Lab 2 PhysioEx Notes Flashcards
the heart’s ability to trigger its own contractions is called …
autorhythmicity
autorhythmicity occurs because the plasma membrane in cardiac pacemaker muscle cells has reduced permeability to … ions but still allows … and … ions to slowly leak into cells
potassium;
sodium; calcium
this leakage of sodium and calcium ions causes the muscles to slowly depolarize until the action potential … is reached and … channels open, allowing … entry from the extracellular fluid.
threshold; L-type calcium;
Ca2+
the spontaneous depolarization-repolarization events occur in a regular and continuous manner in cardiac pacemaker muscle cells, leading to … in the majority of cardiac muscle
cardiac action potentials
There are five main phases of membrane polarization in a cardiac action potential:
phase 0 is similar … in the neuronal action potential. depolarization causes voltage-gated sodium channels in the cell membrane to open, increasing the flow of… ions into the cell and increasing the membrane potential.
🙄depolarization; sodium
There are five main phases of membrane polarization in a cardiac action potential:
in phase 1, the open sodium channels begin to inactivate, decreasing the flow of sodium ions into the cell and causing the membrane potential to fall slightly. at the same time, … close and … channels open. the subsequent decrease in the flow of potassium out of the cell and increase in the flow of calcium into the cell act to … the membrane and curb the fall in membrane potential caused by the inactivation of sodium channels
voltage-gated potassium channels;
voltage-gated calcium;
depolarize
There are five main phases of membrane polarization in a cardiac action potential:
in phase 2, known as the …, the membrane remains in a depolarized state. potassium channels stay closed, and… (…-type) calcium channels stay open. this plateau lasts about … s, or … ms
plateau phase;
long-lasting; L-type;
0.2; 200
There are five main phases of membrane polarization in a cardiac action potential:
in phase 3, the membrane potential gradually falls to more negative values when a second set of … that began opening in phases 1 and 2 allows significant amounts of … to flow out of the cell. the falling membrane potential causes … to close, reducing the flow of calcium into the cell and repolarizing the membrane until the resting potential is reached.
potassium channels;
potassium;
calcium channels
There are five main phases of membrane polarization in a cardiac action potential:
in phase 4, the … is again established in cardiac muscle cells and is maintained until the next depolarization arrives from neighboring cardiac … cells
the total cardiac action potential lasts …-… ms
resting membrane potential;
pacemaker;
250-300
recall that … occurs when a skeletal muscle is stimulated with such frequency that muscle twitches overlap and result in a stronger contraction than a single muscle twitch. when the stimulations are frequent enough, the muscle reaches a state of …, during which the individual muscle twitches cannot be distinguished
wave summation;
fused tetanus
tetanus occurs in skeletal muscle because skeletal muscle has a relatively short … - a period during which action potentials cannot be generated no matter how strong the stimulus
absolute refractory period
unlike skeletal muscle, cardiac muscle has a relatively … refractory period and is thus incapable of … In fact, cardiac muscle is incapable of reacting to any stimulus before approximately the middle of phase … and will not respond to a normal cardiac stimulus before phase …
long;
wave summation;
3;
4
the period of time between the beginning of the cardiac action potential and the approximate middle of phase 3 is the …
the period of time between the absolute refractory period and phase 4 is the …
absolute refractory period;
relative refractory period
the total refractory period of cardiac muscle is …-… milliseconds - almost as long as the contraction of the cardiac muscle
200; 250
phase 2 of the cardiac action potential, when the calcium channels remain open and potassium channels are closed, is called the …
plateau phase
which of the following is true of the cardiac action potential? the cardiac action potential is … than the skeletal muscle action potential
longer
the main anatomical difference between the frog heart and the human heart is that the frog heart has a …
single, fused ventricle
which of the following statements about the contractile activity is true?
the smaller waves represent the …
contraction of the atria
during which portion of the cardiac muscle contraction is it possible to induce an extrasystole?
during …
relaxation
the amplitude of the ventricular systole did not change with the more frequent stimulation because a new contraction could not begin until the …
relaxation phase
which of the following do you think contribute to the inability of cardiac muscle to be tetanized? the … of the cardiac action potential
long refractory period
given the function of the heart, why is it important that cardiac muscle cannot reach tetanus? the ventricles must … and … with each beat to pump blood
contract; relax fully
an extrasystole corresponds to an extra …
ventricular contraction
at rest both the sympathetic and parasympathetic NS are working but the … branch is more active
parasympathetic
stimulation of the sympathetic nervous system increases the … and … of contraction of the heart
rate; force
stimulation of the the parasympathetic nervous system … the heart rate without directly changing the force of contraction. the … nerve (cranial nerve …) carries the signal to the heart.
decreases; vagus; X;
if stimulation of the vagus nerve (…) is excessive, the heart will …
vagal stimulation;
stop beating
A short time after the heart stops beating due to excessive vagal stimulation, the ventricles will begin to beat again. the resumption of the heartbeat is referred to as … and can be the result of … or initiation of a rhythm by the …
vagal escape;
sympathetic reflexes;
Purkinje fibers
the … is a cluster of autorhythmic cardiac cells found in the right atrial wall in the human heart. it has the fastest rate of spontaneous depolarization, and for that reason, it determines the heart rate and is therefore referred to as the heart’s ….
sinoatrial node (SA node); pacemaker
in the absence of parasympathetic stimulation, sympathetic stimulation, and hormonal controls, the SA node generates action potentials … times per min
100
the branch of the autonomic nervous system that dominates during exercise is the …
sympathetic branch
vagal escape probably involves …
sympathetic reflexes
humans are …, which means that the human body maintains an internal body temp within the 35.8-38.2 degrees C range even though the external temp is changing
homeothermic
when the external temperature is elevated, the hypothalamus is signaled to activate … mechanisms, such as … and …, to maintain the body’s internal temperature
heat-releasing;
sweating; vasodilation
during extreme external temperature conditions, the body might not be able to maintain homeostasis and either … (elevated body temperature) or … (low body temperature) could result
hyperthermia; hypothermia
the frog is a .. animal. its internal body temp changes depending on the temp of its external enviro bc it lacks internal homeostatic regulatory mechanisms
poikilothermic
ringer’s solution, aka …, consists of essential electrolytes (…, …, …., …, and ….) in a physiological solution and is required to keep the isolated, intact heart viable
ringer's irrigation; chloride; sodium; potassium; calcium; magnesium
the electrolytes in a ringer’s solution are required to provide for
autorhymicity
the general name for the process that maintains the internal body temperature in humans is …
homeostasis
what effect do you think a fever of 104 degrees F would have on heart rate? … in heart rate
increase
in the 5 degree C Ringer’s solution, the frog heart … than baseline
beat slower
in the 32 degree C Ringer’s solution, the frog heart … than baseline
beat faster
if the human heart were experiencing hypothermia, what do you think would be the effect on heart rate?
… in heart rate
decrease
without the Ringer’s solutions … would not occur
spontaneous cardiac action potentials
the sympathetic nervous system is activated in times of ‘fight or flight,’ and sympathetic nerve fibers release … (also known as …) and … (also known as …) at their cardiac synapses
norepinephrine; noradrenaline; epinephrine; adrenaline
norepinephrine and epinephrine increase the frequency of action potentials by binding to … receptors embedded in the plasma membrane of … cells. working through a … mechanism, binding of the ligand opens sodium and calcium channels, increasing the rate of depolarization and shortening the period of repolarization, thus increasing the heart rate.
ß1 adrenergic; sinoatrial (SA) node;
cAMP second messenger
the parasympathetic nervous system, our ‘resting and digesting branch,’ usually dominates, and parasympathetic nerve fibers release … at their cardiac synapses. acetylcholine decreases the frequency of action potentials by binding to muscarinic cholinergic receptors embedded in the plasma membrane of the … cells
acetylcholine;
SA node
acetylcholine indirectly opens … channels and closes … and … channels, decreasing the rate of …, and thus, decreasing …
potassium;
calcium; sodium;
depolarization;
heart rate
chemical modifiers that inhibit, mimic, or enhance the action of acetylcholine in the body are labeled …
cholinergic
chemical modifiers that inhibit, mimic, or enhance the action of epinephrine in the body are …
adrenergic
if the modifier works in the same fashion as the neurotransmitter, it is an …
if the modifier works in opposition to the neurotransmitter, it is an …
agonist;
antagonist
norepinephrine affects the heart by increasing the rate of … and increasing the … of action potentials
depolarization; frequency
which of the following is true of epinephrine?
it increases the heart rate and mimics the …
sympathetic nervous system
individuals with weakened hearts need to allow maximum time for … and increased … and would therefore most likely benefit from increased … and decreased …
venous return; stroke volume;
force of contraction; heart rate
… decreased the heart rate, and is a cholinergic agonist that decreased the frequency of action potentials
pilocarpine
the effect of … was to mimic the sympathetic nervous system
atropine
the modifiers tested that decrease the heart rate were … and …
digitalis; pilocarpine
to increase the heart rate, the best choices would be … and …
epi; atropine
… decreases heart rate but increases contractile force
digitalis
the primary role of the respiratory system is to distribute … to, and remove … from, all the cells of the body
oxygen; CO2
the respiratory system works together with the circulatory system.
respiration includes …., or the movement of air into and out of the lungs (…) and the …. (via blood) of oxygen and CO2 between the lungs and body cells
ventilation;
breathing;
transport
the heart pumps deoxygenated blood to pulmonary capillaries, where gas exchange occurs between blood and … (air sacs in the lungs), thus oxygenating the blood
alveoli
the heart then pumps the oxygenated blood to body tissues, where oxygen is used for … at the same time, CO2 ( a waste product of metabolism) from body tissues diffuses into the blood. this CO2-enriched, oxygen reduced blood then returns to the heart, completing the circuit
cell metabolism
ventilation is the result of
skeletal muscle contraction
when the … - a dome-shaped muscle that divides the thoracic and abdominal cavities - and the … contract, the volume in the thoracic cavity increases.
diaphragm;
external intercostal muscles
this increase in thoracic volume reduces the pressure in the thoracic cavity, allowing atmospheric gas to enter the lungs ( a process called …)
inspiration
when the diaphragm and the external intercostals relax, the pressure in the thoracic cavity increases as the volume decreases, forcing air out of the lungs ( a process called …)
expiration
inspiration is considered an … process bc muscle contraction requires the use of ATP, whereas expiration is usually considered a … process bc the muscles relax, rather than contract
active;
passive
when a person is running, expiration becomes an active process, resulting from the contraction of … and … muscles . in this case, both inspiration and expiration are considered active processes bc muscle contraction is needed for both
internal intercostal muscles;
abdominal muscles
the amount of air that flows into and out of the lungs in 1 min is the pulmonary …, which is calculated by multiplying the … by the … of each breath (the …)
minute ventilation;
frequency of breathing;
volume; tidal volume
ventilation must be regulated at all times to maintain oxygen in arterial blood and CO2 in venous blood at their normal levels- that is, at their normal …
partial pressures
the … of a gas is the proportion of pressure that the gas exerts in a mixture
partial pressure
oxygen and CO2 diffuse .., from … partial pressures, to … partial pressures
down their partial pressure gradients; high; low
oxygen diffuses from the alveoli of the lungs into the blood, where it can dissolve in plasma and attach to …, and then diffuses from the blood into the tissues. CO2 diffuses from the tissues into blood and then diffuses from the blood into the alveoli for export from the body
hemoglobin
the two phases of ventilation , or breathing, are (1) …, during which air is taken into the lungs, and (2) …, during which air is expelled from the lungs
inspiration; expiration
inspiration occurs as the … and the … contract
external intercostal muscles; diaphragm
during inspiration, the diaphragm flattens as it moves … while the external intercostals, situated between the ribs, … the rib cage. these cooperative actions increase the thoracic volume. air rushes into the lungs bc this increase in thoracic volume creates a …
inferiorly;
lift;
partial vacuum
during quiet expiration, the inspiratory muscles relax, causing the diaphragm to rise … and the chest wall to move … thus, the thorax returns to its normal shape bc of the elastic properties of the lung and thoracic wall. as in a deflating balloon, the pressure in the lungs rises, forcing air out of the lungs and airways
superiorly; inward
although expiration is normally a passive process, … and …. can also contract during expiration to force additional air from the lungs. such forced expiration occurs, for ex., when you …, …, …, or …
abdominal-wall muscles; internal intercostal muscles;
exercise; blow up a balloon; cough; sneeze
normal, quiet breathing moves about … of air (the …) into and out of the lungs with each breath
500 mL (0.5 L); tidal volume
tidal volume can vary due to a person's ... ... ... ... immediate ...
size; sex; age; physical condition; respiratory needs
…: amount of air that can be forcefully inspired after a normal tidal volume inspiration (male, … ml; female, … ml)
inspiratory reserve volume; 3100; 1900
…: amount of air that can be forcefully expired after a normal tidal volume expiration (male, … ml; female, … ml)
expiratory reserve volume (ERV); 1200; 700
…: amount of air remaining in the lungs after forceful and complete expiration (male, … ml; female, … ml)
residual volume (RV); 1200; 1100
… are calculated from the respiratory volumes
respiratory capacities
…: maximum amount of air contained in lungs after a maximum inspiratory effort: TLC = TV + IRV + ERV + RV (male, … ml; female … ml)
total lung capacity (TLC); 6000; 4200
…: maximum amount of air that can be inspired and then expired with maximal effort: VC = TV + IRV + ERV (male, … ml; female … ml)
vital capacity (VC); 4800; 3100
…: amount of air that can be expelled when the subject takes the deepest possible inspiration and forcefully expires as completely and rapidly as possible
forced vital capacity (FVC)
…: measures the amount of the vital capacity that is expired during the first second of the FVC test (normally …-…% of the vital capacity)
forced expiratory volume;
75-85
the contraction of which of the following muscles will increase the thoracic cavity volume during inspiration? the …
external intercostals
at the beginning of expiration, the … in the thoracic cavity increases
pressure
an … disease affects airflow, and a … disease usually reduces volumes and capacities.
obstructive; restrictive
pulmonary fucntion tests such as… can help a clinician determine the difference between obstructive and restrictive diseases.
forced expiratory volume (FEV1)
in obstructive diseases such as chronic bronchitis and asthma, airway radius is decreased. Thus, FEV1 will …
decrease proportionately
… is the amount of air that flows into and then out of the lungs in a minute. = TV (ml/breath) * BPM (breaths/min)
minute ventilation
to calculate a person’s vital capacity, you need to know the …, …, and …
TV; ERV: IRV
measuring a person’s FVC means that you are measuring the amount of air that can be expelled when the subject takes the … and then forcefully expires as … and … as possible
deepest possible inspiration;
completely; rapidly
measuring a person’s FEV1 means that you are measuring the amount of the VC that is … during the first second of the FVC test
VC
for a person suffering an asthma attack, inhaler meds are expected to …
reduce the airway resistance.
which of the following values does not include the ERV? …
tidal volume
