TPR - Ch 9 - Circulatory, lymphatic, and immune system Flashcards
Functions of the cardiovascular (CV) system?
1) Distribute nutrients, O2 (from lungs to rest of the body) and hormones
2) Transport metabolic waste products from tissues to the excretory system
3) Maintain hemostasis of body temp
4) Hemostasis (blood clotting).
Ischemia versus hypoxia.
1) Inadequate blood flow that can result in tissue damage due to a shortage of O2 and nutrients, and the buildup of metabolic waste
2) When adequate circulation is present but the supply of O2 is reduced.
Difference between arteries, arterioles, and capillaries.
Vessels that carry blood away from the heart at a high pressure are ARTERIES. As arteries pass farther from the heart, the pressure of blood decreases, and they branch into increasingly smaller arteries called ARTERIOLES. The arterioles then pass into CAPILLARIES, just wide enough for a blood ell. A
ARTERIOLES have smooth muscle in their wall and can restrict or increase blood flow.
CAPILLARIES are made of thin walls and allows exchange of materials b/t blood and tissue.
Arteries -> arterioles -> capillaries
Capillaries -> ____ -> veins
Venules
The inner lining of all blood vessels is formed by a thin layer of ____. The walls of capillaries are formed from a single layer of such cells.
Endothelial cells.
Role of endothelial cells - vasodilation/constriction
Secretion of particular substances regular diameter of blood vessels. Important for maintaining BP, tissue oxygenation, and thermoregulation.
Role of endothelial cells - inflammation.
Release of inflammatory chemicals from injured tissues stimulate endothelial cells to increase their expression of adhesion molecules, that allow WBC to stick to the endothelial cells and enter injured tissues.
Role of endothelial cells - angionesis.
Formation of new blood vessels. Angiogenic growth factors stimulate endothelial cells to break free from an existing vessel altogether.
Role of endothelial cells - thrombosis.
Thrombosis is blood clotting. Undamaged epethelial cells secrete substances to inhibit coagulation cascade, thus preventing formatin of potentially life threatning clots inside undamaged or unbroken vessels.
Why do mammals have two types of circulation.
1) Pulmonary circulation:blood flow from heart to to lungs and back to the heart
2) Sytemic circulation: the flow of blood from the heart to the rest of the body and back again
By having two separate circulations, most blod passes through only one set of capillaries before returning to the heart. This avoids the massive pressure drop of capillaries. Exception: portal systems.
Define portal systems - exceptions to passing through a single bed of capillaries.
Blood passes first through capillaries in the intestine, then collects to veins to travel to the liver, where the vessels branch and again pass through capillaries.
The portal systems evolve as a direct transport sys. to transport nutrients directly from the intestine to liver or hormones from the hypothalamus to the pituitary, without passing through the whole body.
The right atrium receives deoxygenated blood from the systemic circulation (from these two veins).
Superior and inferior vena cava.
Trace the path of blood through the heart.
1) The RIGHT ATRIUM receives deoxygenated blood from the systemic circulation and pumps it into the RIGHT VENTRICLE.
2) From the right ventricle, blood passes through the pulmonary artery to the lung.
3) Oxygenated blood from the lungs returns throughthe pulmonary veins to the left artery to the lungs.
4) Oxygenated blood from the lungs returns through the pulmonary veins to the left artrium and is pumped into the leff ventricle before being pumped out the heart in the aorta.
Coronary arteries, veins, and sinus.
1) Coronary arteries: The first branches of the aorta, which branch to supply blood to the wall of heart
2) coronary veins: deoxygenated blood from the heart collects in the coronary veins, which merge to form the 3) coronary sinus. Blood in the coronary sinus drains directly into the RA.
The ventricular pressure of the heart is (high/low) while the atrial pressure is (high/low).
The ventricular pressure of the heart is high while the atrial pressure is lower.
Function of the atrioventricular valves.
The AV valves between each ventricle and its atrium is necessary to prevent backflow.
Bicuspid valve.
The AV valve between the left atriuma nd ventricle is the biscuspid or mitral valve.
Tricuspid valve.
The AV valve b/w the right atrium and ventricle is the tricuspid valve.
Give the two semilunar valves.
The pulmonary and aortic semilunar valves. These are the valves between the large arteries and the ventricles.
Where do varicose veins come from?
Failed venous valves. Remember the function of the valve is to prevent backflow.
Cardiac cycle: diastole.
During diastole, the ventricles are relaxed and blood is able to flow into them from the atria. The atria contract during diastole. At the end of diastole, the ventricles contract, initiating systole.
Cardiac cycle: systole.
Systole begins with ventricle contraction. The ensuing buildup of pressure causes the AV valves to close (lub sound). Over the next few ms, the pressure in the ventricles increase, until the semilunar valves open and blood rushes into the aorta and PA. At the end of systole, the ventricles are nearly empty. As a result, the pressure falls, and a small amount of blood flows backward. The valves shut (dup sound).
Explain the lub dup heart sounds.
1) lub: results from the closure of AV valves at the beginning of systole
2) dup: results from the semilunar valves closing at the end of systole.
Hence, Diastole is longer than systole.
Why do atheletes have slow pulses?
They pump more blood each time it contracts. Therefore, it may beat fewer times per minute and still provide adequate circulation. Atheletes have strong hearts.
Stroke volume.
The amount of blood pumped with each systole.
Cardiac output =?
The total amount of blood pumped per minute, defined by:
CO (L/min) = SV(L/beat) * HR (beat/min)
Which has the larger cardiac output? Right or left ventricle?
They are the same. The same amount of blood must pass through both sides of the heart or blood would back up in either the pulmonary or systemic circulatory system.
Two ways to increase cardiac output?
CO = SV * HR –> increase heart rate or stroke volume
***Also a stronger heart has a larger stroke volume
What are two ways we can increase stroke volume?
Frank-Starling mechanism: if the heart muscle is stretched, it will contract more forcefully. We accomplish this by increasing venous return, as more blood received means more pumped out. 2 ways to do this:
1) Increase total V of blood in the circulatory sys. Done by retaining water. Dilating arterioles results in more blood flow to tissues and greater return.
2) Contraction of large veins can propel blood toward the heart.
What do skeletal muscles, cardiac muscles, and neurons have in common.
All muscle cells, including those of cardiac muscle, share with neurons the ability to propagate an action potential across their surface. The AP in all muscle cells, as in neurons, is a wave of depolarization of the plasma membrane facilitated by voltage-gated ion channels.
Cardiac muscle is a functional ____. This is a tissue in which….
Cardiac muscle is a functional syncytium. A syncytium is a tissue in which the cytoplasm of different cells can communicate via gap junctions. In cardiac muscle GJ are found in the intercalated disks, the connections b/t cardiac cells. The depolarization of a cardiac muscle cell can be communicated directly through the cytoplasm (a electrical synapse).
In cardiac muscle GJ are found in the _____, the connections b/t cardiac cells.
Intercalated disks.
The atria and ventricles have separate syncytia. The action potential in the heart is transmitted from the atrial syncytium to the ventricles by the ____.
Cardiac conduction system.
Voltage gated __ and __ channels play an important role in cardiac muscle.
Voltage gated Na+ channels, called fast Na channels.
Slow Ca channels is involved in cardiac muscle action potential as well.
What makes the Ca gated channels in cardiac muscle unique?
Theses channels stay open longer than fast Na channels, causing the membrane to depolarize LONGER in cardiac muscles than in neurons, producing a plateau phase.
T tubules.
The maximize the entry of Ca in the cell, cardiac muscle has involutions of the membrane called T tubules. The APs travel down along T tubules, allow the entry of Ca from the EC environment, and also induce the sarcoplasmic reticulum to release Ca.
The initiation of each action potential that starts each cardiac cycle occurs automatically within the heart itself, in a special region of the right atrium called the __.
Sinoatrial node. SA node. This is the pacemaker of the heart. The SA node exhibits automaticity.
Go through the phases of the SA node.
Phase 4: Unestable resting ψ due to special Na leak channels that are responsible for its rhythmic, automatic excitation
Phase 0: Inward Na leak channels bring cell ψ to the threshold for voltage gated Ca channels to open, and this influx causes the upstroke of the pacemaker.
Phase 3: Repolarization caused by closure of Ca2+ channels and opening of the K+ channels.
The SA node transmits their Ap through the intercalated diks to the rest of the conduction cells in the heart.
Go through the phases if membrane ψ in a cardiac muscle cell (not the SA node).
Phase 0) Depolarization - Fast Na channels open transiently; depolarizatoin occur and once threshold is reached, voltage-gated Na opens
Phase 1) Initial repolarization - Gate Na inactivate; K+ channels open and enter
Phase 2) Plateau - intitial Na+ causes opening of slow to open/close Ca2+ channels finally open; gated K+ still open; transient equlibrium in cell ψ here.
Phase 3) Repolarization - Ca2+ closes; Ka+ still open and continues to repolarize
Phase 4) K+ channels close
Arrange the following terms regarding the Cardiac Conduction System and comment on how they interact: SA node, AV node, the bundle of his, Purkinje fibers, bundle branches, internodal tracts.
AP in the SA node > internodal tracts > AV node > bundle of His > right and left bundle braches > Puerkinje fibers.
The apex of the heart is the first to contract, given an AP in the SA node. The AP spreads down the special conduction pathway quickly, and spreads to the atria more slowly than the specialized conduction fibers.
Regulation of the heart by the autonomic nervous system - role of the parasympathetic NS.
The intrinsic firing of the SA node is 120 beats/min but this is inhibited by the vagus nerve. The vagus nerve contains preganglionic axons which synapse in a ganglia near the SA node. The postganglionoic neurons innervate the SA node and release ACh. ACh inhibits depolarization by binding to receptors on the cells of the SA node. Constant level of inhibition called: vagal tone.
Vagal tone.
The constant level of inhibition provided by the vagus nerve is known as vagal tone.
Random question: does ACh always inhibit the postsynaptic cell? If not, how can different responses be elicited by the same NT?
ACh is a NT released by ALL autonomic preganglion neurons, all PARAsympathetic neurons, and ALL somatic motor neurons. In most cases it is STIMULATORY (causes an AP to occur or an effect on an organ). BUT, whether a NT is stimulatory or inhibitory is dependent on the nature of the RECEPTOR on the postynaptic cell.
Regulation of the heart by the autonomic nervous system - role of the sympathetic NS.
The sympathetic NS affects the heart in two ways:
1) Sympathetic postganglionic neurons directly innervate the heart, releaseing norepinephrine
2) Epinephrine secreted by the adrenal medulla binds to the receptors on cardiac muscle cells.
The effects of sympathetic activation is stimulatory. HR increaes as well as force of contraction.
HR and BP are tightly regulated. What unique structure in the heart can give our nervous system clues to fix things?
We have baroreceptors in the aortic arch and carotid arteries than monitor blood pressure.
The driving force for blood flow is….
A difference in pressure from arteries to vein.
The force opposing blood flow is ___.
Friction.
Ohms law to summarize relationship b/t pressure, flow, and resistance.
ΔP = Q *R
Q = cardiac output = SV * HR R = peripheral resistance
ΔP = Q *R, how can you increase the BP using the Q in the equation
1) increase the force at which the heart conrracts (increase stroke volume)
2) increase the rate of cardiac contraction.
ΔP = Q *R; how can you increase/decrease the BP using the R in the equation.
The principle determinant of resistance is the degree of contraction of arteriole smooth muscle, also known as precapillary sphincters. If arteriole SM contracts, it becomes more difficult for blood to flow from arteries into capillaries, so the resistance goes up, resulting in increase BP.
Adrenergic tone.
A certain amount of pressure in the arteriole system is always desirable to keep all tissues perfused. The constant level of norepinephrine rleased by millions of sympathetic postganglionic axons innervating precapillary sphincters.
