Animal Anatomy Notes PDF

Cranial -- caudal ( lungs is cuadual to the tail) vise versa - rostral - (the eyes are rostral to the ear) -   Tail is dorsal to the sternum (back (up)) The ribcage is ventral to the spine(belly(down)) Towards the inner body - medial More ou...

Cranial -- caudal ( lungs is cuadual to the tail) vise versa - rostral - (the eyes are rostral to the ear) -   Tail is dorsal to the sternum (back (up)) The ribcage is ventral to the spine(belly(down)) Towards the inner body - medial More out- lateral Paw is distal from the body (away from body) Toes located distal from the body but proximal to the paw Muscles are deep the skin The skin is superficial to the body Slide 19 (dorsal and lateral ) - Week 2 Summary The integumentary system consists of skin and its appendages, including hair, glands, and specialized structures like horns and hooves. It serves vital functions such as preventing water loss, protecting against infection, regulating temperature, and sensory perception. The skin is divided into the epidermis and dermis, each with specific layers and functions. Various skin conditions and appendages, including claws, feathers, and mammary glands, highlight the system's complexity and its role in animal health. Highlights - Skin Functions: Prevents water loss & infection. Skin Layers: Epidermis and dermis, each with distinct roles. Appendages: Includes hair, claws, and glands. Specialized Structures: Horns, hooves, and feathers serve different functions. Disease Examples: Conditions like mange and skin tumors. Gland Types: Sebaceous and sweat glands play essential roles. Case Studies: Illustrate common integumentary disorders. Key Insights - Epidermis vs. Dermis: The epidermis is avascular, composed of five layers, while the dermis contains blood vessels and nerves, playing a crucial role in sensation and thermoregulation. Importance of Appendages: Skin appendages like hair follicles and glands are vital for protection, temperature regulation, and sensory functions, demonstrating the skin's multifaceted roles. Skin Diseases: Conditions like squamous cell carcinoma and dermatitis highlight the need for awareness of skin health in pets, emphasizing early detection and treatment. Hoof Structure: The hoof is a complex structure crucial for weight-bearing and movement in ungulates, and conditions like laminitis can severely impact an animal's quality of life. Specialized Glands: Glands such as the uropygial gland in birds provide maintenance functions, including waterproofing feathers, showcasing adaptation to environmental needs. Case Studies Insight: Real-world examples of pruritic dogs and anal gland issues underscore the necessity for veterinary intervention and understanding common pet health issues. Evolutionary Adaptations: Structures like horns and antlers demonstrate evolutionary adaptations for survival, indicating the integumentary system's role in species-specific traits. Thin skin - haired portion of the body (any part of the body w/ hair) Thick hair- no hair (elbows, paw pads) Hypodermis: - - - - Epidermis layer: humans/dogs cells are formed with 2 weeks 1. 2. 3. 4. 5. Squamous cells carcinoma : in cats ,horses/cattle , dogs Cats - more in the nasal cavity , a little bit in the ear Horses- more in the third eye portion Dogs common skin tumors in dogs over 5 years old Forms circular, ulcerated lesions that eat away at the surrounding tissue Skin that receives prolonged skin exposure -- most at risk Sebum has properties that help prevent fungal and bacterial growth. pustules - pimps Sweat glands: Eccrine - helps regulate temperature - Apocrine - coiled tube with single tube emptying onto hair follicle - Mange: Two types of mites- Demodex- long, sausage, cigar shape Sarcoptes- ZOONOTIC, round, -  Frogs have no sweat glands but poison glands Whiskers: (vibrissae) Tactile hairs -- well supplied with sensory endings to be used as probes and feelers Found around the mouth and muzzle Paw pads have all 5 epidermis layer - Only have true sweat glands Pruritic dog Exam :3 yo FS Frenchie - - - 1. 2. 3. 4. 5. 6. Different diagnoses: Work up - - - - Treatment: - - - Anal glands produce either **sebaceous** or **apocrine** secretions **Week 3** Functions of the bones : - - - - - Classification of the bones - - 4 bone shape - - - -  Long bones: longer than wider Short bones: small cubed shaped Flat bones: relatively flat and short Irregular bones: bones that do not fit in any category Bone structure: - - Long bone anatomy: - - - - - \- Covered in a thin layer of articular cartilage -Epiphyseal plate -- located between epiphysis and diaphysis Certain bones have bone marrow for red blood cells  Avian bone: more lighter - - -  - - Common bone features: - - - - - - -  Anatomy of the skull: -  Mandible: - - Vertebral column: Spinal column - Cervical vertebrae: only ones that are not numbered - Sacrum: Types of bone fractures :  Week 4 Joints - Arthro, Articular - - - - Ex: humeroradial joint (on the humerus bone and the radius bone together) Types of joint: - - - - Ex = sutures, fibrous union between splint bones and MC/MT III (horses), gomphosis (fibrous connection anchoring a tooth to its socket) - - - - Cartilaginous joints: Aka amphiarthroses - - symphysis, mandibular symphysis Synovial joint aka diarthroses - - - Anatomy - - - - - - Value of ligaments - - - Cruciate ligament injury - - - Bursae - - - - Stability of synovial joints - Ex: ball and socket joint shoulder =easily can dislocate - - Joint movements - - - Flexion - Extension -  Abduction: - Abduction: movement of an extremity towards the median pane Rotation: - Circumduction: - Types of synovial joint Joint diseases: Septic arthritis :a joint infection due to a bacterial organism Treatment -- must be PROMPT - - - - Osteochondrosis Dissecans:a developmental disorder of medium & large breed dogs & horses Treatment: - Osteoarthritis: a chronic; progressive, non infectious condition of weight bearing joints - - Treatment Lifestyle changes \- Weight loss -Low impact exercise -Non-slip rugs / mats Physical rehabilitation \- Pain management \- NSAIDs \- +/- gabapentin / amantadine \- Librela / Solensia Joint support -Glucosamine + chondroitin supplement \- Joint injections \- +/- Surgery Hip dysplasia -  Week 5 Muscle: - - - Terminology: Muscle fibers= elongated muscle cell Muscle" Myo- Mys- Sacro- -Myosotis \- Sarcoplasm \- Sarcolemma Skeletal muscle: Skeletal ,Striated, voluntary (think to move) - - - - Cardiac muscle: Cardica, striated, involuntary - - - - - Smooth muscle : Visceral, nonstriated, involuntary - - - - - Characteristics: - - - - - Muscle function: Produces movement \- Skeletal mm -- locomotion & manipulation \- Cardiac & smooth mm -- movement of blood throughout body; BP maintenance \- Smooth mm -- propels substances through hollow organs Maintains posture & body position \- by adjusting the positions of the body with respect to gravity Stabilizes joint -By exerting tension on joint (muscle tone) Generate heat \- As muscle contracts, helps to maintain normal body temp Skeletal muscle fibers: - - Myofibrils: - - - - - - - Functional unit of skeletal muscle - Sarcomere Z disk - z disk = sarcomere Myofilaments: - 2 types: - -  SARCOPLASMIC RETICULUM & TUBULES - - SLIDING MODEL OF CONTRACTION STEPS: \- NS stimulates muscle fibers → myosin head on thick filaments attach to myosin binding sites on actin (thin filaments) = cross bridge attachments -Cross bridge attachments form & break several times during contraction → pulls thin filaments toward center of sarcomere \- Steps \#1 & \#2 occur simultaneously in sarcomeres throughout cell ➔ muscle cell "shortens"  **Skeletal muscle**: - - - - - Attachments : - - -  Tendon have no blood supply- a few months to be healed when injured Origin = muscle is attached to a more stable bone site - Insertion = muscle is attached to bone that does move under contraction Action: - - - - - -  Muscle of the head: - - - - - - Muscle of the superficial of neck: - - - Muscle of the thorax: - - - - -   Supraspinatus -- cranial to scapular spine Infraspinatus -- caudal to scapular spine Intercostal muscles -- in between ribs  Muscle of the thoracic limb: - - - - - Muscle of the abdomen: - - - - Muscle of the pelvic: - - - - - - Muscle of the pelvic limb: - - - - - Hamstring: - - - Stay apparatus: - - - Specials senses: Sensory receptors - specially modified nerve endings = generates a nerve pulse = interpreted as a particular sensation Types of stimulus: Mechanical - touch, hearing, balance Thermal- hot, cold electromagnetic - vision Chemical - smell General senses: **Visceral Sensation-** miscellaneous category of internal body sensation, vague and poorly localized (ex: hunger and thirst), Visceral sensations from the hollow visceral organs (such as GI tract or urinary tract) → particularly as stretch sensations **Touch-** a tactile sense: sensation of something being in contact with the surface of the body, Pressure = the sense of something pressing on the body surface, Sensation include: light contact, deep pressure, vibration, hair movement Can also be at a unconscious level, unless its abrupt and sever **Temperature-** the monitoring half of the body's temperature control system Temperature receptors detect increases in the body's temperature → transmits that information to the brain Hypo and hyperthermia - high and low **Pain**- Pain receptors = nociceptor Purpose = to protect the body from damage by alerting the brain to potentially harmful stimuli Nociception = process of experiencing pain Steps Transduction -- the conversion of the painful stimulus into a nerve impulse Transmission -- sending that nerve impulse up the sensory nerve fibers to the spinal cord Modulation -- the spinal cord will modulate, or change, the sensory nerve impulses to influence the information the brain receives Perception -- the brain consciously senses the pain Acute - sharp intense Chronic - dull aching Proprioception : The sense of body position and movement; knowing where the body is in space Operates at the unconscious level Important to animals to stand up right and make accurate, allows to interact with their environment Special sense: **Vision -** 3 layered wall :fibrous (outer) , vascular, nervous layer (inner) Fibrous layer = Admits light into its interior & gives strength and shape to the eyeball Sclera = the "white" of the eye; makes up the majority of the outer fibrous layer Vascular layer = middle layer, uvea Components: Choroid -- consists of mainly pigment & blood vessels Nervous layer: Inner layer; lines the back of the eye (retina) Fundus = used to describe the caudal interior surface of the eye Retina + optic disc = where optic nerve exits the eyeball Contains the actual sensory receptors for vision = rods & cones Retinas: where the visual image is actually formed,sensed & converted into nerve Animals have more rods than cones = sees more grey color Photoreceptor cells = neurons that are modified into the actual sensory receptors for light Rods -- low light vision; more numerous;grey scale Cones -- color vision & detail Nerve fibers all converge at the optic disc →exit the eye via Optic nerve (CN II) No photoreceptors here ∴ blind spot  Compartments: 2 fluid filled compartments:  Extravascular structure: **Conjunctiva** - a thin, transparent membrane that covers the front portion of the eyeball and lines the interior surfaces of the eyelids Bulbar conjunctiva = portion covering the front of the eyeball Palpebral conjunctiva = portion lining the eyelids **Eyelids** - Aka palpebrae Constantly produced → constantly drained  **Eye muscle** - extraocular eye muscles **Taste** - Aka gustatory sense **V O M E R O N A S A L O R G A N** Flehmen response 1\. External ear -- acts as a funnel to collect sound wave vibrations & direct them to the eardrum 2\. Middle ear -- amplifies & transmits the vibrations from the eardrum to the inner ear 3\. Inner ear -- contains the actual sensory receptors that convert the mechanical vibrations into nerve impulses & contains receptors for the equilibrium sense External ear - Structures that collect sound waves & transmit them to the middle ear Tympanic membrane (eardrum) -- paper thin membrane tightly stretched across the opening between the external auditory canal & middle ear Middle ear- Hollowed out area of temporal bone --lined by soft tissue membranes Ossicles -- link tympanic membrane to cochlea of inner ear == where receptors for hearing are located Acts as a system of levers that transmit sound vibrations from the tympanic membrane to the cochlea **Physiology of hearing:** Sound vibrations cause tympanic membrane to vibrate → ossicles in middle ear vibrates → pushes on oval window of cochlea → causes fluid in cochlea to vibrate → tectorial membrane & hair cells to rub against each other → hair cells bend →creates a nerve impulse → travels to brain → interpreted as sound **Equilibrium** - = a mechanical sense that helps the animal maintain its balance by keeping track of the position and movements of the head Receptors are located in the inner ear **Vestibule -** 2 sac like spaces: Utricle & saccule → Within each →sensory epithelium = macula Made up of hair cells covered by a gelatinous matrix containing crystals = otoliths Gravity causes otoliths to put constant pressure on the hair cells Bends hair cells as head moves → generates a nerve impulse Gives information about head position \*\* linear motion\*\* **Semicircular canals-** At base of semicircular canal = enlargement = ampulla → contains receptor structure = crista ampullaris Cone shaped area of hair cells sticking up into a gelatinous structure = cupula No otoliths Cupula floats in fluid When head moves, inertia causes fluid to pull on cupula → bends hairs → generates a nerve impulse → information is sent to the brain \*\* rotational motion\*\*   Week 7 Cardiovasuclor system: - - - - - \- blood There are two parts divided of the heart Pulmonary (lung) circuit - - - Systemic (body) circuit - - - The heart is located in the thoracic cavity. In the mediastinum (the space between the lungs) Hearts size: - -  The heart is covered in a fibrous sac called the **pericardium** 2 parts - - The heart contains 3 layer walls: Outer layer = epicardium a membrane that lies on the external surface of the myocardium Aka visceral layer of the serous pericardium Middle layer = myocardium = heart muscle; cardiac muscle Advantages: Autorhythm ic = can start beating in a steady rhythm without a nerve impulse Does not fatigue Inner layer = endocardium = a membrane that lies on the inner surface of the myocardium Heart chambers consist of 4= 2 atria (singular = atrium) = receive blood into the heart 2 ventricles = pump blood out of the heart Interatrial septum -- divides L & R atria Interventricular septum -- divides L & R ventricles  Interventricular groove -- marks the interventricular septum externally Contains coronary (heart) blood vessels Frequently filled with fat Auricles -- small, wrinkled protruding appendage of the atria externally Vessels Blood enters Right atrium via: cranial vena cava caudal vena cava Blood enters Left atrium via: Pulmonary veins Blood exits Right ventricle via: Pulmonary artery Blood exits Left ventricle via: Aorta Valves: - - Valves: Atrioventricular (AV) valves --between atria and ventricles Right AV valve = tricuspid valve a 3 cusps, or flaps Left AV valve = mitral valve aka bicuspid valve a 2 cusps Semilunar valves -- control blood flow out of the ventricles and into the arteries Right semilunar valve = pulmonary valve a blood flows from the right ventricle into pulmonary artery (into pulmonarycirculation) Left semilunar valve = aortic valve a blood from left ventricle flows into aorta (into systemic circulation)  Conduction system Sinoatrial (SA) node -- an area of cardiac muscle cells that automatically generate the impulses that trigger each heartbeat = the pacemaker of the heart Atrioventricular (AV) node -- in atrioventricular septum Impulse pauses here to allow atria to complete contraction before ventricular Contraction Bundle of His -- in interventricular septum - Electrocardiography Produces an electrocardiogram (ECG, EKG) based on the electrical activity in the heart Components: 1. P wave Conductions traveling from SA node through atria = atrial contraction QRS Complex Conduction through ventricles = ventricular contraction T wave = ventricular relaxation Week 9 Nervous system : **The main controlling and communicating system of the body whose cells communicate via electrical & chemical signals to produce almost immediate response** Basic function: **Sensory input**: using sensory receptors to monitor changes inside & outside the body **Integration**: processing & interpreting sensory input to decide an appropriate response **Motot output**: activating effector organs (muscles & glands) to cause a response  **Central nervous system (CNS)**: brain & spinal cord Integrating and control center of NS **Peripheral Nervous System (PNS): outside of CNS** Consists of: Nerves that extend from brain & spinal cord Spinal nerves carry impulses to & from spinal cord Cranial nerves carry impulses to from the brain **Sensory (afferent) division:** Nerve fibers (axons) carries impulses TO CNS from sensory receptors throughout the body **Somatic sensory fibers:** carry impulses from receptors in the skin, skeletal muscles & joints **Visceral sensory fibers:** carry impulses from visceral organs  **Motor (efferent) division:** Carries impulses FROM CNS to effector organs (muscles & glands) **Somatic nervous system**---somatic motor nerve fibers that conduct impulses from CNS to skeletal mm Allows voluntary control **Autonomic nervous system**---voluntary system consisting of visceral motor nerve fibers that regulate the activity of smooth muscle, cardiac muscle & glands Types of principle cell types - - **Neurons** - - - - - - - - - **Neurons cells body** - - - -  Clusters of cell bodies in CNS = **nuclei** Clusters of cell bodies along the nerves in PNS = **ganglia** **Ganglia** = accumulation of neuron cell bodies in PNS **Neuron processes** - Two types: **Dendrites**: cell processes that are the receptive regions of the cell and provide surface area for receiving signals from other neurons Dendritic spines **Axons:** - Myelin sheath---a fatty, insulating material that forms a layer only around the axon of the neuron (improves electrical conduction) - **Myelin sheath: Myelin sheaths → axons only Dendrites are always nonmyelinated** - - - **Neuro transmission** - - - - -  **Central Nervous system (CNS)---brain and sinal cord** - - **Ventricles**: - **Cerebral hemispheres:** - Just caudal to cerebrum **Diencephalon** - 3 important structures - - - **Brain stem** **the connection between the rest of the brain and the spinal cord** **Composed of:** ** Midbrain** ** Pons** ** Medulla oblongata** - ** Controls functions associated with the heart, respirations, blood vessel diameter, swallowing & vomiting** ** Many cranial nerves originate here** **The brain is protected by the skull (bones), meninges (membranes), and cerebrospinal fluid (watery cusion).** **Meninges: connective tissue membranes that lie just external to the CNS organs:** ** Cover & protect the CNS** ** Protect BVs & enclose venous sinuses** ** Contain CSF** ** Form partitions in the skull** ** 3 meninges:** ** Dura mater -- most superficial** - - ** Protect brain & spinal cord from trauma** ** Helps nourish the brain** ** Infection, inflammation, or cancer in the brain or spinal cord can cause changes to the CSF** ** Sample = CSF tap** Week 10 Respiratory sysytem Respiration can be divided into four main processes: Pulmonary Ventilation - - External Respiration Definition: This process involves the exchange of gases (O₂ and CO₂) between the air in the alveoli and the blood in the pulmonary capillaries. - Transport of Respiratory Gases - - Internal Respiration - - Upper Respiratory Tract Nose and Nasal Passages Nostrils (Nares):\*\* External openings leading to the nasal passages. Nasal Planum:\*\* hairless, pigmented surface. Alar Folds:\*\* Structures aiding in breathing and scent detection. Nasal Septum:\*\* Midline divider separating left and right passages. Hard palate: bony plate separates the dorsal nasal cavity from the mouth Soft palpate: extension of the softpalate, only contains soft tissues -- also separates the dorsal nasal cavity from the mouth  Turbinates (Nasal Conchae):\*\* thin, scroll-like bones increasing surface area, aiding air conditioning by warming, humidifying, and filtering. Pharynx Function:\*\* shared passageway for respiratory and digestive tracts. Divisions: \*\* Nasopharynx (dorsal) and Oropharynx (ventral), leading to the esophagus and larynx. Larynx and Trachea Larynx Structure: \*\* Short, irregular tube connecting pharynx to trachea. Cartilages:\*\* epiglottis (swallowing aid), arytenoid cartilages (vocal cord attachment), thyroid (largest), and cricoid (caudal to thyroid).  Trachea Description:\*\* Extends from the larynx into the thorax, bifurcating into two main bronchi. Composition:\*\* fibrous connective tissue, smooth muscle, and hyaline cartilage rings, maintaining openness during respiration. Lower Respiratory Tract Bronchial Tree and Alveoli Bronchi:\*\* Mainstem bronchi bifurcate into smaller bronchi, leading to bronchioles and alveolar ducts. Alveoli:\*\* microscopic, thin-walled sacs where external respiration occurs. Lined with surfactant to reduce surface tension and prevent collapse. Lungs and Thorax Lung Structure Lobes:\*\* Different animals have varying lobe structures. For example: Cats, dogs, etc.: \*\* Left lung has cranial and caudal lobes; right lung has cranial, middle, caudal, and accessory lobes. Horses: \*\* Left lung has cranial and caudal lobes; right lung has cranial, caudal, and accessory lobes. Thoracic Cavity Content: \*\* Lungs, heart, blood vessels, nerves, trachea, esophagus, lymphatic vessels, and lymph nodes. Pleura:\*\* Thin serosal membrane covering organs and lining the cavity walls with a lubricating pleural fluid, ensuring smooth lung movement during breathing. Physiology of Breathing Pulmonary Ventilation \- \*\*Phases:\*\* Inspiration:\*\* Air flows into the lungs. Expiration: \*\* Gases exit the lungs. Mechanism:\*\* involves volume changes in the thoracic cavity driven by diaphragmatic and intercostal muscle movements. Respiratory Volumes Tidal Volume:\*\* Volume of air inspired and expired during one breath. Minute Volume:\*\* Volume of air moved per minute. Residual Volume:\*\* Air remaining after maximum expiration. Avian Respiratory System Anatomy Bronchi:\*\* Trachea bifurcates into mainstem bronchi, subdividing into secondary bronchi and parabronchi. Syrinx: a unique vocal organ in birds that allows them to produce complex sounds Air Sacs:\*\* Thin-walled structures make up 80% of respiratory system volume, aiding in air reservoir, thermoregulation, and gas exchange facilitation. Airflow Process Cycle:\*\* Requires two inhalations and two expirations to transport one air pocket through the system: First inhalation fills posterior air sacs. First expiration pushes air into the lungs. Second inhalation moves air into anterior air sacs. Second expiration expels air through the trachea. Week 11 Reproductive system: to produce offspring - - - - - - Male reproductive system: - - - Anatomy: - - - Scrotum: sac of skin that houses the testes - - - -  Testes: the male gonad → the organ where the male reproductive cells are formed - - - - - - Spermatic cord: - - - Descent of the testes: Before birth -- testes located in abdominal cavity - Vas deference: muscular tube that connects the tail of the epididymis to the urethra - - - - Accessory glands: - - - - - - - - Seminal vesicle: - - - - prostate gland: - - - - Bulbourthral gland - - -  Penis: Week 12 Digestive system Essential Activities for Food Processing The digestive process involves: Ingestion: Intake of food into the digestive tract. Propulsion: Movement of food through the alimentary canal via swallowing and peristalsis. Mechanical Digestion: Physical breakdown of food, increasing its surface area for enzymatic action. Chemical Digestion: Enzyme-driven breakdown of food into its chemical components. Absorption: Passage of digested nutrients into blood or lymph. Defecation: Elimination of indigestible substances from the body. Digestive Adaptations in Different Animal Types Herbivores Herbivores, such as horses and cattle, consume plant material. Their digestive system includes mechanisms for microbial fermentation: Foregut Fermenters (Ruminants): Cattle, sheep, and goats have a complex stomach with chambers aiding in microbial fermentation. Hindgut Fermenters (Non-ruminants): Horses have an expansive cecum at the junction of the small and large intestines. Carnivores Carnivores like cats depend on meat. They possess specialized teeth (sharp canines and cutting premolars/molars) for tearing flesh. Their digestion is enzymatic, requiring less reliance on microbial fermentation. Omnivores Omnivores, including humans, pigs, and dogs, consume both plant and meat materials, and their digestive systems reflect this dietary flexibility. Ruminants Ruminants (e.g., cows, goats, and sheep) exhibit a multi-chambered stomach comprising: Reticulum: Honeycomb-textured mucosa, allowing contents to pass easily. Rumen: The primary fermentation vat with a complex microbial ecosystem. Omasum: Contains folds for water and salt absorption. Abomasum: The \"true\" stomach, functioning similarly to monogastric stomachs in enzymatic digestion. Avian Digestive Tract Birds have a high metabolic rate requiring efficient digestion. Their system includes: Esophagus: Contains a crop for food storage. Proventriculus: Glandular stomach for initial chemical digestion. Ventriculus/Gizzard: Muscular stomach for grinding food. Small and Large Intestine: Responsible for nutrient digestion and absorption. Detailed Anatomy and Physiology of the Digestive System Alimentary Canal Layers From esophagus to anus, the alimentary canal has four layers: Mucosa: Inner layer with mucus-producing epithelial cells, essential for digestion and absorption. Submucosa: Connective tissue containing glands, blood vessels, and nerves. Muscularis: Layers of smooth muscle responsible for peristalsis and segmentation. Serosa: Outermost layer made of connective tissue and peritoneum. Oral Cavity The oral cavity includes: Teeth: Adapted for various functions across species, such as cutting, tearing, and grinding food. Tongue: A muscular organ with papillae aiding in food manipulation and tasting. Stomach The stomach varies significantly between monogastric animals and ruminants: Monogastric Stomach: Found in dogs, cats, and horses, consisting of regions like cardia, fundus, body, and pylorus. Ruminant Stomach: Four compartments as described earlier. Small and Large Intestines Small Intestine: Principal site for digestion and absorption, comprising the duodenum, jejunum, and ileum. It has structures like villi and microvilli increasing surface area for nutrient absorption. Large Intestine: Involved in water reabsorption and feces formation, including the cecum, colon, rectum, and anus. Accessory Digestive Organs Liver and Gallbladder: Produce and store bile essential for fat digestion. Note, horses do not have a gallbladder. Pancreas: Secretes enzymes crucial for the breakdown of proteins, carbohydrates, and lipids. Week 13 \# Comprehensive Overview of the Endocrine System \#\# Table of Contents 1\. Introduction to the Endocrine System \- Definition and Function \- Major Endocrine Glands 2\. Hormones: Chemical Messengers \- Types of Hormones \- Mechanisms of Hormone Action 3\. Hormone Regulation \- Feedback Mechanisms \- Types of Stimuli for Hormone Release 4\. Major Endocrine Glands and Their Functions \- Hypothalamus \- Pituitary Gland \- Thyroid Gland \- Parathyroid Glands \- Adrenal Glands \- Pancreas 5\. Common Endocrine Disorders \- Diabetes Mellitus \- Hyperthyroidism \- Cushing\'s Syndrome (Hyperadrenocorticism) \#\# Introduction to the Endocrine System \#\#\# Definition and Function \- \*\*Endocrine System:\*\* A collection of glands that produce hormones to regulate processes such as growth, metabolism, and reproduction through chemical signals. \- \*\*Hormones:\*\* Long-distance chemical messengers, secreted into the bloodstream, affecting various cells and tissues across the body. \#\#\# Major Endocrine Glands \- \*\*Pituitary Gland\*\* \- \*\*Parathyroid Gland\*\* \- \*\*Thyroid Gland\*\* \- \*\*Adrenal Glands\*\* \- \*\*Pancreas\*\* \- \*\*Ovaries\*\* \- \*\*Testes\*\* \#\# Hormones: Chemical Messengers \#\#\# Types of Hormones \- \*\*Amino Acid-Based Hormones:\*\* Composed of amino acid chains; hydrophilic and cannot cross the cell membrane. \- \*\*Steroid Hormones:\*\* Derived from cholesterol; hydrophobic and can cross the cell membrane to exert their effects inside target cells. \#\#\# Mechanisms of Hormone Action \- Hormones travel via the bloodstream and bind to specific receptors on or in target cells to exert their effects. \- \*\*Target Cells:\*\* Cells with specific receptors for a given hormone. \#\# Hormone Regulation \#\#\# Feedback Mechanisms \- \*\*Negative Feedback:\*\* Reduces the stimulus for hormone secretion when a certain level is reached, thus maintaining homeostasis. \- \*\*Positive Feedback:\*\* Enhances the stimulus for hormone secretion, amplifying the response. \#\#\# Types of Stimuli for Hormone Release 1\. \*\*Humoral Stimuli:\*\* Changes in blood levels of ions and nutrients. \- Example: Parathyroid hormone, Insulin, Aldosterone. 2\. \*\*Neural Stimuli:\*\* Nerve fibers stimulate hormone release. \- Example: Stress response. 3\. \*\*Hormonal Stimuli:\*\* Hormones trigger the release of other hormones. \- Example: Hypothalamic-pituitary axis. \#\# Major Endocrine Glands and Their Functions \#\#\# Hypothalamus \- \*\*Location:\*\* Ventral part of the brain. \- \*\*Function:\*\* Links the endocrine system to the higher brain functions via the pituitary gland. Acts as a bridge between the nervous and endocrine systems. \- \*\*Hormones Produced:\*\* Regulates hormone release from the anterior pituitary via releasing and inhibiting hormones. \#\#\# Pituitary Gland \- \*\*Anterior Pituitary (Adenohypophysis):\*\* Produces several key hormones like growth hormone, prolactin, TSH, ACTH, FSH, and LH. \- \*\*Growth Hormone (Somatotropin):\*\* Promotes growth, regulates protein metabolism. \- \*\*Prolactin:\*\* Stimulates milk production. \- \*\*TSH:\*\* Stimulates thyroid gland hormone production. \- \*\*ACTH:\*\* Stimulates glucocorticoid production by the adrenal cortex. \- \*\*FSH:\*\* Stimulates ovarian follicle growth. \- \*\*LH:\*\* Facilitates ovulation and corpus luteum formation. \- \*\*Posterior Pituitary (Neurohypophysis):\*\* Stores and releases oxytocin and ADH produced in the hypothalamus. \#\#\# Thyroid Gland \- \*\*Hormones Produced:\*\* \- \*\*Thyroid Hormone (T3 and T4):\*\* Regulates metabolic rate, growth, and development. \- \*\*Calcitonin:\*\* Regulates calcium levels in the blood by inhibiting osteoclast activity resulting in decreased calcium levels. \- \*\*Functions:\*\* Increases metabolic rate, produces heat, supports normal growth and development. \#\#\# Parathyroid Glands \- \*\*Hormone Produced:\*\* \- \*\*Parathyroid Hormone (PTH):\*\* Increases blood calcium levels by acting on bones, kidneys, and intestines. \#\#\# Adrenal Glands \- \*\*Adrenal Cortex:\*\* \- \*\*Mineralocorticoids:\*\* Regulate electrolyte balance (example: Aldosterone). \- \*\*Glucocorticoids:\*\* Influence metabolism and immune response (examples: Cortisol, Cortisone). \- \*\*Androgens:\*\* Weak sex hormones. \- \*\*Adrenal Medulla:\*\* \- \*\*Epinephrine and Norepinephrine:\*\* Mediate fight or flight response. \#\#\# Pancreas \- \*\*Hormones Produced:\*\* \- \*\*Insulin:\*\* Lowers blood glucose levels by facilitating cellular uptake. \- \*\*Glucagon:\*\* Raises blood glucose levels by promoting glycogen breakdown in the liver. \#\# Common Endocrine Disorders \#\#\# Diabetes Mellitus \- \*\*Cause:\*\* Deficiency in insulin production or action. \- \*\*Symptoms:\*\* Hyperglycemia, glucosuria, polyuria, polydipsia, polyphagia, weight loss. \- \*\*Treatment:\*\* Insulin administration, diet management, exercise. \#\#\# Hyperthyroidism \- \*\*Common in Cats\*\* \- \*\*Symptoms:\*\* Nervousness, weight loss, increased appetite, tachycardia, PU/PD. \- \*\*Treatment:\*\* Medication to inhibit thyroid hormone production, radioactive iodine, surgical removal of thyroid gland. \#\#\# Cushing\'s Syndrome (Hyperadrenocorticism) \- \*\*Causes:\*\* Excessive production of cortisol from the adrenal cortex. \- \*\*Common in Dogs and Horses\*\* \- \*\*Symptoms:\*\* Polyuria, polydipsia, polyphagia, alopecia, muscle wasting, slow wound healing. \- \*\*Appearance:\*\* Pot-bellied in dogs.