Biology Final Sem1 PDF

## The Integumentary System - The integumentary system is the organ system that covers and protects the body. - The main organ of the system is the skin. - Skin consists of four types of tissues: - **Epithelial:** covers body surfaces - **Connective:** support and protection - **Muscle:...

## The Integumentary System - The integumentary system is the organ system that covers and protects the body. - The main organ of the system is the skin. - Skin consists of four types of tissues: - **Epithelial:** covers body surfaces - **Connective:** support and protection - **Muscle:** body movement - **Nervous:** communication - **The Epidermis:** the outer, superficial layer of skin. The outer layer is called keratin. - Keratin is a protein that is waterproof and protects the tissues underneath. - Melanocytes are in the inner layer of the epidermis and it is a pigment that absorbs light energy, which protects deeper cells from the damaging effects of ultraviolet rays of sunlight. - **The Dermis:** directly underneath the epidermis and it is the second layer of skin. - The dermis consists of connective tissue that prevents the skin from tearing and to return to its usual state. - The dermis also has nerve cells, muscle fibers, sweat glands, oil glands, and hair follicles. - Beneath the dermis is the subcutaneous layer, which consists of a layer of connective tissue that stores fat and retains body heat. - Hair, fingernails, and toenails are also a part of the integumentary system. - Hair and nails contain keratin and develop from epithelial cells. - Hair grows from narrow cavities in the dermis called hair follicles. - Sebaceous glands lubricate skin and hair. When the gland produces too much oil, the follicle can be blocked, which causes acne, black/white heads, or inflammation. ## Damages to the Skin (Clones) - **First Degree:** cells in epidermis are damaged or may die. There is redness, swelling, and mild pain. - **Second Degree:** cells deeper in epidermis die, and dermis cells are injured or die. There are blisters and pain. - **Third Degree:** cells in epidermis and dermis die. Nerve and muscle cells are injured. Skin function is lost, and the skin needs to be transplanted. There is no pain because of nerve cell damage. ## The Skeletal System - There are 206 bones in the human skeleton. - The human skeleton is divided into two divisions: - **Axial:** includes *the skull, vertebral column, the ribs, and the sternum.* - **Appendicular:** includes *the bones of the shoulders, arms, hands, hips, legs, and feet.* - Bones are connective tissue and are classified as *long, short, flat, or irregular.* - **Long bones:** *arms and legs* - **Flat bones:** *skull* - **Irregular bones:** *face* - **Compact bone:** is found on the outside of all bones and is dense and strong. It contains tubelike structures called *osteons* which contain blood vessels and nerves, providing oxygen and nutrients to *osteocytes* (living bone cells.) - **Spongy bone:** is less dense with many cavities that contain bone marrow. It is found at the center of short bones, or at the ends of long bones. It does not contain compact bone or osteocytes. - **Bone Marrow:** - **Red bone marrow:** produces red and white blood cells and platelets. It is found in the humerus bone of the arm, the femur bone of the leg, the sternum, the ribs, the vertebrae, and the pelvis. Red bone marrow is more common in children than adults. - **Yellow bone marrow:** consists of stored fat. The body can convert yellow marrow to red marrow in cases of anemia or blood loss. - **Bone Formation:** the skeletons of embryos are made of cartilage. Cells in fetal cartilage develop into bone forming cells. This process is called *ossification.* The human body is all bone except the tip of the nose, the lining of movable joints, the outer layer of the ears, and the discs between vertebrae. ## Repair of Bones - **Endorphins:** are chemicals produced in the brain that reduce pain temporarily. - **Bleed clot:** covers the broken ends of bones so that a new one can begin to form. - **Cartilage:** begins to form at the location of the break. - **Osteoblasts:** form after three weeks and create spongy bone around the fracture. - **Compact bone:** eventually replaces the spongy bone. - **Toddlers:** take 4-6 weeks to repair a broken bone. - **Adults:** take six months to repair a broken bone. ## Joint Diseases - **Osteoarthritis:** deterioration of the cartilage, common in the hips, knees, neck, and back. - **Rheumatoid arthritis:** loss of strength and function of joints, causing them to become inflamed or swollen. - **Bursitis:** bursae are fluid sacs located in the shoulders and elbows. *Bursitis* is an inflammation of the bursae, causing pain and swelling. - **Sprains:** are tears in a ligament, caused by a joint being stretched or twisted. ## Types of Joints - **Ball & Socket:** allows for the widest range of motion. Example: hips and shoulders. - **Pivot:** allows for rotation or twisting. Example: elbows and knees. - **Hinge:** allows for back and forth movement. Example: elbows and knees. - **Gliding:** allows for side-to-side movement. - **Sutures:** are not movable. Example: skull and clavicle. ## The Muscular System - There are three types of muscles: - **Smooth muscle:** are involuntary muscles located in the stomach, intestines, bladder, and uterus. - **Cardiac muscle:** are involuntary muscles located in the heart. - **Skeletal muscle:** are voluntary muscles that are attached to bones by tendons, which are tough bands of connective tissue. - **Skeletal Muscle Contraction:** - Skeletal muscles are arranged into *fibers*. - *Muscle fibers* are consist of smaller units called *myofibrils.* - *Myofibrils* consist of *myosin* and *actin*, which are protein filaments. - The *sarcomere* is the functional unit of a muscle and the part of the muscle that contracts. - *Actin filaments* attach within a *myofibril* at Z-lines. - *A-bands* are caused by the overlap of *actin* and *myosin* filaments which attach within a *myofibril*. - *M-lines* consist of only *myosin filaments.* - **Sliding Filament Theory:** - A nerve signal reaches a muscle, causing the *actin filaments* to slide toward one another, causing the muscle to contract. - **Fast-Twitch Muscles:** provide great strength for rapid, short movements, and are very adapted for strength. They appear *light colored* in color. - **Slow-Twitch Muscles:** are easy to contract, but provide great strength. They appear *dark colored* in color. - **Muscles** can metabolize both aerobically and anaerobically. ## The Nervous System - **Neurons:** are specialized cells that: - gather information - interpret information - react to information - **Dendrites:** receive signals called *impulses* from other neurons and conduct them to the *cell body.* - **Cell Body:** contains the nucleus of the neuron, and many of its *organelles*. - **Axon:** carries the nerve impulse from the *cell body* to other neurons and muscles. - **Sodium-potassium pump:** actively transports sodium ions out of the cell and potassium ions into the cell, resulting in a positive charge outside the cell and a negative charge inside the cell. - **Action Potential:** is the name for a nerve impulse. The minimal level of stimulation needed to cause an *action potential* to be produced is called the *threshold.* - **Nerve Impulse:** is either strong enough to travel along the neuron or not strong enough. It does not depend upon the strength of the *action potential.* - **Stimulus:** reaches the threshold of the neuron, channels open, reversing the charge temporarily. The inside of the cell becomes positively charged, while the outside becomes negatively charged. - **Potassium:** moves outside to restore charges. - **Speed of an action potential:** varies. The axon covering of lipid is called *myelin.* The *myelin sheath* has many *gaps* called *nodes.* Sodium and potassium cannot diffuse through *myelin*, but jump across it, which increases the speed. Not every neuron has *myelin*. - **Sharp Pain:** neurons with *myelin* carry impulses related to sharp pain. - **Dull, Throbbing Pain:** neurons without *myelin* carry impulses related to dull, throbbing pain. - **Synapse:** is the small gap between the axon and the dendrite. - **Synaptic Vesicles:** small sacs that carry *neurotransmitters*, which release *neurotransmitters* by *exocytosis*. - **Neurotransmitter:** is a chemical that diffuses across a *synapse* and binds to receptors on the dendrite of a neighboring neuron. ## Organization of the Nervous System - The nervous system consists of two major divisions: - **Central Nervous System (CNS):** - **Brain:** - **Spinal Cord:** - **Peripheral Nervous System (PNS):** - **Sensory Neurons:** carry information to the CNS. - **Motor Neurons:** carry information from the CNS. - **Brain Stem** connects the brain to the spinal cord and is made up of two regions: - **Medulla Oblongata:** relays signals between the brain and spinal cord. It also helps control breathing rate, heart rate, and blood pressure. - **Pons:** relays signals between the cerebrum and cerebellum. - **Cerebellum:** controls balance, posture, and coordination -- the brain's back portion. It is involved in skeletal muscles and motor skills. - **Hypothalamus:** regulates body temperature, thirst, appetite, and water balance. It also partially regulates blood pressure, sleep, aggression, fear, and sexual behaviour. - **Spinal Cord:** is a nerve column that extends from the brain to the lower back. It is protected by the vertebrae. The spinal cord connects body parts to the CNS and it processes reflexes. - **Nerves:** contain sensory and motor neurons. Neurons in the PNS can be classified as either *somatic* or *autonomic.* ## Somatic Nervous System - The somatic nervous system relays information from external sensory receptors to the central nervous system. - Somatic motor nerves relay information from the CNS to skeletal muscles. - This is voluntary. - A *reflex* is a fast response to a change in the environment, which is involuntary. - Most reflexes go to the spinal cord, instead of the brain. ## Autonomic Nervous System - The autonomic nervous system carries impulses from the central nervous system to the heart and other internal organs. - The body responds involuntarily, which is where the "fight or flight" response occurs. - **Sympathetic:** controls organs in times of stress. It increases heart rate and breathing rate. - **Parasympathetic:** controls organs when the body is at rest. - Both the *sympathetic* and *parasympathetic* relay impulses to the same organs, but the overall response depends on the intensities of the opposing signals. ## The Senses - **Sensory Receptors:** specialized neurons in the body that have the ability to *see, hear, taste, smell, touch*, and to detect *motion* and *temperature*. - **Specialized Receptors** are located: - **Nose:** high in the nose. - **Chemicals in the air** send the information to the **olfactory bulb in the brain.** - **Taste Buds:** are areas of specialized chemical receptors on the tongue that detect the tastes of *sweet, sour, salty*, and *bitter*. - **Sight:** - **Cornea:** transparent, yet durable, layer of cells, where the light first enters. The cornea helps focus light through an opening (pupil). - **Iris:** is the colored part of the eye and regulates the size of the eye's opening. - **Lens:** behind the iris and it projects a reversed image onto the retina. - **Vitreous Humor:** is colorless gelatin-like liquid between the lens and retina, where the incoming light travels. - **Retina:** contains numerous receptor cells called **rods** and **cones.** - **Rods:** are light-sensitive cells that are excited by low levels of light. - **Cones:** function in bright light and provide information about color to the brain. - **Hearing & Balance:** - **Canals in the inner ear** are responsible for your sense of *balance* or *equilibrium*. - **Sound waves** enter the *auditory canal* and cause the *eardrum* or *tympanum* called the *tympanic membrane* to vibrate. - **Malleus (Hammer), Incus (Anvil), and Stapes (Stirrup):** three bones in the middle ear that *vibrate*, causing the *oval window* — a membrane that separates the middle ear from the inner ear — to move back and forth. - **Cochlea:** is filled with fluid and lined with tiny hair cells. - **Semicircular Canals:** transmit information about body position and balance to the brain. ## Effects of Drugs - **Drug:** is a substance, natural or artificial, that alters the function of the body. - **Depressants:** drugs that tend to slow down the central nervous system. They lower blood pressure, interrupt breathing, and slow heart rate. They relieve anxiety, but can cause sedation. - **Alcohol:** is a depressant that affects the CNS. It causes a feeling of relaxation and sluggishness. Short-term effects are impaired judgement and reaction time. Long-term effects include reduction in brain mass, liver damage, stomach and intestinal ulcers, and high blood pressure. - **Barbiturates:** act by altering the chemicals in the brain, causing a depressant effect. Chemical imbalances in the nervous system can cause unconsciousness and hallucinations. They are highly addictive. Symptoms include weakness, dizziness, memory problems, confusion, and blurry vision. - **Stimulants:** drugs that increase alertness and physical activity. - **Nicotine:** found in cigarettes. It reverses the effects of dopamine, constricts blood vessels, raising blood pressure, and increasing heart activity. - **Caffeine:** is the most used *stimulant*. It works by binding to adenosine receptors on neurons in the brain. Adenosine slows down neural activity, causing drowsiness. When caffeine binds onto these receptors, it makes us feel more alert and awake. It also increases temporarily epinephrine (adrenaline) levels, causing an energy burst. ## The Circulatory System - The circulatory system transports oxygen and nutrients to cells, and gets rid of waste products. - This is accomplished by the: - **Blood** - **Heart** - **Blood Vessels** - The lymphatic system is part of the circulatory and immune system. ## Functions of the Circulatory System - **Transport oxygen, nutrients, and other materials.** - **Carry disease-fighting cells produced by the immune system.** - **Contain cell fragments and proteins for blood clotting (blood platelets).** - **Distributes heat throughout the body for temperature regulation.** ## Blood Vessels - **Network of channels:** - **Arteries:** carry oxygenated blood from the heart, and are thick-walled, enabling them to withstand high pressure. They have three layers: endothelium, smooth muscle, and connective tissue. - **Arterioles:** branch into smaller vessels. - **Capillaries:** are microscopic blood vessels which allow the exchange of important substances and wastes by diffusion. - **Veins:** are the largest blood vessels which carry deoxygenated blood back to the heart. The endothelial walls of veins are much thinner than the walls of arteries. - Larger veins in the body have flaps of tissue called valves that prevent blood from flowing backwards. - Breathing movements exert squeezing pressure against veins in the chest, forcing blood back to the heart. ## The Heart - The heart is a muscular organ located about the size of your fist, at the center of the chest. - It pumps both oxygenated and deoxygenated blood at the same time, made of cardiac muscle. - It acts in two phases: - **First Phase:** right atrium receives deoxygenated blood, then contracts to fill all of the ventricle with blood. - **Second Phase:** ventricles contract to pump blood out of the heart. - The heart works in a regular rhythm. - **Sinoatrial Node (SA Node):** also known as the *pacemaker*, is the heart's natural pacemaker, sending out signals that tell the heart muscle to contract (electrical signals) in the Left Atrium, and the heart then pulses about 70 times each minute.. - **Pulse:** is when the Left Ventricle contracts. ## Blood - **Blood pressure:** is how much pressure is exerted against the vessel walls by blood. - **Systolic blood pressure** is when the heart reaches its highest beat. - **Diastolic blood pressure** is when the heart reaches its lowest beat. - **Atrioventricular (AV) Node:** transmits the signal through excitable fibers to stimulate both ventricles. - **Plasma:** the clear yellowish fluid portion of blood. It makes up about 90% of blood. - **Water:** is the other 50% of plasma. - **Vitamins and Minerals:** less than 50% of plasma. - **Glucose:** broken down elements from food (rice, glucose, and fats). - **Waste Products:** - **3 groups of white blood cells** that give it its yellow color. - **Helps regulate the amount of water in blood.** - **Produced by the liver.** - **Form blood clots.** - **Red Blood Cells:** carry oxygen to other cells. They are discs pinched in the middle. They have no nucleus and have a lifespan of about 120 days. - **White Blood Cells:** have a nucleus, which is the central, dense part of the cell that contains DNA. It is the *body's disease fighter.* - **Hemoglobin:** a protein in the red blood cells that binds with oxygen and carries it to the other cells. - **Platelets:** are cell fragments that help to form blood clots. - **Fibrin:** weaves a network of fibers across the cut that traps blood substances. The more they are trapped, the more blood clots form. ## Blood Types - The markers determine a person's blood type as: - **A** - **B** - **AB** - **O** - Blood markers are dominant to blood markers. For example: - **O** is recessive - **A** and **B** are dominant - It is impossible to have an AB parent without a child with AB. - The **Rh factor** is a marker found on the surface of red blood cells. ## Atherosclerosis - **Atherosclerosis:** blood clots (and others) can block arteries. This causes the heart to work harder to pump blood, which makes vessels more likely to burst. This condition can cause: - **Heart attack** - **Damage to the heart** - **Death** - **Brain die** or **stroke** ## The Respiratory System - **Breathing:** the mechanical movement of air into and out of the lungs. - **Inhale** = breathe in - **Exhale** = breathe out - **External Respiration:** exchange of gases between the atmosphere and the blood. This happens in the lungs. - **Internal Respiration:** exchange of gases between the blood and the body’s cells. - **Path of Air:** - **1. Mouth or Nose:** hairlike structures called *cilia* filter out foreign substances and send them to the *nasal passages*. - **2. Nasal Passages:** moisten, filter, and warm the air. - **3. Pharynx:** the upper throat. - **4. Epiglottis:** a flap of tissue called *the epiglottis* which covers the opening of the *pharynx*, preventing food particles from entering the *respiratory tubes*. The *epiglottis* allows air to pass from the *larynx* to a long tube in the chest cavity called *the trachea.* - **5. Trachea:** branches into two large tubes called *bronchi*. - **6. Bronchi:** branch into smaller tubes called *bronchioles*. - **7. Alveoli:** the individual air sacs at the end of *bronchioles.* Each *alveolus* wall is *one cell thick.* - **Lungs:** are the largest organs in the respiratory system. Gas exchange occurs there. - **Pulmonary Tuberculosis:** a bacterium infects the lungs, resulting in less elasticity of the lungs. This results in ineffective gas exchange. - **Lung Cancer:** uncontrolled cell growth in lung fissures, which often leads to a persistent cough, shortness of breath, bronchitis, pneumonia, and can lead to death. ## The Excretory System - The excretory system removes toxins and waste products from the body and it regulates the amount of fluids, salts, and pH in the blood. - The excretory system contains: - **Lungs:** - **Skin:** - **Kidneys:** bean-shaped organs that filter out wastes, water, and salts from the blood. - The excretory system is divided into two regions: - **Renal Cortex (outer):** - **Renal Medulla (inner):** - **Renal Pelvis:** in the center of each kidney, which collects the urine. - **Nephrons** are the filtering units in the kidneys. - Each kidney has about 1 million *nephrons.* - **Glomerulus:** a long tube where blood enters *nephrons*. It is surrounded by *bowman’s capsule*. - **Loop of Henle & Bowman’s Capsule:** are in the *nephrons*. - **Renal Artery:** transports nutrients and wastes to the kidney and branches into blood vessels. - **Urea:** nitrogenous waste product that travels through *ureters*. - **Ureters:** thin tubes that carry *urine* (waste) from the *kidneys* to the *bladder*. - **Bladder:** a hollow muscular organ located in the pelvis that serves as a reservoir for *urine*. - **Urethra:** a tube that carries *urine* from the *bladder* to the *outside of the body*. ## Disorders of the Excretory System - **Nephritis:** inflammation of the glomeruli, which can lead to inflammation of the whole kidney. This can cause kidney failure. - **Kidney Stones:** hard deposits that form in the kidney, which might pass in the urine. Large stones can block urine flow, or irritate the lining of the urinary tract. - **Urinary Tract Blockage:** malformations present at birth can lead to blockage of the normal flow of urine. This can lead to permanent damage to the kidneys. - **Polycystic Kidney Disease:** is a genetic disorder in which the kidney has growth of many fluid-filled *cysts*. This can reduce kidney function leading to kidney failure. - **Kidney Cancer:** uncontrolled cell growth often begins in the *glomerulus* and can spread, causing death. ## Kidney Treatments - **Dialysis:** a procedure in which an artificial kidney machine filters out wastes and toxins from the blood. - **Kidney Transplant:** is the surgical placement of a healthy kidney from another person (called a *donor*) into the patient's body. Rejection of the transplant is prevented with medication, such as steroids and cyclosporine. The patient also needs other drugs to prevent infections. ## The Respiratory System - **Breathing:** the mechanical movement of air into and out of your lungs. - **External Respiration:** the exchange of gases between the atmosphere and the blood. This happens in the lungs. - **Internal Respiration:** the exchange of gases between the blood and the body's cells. - **Path of Air:** - **1. Mouth or Nose:** hairlike structures called cilia filter out foreign substances, and send them to the nasal passages. - **2. Nasal Passages:** moisten, filter, and warm the air. - **3. Pharynx:** the upper throat. - **4. Epiglottis:** a flap of tissue called the epiglottis which covers the opening of the pharynx, preventing food particles from entering the respiratory tubes. The epiglottis allows air to pass from the larynx to a long tube in the chest cavity called the trachea. - **5. Trachea:** branches into two large tubes called bronchi. - **6. Bronchi:** branch into smaller tubes called bronchioles. - **7. Alveoli:** the individual air sacs at the end of the bronchioles. Each alveoli wall is one cell thick. - **Lungs:** are the largest organs in the respiratory system. - **Pulmonary Tuberculosis:** a bacterium infects the lungs, resulting in less elasticity of the lungs, resulting in ineffective gas exchange. - **Lung Cancer:** uncontrolled cell growth in lung tissues, resulting in a persistent cough, shortness of breath, bronchitis, pneumonia, and can lead to death. ## The Integumentary System - The integumentary system is the organ system that covers and protects the body. - The main organ of the system is the skin. - Skin consists of four types of tissues: - **Epithelial:** covers body surfaces - **Connective:** support and protection - **Muscle:** body movement - **Nervous:** communication - **The Epidermis:** the outer, superficial layer of skin. The outer layer is called keratin. - Keratin is a protein that is waterproof and protects the tissues underneath. - Melanocytes are in the inner layer of the epidermis and it is a pigment that absorbs light energy, which protects deeper cells from the damaging effects of ultraviolet rays of sunlight. - **The Dermis:** directly underneath the epidermis and it is the second layer of skin. - The dermis consists of connective tissue that prevents the skin from tearing and to return to its usual state. - The dermis also has nerve cells, muscle fibers, sweat glands, oil glands, and hair follicles. - Beneath the dermis is the subcutaneous layer, which consists of a layer of connective tissue that stores fat and retains body heat. - Hair, fingernails, and toenails are also a part of the integumentary system. - Hair and nails contain keratin and develop from epithelial cells. - Hair grows from narrow cavities in the dermis called hair follicles. - Sebaceous glands lubricate skin and hair. When the gland produces too much oil, the follicle can be blocked, which causes acne, black/white heads, or inflammation. ## Damages to the Skin (Clones) - **First Degree:** cells in epidermis are damaged or may die. There is redness, swelling, and mild pain. - **Second Degree:** cells deeper in epidermis die, and dermis cells are injured or die. There are blisters and pain. - **Third Degree:** cells in epidermis and dermis die. Nerve and muscle cells are injured. Skin function is lost, and the skin needs to be transplanted. There is no pain because of nerve cell damage. ## The Skeletal System - There are 206 bones in the human skeleton. - The human skeleton is divided into two divisions: - **Axial:** includes *the skull, vertebral column, the ribs, and the sternum.* - **Appendicular:** includes *the bones of the shoulders, arms, hands, hips, legs, and feet.* - Bones are connective tissue and are classified as *long, short, flat, or irregular.* - **Long bones:** *arms and legs* - **Flat bones:** *skull* - **Irregular bones:** *face* - **Compact bone:** is found on the outside of all bones and is dense and strong. It contains tubelike structures called *osteons* which contain blood vessels and nerves, providing oxygen and nutrients to *osteocytes* (living bone cells.) - **Spongy bone:** is less dense with many cavities that contain bone marrow. It is found at the center of short bones, or at the ends of long bones. It does not contain compact bone or osteocytes. - **Bone Marrow:** - **Red bone marrow:** produces red and white blood cells and platelets. It is found in the humerus bone of the arm, the femur bone of the leg, the sternum, the ribs, the vertebrae, and the pelvis. Red bone marrow is more common in children than adults. - **Yellow bone marrow:** consists of stored fat. The body can convert yellow marrow to red marrow in cases of anemia or blood loss. - **Bone Formation:** the skeletons of embryos are made of cartilage. Cells in fetal cartilage develop into bone forming cells. This process is called *ossification.* The human body is all bone except the tip of the nose, the lining of movable joints, the outer layer of the ears, and the discs between vertebrae. ## Repair of Bones - **Endorphins:** are chemicals produced in the brain that reduce pain temporarily. - **Bleed clot:** covers the broken ends of bones so that a new one can begin to form. - **Cartilage:** begins to form at the location of the break. - **Osteoblasts:** form after three weeks and create spongy bone around the fracture. - **Compact bone:** eventually replaces the spongy bone. - **Toddlers:** take 4-6 weeks to repair a broken bone. - **Adults:** take six months to repair a broken bone. ## Joint Diseases - **Osteoarthritis:** deterioration of the cartilage, common in the hips, knees, neck, and back. - **Rheumatoid arthritis:** loss of strength and function of joints, causing them to become inflamed or swollen. - **Bursitis:** bursae are fluid sacs located in the shoulders and elbows. *Bursitis* is an inflammation of the bursae, causing pain and swelling. - **Sprains:** are tears in a ligament, caused by a joint being stretched or twisted. ## Types of Joints - **Ball & Socket:** allows for the widest range of motion. Example: hips and shoulders. - **Pivot:** allows for rotation or twisting. Example: elbows and knees. - **Hinge:** allows for back and forth movement. Example: elbows and knees. - **Gliding:** allows for side-to-side movement. - **Sutures:** are not movable. Example: skull and clavicle. ## The Muscular System - There are three types of muscles: - **Smooth muscle:** are involuntary muscles located in the stomach, intestines, bladder, and uterus. - **Cardiac muscle:** are involuntary muscles located in the heart. - **Skeletal muscle:** are voluntary muscles that are attached to bones by tendons, which are tough bands of connective tissue. - **Skeletal Muscle Contraction:** - Skeletal muscles are arranged into *fibers*. - *Muscle fibers* are consist of smaller units called *myofibrils.* - *Myofibrils* consist of *myosin* and *actin*, which are protein filaments. - The *sarcomere* is the functional unit of a muscle and the part of the muscle that contracts. - *Actin filaments* attach within a *myofibril* at Z-lines. - *A-bands* are caused by the overlap of *actin* and *myosin* filaments which attach within a *myofibril*. - *M-lines* consist of only *myosin filaments.* - **Sliding Filament Theory:** - A nerve signal reaches a muscle, causing the *actin filaments* to slide toward one another, causing the muscle to contract. - **Fast-Twitch Muscles:** provide great strength for rapid, short movements, and are very adapted for strength. They appear *light colored* in color. - **Slow-Twitch Muscles:** are easy to contract, but provide great strength. They appear *dark colored* in color. - **Muscles** can metabolize both aerobically and anaerobically. ## The Nervous System - **Neurons:** are specialized cells that: - gather information - interpret information - react to information - **Dendrites:** receive signals called *impulses* from other neurons and conduct them to the *cell body.* - **Cell Body:** contains the nucleus of the neuron, and many of its *organelles*. - **Axon:** carries the nerve impulse from the *cell body* to other neurons and muscles. - **Sodium-potassium pump:** actively transports sodium ions out of the cell and potassium ions into the cell, resulting in a positive charge outside the cell and a negative charge inside the cell. - **Action Potential:** is the name for a nerve impulse. The minimal level of stimulation needed to cause an *action potential* to be produced is called the *threshold.* - **Nerve Impulse:** is either strong enough to travel along the neuron or not strong enough. It does not depend upon the strength of the *action potential.* - **Stimulus:** reaches the threshold of the neuron, channels open, reversing the charge temporarily. The inside of the cell becomes positively charged, while the outside becomes negatively charged. - **Potassium:** moves outside to restore charges. - **Speed of an action potential:** varies. The axon covering of lipid is called *myelin.* The *myelin sheath* has many *gaps* called *nodes.* Sodium and potassium cannot diffuse through *myelin*, but jump across it, which increases the speed. Not every neuron has *myelin*. - **Sharp Pain:** neurons with *myelin* carry impulses related to sharp pain. - **Dull, Throbbing Pain:** neurons without *myelin* carry impulses related to dull, throbbing pain. - **Synapse:** is the small gap between the axon and the dendrite. - **Synaptic Vesicles:** small sacs that carry *neurotransmitters*, which release *neurotransmitters* by *exocytosis*. - **Neurotransmitter:** is a chemical that diffuses across a *synapse* and binds to receptors on the dendrite of a neighboring neuron. ## Organization of the Nervous System - The nervous system consists of two major divisions: - **Central Nervous System (CNS):** - **Brain:** - **Spinal Cord:** - **Peripheral Nervous System (PNS):** - **Sensory Neurons:** carry information to the CNS. - **Motor Neurons:** carry information from the CNS. - **Brain Stem** connects the brain to the spinal cord and is made up of two regions: - **Medulla Oblongata:** relays signals between the brain and spinal cord. It also helps control breathing rate, heart rate, and blood pressure. - **Pons:** relays signals between the cerebrum and cerebellum. - **Cerebellum:** controls balance, posture, and coordination -- the brain's back portion. It is involved in skeletal muscles and motor skills. - **Hypothalamus:** regulates body temperature, thirst, appetite, and water balance. It also partially regulates blood pressure, sleep, aggression, fear, and sexual behaviour. - **Spinal Cord:** is a nerve column that extends from the brain to the lower back. It is protected by the vertebrae. The spinal cord connects body parts to the CNS and it processes reflexes. - **Nerves:** contain sensory and motor neurons. Neurons in the PNS can be classified as either *somatic* or *autonomic.* ## Somatic Nervous System - The somatic nervous system relays information from external sensory receptors to the central nervous system. - Somatic motor nerves relay information from the CNS to skeletal muscles. - This is voluntary. - A *reflex* is a fast response to a change in the environment, which is involuntary. - Most reflexes go to the spinal cord, instead of the brain. ## Autonomic Nervous System - The autonomic nervous system carries impulses from the central nervous system to the heart and other internal organs. - The body responds involuntarily, which is where the "fight or flight" response occurs. - **Sympathetic:** controls organs in times of stress. It increases heart rate and breathing rate. - **Parasympathetic:** controls organs when the body is at rest. - Both the *sympathetic* and *parasympathetic* relay impulses to the same organs, but the overall response depends on the intensities of the opposing signals. ## The Senses - **Sensory Receptors:** specialized neurons in the body that have the ability to *see, hear, taste, smell, touch*, and to detect *motion* and *temperature*. - **Specialized Receptors** are located: - **Nose:** high in the nose. - **Chemicals in the air** send the information to the **olfactory bulb in the brain.** - **Taste Buds:** are areas of specialized chemical receptors on the tongue that detect the tastes of *sweet, sour, salty*, and *bitter*. - **Sight:** - **Cornea:** transparent, yet durable, layer of cells, where the light first enters. The cornea helps focus light through an opening (pupil). - **