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AP marieb ch19

Anat and phys Marieb chap 19 blood vessels

3 types of blood vessels Arteries Veins Capillaries
When do arteries not carry oxygenated blood? pulmonary circulation, umbilical vessels of fetus
All blood vessels have three layers except _______ capillaries
Name the three layers found in arteries and veins tunica intima, tunica media and tunica externa
What is the central space where blood flows through the vessel? the lumen
__________ lines the lumen of all vessels simple squamous endothelium
What is the innermost layer and has intimate contact with the blood. tunica intima
What layer of the blood vessel is circularly arranged smooth muscle cells and sheets of elastin and is responsible for relaxing or constricting based on the body's needs tunica media
What is composed largely of loosely woven collagen fibers that protect and reinforce the vessel. It also anchors the vessels to surrounding structures tunica externa
Why would an artery have a thicker tunica media layer? Contain muscle and elastic fibers to aid in stretch and withstand pressure
Name the three types of arteries Elastic, muscular and arterioles
_____ arteries have large thick walls, elastin in all three tunics, large lumen with low resistence and act as pressure resevoirs Elastic arteries
Elastic arteries are also called the _______ arteries Conducting
______ arteries deliver blood to organs and have more smooth muscle to aid in vasoconstriction Muscular
Muscular arteries are also called the _______ arteries Distributing
_____ are the smallest arteries, lead to capillary beds, and are associated with peripheral resistance arterioles
Name some characteristics of veins: Thiner walls and larger lumens than arteries, have thin tunica media but thick tunica externa consisting of collagen fibers, have valves
Veins are also called ___________ vessels (blood resevoirs) Capacitance
How do veins serve as blood reservoirs? They are usually only partially filled
_________ are formed when capillary beds unite, are very porous, and have one or two layers of smooth muscle cells Venules
What are venous valves formed from and where are they most abundant and where are they absent? folds of the tunica intima; in the veins of the limbs, where the upward flow of blood is opposed by gravity; they are absent in veins of the ventral body cavity
The venous system contains about what % of the total blood volume? 65%
Name the three types of capilaries Continuous, Fenestrated, Sinusoidal
What are the most permeable capillaries? sinusoids (wide, tortuous channels)
What are the 2nd most permeable capillaries? fenestrated capillaries
What are the most common least permeable capillaries and why? continuous capillaries, which lack pores
What is found on capillaries and aid in the exchange between the blood and interstitial fluid? clefts
What is a cuff of smooth muscle fibers that surround the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary called precapillary sphincter
What do vascular shunts connect? terminal arteriole and venule at opposite ends of a capillary bed
Where are continuous capillaries found? Skin and muscles and brain
Tight junctions in the continuous capillaries of the brain form the _______ blood brain barrier
Sinusoidal capillaries are found in the ______ Liver, bone marrow, lymphoid tissues, and spleen
What removes and destroys any contained bacteria and are found in the lining of the endothelium of the sinusoids in the liver? Kupffer cells
In a capillary bed, what is the vessel structurally intermediate between an arteriole and a capillary? metarteriole
Which circulation system transports oxygen-poor, carbon dioxide rich blood to the lungs for oxygenation and carbon dioxide unloading? pulmonary circulation
Which circulation system transports oxygenated blood from the left ventricle to all body tissues via the aorta and its branches? systemic circulation
What regulates the relative amount of blood entering a capillary bed? local chemical conditions and arteriolar vasomotor nerve fibers
What low-pressure adaptations ensure venous blood is returned to the heart at the same rate it is pumped into the circulation? large diameter lumens and valves that prevent blood from backflowing
What is a homeostatic imbalance of veins that causes them to become tortuous and dilated because of leaky valves? Varicose veins
What are several factors that contribute to varicose veins? heredity; prolonged standing in one position, obesity, pregnancy; elevated venous pressure
What are highly specialized, flattened veins with extremely thin walls composed only of endothelium called and where are they found? venous sinuses, ie coronary sinus of the heart and dural sinuses of the brain
What are alternate blood pathways in case one branch is cut or blocked by a clot, provided by anastomoses called? collateral channels
Where do arterial anastomoses occur? around joints, abdominal organs, the brain and the heart
What is friction encountered by blood in the systemic circulation called and what are the 3 important sources? peripheral resistance; blood viscosity, vessel length, and vessel diameter
What is the internal resistance to flow that exists in all fluids and is related to the thickness or "stickiness" of a fluid? blood viscosity
How is blood flow related to the peripheral resistance in the systemic circulation? inversely proportional
What is the pressure that propels the blood to the tissues called? mean arterial pressure (MAP) and it is roughly equal to the diastolic pressure plus one-third of the pulse pressure
In what 3 ways do veins adapt to venous return to overcome low pressure? respiratory pump-breathing which squeezes veins & forces blood toward heart;muscular pump-as skeletal muscles surrounding deep veins contract/relax, they 'milk' blood toward heart;layer of smooth muscle around veins that constricts under SNS control
Cardiac output (CO) is equal to Stroke volume times what? heart rate
What is normal CO (cardiac output)? 5.0 to 5.5 L/minute
What is usually in charge of heart rate? cardioinhibitory center in the medulla
What nerves maintain the resting heart rate? parasympathetic vagus nerves
During stress, which center take over, activating the sympathetic nervous system and increasing both heart rate (by acting on SA node) and stroke volume (by enhancing cardiac muscle contractility)? cardioacceleratory center
What is the neural center - the cluster of neurons in the medulla - that oversees changes in the diameter of blood vessels called? the vasomotor center
How does the cardiovascular center integrate blood pressure control? by altering cardiac output and blood vessel diameter
How is vasomotor tone achieved in the arterioles? by impulses transmitted by the vasomotor center, along sympathetic efferents called vasomotor fibers and innervate the smooth muscle of blood vessels, (mainly arterioles)
What happens in the carotid sinuses when arterial blood pressure rises? neural receptors called baroreceptors are stretched, sending a rapid stream of impulses to vasomotor center which results in vasodilation of arterioles and veins and a decline in blood pressure
What does a decline in mean arterial pressure (MAP) initiate? reflex vasoconstriction and increases cardiac output, causing blood pressure to rise.
What are regulated together so that changes in blood pressure are minimized? peripheral resistance and cardiac output
What is the function of rapidly responding barorecptors? to protect the circulation against short-term changes in blood pressure, such as those which occur when you change your posture
When do chemoreceptors in the aortic arch and large arteries of the neck transmit impulses to the cardioacceleratory center, to increase cardiac output and to the vasomotor center, which causes reflex vasoconstriction? when the oxygen content or pH of the blood drops sharply or the CO2 levels rise
What are the 2 most prominent chemoreceptors located close by the baroreceptors in the carotid sinus and aortic arch? carotid and aortic bodies
Where are reflexes that regulate blood pressure found? integrated in the medulla of the brain stem
Hormones that affect blood pressure are: Adrenal medulla hormones - norepinephrine and epinephrine; atrial natriuretic peptide (ANP); ADH(vasopressin); angiotensin II
What mechanisms are a long term control of blood pressure? renal mechanisms
How does the direct renal mechanism alter blood volume? dependently or independently of hormones independently
How does the indirect renal mechanism (renin-angiotensin mechanism) alter blood volume? kidneys release renin into blood which triggers a series of reactions that produce angiotensin II which increasing peripheral resistance via its potent vasoconstriction properties
How does aldosterone affect blood pressure? enhances renal reabsorption of sodium and prods posterior pitutiary to release ADH, which promotes more water reabsorption, causing both blood volume and blood pressure to rise
What is hypotension? low blood pressure - systolic pressure below 100 mm Hg
What is orthostatic hypotension? temporary low blood pressure and dizziness when suddenly arising
What can chronic hypotension be a sign of? Addison's disease; hypothyroidism, or severe tissue wasting. Can be an important signs of circulatory shock
What can happen in cases of prolonged hypertension? heart failure, vascular disease, renal failure, and stroke
What factors can contribute to hypertension? diet; obesity; age (over 40); diabetes mellitus; heredity; stress; smoking
How can primary hypertension be controlled? by restricting salt, fat, and cholesterol intake, losing weight, stopping smoking, managing stress, and antihypertensive drugs (diuretics, beta-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors.
What is the function of tissue perfusion? delivery of oxygen and nutrients to and removal of wastes from, tissue cells, gas exchange in the lungs; absorption of nutrients from digestive tract; urine formation in the kidneys
What is the primary role of the sympathetic nervous system in ruling blood vessel diameter? vasoconstriction
What is the dramatically increased blood flow into a tissue that occurs after the blood supply to the area has been temporarily blocked? reactive hyperemia
What organ in the the body is the most metabolically active but the least able to store essential nutrients? the brain
What is the usual result of pressures over 160 mm Hg, which dramatically increases brain capillary permeability? cerebral edema
What is the force exerted by a fluid pressing against a wall? hydrostatic pressure
What is the process of forcing fluids thru the capillary walls via capillary hydrostatic pressure? filtration
What is the force opposing a hydrostatic pressure, created by the presence in a fluid of large nondiffusible molecules such as plasma proteins, called? colloid osmotic pressure
What is the condition called in which blood vessels are inadequately filled and blood cannot circulate normally resulting in inadequate blood flow to meet tissue needs? circulatory shock
What is the most common form of circulatory shock, resulting from large scale loss of blood, as in hemorrhage, severe vomiting or diarrhea or extensive burns? hypovolemic shock
What occurs when the heart is so inefficient that it cant sustain adequate circulation, usually caused by myocardial damage, such as heart attack? cardiogenic shock
What is a degenerative vascular disease that decreases the elasticity of arteries? arteriosclerosis
What is the formation of fatty subendothelial lesions called? atherosclerosis
Where is the steepest drop in BP? in the arterioles, where resistance is greatest
What does arterial blood pressure depend on? compliance of the elastic arteries and on how much blood is forced into them
When does arterial blood pressure peak? during systole
What varies directly with CO (cardiac output), peripheral resistance, and blood volume? blood pressure
How does the vasomotor center regulate blood pressure? regulates blood vessel diameter
How do kidneys regulate low bp? releasing renin, which triggers the formation of angiotensin II (a vasconstrictor) and release of aldosterone
What is the major cause of myocardial infarct, stroke, and renal disease? hypertension
What is considered chronic hypertension? 140/90 or higher
Which other 2 organs are most affected vascularly by chronic hypertension? eyes and kidneys
How do water soluble substances move across capillary walls? thru clefts or fenestrations
Where do fat-soluble substances pass thru the capillary wall? through the lipid portion of the endothelial cell membrane
How are larger molecules transported through capillary walls? actively transported via pinocytotic vesicles or caveolae
What collects the small net loss of fluid and protein into the interstitial space and returns it to the cardiovascular system? the lymphatic vessels
By which week is the fetal vasculature functioning? the 4th week
What results in the failure of vessels to transport blood? Ischemia
Symptoms of blood vessel ischemia Pain, pulselessness, pallor, parenthesia, paralysis, coolness
Definition of blood pressure The force exerted against the walls of the (large) arteries due to the pumping of the heart
Where are baroreceptors located? Aortic arch, carotid sinus
Sensory nerves involved in maintaining BP? Glossopharyngeal (CN IX) and vagus (CN X)
Hormones involved in maintaining BP Epinephrine and norepinephrine
Rapidly acting mechanisms involved in maintaining BP? Baroreceptors, sensory nerves, medulla oblongata, motor nerves, nor/epinephrine
What are slow acting mechanisms? Hormone regulated long-term maintenance
Where is atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) produced? The heart (also lower BP)
What causes vasodilation of vessels of skin? Temperature elevation
When body temp. increases more blood flows to skin thereby releasing: Heat and lowering body temp
When body temp. decreases less blood flows to skin thereby: Diverting warm blood to core of body
With age baroreceptors become less effective. This can result in: Dizziness and falls
With age, increased capillary membrane permeability, there's increased: Edema formation
What areas of the body do not have capillaries? lens, cornea, cartilage, epithelial layers
A cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter? Vasomotor Center
Which of the receptors are located in the carotid sinuses, aortic arch, and walls of the large arteries of the neck and thorax? Baroreceptors
Receptors located in the carotid sinus, aortic arch, and large arteries of the neck? Chemoreceptors
Hormone that causes intense vasoconstriction in the cases of extremely low BP? Antidiuretic Hormone
Hormone that causes blood volume and blood pressure to decline, causes generalized vasodilation? Atrial Natriuretic Peptide
Hormones that cause generalized vasoconstriction and increased cardiac output? Epinephrine and Norepinephrine
Generated by kidney release of renin, causes vasoconstriction? Angiotensin II
Which branch of the autonomic nervous system innervates blood vessels and which layer is innervated? What are the effector cells that carry out the response? Sympathetic vasomotor, tunica media, smooth muscle
The vascular shunt is comprised of the ________ and the ________. Metarteriole and the thoroughfare channel
Short term BP mechanisms are mediated by the NS and blood borne chemicals. This is done via _______, ________, and occassionally __________. Reflex arcs involving baroreceptors, vasomotor centers of the medulla, and occasionally inputs from chemoreceptors.
Long term BP mechanisms are influenced by ______ and ________. Hormonal controls such as NE, epinephrine, angiotensin II, ANP, ADH; and renal regulation via renin-angiotensin mechanism and aldosterone.
List some intrinsic mechanisms of autoregulation of blood flow (metabolic)amounts of pH, O2, CO2, prostagladins, adenosine, nitric oxide, endothelins and (myogenic) stretch
List some extrinsic mechanisms of autoregulation of blood flow (nerves) sympathetic, (hormones) alpha and beta receptors, angiotensin II, ADH, ANP
items that cause vasoconstriction Sympathetic nervous system, alpha receptors of epinephrine and norepinephrine, angiotensin II, ADH, Endothelins, myogenic stretch
items that cause vasodialation Decrease pH or O2, increase CO2, K, prostoglandins, adenosine, nitric oxide, ANP, beta receptors of epinephrine and norepinephrine
Peripheral resistance increases in anemia T/F False
Peripheral resistance is inversely related to the diameter of the arterioles T/F True
A local increase in histamine would not result in the dilation of the feeder arterioles and opening of the precapillary sphincters in systemic capillary beds. False
The presence of ___________ stabilizes the wall of capillaries. pericytes
An elastic lamina on both sides of the tunica media is a characteristic of: muscular arteries
When would the capillary beds surrounding the gastrointestinal organs be open? during a meal
Fluids would be likely to leave or filter out of the capillary if: net hydrostatic pressure (HP) is greater than net osmotic pressure (OP).
Cardiogenic shock is most likely to result from: multiple heart attacks
Created by: hkrawietz