ZOOL 2200: Week 7 Flashcards, Exam 3

Blood: Erythrocytes (Red Blood Cells): Requirements for Erythrocyte Production

A shortage of any of these 3 components can lead to anemia (low RBC counts). Iron: Component of hemoglobin (heme portion) Normal hemoglobin content of blood: • Men: 13-18 gram / dL • Women: 12-16 gram / dL Folic acid: Necessary for DNA replication, thus cell proliferation. Vitamin B12: Necessary for DNA replication, thus cell proliferation. (proliferation = cell grows & division)

Blood: Erythrocytes Structure

Biconcave discs: Provides larger surface area for diffusion of O2 across the membrane. (increase surface area = increase diffusion rate). Thinness of the cell enables O2 to diffuse rapidly between the exterior and innermost regions of the cell (decrease diffusion distance). Flexible membrane: Allows RBCs to travel through narrow capillaries without rupturing.

Blood: Erythrocytes (Red Blood Cells): Erythropoiesis

Erythrocyte production. RBCs have a short lifespan about 120 days (there's no cellular machinery for repair or cell division). Spleen removes most of old erythrocytes from circulation. RBC's must be replaced at rate of 2 to 3 million million cells per second. Erythropoiesis occurs in bone marrow. Pluripotent stem cells in red bone marrow differentiate into different types of blood cells.

Blood: 3 Element Composition: Erythrocytes, Leukocytes, and Platelets

Erythrocytes: Red blood cells. Important in O2 transport. Leukocytes: White blood cells. Immune system's mobile defense units. Platelets: Cell fragments. Important in hemostasis.

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Contraction Sliding Filament Model - Cross Bride

Myosin is a motor protein, it uses energy from ATP, clipping off the phosphate group, to bind to a power stroke, and detach from actin (takes 2 ATP). 1.) Binding of myosin to actin. Inorganic phosphate is released. 2.) Power stroke. Actin gets pulled toward middle of sacomere. 3.) Rigor (myosin in low-energy form). ADP is released. New ATP binds to myosin head. 4.) Unbinding of myosin and actin. ATP is hydrolyzed. 5.) Cocking of the myosin head (myosin in high-energy form). Cycle repeats.

Muscle Physiology: Skeletal Muscle Fiber Structure: Fiber Length Diagram

Normal Resting Length: Optimal thick and thin filament overlap for efficient cross-bridge cycling. Maximum tension can be developed. Decreased Length (Below Normal): Sarcomeres are already contracted. Cross-bridge cycling is less efficient. Tension is decreased. Increased Length (Above Normal): Sarcomeres are stretched apart. Cross-bridge cycling is less efficient. Tension is decreased. (stretch receptors in muscles help prevent overstretching).

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Contraction, Energy supply, Phosphocreatine

Phosphocreatine: Phosphocreatine helps regenerate ATP. Phosphocreatine serves as an immediate source of Pi during exercise. Diagram Info: During muscle relaxation, creatine acquires a phosphate group from ATP to become phosphocreatine. During muscle contraction, phosphocreatine donates its phosphate group to ADP, converting it back into ATP. This process involves just one enzymatic step and is rapid. The level of phosphocreatine in muscle cells is only three to five times that of free ATP. [phosphocreatine] = 3 to 5 X [ATP] Excess creatine is excreted.

Blood: Erythrocytes, Leukocytes, and Platelets, Total Blood Volume

Plasma: 55% of whole blood volume. Buffy coat: 1% of whole blood volume [consists of leukocytes & platelets]. Erythrocytes: 45% of whole blood volume

Blood: Platelets: Hemostasis: Platelet Plug

Starts when von Willebrand factor (vWf) binds to exposed collagen in the damaged wall of vessel. Platelets bind vWF and become sticky. Platelets release ADP, which causes the surface of nearby circulating platelets to become sticky in order to adhere to the first layer of aggregated platelets - a positive feedback loop. Nearby undamaged endothelial cells release prostacyclin and nitric oxide (NO) to prevent platelet aggregation from spreading beyond injured area. Actin-myosin complex contracts to compact and strengthen the plug. Serotonin, epinephrine, and thromboxane A2 released from the platelet plug induce further vasoconstriction. Platelets also produce coagulation factors for clot formation.

Muscle Physiology: Skeletal Muscle Fiber Structure: Sarcomere

Structure: Inside a muscle fiber sarcomeres are aligned end to end. Shortening a sarcomere shortens the entire muscle (top relaxed, bottom contracted). Key Components: M Line: Located in the center, where myosin attaches (M = middle & myosin) (not included in figure). Z Lines: Found at the ends, serving as actin attachment sites (Z at end of the alphabet). H Zone: Area with only thick filaments (H = a fat letter). I Band: Area with only thin filaments. (I = a skinny letter). A Band: Encompasses all of the thick filaments.

Muscle Physiology: Skeletal Muscle Fiber Structure: Strength of Muscle Contractions

The strength of muscle contractions are effected by ... Number of muscle fibers stimulated (more = stronger). Frequency of stimulation (more frequency = more intense). Initial length of muscle fibers [optimal resting length before starting contraction = optimal contraction strength]

Muscle Physiology: Skeletal Muscle Fiber Structure: Myofilaments

Thick Filaments (Myosin) Composition: Myosin molecules form dimers consisting of tail regions (wrapped together), neck, and head region. The head region contains an ATPase site for ATP and an Actin-binding site. Myosin uses energy from ATP to perform muscle contraction and move actin. Thin Filaments (Actin): Composed of actin and two regulatory proteins; tropomyosin and troponin. Each actin molecule has a myosin binding site. G-actin molecules combine to create F-actin, which forms a double helix. Tropomyosin covers myosin binding sites on actin to prevent contraction in relaxed muscles. Troponin is what moves tropomyosin off and on binding sites. Troponin has a Ca+ binding site allowing muscle contraction. Sarcomere: Consists of both thin and thick filaments, including actin and myosin.

Blood: Leukocytes Origins

Ultimately originate from same undifferentiated multipotent stem cells (hematopoietic) in red bone marrow. Granulocytes and monocytes are produced only in bone marrow. Most new lymphocytes are actually produced by lymphocytes already in lymphoid tissues such as lymph nodes and tonsils. Total number of white cells and percentage of each type may vary considerably to meet changing defense needs.

Muscle Physiology: Skeletal Muscle Fiber Structure: Fiber Types Table

(May review lecture 9 slides 33-44, 7:40 timestamp) *important for exam

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Fatigue Diagram

(a) twitches from single APs. (b) eventual drop off in tension as fatigue happens. (c) squeezing grip, first time results in more tension, second time less due to fatigue.

Blood: Leukocytes (WBCs): Basophils

1% of circulating leukocytes. Like eosinophils play a role in parasite defense and allergies. (secrete chemical mediators of inflammation and allergic reactions) Synthesize store and release: Histamine & Heparin. (antihistamine taken for allergies blocks the release of histamine from basophils). (heparin, anticoagulant, enhances inflammatory response, prevents blood from in the area from clotting, better efflux of clotting factors and neutrophils out of bloodstream).

Blood: Leukocytes (WBCs): Eosinophils

1-4% of circulating leukocytes. An increase in circulating eosinophils are associated with: Allergic conditions such as asthma and hay fever. Internal parasite infestations, such as worms. (Secrete enzymes to kill parasites; contribute to tissue damage in allergic reactions).

Muscle Physiology: Skeletal Muscle Fiber Structure: Characteristics of Contractions

2 main types of muscle contractions ... Isotonic: Contraction creates force and causes movement (bench press). Isometric: Contraction creates force without causing movement (wall sit). (Both involve cross-bridge cycling)

Blood: Leukocytes (WBCs): Monocytes

2-8% of circulating leukocytes. Emerge from bone marrow while still immature and circulate for 1 or 2 days before settling down in various tissues in body. Mature and enlarge in resident tissue and become known as macrophages. Macrophages' life span can range from several months to years. Release chemical messengers that start inflammatory response (bring neutrophils to help) (bone marrow releases more monocytes).

Blood: Leukocytes (WBCs): Lymphocytes

20-40% of circulating lymphocytes. Provide immune defense against specifically programed targets. Live about 100-300 days. Three types of lymphocytes: • B lymphocytes secrete antibodies. • T lymphocytes help activate immune system. protect against viruses/cancer. • Null or Natural killer cells secrete factors that lead to the death of infected/tumor cells. protect against viruses/cancer.

Muscle Physiology: Muscles in the Body

3 types ... Skeletal: Body movement (striated, highly arranged, voluntary/conscious control) Cardiac: Pump blood (striated, highly arranged) Smooth: Move material into, out of, and within the body (striated, not as organized, contraction strength lower)

Muscle Physiology: Skeletal Muscle Fiber Structure: Fiber Types

3 types of fibers: Based on contraction speed and resistance to fatigue. fast-twitch glycolytic (anaerobic glycolysis, fast to contract & relax), fast-twitch oxidative (aerobic, medium to contract & relax), slow-twitch oxidative (aerobic, slow to contract & relax)

Blood: Leukocytes (WBCs): Neutrophils

50-80% of circulating leukocytes. Phagocytic specialists (cell eating). Functions: First defenders on scene of bacterial invasion. Very important in inflammatory responses. Scavenge to clean up debris (microorganisms, abnormal cells, foreign particles).

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Contraction Energy Supply

ATP is needed for ... Crossbridge formation. Crossbridge detachment. Calcium reuptake into the sarcoplasmic reticulum. Pumping Na+ out and K+ into the cell.

Blood: Plasma Constituents & Functions: Plasma Proteins

Albumins: Transport many substances non-specifically; contribute most to colloid osmotic pressure 60% of plasma protein. Alpha and Beta Globulins: Transport specific water-insoluble substances; clotting factors; inactive precursor molecules. Gamma Globulins: Antibodies. Fibrinogen: Inactive precursor for the fibrin meshwork of a clot.

Blood: Platelets

Also called thrombocytes. 100,000 - 500,000 per mL blood. Play a large role in hemostasis. Cell fragments are shed from megakaryocytes (in bone marrow): Lack nuclei. Have organelles and cytosolic enzymes for generating energy and synthesizing secretory products. High concentrations of actin and myosin.

Muscle Physiology: Skeletal Muscle Fiber Structure: Regulation of Muscle Contraction Diagram

At Rest: Tropomyosin covers binding sites, preventing cross-bridge formation. Calcium is Present: Moves tropomyosin out of the way results in cross-bridge formation. Power Stroke. Detachment because another molecule of ATP binds. Energized State: Repeated cross-bridge cycling can occur as long as calcium is present, leading to muscle contraction. When calcium is no longer present there is a return to resting conditions.

Blood: Erythrocytes (Red Blood Cells): Erythrocyte Lifecycle

Basic: (Bone marrow → bloodstream → spleen → heme separated & converted to bilirubin → globin recycled → iron carried in blood via transferrin (plasma protein) → bilirubin & iron arrive in liver → bilirubin excreted → iron stored in liver until needed for erythropoiesis) Detailed: Erythrocytes (RBCs) begin in the bone marrow via erythropoiesis. They are released into the bloodstream and 120 days later, they are taken up by the spleen. Heme is separated and converted into bilirubin. Globin (amino acids) are recycled. Iron is carried by transferrin in the bloodstream. Bilirubin and iron end up in the liver. Bilirubin is excreted as bile or ends up in the bloodstream and is excreted in urine. Iron can be stored in the liver using ferritin and released into the bloodstream as transferrin when needed. Dietary iron is picked up by transferrin and delivered to the bone marrow for erythropoiesis. Kidneys Role: Kidneys produce erythropoietin (EPO) in response to low oxygen-carrying capacity. EPO signals the bone marrow to produce more red blood cells. (EPO can be administered to cancer patients or abused by for doping purposes to enhance endurance and performance).

Muscle Physiology: Skeletal Muscle Fiber Structure: Motor Units are All or None

Brain initially estimates number of motor units needed. If more are needed recruitment happens; more or larger motor units stimulated. (box of pillows vs. books).

Muscle Physiology: Skeletal Muscle Fiber Structure: Regulation of Muscle Contraction

Calcium regulates muscle contraction. Relaxed muscle: No calcium. Tropomyosin blocks myosin binding sites. No cross bridge formation. Contracting muscle: Calcium present. Troponin moves tropomyosin. Myosin binding sites exposed. Cross bridge formation.

Muscle Physiology: Skeletal Muscle Fiber Structure: Causes of Muscle Fatigue

Central fatigue = psychological fatigue High-intensity exercises: Build up of lactic acid. Compression of blood vessels. Depletion of acetylcholine (neuromuscular fatigue). Low intensity exercises: Depletion of energy reserves. Other possibilities: Build up of inorganic phosphates (due to frequency phosphate group clipping). Changes in ion distribution.

Blood: Erythrocytes (Red Blood Cells): Polycythemia

Characterized by too many circulating RBCs and elevated hematocrit. Causes problems with viscosity of blood making it difficult to pump - can result in heart failure. Two general types Primary & Secondary.

Blood: Leukocytes

Colorless - lack hemoglobin. Vary in structure, function, and number. Somewhat larger than erythrocytes. Five different types of circulating leukocytes: Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils. [listed order most to least numerous] (Never Let Me Eat Burritos)

Muscle Physiology: Muscle Functions

Controlled muscle contraction allows ... Purposeful movement of the whole body or parts of the body. Allows manipulation of external objects. Propulsion of contents through various hollow internal organs. Emptying contents of certain organs to the external environment.

Muscle Physiology: Skeletal Muscle Fiber Structure: Gating of Sarcoplasmic Reticulum

DHP receptors on T tubules are voltage sensitive ... They change the shape in response to AP. Which opens Ryanodine receptors on sarcoplasmic reticulum. Ca2+ rushes into the sarcoplasm (down electrochemical gradient). (repeated APs = channel stays open longer more leaking = strength of contraction).

Muscle Physiology: Skeletal Muscle Fiber Structure: Excitation-Contraction Coupling

Diagram Orientation: A motor neuron and the muscle fibers it innervates. During excitation-contraction the muscle fibers contract in response to APs coming down motor the motor neuron. The motor end plate is where motor neuron connects to muscle fiber, it contains nicotinic cholinergic receptors. The nicotinic cholinergic receptors are always excitatory - meaning if a motor neuron fires muscles will contract. Diagram Steps: 1.) Acetylcholine (ACh) is released from the axon terminal of a motor neuron and bind to receptors in the motor end plate. This binding elicits an end-plate potential, which triggers an action potential in the muscle cell. 2.) Action potential propagates along the sarcolemma and down T tubules. 3.) The AP triggers Ca2+ release from SR (sarcoplasmic reticulum). 4.) Ca2+ binds to troponin, exposing myosin-binding sites. 5.) Crossbridge cycle begins (muscle fiber contracts). 6.) Ca2+ is actively transported back into lumen of SR following the action potential.

Muscle Physiology: Skeletal Muscle Fiber Structure: Sarcomere & Muscle Contraction

During contraction, actin is pulled across myosin towards the M-line. Z-discs come closer together, leading to the shortening of the I-band and H-zone (HI is the short way to say hello). A-band remain the same (as myosin itself doesn't contract; they pull actin to shorten the sarcomere).

Blood: Platelets: Clot Dissolution

Fibroblasts from surrounding connective tissue form a scar at the vessel defect. Plasmin (fibrinolytic enzyme) dissolves clot: Produced by the liver in inactive form plasminogen. Activated by cascade reaction started by factor XII. Phagocytes remove the products of clot dissolution.

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Contraction, Energy Supply Diagram

First 4 minutes of exercise: First thing used is creatine phosphate for light or intense exercise. Light exercise transitions to aerobic metabolism. Intense transitions to anaerobic glycolysis, building up lactic acid, and causing fatigue.

Blood: Erythrocytes (Red Blood Cells): Hemoglobin

Found only in red blood cells. Each red blood cell has more than 250 million hemoglobin molecules (cell > 250 million). Molecule consists of two parts globin portion & heme groups. Pigment containing iron: Appears reddish when oxygenated. Appears bluish when deoxygenated.

Blood: Erythrocytes (Red Blood Cells): Hemoglobin Structure

Globin portion: Protein composed of four highly folded polypeptide chains. Heme groups: Four iron-containing nonprotein groups. Each is bound to one of the polypeptides. Each can carry 1 molecule of O2.

Blood: Erythrocytes (Red Blood Cells): Erythrocyte Enzymes

Glycolytic enzymes: Necessary for generating the energy needed to fuel active transport mechanisms. Which are involved in maintaining proper ionic concentrations within the cell. Rely on glycolysis for ATP formation. Carbonic anhydrase: * Critical in CO2 transport. Catalyzes reaction that leads to conversion of metabolically produced CO2 into bicarbonate ion (HCO3 - ). (primary form in which CO2 is transported in blood). *(Important for test)

Blood: Erythrocytes (Red Blood Cells): Erythropoiesis Diagram

Hematopoietic stem cells (i.e. pluripotent) originate in the bone marrow. They can differentiate into myeloid or lymphoid stem cells. Lymphoid stem cells become lymphocytes. Myeloid stem cells may become: Erythrocytes (red blood cells), Monocytes, Neutrophils, Basophils, Eosinophils, Megakaryocytes (which shed platelets), Reticulocytes (still have a nucleus). Reticulocytes mature into erythrocytes (lose nucleus, filled with hemoglobin). Erythrocytes are released into the bloodstream.

Blood: Platelets: Hemostasis: Vascular Spasm

Injured vessels vasoconstrict slowing blood flow: The sympathetic nervous system causes vasoconstriction (SNS innervates arterials and veins). Damaged endothelial cells release a chemical messenger, causing smooth muscle lining, arterial, and veins to also vasoconstrict.

Muscle Physiology: Skeletal Muscle Fiber Structure: Isometric Vs. Isotonic Contraction

Isometric Contractions: Muscle generates tension but not movement. Isotonic Contractions: Muscle shortens, generates tension, and produces movement. (Both involve cross-bridge cycling)

Muscle Physiology: Skeletal Muscle Fiber Structure: Number of Muscle fibers Stimulated

Motor unit X innervates = 5 fibers Motor unit Y innervates = 7 fibers (stronger motor unit, innervates more fibers resulting in more tension) X + Y = even more tension

Muscle Physiology: Skeletal Muscle Fiber Structure

Multinucleated Sarcolemma = plasma membrane Sarcoplasm = cytoplasm 2 types of myofilaments: Thick & Thin

Muscle Physiology: Skeletal Muscle Structure

Muscle fibers are the cellular units of muscles. They extend the entire length of the skeletal muscle. Are multinucleated due to the fusion of multiple cells. Hypertrophy is the process of increasing cell size in muscles - involves the existing set number of muscle fibers. Do not regrow if damaged.

Muscle Physiology: Skeletal Muscle Fiber Structure: Switching Fiber Types

Muscles are a mixture of fiber types. Training can cause changes in fiber types: Endurance/aerobic training switches fast-twitch glycolytic to fast-twitch oxidative. Strength training causes switch from fast-twitch oxidative to fast-twitch glycolytic.

Blood: Leukocytes Types

Polymorphonuclear granulocytes [many-shaped nucleus; granule-containing cells]: Neutrophils: Granules are neutral and show no dye preference (Neutral; take up red & blue dye) (phils = granules). Eosinophils: Granules have an affinity for the red dye eosin (eosin = red dye) (phils = granules). Basophils: Granules have an affinity for a basic blue dye (baso = basic blue) (phils = granules). Mononuclear Agranulocytes [single-nucleus; cells lacking granules]: Monocytes: Have oval or kidney-shaped nucleus. Lymphocytes: Smallest of the leukocytes; usually have large spherical nucleus that occupies most of cell.

Blood: Platelets: Hemostasis

Prevents blood loss from a broken blood vessel. Involves three major steps: 1.) Vascular spasm: Reduces blood flow through a damaged vessel. 2.) Formation of a platelet plug: Further reduces blood flow. 3.) Blood coagulation (clotting): Transformation of blood from a liquid into a solid gel.

Blood: Erythrocytes (Red Blood Cells): Hemoglobin Binding

Primary role is to carry O2: 98.5% of O2 in blood is bound to hemoglobin. (O2 not water-soluble, needs carrier protein to secure enough for cellular respiration). Also combines with: Carbon dioxide: takes it back to lungs for removal. Acidic hydrogen: ion portion (H+) of ionized carbonic acid - buffers pH. Carbon monoxide: preferentially binds to hemoglobin (over O2 - carbon monoxide poisoning). Nitric oxide: vasodilator produced in lungs and carried to peripheral tissues.

Blood: Erythrocytes (Red Blood Cells): Polycythemia Primary, Secondary, and Relative

Primary: Caused by tumorlike condition of bone marrow. Erythropoiesis proceeds at uncontrolled rate. Secondary polycythemia: Erythropoietin induced adaptive mechanism to improve blood's O2 carrying capacity due to prolonged reduced O2 delivery to the tissues (EPO - signal RBC production) . Occurs normally in people living at high altitudes. Relative polycythemia: Normal amount of RBCs in less plasma (plasma donation). Or dehydration.

Blood: Erythrocytes

Red blood cells (RBCs). Contain no nucleus, organelles, or ribosomes. Structure is well suited to the main function of O2 transport in blood because of their biconcave discs and flexible membrane.

Blood: Erythrocytes (Red Blood Cells): Anemia

Refers to a below-normal O2 carrying capacity of the blood. Characterized by low hematocrit = low RBC count. Causes of anemia: Nutritional anemia - often iron deficiency. Pernicious anemia - lack of B12 (genetic condition, veganism). Aplastic anemia - destruction of bone marrow (radiation exposure). Renal anemia - renal damage ↓ erythropoietin (kidney malfunction, low EPO production). Hemorrhagic anemia - excessive blood loss. Hemolytic anemia - hemolysis of circulating RBCs (destruction of circulating of RBCs, may be due to toxins)

Blood: Platelets: Hemostasis: Clot Formation

Reinforces platelet plug; converts blood in the vicinity of vessel injury into a nonflowing gel. Clotting factors are always present in blood plasma in inactive precursor form: Vessel damage that exposes the collagen initiates a cascade of reactions that involve successive activation of clotting factors. Convert fibrinogen into fibrin by means of the intrinsic clotting pathway.

Blood: Platelets, Life Span, Storage, and Hormonal Production

Remain functional for about 10 days. Removed from circulation by tissue macrophages (via phagocytosis). About ⅓ are stored in blood-filled spaces in the spleen: They are released when needed by sympathetically induced splenic contraction. Thrombopoietin: A hormone produced by the liver that increases the number of megakaryocytes and, therefore, increases platelet production (liver = regulates platelet production).

Blood: Volume

Represents about 8% of total body weight. Consists of three types of specialized cellular elements suspended in plasma. Average volume: 5 liters in women. 5.5 liters in men.

Muscle Physiology: Skeletal Muscle Fiber Structure: Fiber Length

Resting length of muscle is where fiber can develop the greatest amount of tension. Due to the maximum overlap of thick filament and thin filaments that produce good cross-bridges. Most muscles are at the optimum length.

Muscle Physiology: Muscle Contraction Sliding-Filament Model

Sarcomere shortens. Thin filaments being pulled towards the M-line: A band - no change I band - shortens H zone shortens

Muscle Physiology: Skeletal Muscle Fiber Structure: Sarcoplasmic Reticulum & Transverse Tubules

Sarcoplasmic Reticulum: Specialized Endoplasmic Reticulum. Terminal cisternae sequester Ca+ (intracellular storage site for Ca+, regulate contractions). Transverse tubules: Continuation of the plasma membrane. Allow action potentials to reach the cell interior.

Blood: Platelets: Clotting Cascade

Series of steps involving 12 plasma clotting factors that lead to the final conversion of fibrinogen into a stabilized fibrin mesh. May be triggered by: Intrinsic pathway: Involves 7 separate steps. (more steps = less likely to form a clot where there is no damaged vessel). Set off when factor XII (12), Hageman factor, is activated by coming into contact with exposed collagen in the injured vessel or a foreign surface, such as a glass test tube. Extrinsic pathway: Requires only 4 steps. Requires contact with tissue factors external to the blood. Tissue thromboplastin is released from traumatized tissue which directly activates factor X (extensive tissue damage, anti-clotting medication being administered to avoid inappropriate clots forming). *(For test: which system has more stems, know thrombin turns fibrinogen to fibrin, and multiple steps mean multiple spots for regulation and amplification)

Muscle Physiology: Skeletal Muscles, Origin & Insertion

Skeletal muscles can only pull, not push. Muscles work in antagonistic pairs (one contracts & one relaxes). Origin: Portion of muscle with attachment to stationary bone. Insertion: Portion of muscle with attachment to the movable bone.

Blood: Erythrocytes (Red Blood Cells): Filtering and Destruction of Erythrocytes

Spleen filters and removes old erythrocytes: Spleen macrophages filter blood by phagocytosis of old fragile RBCs. Liver metabolizes byproducts from breakdown of erythrocytes: Hemoglobin catabolized ... After iron removed, heme → bilirubin. Bilirubin released into bloodstream. Travels to liver for further metabolism. Products of bilirubin catabolism secreted in bile to intestinal tract or released into bloodstream and excreted in urine.

Muscle Physiology: Skeletal Muscle Fiber Structure: Fiber Types, Sprinter vs. Marathon Runner

Sprinters: Predominantly have fast-twitch glycolytic fibers. Individual muscle fibers are larger in diameter. Marathon Runners: Not fewer muscle fibers, but more slow-twitch fibers which have smaller diameters. Tend to have lean, long muscles (for endurance).

Muscle Physiology: Skeletal Muscle Fiber Structure: Frequency of Stimulation

Twitch: Muscle completely relaxes between contractions. Summation: Muscle doesn't relax before second stimulation and contraction becomes stronger. Tetanus: Muscle doesn't relax between numerous stimulations and a sustained contraction occurs.

Muscle Physiology: Skeletal Muscle Fiber Structure: Twitch, Summation, and Tetanus Diagram

Twitch: Single action potential leads to calcium release and cross-bridge cycling, tension develops, calcium is reabsorbed into the sarcoplasmic reticulum, and relaxation. Summation: Multiple action potentials before complete relaxation. More calcium is released, cross-bridge cycling, and stronger contractions. Some calcium is reabsorbed between stimuli. Incomplete Tetanus: Continuous stimulation with a slight relaxation between contractions. Muscle feels almost fully contracted. Complete Tetanus: High-frequency stimulation without relaxation. Maximum tension is sustained until stimulation stops, then relaxation begins.

Blood: Plasma Constituents & Functions

Water (90%): Transport medium, carries heat. Electrolytes (1%): Needed for membrane excitability; osmotic distribution of fluid between ECF and ICF; buffer pH changes. (ex: Na+, K+, Cl-, Ca+) Nutrients, wastes, gases, hormones (1-3%): Transported in blood; blood gas CO2 plays a role in acid-base balance. Plasma proteins (6-8%): In general, exert an osmotic effect important in the distribution of ECF between vascular and interstitial compartments; buffer pH changes.

Muscle Physiology: Skeletal Muscle Fiber Structure: Muscle Contraction, Energy Supply, When Phosphocreatine & ATP Run Out

When phosphocreatine and ATP run out ... Quick energy from: Anaerobic glycolysis Slower energy from: Aerobic metabolism Diagram Information: Anaerobic Glycolysis: Glucose is converted to pyruvate. In the absence of oxygen, pyruvate becomes lactate (lactic acid). This process is fast but leads to fatigue quickly. Makes a some ATP. Aerobic Metabolism: Requires oxygen for the electron transport chain. Can use glucose or fatty acids for energy. Significantly more ATP produced. More efficient but slower, suitable for less intense muscle contraction.

Blood: Immune System & Leukocytes

White blood cells. Mobile units of body's immune defense system. Immune system: Made of leukocytes, their derivatives (chemical messengers), and variety of plasma proteins. Recognizes and destroys or neutralizes materials within body that are foreign to "normal self". Functions: Defends against invading pathogens. Identifies and destroys cancer cells that arise in body. Functions as a "cleanup crew" that removes worn-out cells and tissue debris.