physiology exam 3

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Describe excitation-contraction coupling in heart muscle

Action potential spreads through gap junctions, Ca2+ released from plasma membrane and SR, Ca2+ binds to troponin, cross bridge cycle

Describe the banding pattern of a myofibril

Alternating thick and thin bands that create striations

minute ventilation

volume of air breathed in and out in one minute

alveolar ventilation

volume of air exchanged between the atmosphere and the alveoli per minute

fenestrated capillaries

wide intercellular pores covered by layer of mucoprotein to restrict passage of certain molecules

Vasodialation

widening of blood vessels, decrease blood pressure

congestive heart failure

Congestive heart failure- cardiac output is not sufficient to maintain blood flow required by the body

how to calculate Mean Arterial Pressure

DBP = 1/3 (SBP-DBP)

flow of blood through the heart in pulmonary circuit

Deoxygenated blood enters the right side through vena cavae -> right atrium -> right AV valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk and arteries -> lungs

Explain excitation-contraction coupling in skeletal muscles

Electrical excitation of the muscle fiber triggers the release of Ca2+ from the sarcoplasmic reticulum, Ca2+ binding to troponin leads to contraction

sarcomere

Functional unit of contraction, between two z lines

categories of hypoxia

Hypoxic Anemic Circulatory histotoxic

how exercise training affects skeletal muscles

Increased ability to use fatty acids as fuel and increased intracellular triglyceride storage, increase capillary density, increase in number of mitochondria, increase in Krebs Cycle enzymes, muscle does not change in size

relationship between stroke volume and venous return

Increased venous return increases end diastolic volume which increases stroke volume

Differentiate between extrinsic pathway of coagulation and intrinsic pathway of coagulation

Intrinsic- activated by exposed collagen Extrinsic- released from damaged tissue

structure of myocardium

Mass of cardiac muscle cells connected to each other by gap junctions

Describe skeletal muscle summation

Muscle stimulated again before relaxation

ECG waves

P wave- depolarization of atria QRS wave- depolarization of ventricles T wave- repolarization of ventricles

how does Boyle's law relate to pressure and volume in lungs

Pressure difference between two areas drive air flow into and out of the lungs

regulation of red blood cell production

Reduced oxygen-carrying capacity of RBCs -> Erythropoietin (EPO) produced in kidneys -> more RBCs developed in red bone marrow -> increased oxygen-carrying capacity of RBCs

tetanus

a sustained muscular contraction resulting from a rapid series of nerve impulses

motor end plate

area of the muscle fiber sarcolemma where a motor neuron stimulates skeletal muscle

role of coagulation proteins in homeostasis

cause blood clotting

continuous capillaries

cells are closely joined together, no/narrow intracellular channels

single unit smooth muscle

cells electrically linked by gap junctions, act as one unit

H zone

central region of A band, contains only THICK (not overlapped by thin) at center of sarcomere

isotonic muscle contraction

change in muscle length (concentric or eccentric)

Hyperoxia

condition of having an above-normal arterial PO2, only occur when breathing supplemental O2, can be dangerous

hypoxia

condition of having insufficient O2 at the cell level

A band

contains both thick and thin filaments

three types of capillaries

continuous, fenestrated, discontinuous

Differentiate between thick and thin muscle fibers

Thick- myosin Thin- actin

sliding filament theory

contraction is accomplished by thin filaments from opposite side of each sarcomere sliding closer together between thick filaments

causes of atherosclerosis

damage to endothelium such as smoking, hypertension, high blood cholesterol, diabetes

muscle fatigue

decline in muscle tension as a result of pervious contractile activity, even though stimulation continues

atrophy

decrease in size of muscle cells

function of arterioles

distribute cardiac output among systemic organs depending on needs, control by intrinsic and extrinsic factors

autorhythmic cells

do not contract, initiate action potentials and spread impulse throughout the heart

internal respiration

exchange of O2 and CO2 between the bloodstream and tissues

external respiration

exchange of O2 and CO2 between the external environment and the cells of the body

Fast-glycolytic (type IIx) fibers

fewer capillaries and mitochondria than slow- twitch, not as much myoglobin, large store of glycogen and high concentration of glycolytic enzymes which enable them to metabolize anaerobically

tension

force exerted on an object by contracting muscle

load

force exerted on the muscle by weight of object

control of muscle tension by nervous system

frequency of stimulation, motor unit recruitment

discontinuous capillaries

great distance between cells

Slow-oxidative (type I) fibers

have a rich capillary supply, numerous mitochondria and aerobic respiratory enzymes, and a high concentration of myoglobin

risk factors of atherosclerosis

high blood cholesterol

hypertrophy

increase in size of muscle cells

significance of recruitment of motor neurons

increased number of active motor units, increase force of contraction

function of gamma motor neurons

innervate muscle spindle

Fast-oxidative glycolytic (type IIa) fibers

intermediate fibers fast- twitch fibers, high oxidative capacity so more resistant to fatigue

structure of veins

large radius offers little resistance to blood flow, valves. has three layers (tunica externa, tunica media, tunica interna)

how lung compliance affects breathing

less compliant the lings are, the more work is required to produce a given degree of inflation

M line

line at center of thick filaments (A band) serve to anchor thick filaments to help them stay together during a contraction

how elasticity affects breathing

lungs return to initial size after being stretched

isometric muscle contraction

muscle cannot shorten because load is too great, can be voluntary

energy sources for skeletal muscle

muscle glycogen, muscle triglyceride, plasma free fatty acids, plasma glucose

eccentric muscle contractions

muscle lengthens

concentric muscle contractions

muscle shortens

vasoconstriction

narrowing of blood vessels, increase blood pressure

structure of arteries

no valves, more muscular, has three layers (tunica externa, tunica media, tunica interna)

circulatory shock

occurs when blood pressure falls so low that adequate blood flow to the tissues can no longer be maintained

I band

only contains thin filaments

flow of blood through the heart in systemic circuit

oxygenated blood enters left side through pulmonary veins -> left atrium -> left AV valve -> left ventricle -> aortic semilunar valve -> aorta -> tissues

atmospheric pressure

pressure exerted by the weight of the gas in the atmosphere

intra-alveloar pressure

pressure inside lungs

roles of creatine in muscle physiology

produced in liver and kidneys, can be supplemented to increase muscle weight, strength, and performance during short term, high intensity workouts

control of muscle tension by muscle

properties of skeletal muscle(length of fiber at onset of contraction, type of skeletal muscle, extent of fatigue, x-sectional of fiber)

ECG

record of overall spread d electrical activity through the heart

significance of pulmonary surfactant

reduces surface tension, helps maintain lung stability

roles of troponin

regulatory protein, 3 units that bind to tropomyosin, bind to actin, binds with Ca2+

roles of tropomyosin

regulatory protein, resting, covers myosin binding sites blocking interaction

maintenance of blood volume by aldosterone

responds to low blood pressure and low blood flow to kidneys, regulated by Renin-angiotensin aldosterone system, increases reabsorption of Na+

maintenance of blood volume by ADH

responds to low blood volume/ increased blood osmolarity, increases water retention

muscle twitch

response of a single muscle fiber to a single action potential

function of veins

return blood to heart, blood reservoir, low pressure system

motor unit

single motor neuron and all the muscle fibers it innervates

function of capillaries

sites of exchange between blood and surrounding cells

structure of arterioles

smaller diameter than arteries

Compare cardiac, smooth, and skeletal muscle-Troponin in excitation-contraction coupling

smooth -no skeletal/ cardiac- yes

function of arteries

take blood away from the heart, low resistance elastic conduits, pressure reservoir

Boyle's law

the pressure exerted by a gas varies inversely with the volume of the gas (p=1/v)

structure of capillaries

thin walled, extensively branches, precapillary sphincters

function of muscle spindle

to sense muscle length, resist tendency for passive stretch of muscles by gravitational forces when person is upright

causes of hypertension

too little blood to fill vessels, heart is too weak to drive blood

Explain the function of T tubules

tunnels open to the extracellular environment of muscle cell. able to conduct action potentials

causes of muscle fatigue

type of skeletal muscle, intensity/duration, individual fitness

multi-unit smooth muscle

units must be separately stimulated by nerves to contract, no gap junctions

alpha and gamma co-activation

upper motor neurons will simultaneously stimulate alpha motor neurons that innervate the muscle (extrafusal) fibers to contract and gamma motor neurons that innervate the muscle spindle (intrafusal fibers) to contract at the same time

role of creatine phosphate in muscle physiology

utilized at onset of contractile activity, limited by stores in body, phosphorylates ADP to ATP in muscles

composition and function of plasma

-90% water- dissolves materials, acts as fluid for transport -7-9% proteins- maintain osmotic pressure of blood (albumins), lipid transport, immunity (antibodies), clotting factors, various enzymes

describe muscle relaxation

-AP stops -Active reuptake of Ca2+ into sarcoplasmic reticulum by Ca2+/ATP pump

function of gap junctions in cardiac muscle cells

-Action potentials pass between cells through gap junctions -Any cell in myocardium can stimulate all cells in the myocardium- behaves as a single functional unit

function of the lymphatic system

-Aids immune system -Removal of interstitial fluid and return unidirectionally to heart -Absorbs and transports fatty acids

explain the cross-bridge cycle

-Resting fiber, cross bridge is not attached to actin -Cross bridge binds to actin -P is released, causing conformational change in myosin -Power stroke causes filaments to slide, ADP released -New ATP binds to myosin head, allowing it to release from actin -ATP is hydrolyzed causing cross bridge to return to original orientation

Compare the different characteristics of skeletal, smooth, and cardiac muscle

-Skeletal- voluntary, striated -Cardiac- only found in the heart, involuntary striated -Smooth- components of hollow organs and tubes, unstriated, involuntary

different types of skeletal muscle fibers

-Slow-oxidative (type I) -Fast-oxidative glycolytic (type IIa) -Fast-glycolytic (type Iix)

Explain the roles of ATP in muscle contraction

-Splitting of ATP by myosin ATPase provides energy for power stroke -Binding of new ATP to myosin lets cross bridge detach from actin filament so cycle can be repeated -Active transport of Ca2+ back into sarcoplasmic reticulum, return to resting state

patellar knee jerk reaction as it relates to muscle spindles

-Striking patellar ligament stretches tendon and quadriceps femoris muscle -Spindle is stretched, activating sensory neuron -Sensory neuron activates alpha motor neuron -Alpha motor neuron stimulated extrafusal muscle fibers to contract

length tension relationship of skeletal muscles

-Tension is maximal when length of sarcomere is between 2.0 and 2.25 micro meters -When the sarcomere length is shorter than 2.0 μm, the force generated by muscle contraction declines with decreasing sarcomere length -When the sarcomere lengths are greater than about 2.2 μm, the tension produced by the muscle contraction decreases with increasing sarcomere length

structure of smooth muscle

-Thick myosin filaments -Thin actin filaments- has tropomyosin, LACK troponin -Intermediate filaments- do not directly participate in contraction, form part of cytoskeletal framework that supports cell shape

structure of alveoli

-Thin-walled inflatable sacs -Pulmonary capillaries encircle each alveolus -Can be type I or type II

two types of heart cells

-auto rhythmic cells -contractile cells

peripheral chemoreceptors

-found in carotid and aortic bodies -respond to changes in arterial blood -stimulated by PO2, PCO2, H+

structure of the heart

-hollow, muscular organ located in thoracic cavity -4 chambers (2 atria, 2 ventricles) -Two sets of valves (atrioventricular and semilunar)

central chemoreceptors

-located in medulla -respond to changes in brain extracellular fluid H+ (H+ from increase in PCO2)

Explain how the lymph and lymphatic system relate to the blood and cardiovascular system

-lymphatic system transports fluid from the interstitial space back to the blood through a system of lymphatic vessels. -lymph is eventually returned to the vascular system at the subclavian veins

homeostasis (circulatory system)

-prevents blood loss from a broken blood vessel -three steps (vascular spasm, formation of platelet plug, blood coagulation)

how valves open and close

-when pressure is greater behind the valve, it OPENS -When pressure is greater in front of the valve, it CLOSES

process of expiration

-Relaxation of the diaphragm muscle -Decrease lung volume -Increases Intra-alveolar pressure above atmospheric pressure -Air leaves lungs

order of recruitment of muscle fiber types

1. slow-oxidative fibers 2. fast-oxidative fibers 3. fast-glycolytic fibers

Describe the function of skeletal muscle

-Movement of the body -Posture -Generation of body heat -Movement of substances (urinary tract) -Nutrient reserves -Support soft tissues and organs

Distinguish between the systemic and the pulmonary circulation.

-Pulmonary circulation- brings deoxygenated blood to lungs -Systemic circulation- brings oxygenated blood to tissues

Describe the different levels of muscle structure

-Muscle- number of muscle fibers bound by connective tissue -Muscle fiber- muscle cell -Myofibrils- contractile element of muscle fiber -Myofilaments- thick/thin

functions of the respiratory system

-Obtain O2 for use by the body's cells and to eliminate the CO2 the body cells produce -Vocalization -Acid/base balance

Compare cardiac, smooth, and skeletal muscle- voluntary/involuntary

cardiac/smooth-involuntary skeletal- voluntary

Explain the power stroke

-Attachment of a myosin cross bridge to a thin filament -Swiveling of myosin = power stroke -Detachment of the cross bridge from the thin filament -Reattach to new actin binding site -Repeat cycle

Explain how the pressure differences within the heart chambers are responsible for blood flow during the cardiac cycle.

-Blood pressure rises above pressure in atria- atrioventricular valves shut -Blood pressure in ventricles exceeds pressure of arteries- blood flow out of ventricles -Pressure in ventricles drops below arterial pressure- AV values open allowing blood to flow into ventricles

components of the cardiovascular system

-Blood- transport medium (cells suspended in fluid) -Heart- pump (drives circulation) -Blood vessels- tubing that conducts blood through circulation

excitation-contraction coupling in smooth muscle

-Calcium from sarcoplasmic reticulum and extracellular environment increase intracellular calcium concentrations -Calcium binds to calmodulin (no troponin) -Activates myosin light chain kinase (MLCK) -MLCK phosphorylates myosin light chains -Phosphorylated myosin forms cross ridges with actin to initiate contraction

structure of myosin

-Component of thick filament -Heads form cross bridges between thick and thin filaments -Myosin heads have actin binding site, ATP binding site, ATPase

RBC

-Contains hemoglobin- binds to oxygen -No nucleus or organelles -Biconcave disc- provides larger surface area for diffusion of O2 -Flexible membrane- allows RBCs to travel through narrow capillaries without rupturing

process of inspiration

-Contraction of diaphragm -Increase lung volume -Intra-alveolar pressure decreases below atmospheric pressure -Air enters the lungs

Describe factors that contribute to venous return against gravity

-Driving pressure from cardiac contraction -Sympathetically induced venous vasoconstriction -Skeletal muscle activity- contraction acts to pump veins, Increases venous return with increased activity -Effect of venous valves- prevent backflow of blood

components of blood

-Erythrocytes- red blood cells -Leukocytes- white blood cells -Platelets- cell fragments used in clotting -Plasma- liquid portion of blood (contains proteins, nutrients, hormones, electrolytes)

formed elements of blood

-Erythrocytes- red blood cells -Leukocytes- white blood cells -Thrombocytes- platelets

Explain the force velocity curve of skeletal muscle

-For muscles to contract, they must generate force that is greater than the opposing forces -The greater the force, the slower the contraction

effects of Golgi tendon organs

-Found in tendons- prevent separation of bone and muscle -Inhibitory synapses on motor neurons of the contracting muscle -Excitatory synapses on motor neurons of ipsilateral antagonists

cardiac cycle during systole

-Isovolumetric contraction- ventricles contract but no blood is ejected -Ejection- blood flows out of ventricles

cardiac cycle during diastole

-Isovolumetric relaxation- semilunar valves prevent backflow, no change in ventricular volume -Rapid filling- Av valves open, allowing blood to flow into ventricles -Atrial contraction

phases of muscle twitch

-Latent period -Contraction time- increase muscle tension to peak -Relaxation time - decrease muscle tension

Explain the refractory period of the heart, and it's importance

-Long refractory period due to long duration of action potentials in the heart -Summation of contraction is prevented -Allows time for the heart to refill

effects of intensity of energy source for skeletal muscles

-Mild exercise- 10% plasma glucose, 80% PLASME FREE FATTY ACIDS, 10% muscle triglyceride -Moderate exercise- 5% plasma glucose, 25% plasma free fatty acids, 25% mucle triglyceride, 45% MUSCLE GLYCOGEN -Heavy exercise- 10% plasma glucose, 10% plasma free fatty acids, 10% muscle triglyceride, 70% MUSCLE GLYCOGEN

4 steps of external respiration

1. Ventilation- movement of air in and out of the lungs 2. Exchange with air- O2 and CO2 are exchanged between air 3. Transport- blood transports O2 and CO2 between lungs and tissues 4. Exchange with tissues- O2 and CO2 are exchanged between tissues and blood

contractile cells

99% of cardiac muscle cells, do mechanical work of pumping, normally do not initiate own action potentials

calculation for alveolar ventilation

= (tidal volume - dead space) x respiratory rate

calculaitiom for minute ventilation

=tidal volume (ml/breath) x respiratory rate (breaths/min)

role of platelets in homeostasis

aggregate on contact with exposed collagen in damaged wall of the vessel, release ADP which causes the surface of nearby circulating proteins to become sticky

how surface tension affects breathing

air in lungs is moist, increasing surface tension and potentially leading to kung collapse at expiration

hypertension

blood pressure above 140/90 mm HG, can be primary or secondary

hypotension

blood pressure below 100/60 mm Hg

mechanism leading to tetanus

calcium is constantly in the cytoplasm, multiple twitches sent to fiber before one contraction completes so that 2nd added to 1st

Compare cardiac, smooth, and skeletal muscle-stimulation

cardiac- gap junctions smooth-alpha motor neuron skeletal- autonomic neurons

Compare cardiac, smooth, and skeletal muscle- gap junctions

cardiac-yes smooth- only single unit skeletal- no

Compare cardiac, smooth, and skeletal muscle-Source of calcium in excitation-contraction coupling

cardiac/skeletal- sarcoplasmic reticulum smooth- sarcoplasmic reticulum AND extracellular

Compare cardiac, smooth, and skeletal muscle- striation

cardiac/skeletal- yes smooth-no


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