physiology exam 3
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
