test 1b anatomy 2
________ is to slow heart rate as ________ is to fast heart rate.
1- bradycardia 2- tachycardia
In cardiac muscle, the fast depolarization phase of the action potential is the result of ________ membrane permeability to ________ ions.
1- increased 2- sodium
_____ is to contraction and ________ is to relaxation
1- systole 2- diastyle
One of the changes that occurs in the pacemaker potential (unstable resting membrane potential) in the SA node (an autorhythmic cell) is a decreased efflux of what ion?
potassium
Depolarization of the ventricles is represented on an electrocardiogram by the
QRS complex
Blood returning to the heart from the pulmonary circuit first enters the
left atrium
Rupture of the papillary muscles in the left ventricle may result in
mitral valve regurgitation of blood into atrium, and/or prolapsed valve
Tetanic muscle contractions don't occur in a normal cardiac muscle because
open calcium channels cause the refractory period to last until the muscle relaxes
Acetylcholine slows the heart because it
opens potassium ion channels in SA node cells and causes the pacemaker potential to depolarize more slowly.
Chemoreceptor reflexes respond to
pH, oxygen, carbon dioxide
In order to cause cardiac muscle contraction, the contractile cells must also depolarize. What causes the depolarization of the contractile cells?
the flow of positive ions from adjacent cells
If the pacemaker cells in the SA node become more permeable to potassium ions
the membrane will hyperpolarize/depolarize more slowly, and the heart rate will decrease
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes
The T wave on an ECG tracing represents
ventricular repolarization
The hormone that produces cardiovascular effects similar to activation of the sympathetic nervous system is
epinephrine
adrenal medulla secretes
epinephrine
describe how autoregulation automatically adjusts tissue perfusion to your biceps brachii when you are lifting weights.
Oxygen decreases Carbon dioxide increases Lactic acid increases vasodilates and takes more blood into tissue
A person notices his or her heart beat because he or she senses blood being pumped by the heart. Excessive caffeine intake can lead to irregular heart rhythms (arrhythmias) that patients perceive as "skipped beats." Given that caffeine is a stimulant, which of the following mechanisms best explains the reason for the feeling that the heart skipped a beat?
Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
If there is a complete block between the SA node and the AV node, how would the ECG be affected?
The rate of P waves will be faster than the rate of QRS complexes.
Each of the following will lead to a decrease in blood
increased levels of ANP (atrial natriuretic peptide). decrease in blood volume. reduced thirst. decreased peripheral resistance.
Sensory neurons that are part of chemoreceptor reflexes are found in the
medulla oblongata
Increased levels of carbon dioxide in the blood will result in decreased
parasympathetic stimulation of the heart.
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important?
so blood is forced upward, toward the semilunar valves
Arteriosclerosis can lead to
stroke coronary heart disease hypertension
Analysis of the electrocardiogram can reveal all of the following except the
stroke volume
The volume of blood ejected from each ventricle during a contraction is called the
stroke volume
If the connection between the SA node and AV node becomes blocked,
the ventricles will beat slower, because the AV node depolarizes slower than the SA node
Repolarization of an autorhythmic cell is due to the opening of which channels?
voltage-gated potassium channels
Negative Feedback in the HPT Axis: Which of the following is NOT produced by high levels of Thyroid Hormones in the blood?
Increased secretion of Thyroid Hormones due to reduced TSH and TRH
the middle layer in the heart wall is composed of:
cardiac muscle cells
Hypothalamus secretes
corticotropin releasing hormone
Drugs known as calcium channel blockers such as nifedipine can be used to
decrease the force of cardiac contraction.
Which of the following would have the greater effect on vascular resistance?
decreasing the diameter of a blood vessel by 1/2
The P wave of the electrocardiogram is a signal from
depolarization of the atria.
The ________ is the volume of blood in a ventricle at the beginning of systole.
end-diastolic volume
The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.
end-systolic volume
The normal pacemaker of the heart is located in
sinoatrial node
how many pulmonary veins are there?
4
lisrt the intrinsic muscles conduction system in order
1- SA node 2- AV node 3- AV bundle 4- Branches 5- Purkinje fibers
anterior pituitary gland secretes
thyroid stimulating hormone
baroreflex:
Baroreceptors inform the medulla oblongata about changes in blood pressure, producing a programmed and rapid response to return the body to equilibrium. A larger blood volume will stretch the aorta, and the baroreceptors will trigger the Cardioinhibitory Center of the brainstem in response. Norepinephrine from the post-ganglionic neuron will trigger SA Node Pacemaker cells to depolarize more quickly, therefore increasing heart rate.
A portal system is defined as a circulatory pathway in which blood passes through TWO capillary beds before returning to the right atrium, not one capillary bed
The hypothalamus releases hormones into the first capillary bed of a portal system, which are then delivered to a second capillary bed in the Anterior Pituitary gland.
Myogenic autoregulation can be defined as:
The main component of this reflex is when the baroreceptors release nitric oxide on the aorta and carotid arteries, leading to an immediate vasodilation and decrease in blood pressure.
When chemoreceptors in the carotid or aortic bodies detect INCREASED oxygen or DECREASED carbon dioxide:
The medulla oblongata causes a decrease in Heart Rate and vasodilation
Collateral ganglia contain the cell bodies of sympathetic neurons innervating tissues and organs in which cavity?
abdominopelvic
Homeostatic mechanisms in response to blood loss include all of the following
activation of ADH secretion. activation of aldosterone secretion. increased thirst and water intake. uptake of interstitial fluid due to reduced capillary pressure.
Hypothalamus (via posterior pituitary) secretes
antidiuretic hormone
Sympathetic innervation of the heart:
arrives in postganglionic fibers within the cardiac nerves.
Blood flow to a tissue will increase if the
arterioles dilate
the ear like extension of the atrium is the:
auricle
________ is the regulation of blood flow by local mechanisms within a capillary bed.
autoregulation
Total peripheral resistance is related to all including
blood viscosity. the flow characteristics. the length of a blood vessel. blood vessel diameter
The heart is innervated by ________ nerves.
both parasympathetic and sympathetic
The long plateau phase of the cardiac muscle action potential is due to
calcium channels remaining open
the function of the atrium is to:
collect blood and pump blood to the ventricle
autonomic motor neurons
conduct impulses to smooth and cardiac muscles and glands
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
fast calcium
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
gap junctions
Pacemaker cells in the SA node
generate action potentials that spread to the myocardium.
Stimulation of the aortic baroreceptors results in
increased activity by the parasympathetic nervous system.
Which of the following factors will increase the net filtration pressure to move fluid out of capillaries?
increased blood hydrostatic pressure decreased tissue hydrostatic pressure decreased plasma albumen
contractions of the pappilary muscles:
prevent the atrioventricular valves from reversing into the atria.
Natriuretic peptide release by the heart:
results in increased sodium loss in urine.
Blood returning to the heart from the systemic circuit first enters the:
right atrium
parasympathetic division
About 75% of all parasympathetic control travels along the Vagus Nerve, cranial nerve X. Its neurons release ACh from both the pre- and post-ganglionic fibers. Because of its long pre-ganglionic fibers, it can innervate many organs simultaneously. It is also called the craniosacral division, because its fibers emerge from the brainstem and the sacral region.
As the heart rate slows, ________ get(s) longer.
diastole
Each of the following factors will increase cardiac output except
increased parasympathetic stimulation.
Which of the following would increase heart rate?
increased sympathetic stimulation of SA node decreased parasympathetic stimulation of SA nodal fibers increased levels of norepinephrine and/or epinephrine faster depolarization of the pacemaker potential.
Each of the following changes will result in increased blood flow to a tissue:
increased vessel diameter. relaxation of precapillary sphincters. increased blood pressure. decreased peripheral resistanc
