Chr. 21 - Blood Vessels and Hemodynamics Flashcards
(145 cards)
1
Q
[21.1] What are arteries?
A
Blood vessels carrying blood away from the heart.
2
Q
[21.1] What are arterioles?
A
Smaller arteries more distal from the heart.
3
Q
[21.1] What are capillaries?
A
Tiny blood vessels with thin walls to allow exchange of substances with tissues.
4
Q
[21.1] What are venules?
A
Small veins forming from capillaries as blood begins to return to the heart.
5
Q
[21.1] What are veins?
A
Blood vessels carrying blood to the heart.
6
Q
[21.1] What are the layers of a blood vessel’s structure?
A
- Tunica interna
- Tunica media
- Tunica externa.
7
Q
[21.1] Describe the tunica interna.
A
The inner lining of a blood vessel in direct contact with blood, comprised of multiple layers: endothelium and the basement membrane.
8
Q
[21.1] Describe the tunica media.
A
The middle layer of blood vessels comprised of muscular and connective tissues, varying among blood vessels. Provides ability of vasoconstriction and vasodilation.
9
Q
[21.1] Describe the tunica externa.
A
The outer covering of a blood vessel consisting of elastic and collagen fibers, nerves, and blood vessels supplying themselves - vasa vasorum.
10
Q
[21.1] What is the internal elastic lamina?
A
A layer of elastic fibers in between the tunica interna and tunica media.
11
Q
[21.1] What is the external elastic lamina?
A
A layer of elastic fibers in between the tunica media and tunica externa.
12
Q
[21.1] Describe elastic arteries.
A
Largest arteries in the body diameter-wise, but with thin walls and large internal/external elastic laminae and a proportionally thicker tunica media that incorporates elastic lamellae. Also known as conducting arteries.
13
Q
[21.1] What is the function of elastic arteries, and how is this achieved?
A
Aid in propelling blood to the body as the ventricles relax. Done by forming a pressure reservoir, stretching as blood is pumped into them by the heart. Once stretched, their elastic nature recoil and squeeze blood further along , exerting the stored pressure as they return to normal shape.
14
Q
[21.1] Describe muscular arteries.
A
Medium-sized arteries containing higher amounts of smooth muscle and fewer elastic fibers. Capable of greater vasoconstriction and vasodilation and feature thicker internal elastic lamina while having thinner external elastic lamina. Tunica externa thicker than tunica media and contains fibroblasts and collagen fibers allowing for changes in diameter of vessel without causing negative effects.
15
Q
[21.1] What is anastomoses?
A
The union of two or more arteries supplying the same body region.
16
Q
[21.1] What is collateral circulation?
A
The alternative blood flow to a body part through anastomoses.
17
Q
[21.1] What are end arteries?
A
Arteries that do not anastomoses.
18
Q
[21.1] What is a metarteriole?
A
The terminal end of an arteriole as it reaches the capillary junction.
19
Q
[21.1] What is the precapillary junction?
A
A sphincter formed by muscle cells of the arteriole monitoring blood flow into the capillary.
20
Q
[21.1] What is resistance in terms of blood vessel?
A
Opposition of blood flow due to friction of blood and blood vessels. Inversely related to blood vessel size.
21
Q
[21.1] What is a postcapillary venule?
A
A venule receiving blood from a capillary.
22
Q
[21.1] What is microcirculation?
A
The flow of blood from a metarteriole into a capillary, then into a postcapillary venule.
23
Q
[21.1] What are exchange vessels?
A
Capillaries, as they are the primary site of substance exchange with interstitial fluid.
24
Q
[21.1] What is a capillary bed?
A
A network of 10-100 capillaries arising from a single metartiole.
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[21.1] What is vasomotion?
The intermittent contraction and relaxation of smooth muscle in arterioles promoting blood flow into capillaries.
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[21.1] What is a thoroughfare channel?
The distal end of the main channel of a capillary branching from the arteriole, containing no smooth muscle.
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[21.1] What are the types of capillaries?
1. Continuous capillaries
2. Fenestrated capillaries
3. Sinusoids.
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[21.1] What are continuous capillaries?
Majority of capillaries, defined by the plasma membrane of endothelial cells forming a continuous tube interrupted by intercellular clefts.
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[21.1] What are intercellular clefts?
Gaps in neighbouring endothelial cells.
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[21.1] Describe fenestrated capillaries.
Capillaries with small pores, fenestrations, in their plasma membranes.
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[21.1] Describe sinusoids.
Wider and more winding capillaries with large fenestrations and intercellular clefts, allowing for proteins and blood cells to enter and exit the blood.
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[21.1] What is a portal system?
When blood passes from one capillary network to a different capillary network.
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[21.1] What are muscular venules?
Venules extending from postcapillary venules featuring smooth muscle.
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[21.1] What are the differences in the structure of veins compared to arteries?
While composed of the three basic layers, the tunica interna and tunica media of veins are considerably thinner, and lack internal/external elastic laminae.
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[21.1] What are valves in relation to blood vessels?
Thin folds of the tunica interna within veins preventing backflow of blood in veins due to lower pressures.
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[21.1] What is a vascular sinus?
A vein with thin endothelial wall and no smooth muscle and extra dense connective tissue providing support.
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[21.1] What are anastomotic veins?
Vein connections between venous channels, forming a ladder-like connection between two veins following an artery.
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[21.1] What are superficial veins?
Veins in the subcutaneous layer unaccompanied by parallel arteries.
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[21.1] What are deep veins?
Veins travelling between skeletal muscle.
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[21.1] What are blood reservoirs?
A large portion of blood volume that remains in veins that can be diverted quickly by venoconstriction.
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[21.2] What is capillary exchange?
The movement of substances between blood and interstitial fluid.
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[21.2] What are the basic mechanisms of capillary exchange?
Diffusion, transcytosis, and bulk flow.
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[21.2] What is transcytosis in terms of capillary exchange?
Substances are enclosed in pinocytic vesicles of endothelial cells, transported across the cell, and expelled by exocytosis.
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[21.2] What is bulk flow in terms of capillary exchange?
The pressure-driven passive process of a large amount of ions or molecules flowing in the same direction and is mostly used for solute exchange between blood and interstitial fluid.
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[21.2] What is filtration?
Bulk flow from blood capillaries into interstitial fluid.
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[21.2] What is reabsorption?
Bulk flow from interstitial fluid into capillaries.
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[21.2] What are the pressures of fiiltration?
Blood hydrostatic pressure and interstitial fluid osmotic pressure.
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[21.2] What is blood hydrostatic pressure?
Pressure exerted on blood by the pumping action of the heart, pushing fluid into interstitial fluid.
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[21.2] What is interstitial fluid osmotic pressure?
The pressure exerted by concentration of solutes within interstitial fluid pulling fluid into the interstitial fluid. Usually low or negligble.
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[21.2] What are the pressures of reabsorption?
Blood colloid osmotic pressure and interstitial hydrostatic pressure.
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[21.2] What is blood colloid osmotic pressure?
Pressure exerted by the concentration of solutes within the blood, pulling fluid into the blood
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[21.2] What is interstitial fluid hydrostatic pressure?
A negligible pressure exerted by interstitial fluid pushing fluid into the blood.
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[21.2] What is net filtration pressure?
Balance between filtration pressures and reabsorption pressures indicating the direction of fluid movement. Mainly calculated by blood hydrostatic pressure and blood colloid osmotic pressure.
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[21.2] Describe the action of net filtration pressure as it travels through a capillary.
At the metarteriole, net filtration pressure favours filtration as blood hydrostatic pressure is higher than blood colloid osmotic pressure. As it travels to the postcapillary venule end, BHP drops under BCOP and favours reabsorption.
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[21.3] What is hemodynamics?
The forces involved in circulating blood.
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[21.3] What is blood flow?
The volume of blood that flows through any tissue during a given time period.
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[21.3] What is blood pressure?
The hydrostatic pressure exerted by blood on the walls of blood vessels.
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[21.3] What is systolic blood pressure?
The pressure on blood vessels during ventricular contraction.
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[21.3] What is diastolic blood pressure?
The pressure exerted on blood vessels during heart relaxation.
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[21.3] What is mean arterial pressure?
The average blood pressure in arteries, calculated as:
MAP = dBP + 1/3 (sBP - dBP)
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[21.3] What is vascular resistance?
The opposition of blood flow due to friction between blood and blood vessels.
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[21.3] List the factors affecting vascular resistance.
1. Size of the lumen
2. Blood viscosity
3. Total blood vessel length
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[21.3] Describe how the size of the lumen affects vascular resistance.
Smaller lumens lead to greater resistance, with resistance being inversely proportionate to diameter to the fourth power
R = 1/d^4
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[21.3] Describe how blood viscosity affects vascular resistance.
The ratio of concentration of red blood cells to plasma, as well as amount of plasma proteins, affects the thickness of blood proportionally.
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[21.3] Describe how total blood vessel length affects vascular resistance.
The greater amount of blood vessels leads to a greater distance needed to circulate blood through, increasing resistance.
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[21.3] What is systemic vascular resistance?
The total vascular resistance given by systemic blood vessels.
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[21.3] What is venous return?
The volume of blood flowing back to the heart through systemic veins. Moved primarily by ventricular contractions, as well as the skeletal muscle pump and the respiratory pump.
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[21.3] Describe the skeletal muscle pump.
The contraction of skeletal muscles squeezing blood vessels and generating pressure sending blood in veins to the heart.
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[21.3] What is the respiratory pump?
Contraction and relaxation of the diaphragm increasing and decreasing respectively thoracic pressure, acting on veins to compress generating blood flow.
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[21.3] What is circulation time?
The time required for a drop of blood to pass from the right atrium, through the pulmonary and systemic circuits, and return to the right atrium. Appr. 1 min.
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[21.4] What involvement in blood pressure does the cardiovascular center of the medulla have?
Controls neural, hormonal, and local negative feedback systems regulating blood pressure.
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[21.4] How does the cardiovascular center monitor blood pressure?
Chemoreceptors, proprioceptors, and baroreceptors.
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[21.4] What are cardiac accelerator nerves?
Sympathetic nerves extending from the cardiovascular center into the heart responsible for exciting cardiac muscle.
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[21.4] How does parasympathetic stimulation reach the heart?
Through the vagus X nerves extending into the heart.
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[21.4] Describe baroreceptors.
Pressure-sensitive receptors located in aorta, internal carotid arteries, and others in the neck and chest.
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[21.4] What are the important baroreceptor reflexes?
Carotid sinus reflex and aortic reflex.
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[21.4] Describe the carotid sinus reflex.
Baroreceptors in the carotid sinuses detect increase in pressure acting on them. They stimulate sensory axons in the glossopharyngeal IX nerve that lead to the cardiovascular center and ultimately signal to decrease blood pressure. When stimulated less, the generate impulses slower, lowering the effect.
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[21.4] Describe the aortic reflex.
Baroreceptors in the ascending aorta and arch of aorta detect increases in pressure and stimulate the vagus X nerve to decrease blood pressure. When stimulated less, generate impulses slower to lower the effect.
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[21.4] Describe chemoreceptor reflexes.
Sensory receptors in carotid and aortic bodies monitoring chemical composition of blood.
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[21.4] List the main hormonal regulations of blood pressure.
1. RAA system
2. Epinephrine/norepinephrine.
3. Antidiuretic hormone
4. Atrial natriuretic peptide
81
[21.4] Briefly describe how the RAA system regulates blood pressure.
Stimulations of juxtaglomerular cells by decrease of pressure initiates secretion of renin by kidneys in to blood. Renin and angiotensin converting enzyme converts angiotensinogen into angiotensin I, then to angiotensin II which causes vasoconstriction and secretion of aldosterone. Aldosterone promotes reabsorption of sodium, and thus water, increasing blood pressure.
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[21.4] Describe how epinephrine and norepinephrine regulate blood pressure.
These hormones increase cardiac output by stimulating rate and force of heart contractions and vasoconstriction.
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[21.4] Describe how antidiuretic hormone regulates blood pressure.
Promotes vasoconstriction and movement of water from kidney tubules into bloodstream.
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[21.4] Describe how atrial natriuretic peptide regulates blood pressure.
Causes vasodilation and promotes loss of salt and water in urine, reducing blood volume.
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[21.4] What stimuli cause autoregulatory changes in blood flow?
Physical changes and vasodilating/vasoconstricting chemicals.
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[21.4] Describe physical changes causing autoregulatory changes in blood flow.
Warming promotes vasodilation and cooling promotes vasoconstriction, as well as the myogenic response of smooth muscle.
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[21.4] Generally, what are vasodilating and vasoconstricting chemicals?
Chemicals released by many different cells that cause either vasoconstrictive or vasodilating effects.
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[21.5] What is the pulse?
The alternating expansion and recoil of elastic arteries caused by contraction of the heart.
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[21.5] What is tachycardia?
A pulse rate over 100.
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[21.5] What is bradycardia?
A pulse rate under 50.
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[21.5] What is a sphygmomanometer?
The device used to measure blood pressure.
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[21.5] What are Korotkoff sounds?
The sounds heard while auscultating a blood pressure.
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[21.5] What is pulse pressure?
The difference between systolic and diastolic pressure.
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[21.6] What is shock?
The failure of the cardiovascular system to deliver sufficient oxygen and nutrients to meet cellular metabolic needs.
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[21.6] List the types of shock.
1. Hypovolemic
2. Vascular
3. Cardiogenic
4. Obstructive
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[21.6] What is hypovolemic shock?
An insufficient volume of blood to carry nutrients or oxygen to cells.
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[21.6] What is cardiogenic shock?
Dysfunction of the heart due to lack of blood supply.
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[21.6] What is vascular shock?
Dysfunction with the vascular system leading to insufficient distribution of nutrients and oxygen to cells.
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[21.6] What is obstructive shock?
Dysfunction of the cardiovascular system due to physical obstruction leading to insufficient distribution of nutrients and oxygen to cells.
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[21.6] What are common causes of hypovolemic shock?
Hemorrhage, excessive sweating, diarrhea or vomiting, excessive urination.
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[21.6] What are common causes of cardiogenic shock?
Myocardial infarction, ischemia of the heart, valve pathologies, excessive preload or afterload, arrhythmias.
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[21.6] What are subcategories of vascular shock?
Anaphylaxis, neurogenic shock, septic shock.
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[21.6] What is a common cause of obstructive shock?
Pulmonary embolism.
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[21.6] List the negative feedback systems responding to hypovolemic shock.
1. Activation of RAA
2. Secretion of antidiuretic hormone
3. Activation of sympathetic nervous division.
4. Release of local vasodilators.
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[21.6] Describe the activation of RAA negative feedback system as it relates to hypovolemic shock.
Decreased blood flow to kidneys stimulates juxtaglomerular cells, releases renin. Renin transforms angiotensinogen into angiotensin I. In the lungs, ACE transforms angiotensin I into angiotensin II. Angiotensin II causes vasoconstriction and release of aldosterone. Aldosterone promotes resorption of sodium and water from the kidneys, increasing blood pressure.
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[21.6] Describe how secretion of antidiuretic hormone responds to hypovolemic shock.
When a decrease in blood pressure is detected, the posterior pituitary releases ADH, which enhances water reabsorption in the kidneys, conserving blood volume. Also causes vasoconstriction.
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[21.6] Describe how the sympathetic nervous division responds to hypovolemic shock.
Aortic and carotid baroreceptors detect decreasing blood pressure and trigger the sympathetic division. Systemic vasoconstriction occurs, increasing systemic vascular resistance. Heart rate and contractility increases.
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[21.6] Describe how release of local vasodilators responds to hypovolemic shock.
In response to hypoxia, cells release vasodilating agents dilating arterioles and relaxing precapillary sphincters, promoting local blood flow. This can lead to decreasing systemic vascular resistance and thus decreasing blood pressure.
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[21.6] What are common signs and symptoms of shock?
1. Systolic blood pressure below 90
2. Rapid, thready heart rate
3. Pale and diaphoretic
4. Altered mental status
5. Thirst
6. Nausea
7. Also mentions low pH, no way to really know this without lab results, but who is running labs on someone in shock lol
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[21.7] What are circulatory routes?
The system of arteries, arterioles, capillaries, venules, and veins organized throughout the body.
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[21.7] What is system circulation?
All arteries and arterioles that carry oxygenated blood from the left ventricle, and all the venules and veins returning deoxygenated blood to the right atrium.
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[21.7] What are the subdivisions of systemic circulation?
Coronary circulation, cerebral circulation, and hepatic portal circulation.
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[21.7] What is pulmonary circulation?
The blood circuit bringing deoxygenated blood from the right ventricle to the lungs, and oxygenated blood from the lungs to the left atrium.
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[21.7] What is fetal circulation?
Special structures within a fetus for blood flow.
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[21.7] What are the main veins that drain into the right atrium?
1. Superior vena cava
2. Inferior vena cava
3. Coronary sinus.
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[21.8] What is the aorta?
The largest artery of the body containing four sections, extending from the left ventricle.
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[21.8] What are the sections of the aorta?
1. Ascending aorta
2. Arch of aorta
3. Thoracic aorta
4. Abdominal aorta.
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[21.8] What is the ascending aorta?
The portion of the aorta emerging from the left ventricle to the pulmonary trunk. Two coronary arteries branch off the ascending aorta.
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[21.8] What is the arch of aorta?
Section of the aorta extending from the ascending aorta, arching left of the aorta and bending to descend, ending at T4/T5. Three arteries branch off.
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[21.8] What is the thoracic aorta?
Continuation of the aorta at T4/T5 and extending through the aortic hiatus of the diaphragm.
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[21.8] What is the abdominal aorta?
Extension of the aorta continuing from the inferior aspect of the hiatus of the diaphragm and descending to L4 and splitting into the common iliac arteries.
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[21.8] What are the common iliac arteries?
Arteries extending off the abdominal aorta.
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[21.9] What are the aortic sinuses?
Three dilations at the origin of the ascending aorta, giving rise to the left and right coronary arteries as well as one more we don't care about.
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[21.10] What are the three major arteries branching from the arch of aorta?
1. Brachiocephalic trunk
2. Left common carotid artery
3. Left subclavian artery
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[21.10] Which arteries derive from the brachiocephalic trunk?
The right subclavian and right common carotid.
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[21.10] What is the axillary artery?
Continuation of right subclavian artery in axillary region, beginning at inferior border of first rib, ending as it crosses distal margin of teres major.
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[21.10] What is the brachial artery?
A continuation of axillary artery into arm, beginning at border of teres major and ending at a bifurcation into radial and ulnar arteries.
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[21.12] What are the unpaired visceral arteries branching arising from the abdominal aorta?
1. Celiac trunk
2. Superior mesenteric artery
3. Inferior mesenteric artery
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[21.12] List the paired branches arising from the abdominal aorta.
1. Suprarenal artery
2. Renal artery
3. Gonadal artery
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[21.13] Which arteries arise from the common iliac arteries.
Internal iliac arteries and external iliac arteries.
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[21.13] Which arteries arise from the external iliacs?
Femoral arteries.
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[21.13] Which arteries arise from the femoral arteries?
The popliteal arteries.
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[21.13] Which arteries arise from the popliteal arteries?
Anterior and posterior tibial arteries.
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[21.14] Describe the coronary sinus.
Main vein of heart, located in the coronary sulcus and opens directly into the right atrium. Receives from great cardiac vein, middle cardiac vein, and small cardiac vein.
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[21.14] Describe the superior vena cava.
Vein extending inferiorly from the first rib, formed by union of right and left brachiocephalic veins. Drains upper limbs, head, neck and thorax.
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[21.14] Describe the inferior vena cava.
Begins anterior of fifth lumbar from union of common iliac veins and ascends to right atrium. Drains everything inferior of thorax.
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[21.15] What are the three main pair of veins draining the head?
1. Internal jugular
2. External jugular
3. Vertebral veins
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[21.15] List the deep veins of the upper limbs.
1. Brachiocephalic veins
2. Subclavian veins
3. Axillary veins
4. Brachial veins
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[21.15] List the superficial veins of the arm.
1. Cephalic veins
2. Basilic veins
3. Median cubital veins
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[21.18] List the main veins of abdomen and pelvis.
1. Inferior vena cava
2. Common iliac veins
3. Internal iliac veins
4. External iliac veins
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[21.20] What is the hepatic portal circulation?
A system of veins carrying venous blood from the GI organs and spleen to the liver.
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[21.21] What is pulmonary circulation?
A circulation system carrying blood from the heart to the lungs and back.
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[21.21] What is the pulmonary trunk?
An artery emerging from the right ventricle and dividing into right and left pulmonary arteries.
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[21.21] What are the right and left pulmonary arteries?
Divisions of the pulmonary trunk carrying blood to the right and left lung respectively.
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[21.21] What are the pulmonary veins?
Veins formed from venules and pulmonary capillaries carrying oxygenated blood to the heart.
