Term
|
Definition
| carry blood away from heart; sometimes called resistance vessels because they have relatively strong, resilient tissue structure that resists high blood pressure |
|
|
Term
|
Definition
•carry blood back to heart
•greater capacity for blood containment than arteries
•thinner walls, flaccid, less muscular and elastic tissue
•collapse when empty, expand easily
•subjected to relatively low blood pressure |
|
|
Term
|
Definition
connect smallest arteries to veins; site where nutrients, wastes, and hormones pass between the blood and tissue fluid through the walls of the vessels (exchange vessels)
–absent or scarce in tendons, ligaments, epithelia, cornea and lens of the eye |
|
|
Term
| tunica interna (tunica intima) |
|
Definition
–lines the blood vessel and is exposed to blood
–endothelium |
|
|
Term
|
Definition
•simple squamous epithelium overlying a basement membrane and a sparse layer of loose connective tissue
•acts as a selectively permeable barrier
•secrete chemicals that stimulate dilation or constriction of the vessel
•normally repels blood cells and platelets that may adhere to it and form a clot
•when tissue around vessel is inflamed, the endothelial cells produce cell-adhesion molecules that induce leukocytes to adhere to the surface |
|
|
Term
|
Definition
–middle layer
–consists of smooth muscle, collagen, and elastic tissue
–strengthens vessel and prevents blood pressure from rupturing them
–vasomotion |
|
|
Term
|
Definition
| changes in diameter of the blood vessel brought about by smooth muscle; change in vessel radius |
|
|
Term
| tunica externa (tunica adventitia) |
|
Definition
–outermost layer
–consists of loose connective tissue that often merges with that of neighboring blood vessels, nerves, or other organs
–anchors the vessel and provides passage for small nerves, lymphatic vessels
–vasa vasorum |
|
|
Term
|
Definition
| small vessels that supply blood to at least the outer half of the larger vessels |
|
|
Term
| conducting (elasticor large) arteries |
|
Definition
•biggest arteries
•aorta, common carotid, subclavian, pulmonary trunk, and common iliac arteries
•external elastic lamina at the border between media and externa
•expand during systole, recoil during diastole which lessens fluctuations in blood pressure |
|
|
Term
| distributing (muscular ormedium) arteries |
|
Definition
•distributes blood to specific organs
•brachial, femoral, renal, and splenic arteries
•smooth muscle layers constitute three-fourths of wall thickness |
|
|
Term
|
Definition
-weak point in an artery or the heart wall
–forms a thin-walled, bulging sac that pulsates with each heartbeat and may rupture at any time
–most common sites: abdominal aorta, renal arteries, and arterial circle at the base of the brain
–result from congenital weakness of the blood vessels or result of trauma or bacterial infections such as syphilis
•most common cause is atherosclerosis and hypertension |
|
|
Term
|
Definition
–smallest arteries
-control amount of blood to various organs
-most significant point of control over peripheral resistance and flow |
|
|
Term
|
Definition
| –short vessels that link arterioles to capillaries |
|
|
Term
|
Definition
–baroreceptors (pressure sensors)
•in walls of internal carotid artery
•monitors blood pressure –signaling brainstem
–decreased heart rate and vessels dilation in response to high blood pressure |
|
|
Term
|
Definition
| -chemoreceptors •oval bodies near branch of common carotids •monitor blood chemistry •mainly transmit signals to the brainstem respiratory centers •adjust respiratory rate to stabilize pH, CO2, and O2 |
|
|
Term
|
Definition
-chemoreceptors
•one to three in walls of aortic arch
•same function as carotid bodies |
|
|
Term
|
Definition
| distinguished by ease with which substances pass through their walls and by structural differences that account for their greater or lesser permeability |
|
|
Term
| Three Types of Capillaries |
|
Definition
•continuous capillaries
•fenestrated capillaries
•sinusoids (discontinuous capillaries) |
|
|
Term
|
Definition
-occur in most tissues
–endothelial cells have tight junctions forming a continuous tube with intercellular clefts
•allow passage of solutes such as glucose
–pericytes wrap around the capillaries and contain the same contractile protein as muscle
•contract and regulate blood flow |
|
|
Term
|
Definition
-kidneys, small intestine
–organs that require rapid absorption or filtration
–endothelial cells riddled with holes called filtration pores (fenestrations)
•spanned by very thin glycoprotein layer
•allows passage of only small molecules |
|
|
Term
| sinusoids (discontinuous capillaries) |
|
Definition
-liver, bone marrow, spleen
–irregular blood-filled spaces with large fenestrations
–allow proteins (albumin), clotting factors, and new blood cells to enter the circulation |
|
|
Term
|
Definition
•blood pools in the lower legs in people who stand for long periods stretching the veins
–blood backflows and further distends the vessels, their walls grow weak and develop into varicose veins
•hereditary weakness, obesity, and pregnancy also promote problems
•hemorrhoids are varicose veins of the anal canal |
|
|
Term
|
Definition
–heart -> arteries -> arterioles -> capillaries -> venules -> veins
–passes through only one network of capillaries from the time it leaves the heart until the time it returns |
|
|
Term
|
Definition
| –blood flows through two consecutive capillary networks before returning to heart |
|
|
Term
|
Definition
| the point where two blood vessels merge |
|
|
Term
| arteriovenous anastomosis (shunt) |
|
Definition
| –artery flows directly into vein bypassing capillaries |
|
|
Term
|
Definition
–most common
–one vein empties directly into another |
|
|
Term
|
Definition
–two arteries merge
–provides collateral (alternative) routes of blood supply to a tissue |
|
|
Term
|
Definition
•blood supply to a tissue can be expressed in terms of flow and perfusion
•important for delivery of nutrients and oxygen, and removal of metabolic wastes |
|
|
Term
|
Definition
| the amount of blood flowing through an organ, tissue, or blood vessel in a given time (ml/min) |
|
|
Term
|
Definition
| the flow per given volume or mass of tissuein a given time (ml/min/g) |
|
|
Term
|
Definition
–the force that blood exerts against a vessel wall
•measured at brachial artery of arm using sphygmomanometer
•one of the body’s chief mechanisms in preventing excessive blood pressure is the ability of the arteries to stretch and recoil during the cardiac cycle
•importance of arterial elasticity
–expansion and recoil maintains steady flow of blood throughout cardiac cycle, smoothes out pressure fluctuations and decreases stress on small arteries
•BP determined by cardiac output, blood volume and peripheral resistance |
|
|
Term
|
Definition
| peak arterial BP taken during ventricular contraction (ventricular systole) |
|
|
Term
|
Definition
| minimum arterial BP taken during ventricular relaxation (diastole) between heart beats |
|
|
Term
|
Definition
–difference between systolic and diastolic pressure
–important measure of stress exerted on small arteries by pressure surges generated by the heart |
|
|
Term
| blood viscosity “thickness” |
|
Definition
•RBC count and albumin concentration elevate viscosity the most
•decreased viscosity with anemia and hypoproteinemia speed flow
•increased viscosity with polycythemia and dehydration slow flow |
|
|
Term
|
Definition
| most powerful influence over flow |
|
|
Term
|
Definition
| by muscular effort that results in smooth muscle contraction |
|
|
Term
|
Definition
| by relaxation of the smooth muscle |
|
|
Term
|
Definition
•from aorta to capillaries, blood velocity (speed) decreases
•from capillaries to vena cava, flow increases again |
|
|
Term
|
Definition
-growth of new blood vessels
–occurs in regrowthof uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors
–controlled by growth factors |
|
|
Term
|
Definition
| of medulla oblongata exerts sympathetic control over blood vessels throughout the body |
|
|
Term
| vasomotor center is the integrating center for three autonomic reflexes |
|
Definition
•baroreflexes
•chemoreflexes
•medullary ischemic reflex |
|
|
Term
|
Definition
–an automatic, negative feedback response to changes in blood pressure
–inhibit the sympathetic cardiac and vasomotor neurons reducing sympathetic tone, and excite vagal fibers to the slowing of heart rate and cardiac output –thus reducing BP
-important in short-term regulation of BP but not in cases of chronic hypertension |
|
|
Term
|
Definition
| –an automatic response to changes in blood chemistry –especially pH, and concentrations of O2 and CO2 -called aortic bodies and carotid bodies –located in aortic arch, subclavian arteries, external carotid arteries -primary role: adjust respiration to changes in blood chemistry |
|
|
Term
| medullary ischemic reflex |
|
Definition
-automatic response to a drop in perfusion of the brain
–medulla oblongata monitors its own blood supply
-other brain centers can affect vasomotor center
–stress, anger, arousal can also increase BP |
|
|
Term
|
Definition
–potent vasoconstrictor
–raises blood pressure |
|
|
Term
|
Definition
–promotes Na+ and water retention by kidneys
–increases blood volume and pressure |
|
|
Term
| atrial natriuretic peptide |
|
Definition
–increases urinary sodium excretion
–reduces blood volume and promotes vasodilation
–lowers blood pressure |
|
|
Term
|
Definition
-promotes water retention and raises BP
–pathologically high concentrations- vasoconstrictor |
|
|
Term
| epinephrine and norepinephrine effects |
|
Definition
–most blood vessels
•binds to adrenergic receptors- vasoconstriction
–skeletal and cardiac muscle blood vessels
•binds to adrenergic receptors- vasodilation |
|
|
Term
| The Two Purposes of Vasomotion |
|
Definition
•general method of raising or lowering BP throughout the whole body
•important in supporting cerebral perfusion during a hemorrhage or dehydration
•method of rerouting bloodfrom one region to another for perfusion of individual organs |
|
|
Term
| The Routing of Blood Flow Examples |
|
Definition
–vigorous exercise dilates arteries in lungs, heart and muscles
•vasoconstriction occurs in kidneys and digestive tract |
|
|
Term
|
Definition
–two way movement of fluid across capillary walls
-the most important blood in the body is in the capillaries
-only through capillary walls are exchanges made between the blood and surrounding tissues
-diffusion is the most important form of capillary exchange
–glucose and oxygen being more concentrated in blood diffuse out of the blood
–carbon dioxide and other waste being more concentrated in tissue fluid diffuse into the blood |
|
|
Term
| Filtration and Reabsorption |
|
Definition
•hydrostatic pressure
•capillaries reabsorb about 85% of the fluid they filter
•other 15% is absorbed by the lymphatic system and returned to the blood |
|
|
Term
|
Definition
–physical force exerted against a surface by a liquid
•blood pressure is an example |
|
|
Term
|
Definition
–the accumulation of excess fluid in a tissue
–occurs when fluid filters into a tissue faster than it is absorbed |
|
|
Term
| The three primary causes of edema |
|
Definition
–increased capillary filtration
•kidney failure, histamine release, old age, poor venous return
–reduced capillary absorption
•hypoproteinemia, liver disease, dietary protein deficiency
–obstructed lymphatic drainage
•surgical removal of lymph nodes |
|
|
Term
|
Definition
•tissue necrosis
–oxygen delivery and waste removal impaired
•pulmonary edema
–suffocation threat
•cerebral edema
–headaches, nausea, seizures, and coma
•severe edema or circulatory shock
–excess fluid in tissue spaces causes low blood volume and low blood pressure |
|
|
Term
|
Definition
| any state in which cardiac output is insufficient to meet the body’s metabolic needs |
|
|
Term
|
Definition
| inadequate pumping of heart (MI) |
|
|
Term
|
Definition
| cardiac output is low because too little blood is returning to the heart |
|
|
Term
| three principal forms of circulatory shock |
|
Definition
1. hypovolemic shock
2. obstructed venous return shock
3. venous pooling (vascular) shock |
|
|
Term
|
Definition
-most common
-loss of blood volume: trauma, burns, dehydration |
|
|
Term
| obstructed venous return shock |
|
Definition
| -tumor or aneurysm compresses a vein |
|
|
Term
| venous pooling (vascular) shock |
|
Definition
| long periods of standing, sitting or widespread vasodilation |
|
|
Term
|
Definition
| bacterial toxins trigger vasodilation and increased capillary permeability |
|
|
Term
|
Definition
| severe immune reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability |
|
|
Term
| transient ischemic attacks (TIAs) |
|
Definition
–brief episodes of cerebral ischemia
–lasts from a moment to a few hours
–often early warning of impending stroke |
|
|
Term
| stroke- cerebral vascular accident (CVA) |
|
Definition
–sudden death of brain tissue caused by ischemia
•atherosclerosis, thrombosis, ruptured aneurysm
–effects range from unnoticeable to fatal
•blindness, paralysis, loss of sensation, loss of speech common
–recovery depends on surrounding neurons, collateral circulation |
|
|
Term
|
Definition
•most common cardiovascular disease affecting about 30% of Americans over 50
•“the silent killer” |
|
|
Term
|
Definition
| –obesity, sedentary behavior, diet, nicotine |
|
|
Term
|
Definition
–secondary to other disease
–kidney disease, hyperthyroidism |
|
|
