like a moisturizer for your skin and hair, keeping them soft and healthy. Sebaceous glands can be found in the dermis. Sometimes these glands can get clogged though and cause a sebaceous cyst, kind of like when a pipe gets clogged Sweat Glands: These glands are also called sudoriferous glands, and they make sweat. Sweat is a watery liquid that helps cool down your body when you get hot like when you’re playing outside on a sunny day There are two types of sweat glands Eccrine: release sweat directly onto your skin through tiny holes called pores. You can find them all over your body Apocrine: release sweat into the hair follicles. You can find these in areas with lots of hair, like your armpits Tail Glands: special glands near the base of their tails These glands make scents that animals to use to communicate with each other Anal Glands: these glands are near an animals bottom. These glands make a smelly liquid that has information about the animal Claws and Dewclaws Imagine your fingernails, but much thicker ad stronger, and on an animal. Claws: hard outer coverings found on an animals digits (toes) Dewclaws: leftover claws from a long, long time ago when animals feet’s might have looked different. They’re considered revolutionary remnants of digits Dogs and cats usually have dewclaws on their front feet, which is like their thumbs Cows, pigs, and sheep sometimes have dewclaws on their back feet, which is like “extra pinky toes” Hoof: horny outer covering of digits of ungulates (animals like horses, cows, pigs, and deer) Each hoof covers a digit, helps them walk and run on all kinds of grounds without getting hurt Hoofs protect the sensitive bones and tissue inside an animals feet Not all hooves are weight bearing (example, a horse stands on one hoof per leg, but a cow stands on two hoofs per leg) Modified epithelial layer, underneath the hard outer part of the hoof is the corium is like the quick of your fingernail-its full of blood vessels and nerves, which means its sensitive to pain Hoofs never stop growing, Firmly attached to the periosteum provides nutrients to inner layer of the hoof The Equine Hoof Divided into three parts: Wall: the hard, outer part of the hoof The wall has three parts: Toe: where the horses toenail is Quarters: sides of the hoof Heel: back part of the hoof Sole: the bottom of the hoof that touches the ground Frog: triangular shaped part on the bottom of the hoof a little bit softer than the wall and sole Helps with shock absorption as the horse moves Laminitis: painful disorder affecting the feet of horses and ponies laminae are inflamed, which means they are swollen and sore The horse or pony might be lame (trouble walking) Horns: hard, pointy things that stick out of the heads of animals like cows, goats, and sheep structurally like hair Mass of horny keratin Grows continuously Not sex related (males and females can have them) Horns vs. Antlers Horns NOT sex specific Epidermal in origin Grow continuously Hollow Communicate directly with frontal sinus Antlers Primarily on males Dermal in origin Fall off once a year Begin as bony protuberance from the skull Lack central core and internal blood supply Velvet skin  The Skeletal System Bone Bone function: Bones have many important functions, including: The second hardest substance in the body Cells that produce bone are called osteoblasts Osteoblasts harden the cells through a process called ossification Bone Function: bones have many important functions, including: Support: They provide a framework for the body, helping you to stand upright Protection: They surround and safeguard vital organs. For example, the ribs protect your heart and lungs Leverage: They act as levers for muscles, allowing for movement Storage: They store important minerals like calcium Blood Cell Formation (Hematopoiesis): They produce red blood cells in the bone marrow Spongy bone Types of Bone There are two main types of bone: Cancellous Bone: Lighter and spongy Tiny “spicules” of bone that appear randomly arranged Spaces between the “spicules” contain bone marrow Compact Bone: Heavier and dense Shafts of long bones compact bone Outside layer of all bones Composed of Haversian systems Membranes involved in bone structure Imagine your bones are like gifts. They need wrapping paper to keep them safe, right? Bones have special coverings called membranes that are like wrapping paper for them The periosteum is the outer layer that covers most of the bone. It’s tough and strong, just like good wrapping paper. The periosteum helps your bones grow bigger and stronger and also helps them heal if you break one Outer layer is composed of fibrous tissue Inner layer contains osteoblasts But just like presents have boxes under the wrapping paper, = some bones have a hollow space inside. The endosteum is the membrane that lines the inside of those hollow spaces within bones. Its a softer membrane and helps your bones grow and stay healthy from inside E Bone Cells Three types of cells contribute to bone structure and function: Osteoblasts: Cells that form new bone They’re like the construction workers who make new bone material Osteocytes: Mature bone cells that maintain the bone matrix They’re like the caretakers of the bone. They live inside the bone material and make sure everything is working properly Osteoclasts: Cells that break down and remodel bone They are like the demolition crew. Their job is to break down old or damaged bone so that new bone can be built in its place. Blood Supply to Bone You know how your bones are like a busy construction site with different cells working hard? Well, just like any busy construction site, your bones need deliveries of important Volkmann Canals supplies to keep working The most important delivery that bones get is blood. Blood brings oxygen and nutrients that the bone cells need to stay alive and healthy Blood Vessels Blood supply comes from periosteum The blood travels to your bones through special tunnels called Volkmann canals. Think of Volkmann canals like roads for blood delivery trucks to drive on inside your bones Big bones even have bigger tunnels called nutrient foramina Nutrient Foramina for even more important deliveries. Nutrient foramina are like highways that carry big trucks with lots of supplies, including: Large blood vessels Lymph vessels Nerves Bone Formation Imagine your bones starting out like soft, bendy play-doh. That play-doh is actually something called cartilage, which is what a lot of your bones are made of before they become hard. As you grow, special cells come along and gradually replace the soft cartilage with strong bone material. This process is called endochondral bone formation (also known as cartilage bone formation) But not all bones start as cartilage. Some bones in your head, like the flat bones of your skull, are formed differently. They start as fibrous tissue membranes, kind of like strong fabric. Then those membranes turn directly into bone, and that’s called intramembranous bone formation Occurs in certain skull bones only Bone forms in the fibrous tissue membranes that cover the brain in the developing fetus Creates flat bones of the cranium Long bones, like the ones in your arms and legs, start growing from the middle, called the shaft or diaphysis. Then other areas at the ends of the bones, called epiphyses start growing too, and that’s what makes you taller. 2 areas of cartilage remain in the long bones Epiphyseal plates Bone Shapes There are four shapes of bones 1. Long bones are shaped like sticks or poles, and they’re perfect for helping you move. Some examples are the ones in your arms and legs, like your femur. Long bones are longer than they are wide 2. Short bones are shaped like chunky cubes or small blocks. They’re found in places like your wrists and ankles. 3. Flat bones are flat and sometimes a bit curved, just like a pancake or a plate They’re good for protecting things, like your brain (skull), and your heart (ribs) 4. Irregular bones are all the funny-shaped ones that don’t really look like sticks, blocks, or plates. They have all sorts of bumps and grooves on them. Think of the vertebrae in your back Bone Marrow It fills the spaces within bones. Think of it like the jelly in a donut. But instead of a donut, bone marrow is a soft, spongy material RedBone There are two types of bone marrow: Marrow Red bone marrow is like a busy factory that makes red blood cells. Hematopoetic tissue forms red blood cells Red blood cells are like tiny delivery trucks that carry oxygen all over your body, so you can run and play Yellow Bone Marrow Yellow bone marrow is mostly made of fat. It’s like a storage room for energy Primarily made of adipose connective tissue Can revert to red bone marrow Done TOW One Bone Features Bones also have special features like bumps, holes, and smooth spots Some bone features help bones connect to each other, like puzzle pieces, to make joints so you can move. These special places where bones connect are called articular surfaces, and they’re covered in a smooth, slippery material called articular cartilage. Articular cartilage helps your bones Head move smoothly against each other without hurting, like oil for your joints Some examples of articular surfaces are: Condyles: large, round articular surfaces Heads: spherical articular surfaces, usually found on the facet proximal end of long bones Facets: flat articular surfaces Helps reduce friction Bones also have bumps and projections called processes. Processes are like handles or hooks on bones where your muscles attach Some processes are smooth to help form joints Other processes are rough, which gives the tendons a good grip to attach your muscles so you can bend and move Have you ever seen a hole in a bone? Those holes are called foramina. Foramina are like tunnels that let important things like blood vessels and nerves pass through the bone Bones can also have depressed or sunken areas on them called fossae. Fossae are like little dips or bowls in the bone The skeleton Imagine your skeleton is like a giant puzzle, but instead of flat pieces, it’s made of all bones in your body This framework is divided into two main parts: 1. The axial skeleton is like a central support beam of your body. It includes: The skull consists of 37 or 38 separate bones skulls bones are united by bones called sutures The mandible is connected to the rest of the skull by a synovial joint Broken down into three joints: Bones of the cranium Bones of the ear Bones of the face Bones of the cranium: External bones Frontal bones (2) Interparietal bones (2) Occipital bones (1) Parietal bones (2) Temporal bones (2) Internal bones Sphenoid bone (1 Behind the eye and below front of brain Ethemoid bone (1) - roof of nasal cavity Hyoid Bone Also called the hyoid apparatus Located high in the neck just above the larynx Bones of the Ear Malleus (2) Incus (2) Stapes (2) Bones of the Face External bone Incisive bones (2) Lacrimal bones (2) Mandible (1 or 2) Maxillary bones (2) Nasal bones (2) Zygomatic bones (2) Internal bones Vomer bones (1) Palatine (2) Turbinates (4) Vertebrae Vertebrae are like strong, little building blocks that make up your backbone, also called the spinal column Consists of: Body Spinous Process Articular process Arch Processes Vertebral arches line up from the spinal canal Contain several processes: Spinous process (1) Transverse processes (1) Transverse Process Articular processes (2) Vertebrae are separated by discs made of cartilage, which is a soft and bendy material These discs act like cushions, so your bones don’t rub together when you move Vertebrae come in different shapes and sizes depending on where they are in your backbone: 1. Cervical vertebrae are in your neck C1- also known as the atlas C2- also known as the axis 2. Thoracic vertebrae are in your chest located dorsal to the thorax 3. Lumbar vertebrae are in your lower back located dorsal to the abdomen 4. Sacral vertebrae are in your pelvis located dorsal to the pelvis form the sacrum 5. Coccygeal vertebrae are in your tail bones of the tail Ribs Ribs are the long, curved bones that form the ribcage Imagine your ribcage as a protective fence around your chest Ribs contain flat bones that form the lateral walls of the thorax The dorsal heads of the ribs articulate with the thoracic cavity Costal Cartilage Let’s your chest expand and contract when you breathe ventral ends of the ribs Costochrondal Junction Like a special connection point that lets your chest move when you breathe area where costal cartilage meets bony ribs Floating Ribs cartilage does not join anything at all Sternum Like the central anchor for your ribs in the front. forms the floor of the thorax composed of sternebrae Manubrium: This is the top part of the sternum. It’s where the first rib attaches most cranial sternebrae Xiphoid process: This is the pointy part at the bottom of the sternum most caudal sternebrae Appendicular Skeleton Think of the appendicular skeleton as all the bones that help you move around Thoracic Limb (Arm) Scapula (shoulder blade): This is a flat, triangular bone in your shoulder. It’s an important part of your shoulder joint and has a big ridge on it called the spine of the scapula where muscles attach Tubercles Spine of the scapula- longitudinal ridge on lateral surface Humerus The humerus is a bone in your arm. It helps form part of your shoulder joint and your elbow joint Tubercles are parts of the humerus that stick out a bit, and they’re where your shoulder muscles attach so you can move your arm The humerus also has condyles, which are smooth surfaces at the bottom of the bone. They help the humerus connect with other bones in your elbow to make it bend Epicondyle Trochlea: resembles a pulley Condyle Capitulum: formation of the elbow joint Olecranon fossa Dent in your humerus bone. Located above the condyles The olecranon fossa fits with a part of your ulna bone called the trochlear notch Epicondyles Non- Articular Antebrachium 2 bones form the antebrachium Ulna Radius Ulna and Radius (Forearm) The ulna makes up your elbow, and the radius is Trochlear the bone that connects to your wrist Notch Anconeal Olecranon Process process Point of the elbow Trochlear Notch Olecranon - Articular surface process Anconeal Process Shaft Styloid process Coronoid process Fits into the Olecranon fossa of the humerus Coronoid Processes Articulate with radius Radius Main weight bearing bone Styloid Process Articulates with bones of the carpus Carpal bones (Wrist) These are a group of small bones that allow for flexibility in your wrist There are 2 rows of carpal bones: Proximal row bones are named Distal row bones are numbered medial to lateral Metacarpal Bones (hand) These bones connect your wrist to your fingers Extend dismally from distal carpal bones to proximal phalanges Dogs & Cats 5 digits Numbered medial to lateral Metacarpal 1: dewclaw Horses One large metacarpal bone Metacarpal III 2 smaller vestigial metacarpal bones - Metacarpal II & IV - Non-weight bearing Cattle Two fused metacarpal bones Metacarpal III and IV Phalanges (Fingers): These are the bones in your fingers Thoracic Limb Phalanges- Equine 1 digit with 3 phalanges Proximal phalanx Middle phalanx Distal phalanx 3 sesamoid bones 2 proximal 1 distal Thoracic Limb Phalanges- Bovine (cow) 4 digits on each limb 2 support weight 2 are vestigial - dewclaws Each weight bearing digit has: Proximal phalanx Middle phalanx Distal phalanx Thoracic Limb Phalanges- Canine & Feline Digit I Proximal phalanx Distal phalanx Digits II to V Proximal phalanx Middle phalanx Distal phalanx Ungual process Referred to as the “quick” Curved extension of the distal phalanx that is surrounded by the claw Pelvic Limb The pelvic limb is made up of all the bones from your hip to your toes Pelvis: This is like a big, strong basin that holds everything together. It connects your legs to your spine and protects important organs inside your belly Joins the axial skeleton dorsal at the left and right sacroiliac joints Comprised of 3 bones: Ilium Ischium Pubis Pubic symphysis cartilaginous joint that joins the 2 halves Acetabulum: round socket on each side of the pelvis where the femur (your thigh bone) connects (the hip joint) Obturator foramina 2 large holes on each side of pubic symphysis Ilium The biggest bone in your pelvis, and you can feel it sticking out on your sides Most cranial bone Cattle & Horses Tuber sacrale projects medially and joins with the sacrum to form the sacroiliac joint Tuber coxae projects laterally and is called the point of the hip In cows and horses, the ilium has a special part that sticks out even more, called the “hooks” Ischium The bone that you sit on. It has a bumpy part called the ischial tuberosity main rear-projecting process In cattle known as “pins” most caudal bone Forms caudal portion of pelvic floor Pubis The smallest bone in your pelvis and helps form the front part of the pelvic floor Femur (thigh bone) Head Greater trochanter This is the longest bone in your whole body. It connects your hip Neck to your knee and helps you run and jump Proximal end forms part of hip joint Shaft Distal end forms stifle joint with patella & tibia Coxofemoral joint (hip joint): lets you move your leg in all sorts Medial epicondyle of directions Lateral epicondyle Trochanters: large processes that stick out from the bone and where the hip and thigh muscles attach Trochlea Patella (kneecap) This bone is like a little shield that protects your knee joint. You can even feel it move around when you bend and straighten your leg Large sesamoid bone Protects the tendon Fabellae 2 small sesamoid bones in proximal gastrocnemius muscle tendons of dogs and cats Tibia (shinbone) Patella This is the bigger bone in your lower leg and the one that you feel when you touch your shin Head of fibula It is the main weight-bearing bone of lower limb Proximal end forms the stifle joint with the femur Tibial crest Distal end forms the tarsal joint with the tarsus Tibial tuberosity Shaft of tibia patellar ligament attachment site Tibial Crest Shaft of fibula Crest distal to tibial tuberosity Medial malleolus Palpable process at distal end Fibula (calf bone) This bone is thinner than the tibia and runs alongside it It helps stabilize your ankle and provides attachment points a for muscles Parallel to tibia Medial malleolus Lateral malleolus Non-weight-bearing Lateral malleolus The part that you can feel on the bottom of your fibula on the outside of your ankle. That bump is the lateral malleolus Palpable process at distal end  Calcaneal Tarsus Tuberosity A group of small bones that connect Tibial tarsal bone your lower leg to your foot Fibular tarsal bone Tibial 2 rows of tarsal bones tarsal Proximal row is named bone Distal row is numbered medial to lateral Dorsal Metatarsal Calcaneal tuberosity sesamoid bone point of attachment for the bone tendon of the gastrocnemius muscle Plantar Metatarsal Bones sesamoid Dogs & Cats bones 4 metatarsal bones Numbered medial to lateral Phalanges Metatarsal II-V Visceral Skeleton Made up of bones that form inside the soft tissues of your body. These bones aren’t connected like the bones in your arms and legs Bones that form in organs Os cordis: These bones are found in the heart of cattle and sheep Os penis: This bone is found in the penis of dogs, beavers, raccoons, and walruses Os rostri: This bone is found in the nose of swine Joints There are three general classifications: Fibrous joints: These joints are immovable meaning they don’t move at all. They’re held together really tightly by fibrous tissue, which is like strong glue An example would be the sutures in your skull or Sutures between skull bones the splint bones of horses Cartilaginous joints: These joints are slightly movable, meaning they can move a little bit They’re connected by cartilage Some examples are intervertebral discs in your spine and the mandibular symphysis and the pubic symphysis Mandibular symphysis Synovial Joints: These joints are freely movable, meaning they can move in all sorts of directions They also have a special design: Articular surfaces: These are smooth, slippery surfaces on the ends of the bones that come together at a joint Ligaments: These are strong bands of tissue that connect bone to bone and help keep the joint stable Fluid-filled joint cavity enclosed by a joint capsule - synovial membrane - synovial fluid Synovial Joint Movements Flexion and extension These movements are opposites Increase or decrease the angle between two bones Addiction and Abduction Think about standing with your arms straight down at your sides. If you move your arms out to the side (like your making a snow angel), that’s abduction When you bring your arms back down to your sides, that’s adduction Like moving towards and away from your body Also opposite movements Move an extremity toward or away from medial plane Rotation Imagine holding your arm straight out and turning your hand so your palm faces up and then down, this is rotation Twisting movement of a part on it’s own axis Circumduction Like drawing a circle with your finger movement of an extremity so that the distal end moves in a circle Hinge Joints Like a door opening and closing. Only move in one direction One joint surface swivels around another ONLY capable of flexion and extension Gliding Joints Like rocking back and forth Rocking motion of one joint surface on the other Primarily capable of flexion and extension Abduction and adduction possible Pivot Joints Like turning your head One bone pivots (rotates) on another Only capable of rotation Ball and Socket Joints Like moving a joystick Allow for all joint movements  The Muscular System Made up of cells that can shorten or contract Four Common Characteristics: Excitability: Muscles are like superheroes who are always ready for action. This means they can react to signals from your brain super fast Contractibility: This is a muscles superpower to get shorter. When muscles contract, they’re like a rubber band being stretched and then let go Extensibility: Even superheroes need to stretch. Muscles can stretch out, becoming longer when needed Elasticity: And just like a rubber band, muscles can bounce back to their original shape Muscles have 3 primary functions: 1. To provide motion 2. To maintain posture 3. To generate heat There are 3 types of muscles: 1. Skeletal Muscle Controlled by conscious mind moves bones of the skeleton 2. Cardiac Muscle found only in the heart 3. Smooth Muscle found all over the body carries out unconscious, internal movements of the body Skeletal Muscle Imagine your body is like a puppet, and skeletal muscles are the strings that make it dance. Skeletal muscles are special because you can control them with your mind Surrounded by a fibrous connective sheath called the epimysium Has a thicker central belly and two or more attachment sites at each end Skeletal Muscle Attachments Tendons Like super strong cords that attach your muscles to your bones. Kind of like the tough strings that hold a puppet together, connecting the moving parts to the wooden pieces When your muscles contract, the tendons help pull on your bones, making them move Aponeuroses Similar to tendons but are flat and sheet-like instead of being round and cord-like They also attach muscles to bones, but they can also connect muscles to other muscles Think of them like strong, sticky tape that helps hold everything in place Skeletal Muscle Attachment Sites Origin: the more stable attachment site to the bone Insertion: site that undergoes most of the movement when the muscle contracts Muscle Actions Nerve Impulses First, your brain sends a message, like a secret signal, called a nerve impulse, to tell your muscles what to do. Think of it like a walkie-talkie message from your brain to your muscles Agonist (Prime Mover) The agonist is the main muscle responsible for a particular movement. It’s like the team captain who leads the action For example, when you bend your arm, your bicep muscle is the agonist, contracting to lift your arm Antagonist Every superhero needs a sidekick, and for muscles, that’s the antagonist. This muscle does the opposite of the agonist, relaxing so the movement can happen smoothly. In our arm bending example, the tricep muscle is the antagonist, relaxing as the bicep contracts Synergist Sometimes, a movement needs extra help, and that’s where the synergists come in. These muscles work together with the agonist to help it out, making the movement stronger or more precise. They’re like the rest of the team, supporting the captain Fixator Now imagine, trying to build a tower of blocks on a shaky table. Fixator muscles are like the steady table- they keep your joints stable so the other muscles can do their jobs effectively Muscle Naming Muscles get their names from clues that tell us about what they do, how they look, or where they are in the body Here’s how it works: Action Some muscles are named after the actions they help us do. For example, the flexor muscles help you flex your muscles, and the extensor muscles help you extend them Shape Some muscles are named after their shape For instance, the deltoid muscle is shaped like a triangle, and guess what the Greek letter for “triangle” is delta Location Just like you live in a house with different rooms, your muscles have specific locations in your body. For example, the intercostal muscles are found between the ribs (the word “costal” refers to ribs) Direction of fibres Muscles are made of fibers that run in different directions. Sometimes, a muscle’s name tells us about the direction its fibers runs Number of Heads or Divisions Some muscles have different parts or divisions, kind of like how a toy robot might have different sections that connect together. The number of parts can also be a clue in their name. For example, the biceps brachii muscle has two heads Attachment Site finally, remember how we talked about tendons connecting muscles to bones. Well, some muscles are named after the specific bones they attach to For example, the brachiocephalius muscle attaches to the brachium (upper arm bone) and the head] Types of Muscles Cutaneous Muscles Special muscles that live under your skin They’re thin and flat, kind of like sheets of fabric, and they don’t always attach to bones like other muscles do. Instead of moving your bones around, cutaneous muscles help you move your skin Think about a horse twitching its skin to get a bug off Head & Neck Muscles Imagine your head is like a giant bobblehead Head and neck muscles are like strong strings that help you move your head around. They control your facial expressions, so you can smile, frown, or make funny faces They also help you chew your food (mastication) They help you move your eyes and ears They even help you hold your head up high They allow your head and neck to bend, stretch, and even move side to side Some examples of head and neck muscles are: Masseter: for chewing Trapezius: helps your head and neck do all sorts of things Brachiocephalicus: helps your head and neck move in different ways Abdominal Muscles Special group of muscles in your tummy. They’re like a strong wall that holds everything in place Functions: Support your insides: Your abdominal muscles act like a strong, protective hug, keeping all those organs safe and sound Help you bend: When you bend forward to pick up something or tie your shoes, your abdominal muscles are hard at work. They help you flex your back, kind of like bending a ruler Help you breathe: They work with other muscles to help you take deep breaths in and out Help when you strain: Anytime we lift something super heavy. Your abdominal muscles help you push and pull with extra strength, like when your pooping or even giving birth Your abdominal muscles join together in the middle of your tummy at a line called the linea alba. There are a few different abdominal muscles: External abdominal oblique: On the outside of your tummy Internal abdominal oblique: On the inside of your tummy Rectus abdominis: Also known as the “six-pack” muscles Transversus abdominis: Deep inside your tummy, like a secret layer of strength Limb Muscles The ones in your arms and legs that help you run, jump, kick, and play Locomotion: moving from one place to another Adductor: body’s tiny huggers. They move your limbs closer to the center of your body Think of hugging a teddy bear, the adductor muscles in your arms help you pull that teddy bear close for a big hug Abductor: move your limbs away from the center of your body Imagine your stretching your arms out wide to reach a toy. Abductor muscles in your arms help you reach as far as you can Thoracic Limb Muscles Latissimus dorsi: Imagine a strong strap going from your back to your upper arm bone Pectoral: Think of giving yourself a big hug, the muscles in your chest help you do this Deltoid: Helps you lift your arms up high Muscles of the Forelimb Carpal and digital muscles Found distal to the elbow joint Extensor carpi radialis Deep digital flexor Brachial: Help you bend and straighten your arm There are two main brachial muscles: Biceps brachii: Makes your arm bend at the elbow Triceps brachii: Helps you straighten your arm back out again Pelvic Limb Muscles The ones in your hips and back legs Gluteal Muscles: These are in your buttocks. Give you the power to move your legs back and sideways Hamstring muscles: At the back of your thigh, help you bend your knee Hamstring muscles include: Semimembranosus: Muscle helps you extend your thigh and bend your knee Semitendinosus: Helps with extending your hip and bending you knee Biceps femoris: Helper for extending your hip and bending your knee Quadriceps Femoris: Help you to straighten your leg This includes: Rectus femoris: Helps you extend your knee and flex your hip Vastus lateralis: Helps extend the knee Vastus intermedius: Deep helper for extending your knee Gastrocnemius: Muscle that lets you stand on your tiptoes, also known as your calf muscle Muscles of Respiration Increase and decrease the size of the thoracic cavity Inspiratory muscles Diaphragm External intercostal muscles (help us breathe in) Expiratory muscles Internal intercostal muscles (help us breathe out) abdominal muscles Skeletal Muscle Cells These are the building blocks of your muscles They are long and thin like spaghetti, but they are very strong. Skeletal muscle cells are controlled by your brain Think of it like this, your brain is a remote control, and your muscles are like a toy car. When you push a button on the remote control, the toy car moves. Cell membrane= sarcolemma Multinucleated as many as 100 or more located just below the sarcolemma Most of the fiber is made up of myofibrils composed of actin and myosin Prominent organelles between the myofibrils in a muscle fibre include: Many energy producing mitochondria Extensive network of sarcoplasmic reticulum Storage for calcium ions System of transverse tubules that extend in from the sarcolemma Myofibrils are like tiny threads bundled together inside the muscle cell They’re made up of special proteins called actin (thin and light) and myosin (thick and dark) that work together to make the muscle cell contract Each contractile unit is called a sarcomere Sacromeres lined up end to end = 1 myofibril Neuromuscular Junction Like a special meeting place where your nerves and muscles can talk to each other Imagine having a friend named muscle man. He’s really strong, but he needs instructions on what to do. You are like the brain and you need to tell him when to lift his arm. You would then send a message along a special wire called a nerve. The neuromuscular junction is the place where the end of the wire gets really close to muscle mans arm, but they don’t actually touch There’s also a tiny gap called the synaptic space between the nerve and the muscle cell No nerve supply= no contraction= atrophy To send the message across the gap, the nerve releases a special chemical messenger called acetylcholine. It’s like throwing a tiny ball of instructions across the space Muscle man has special catcher mitts on his arm called receptors. When the acetylcholine ball lands in the mitt, muscle man knows exactly what to do. This starts the process of muscle contraction, making him lift his arm Once muscle man is finished, another helper called acetylcholinesterase comes along and cleans up the acetylcholine. This stops the message and lets him relax his arm again Motor Unit A motor unit is like a tiny team It is made up of one nerve and all the muscle fibers that nerve connects to. It’s like a coach (the nerve) and a group of players (the muscle fibers) working together to make a movement Connective Tissue Layers Imagine your muscles are like a big box of crayons. Inside the box, you have lots of individual crayons (muscle fibers). To keep the crayons from rolling around and breaking, they are organized into smaller bundles (fascicles) wrapped in paper (perimysium). Then all the bundles are wrapped together in a big piece of cardboard (epimysium) to hold everything together in the box Endomysium: The thinnest layer and it wraps around each individual muscle fiber (like the paper around each crayon) Perimysium: A bit of a thicker layer and it bundles groups of muscle fibers (like the paper around a small bundle of crayons) Epimysium: The toughest, outermost layer that surrounds the entire muscle (like the cardboard box) Initiation of Muscle Contraction & Relaxation 1 · 1 Nerve Impulses reaches the end bulb of the motor nerve fiber I Your brain tells your muscles to move by sending a message through your nerves I· Acetylcholine is released into the synaptic space I Think of it like a phone call from your brain to your muscles. When the message gets to the end of the nerve, it releases a special chemical called acetylcholine II Acetylcholine molecules bind to receptors on the surface of the sarcolemma When the acetylcholine key attaches to the door (the sarcolemma), it unlocks the door and lets the message from the brain come in. This message tells the muscle cell to start contracting. I Impulse travels along the sarcolemma and through the T- tubules to the interior of the cell The sarcolemma is like a fence around the muscle cell. The message needs to get past the fence to tell the inside of the muscle cell to contract. - T-tubules are like tiny tunnels that go through the fence. The message can travel through these tunnels to reach the inside of the muscle cell. This allows the message from the brain to quickly reach all parts of the muscle cell and tell it to contract! I Impulse reaches the sarcoplasmic reticulum Inside the muscle cell, there's a special storage area called the sarcoplasmic reticulum. The sarcoplasmic reticulum is like a warehouse that stores calcium. When the message from the brain reaches the sarcoplasmic reticulum, it's like a signal telling the warehouse to open up and release the calcium! This calcium then goes on to help the muscle fibers inside the cell to shorten and contract. I Calcium ions are released into the sarcoplasm The sarcoplasm is like the big open space inside the muscle cell. It's like the main room of the factory. When the sarcoplasmic reticulum releases calcium, it goes into the sarcoplasm. Now the calcium is ready to help the muscle fibers contract and make the muscle move! I Calcium ions diffuse into the myofibrils and stimulates them to contract Myofibrils are like tiny ropes inside the muscle cell that do the actual work of contracting. Think of them as the workers in the muscle factory. Calcium is like their boss. When calcium goes into the myofibrils, it tells the workers (the tiny ropes) to start pulling. This pulling makes the myofibrils shorter, which makes the whole muscle cell shorter, and that's how the muscle contracts Characteristics of Muscle Contraction All-or-Nothing Principle (think of tug-of-war. Either everyone pulls as hard as they can, or no one pulls at all. There’s no in between Nervous system controls the number of muscle fibers it stimulates for a particular movement Muscle memory Chemistry of Muscle Contraction The special fuel that muscle use is called ATP. Its like the gasoline that powers your car ATP gives muscles the energy they need to contract and relax. ATP is produced from mitochondria To make ATP, mitochondria need two main ingredients: Glucose: Like the sugar your body gets from food Muscles store some glucose as glycogen just in case they need that extra energy Oxygen: The air that we breathe. Muscles have a special protein called myoglobin that helps them store oxygen When your muscles have enough oxygen, they can make ATP using a process called aerobic metabolism But sometimes your muscles work so hard that they use up all the available oxygen. When this happens, they have to switch to a less efficient way of making ATP called anaerobic metabolism (think of car sputtering when running out of gas) Anaerobic metabolism produce a waste called lactic acid, which can build up in your muscle and make them feel sore Heat Production All the energy that your muscles use to contract and relax, the ATP we talked about, actually produces heat as a byproduct Our body uses this heat from muscle movement to help keep your temperature just right. This is called thermal regulation If your muscles produce more heat than your body needs you might start to feel hot and sweaty. Your body will try to cool down by sweating or panting But if your muscles don’t produce enough heat to keep you warm, you’ll start to shiver. Shivering is your body’s way of making your muscles work harder to generate more heat Cardiac Muscle ONLY found in your heart This muscle is involuntary They are small, but they’re longer than they are wide. They also have lots of branches like a tree, which helps them connect to other cardiac muscle cells Securely attached to one another (end to end) and they have special connections called intercalated discs Physiology of Cardiac Muscle Cardiac cells contract without any external stimulation Groups of cardiac muscle cells contract at the rate of the most rapid cell in the group Contractions are rapid and wavelike Your heart has a special system called the internal conduction system that helps control its beat This system has a sinoatrial (SA) node located in the wall of the right atrium of the heart The SA node is like a tiny drummer that creates the impulse that makes your heart beat The impulse then follows a specific path through the hearts conduction system This system makes sure that the impulse travels in the right direction and at the right speed to make your heart beat properly Nerve Supply The sympathetic nerves tell your heart to beat harder and faster when you are excited or scared The parasympathetic nerves tell your heart to beast slower and more gently when you are resting Sympathetic fibers stimulate the heart to beat harder and faster as part of the “fight or flight” response Parasympathetic fibers inhibit cardiac function, causing the heart to beat more slowly and with less force Smooth Muscle You can’t control smooth muscle with your thought. It works involuntarily and is non-striated Smooth muscle cells are small and shaped like spindles. They have one nucleus Actin and myosin filaments arranged as small contractile units that crisscross the cell Visceral Smooth Muscle Found in the walls of many of your internal organs, like your tummy and intestines. These muscles work together to form large sheets that help things move inside your body Imagine it like a big, stretchy blanket that wraps around your organs This blanket can also squeeze and relax to help move things along, kind of like squeezing toothpaste out of a tube It helps push food through the intestines and helps your bladder squeeze to pee Even though it works on its own, it can also have messages sent to it through special nerves Multi-Unit Smooth muscle Type of smooth muscle made up of individual cells or small groups of cells that work independently. These muscles are found in places in your body where small, delicate contractions are needed Needs a separate signal for your nervous system for each cell or small group to contract. This means our brain has more control over these muscles