Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
ch. 20
blood vessels
| Question | Answer |
|---|---|
| arteries | carry blood away from heart Including Pulmonary Arteries carrying blood LOW in oxygen from the right ventricle to the lungs |
| Veins | carry blood back to heart: Including Pulmonary Veins carrying blood HIGH in oxygen back from the lungs to the Left Atrium Greater capacity for blood containment than arteries Thinner walls, flaccid, less muscular and elastic tissue |
| Capillaries | Most bring Nutrients and oxygen to the Tissues and take carbon dioxide and wastes away: due to diffusion through the wall of the capillary (connect smallest arteries to smallest veins) exchange vessels |
| Tunica Interna (Tunica Intima) | Lines the blood vessel and is exposed to blood Acts as a selectively permeable barrier Secretes chemicals that stimulate dilation or constriction of the vessel Elastic layer is thicker in Arteries |
| Tunica media | Middle layer consists of: Smooth Muscle: Regulates diameter of the blood vessel (WHEN SMOOTH MUSCLE CONTRACTS: BLOOD VESSEL CONSTRICTS OR NARROWS) Collagen, and Elastic Tissue: Strengthens vessels and prevents blood pressure from rupturin |
| Tunica externa (Tunica Adventitia) | Outermost layer Consists of loose connective tissue with some elastic fibers Additional Collagen fibers in Arteries |
| blood flow | Heart ->Elastic Arteries -> Muscular Arteries -> Arterioles -> Capillaries -> Venules -> Veins -> Heart |
| Differences between Arteries and veins | Thicker muscle layer in Arteries and more Elastic Fibers Cut veins collapse due to thinner walls ; Arteries hold shape due to thicker walls Veins contain valves to prevent blood back-flow tunica intima is wrinkled in relaxed in artery but smooth in vein |
| Elastic Arteries | Biggest arteries closest to heart Aorta, common carotid, subclavian, pulmonary trunk, brachiocephalic artery, and common iliac arteries Tunica Media has more elastic fibers but less muscle Expand during systole, recoil during diastole |
| Muscular ( medium) Arteries | Distributes blood to specific organs and Skeletal Muscle Brachial, femoral, renal, and splenic arteries Tunica Media has thicker Smooth muscle layers: constitute three-fourths of wall thickness Majority of arteries are Muscular Arteries |
| Arterioles | smallest arteries Control amount of blood to various organs Thinner muscle layer than large arteries and very little tunica externa Low oxygen level in tissues causes results in Vasodilation to increase blood flow to more active tissues |
| Anastamosis | Branches of 2 or more arteries providing alternative routes for blood to reach a tissue or organ * Leads to “Collateral Circulation “ to same area |
| Aneurysm | Thinner weak point in artery or 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 base of brain |
| Arterial Sense Organs | Sensory structures in walls of major vessels that monitor blood pressure and chemistry Transmit information to brainstem to regulate heart rate, blood vessel diameter, and respiration |
| Carotid sinuses: baroreceptors | In walls of internal carotid artery Monitor blood pressure Transmit signals through glossopharyngeal nerve Allow for baroreflex |
| Carotid bodies: chemoreceptors | Oval bodies near branch of common carotids Monitor blood chemistry Transmit signals through glossopharyngeal nerve to brainstem respiratory centers Adjust respiratory rate to stabilize pH, CO_2, and O_2 |
| Aortic bodies: chemoreceptors | One to three bodies in walls of aortic arch Same structure and function as carotid bodies, but innervation is by vagus nerve |
| Continuous capillaries | occur in most tissues Endothelial cells have tight junctions forming a continuous tube with intercellular clefts Allow passage of solutes such as glucose Oxygen and carbon dioxide gases easily pass |
| Sinusoids (discontinuous capillaries): | liver, bone marrow, spleen Irregular blood-filled spaces with large gaps in endothelium Allow proteins (albumin), clotting factors, and new blood cells to enter the circulation Most porous of capillaries |
| Capillary Beds | Capillary beds are networks of 10-100 capillaries Usually supplied by a single arteriole. At distal end, capillaries transition to venules At any given time, three-fourths of body’s capillaries are shut down |
| precapillary sphincters | control flow |
| Venules | smallest veins; collect blood from capillaries Even more porous than capillaries so also exchange fluid with surrounding tissues 1. Smallest Venules: Tunica Interna and Tunica Externa only |
| Venous sinuses | Veins with especially thin walls, large lumens, and no smooth muscle Dural venous sinus and coronary sinus of the heart Not capable of vasomotor responses |
| Large veins | diameter larger than 10 mm Venae cavae, pulmonary veins, internal jugular veins, and renal veins |
| Varicose Veins | Blood pools in the lower legs of people who stand for long periods stretching the veins |
| Circulatory Routes | Simplest and most common route for blood 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 |
| Portal system | Blood flows through two consecutive capillary networks before returning to heart Between hypothalamus and anterior pituitary: Hypophyseal Portal System |
| Hepatic Portal System | Between intestines to liver |
| Venous anastomosis | circulatory route Most common One vein empties directly into another Reason vein blockage is less serious than arterial blockage and repair to Varicose veins is successful |
| Arterial anastomosis | circulatory route Two arteries merge Provides collateral (alternative) routes of blood supply to a tissue Coronary circulation and common around joints |
| Blood flow | the amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min.) |
| Perfusion | the flow per given volume or mass of tissue in a given time (mL/min./g) |
| Hemodynamics | Physical principles of blood flow based on pressure and resistance The greater the pressure difference between two points, the greater the flow; the greater the resistance, the less the flow |
| Blood pressure (BP)— | the force that blood exerts against a vessel wall |
| Systolic pressure | peak arterial BP taken during ventricular contraction (ventricular systole) |
| Diastolic pressure | minimum arterial BP taken during ventricular relaxation (diastole) between heart beats |
| Pulse pressure | difference between systolic and diastolic pressure Important measure of driving force on circulation and of stress exerted on small arteries by pressure surges generated by the heart |
| Cardiac Output | Amount of Blood from Left Ventricle to Aorta per minute = 5.25 liters per minute Increase in stroke volume or Heart Rate: Increases blood pressure |
| Blood Volume | : 5 Liters Drop in blood volume( hemorrhage , dehydration) and blood pressure drops Increse in Blood Volume(reain Water) and Blood Pressure increases |
| Resistance: Peripheral Resistance | the opposition to flow that blood encounters in vessels away from the heart |
| Blood Viscosity | Thicker or more Viscose the blood(polycythemia) ->the higher the blood pressure -Thinner, less viscose the blood(anemia)-> Lower blood pressure |
| Elasticity of blood vessels: | Arteries may stretch to help maintain lower blood pressure If Arterial wall Harden (Arteriosclerosis)-. Blood pressure Increases |
| Arteriosclerosis | stiffening of arteries due to deterioration of elastic tissues of artery walls: Elasticity reduced |
| Atherosclerosis | build up of lipid deposits that become plaques: narrows blood vessel |
| Hypertension | high blood pressure Chronic resting BP > 140/90 Consequences Can weaken arteries, cause aneurysms, promote atherosclerosis |
| Hypotension | chronic low resting BP Caused by blood loss, dehydration, anemia |
| Vasoreflexes | changes in vessel radius Vasoconstriction and Vasodilation |
| blood velocity (speed) decreases for 3 reasons | Greater distance, more friction to reduce speed 2. Smaller radii of arterioles and capillaries offers more resistance 3. Farther from heart, the number of vessels and their total cross-sectional area become greater and greater |
| Autoregulation | the ability of tissues to regulate their own blood supply |
| Vasoactive chemicals | substances secreted by platelets, endothelial cells, and perivascular tissue to stimulate vasomotor responses Histamine, bradykinin, and prostaglandins stimulate vasodilation Endothelial cells secrete prostacyclin and nitric oxide (vasodilators) |
| Reactive hyperemia | If blood supply cut off then restored, flow increases above normal |
| Angiogenesis | growth of new blood vessels Occurs in regrowth of uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors |
| Vasomotor center is the integrating center for three autonomic reflexes | Baroreflexes Chemoreflexes Medullary ischemic reflex |
| Baroreflex | automatic, negative feedback response to change in blood pressure govern short-term regulation of BP |
| Chemoreflex | an automatic response to changes in blood chemistry Especially pH, and concentrations of O_2 and CO_2 |
| Medullary ischemic reflex | automatic response to a drop in perfusion of the brain |
| Angiotensin II | potent vasoconstrictor 1)potent vasoconstrictor: Raises blood pressure 2)Promotes Na^+ and water retention by kidneys: Increases blood volume and pressure |
| Atrial natriuretic peptide | increases urinary sodium excretion which increases water loss thru kidney 1)Reduces blood volume and 2) promotes vasodilation: Lowers blood pressure |
| Capillary exchange | two-way movement of fluid across capillary walls Water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, carbon dioxide, ammonia |
| Diffusion | is the most important form of capillary exchange Glucose and oxygen, being more concentrated in blood, diffuse out of the blood Large particles such as proteins held back |
| Lipid-soluble substances | Steroid hormones, O_2, and CO_2 diffuse easily through plasma membranes |
| Water-soluble substances | Glucose and electrolytes must pass through filtration pores and intercellular clefts |
| Trancytosis | endothelial cells pick up material on one side of their membrane by pinocytosis or receptor-mediated endocytosis, transport vesicles across cell, and discharge material on other side by exocytosis |
| “Starlings Law” | Opposing forces Blood hydrostatic pressure drives fluid out of capillary Colloid osmotic pressure (COP) draws fluid back into capillary |
| Hydrostatic pressure | Physical force exerted against a surface by a liquid Blood pressure in vessels is hydrostatic pressure |
| Glomeruli | devoted to filtration |
| Alveolar capillary | devoted to absorption |
| Edema | accumulation of excess fluid in a tissue Occurs when fluid filters into a tissue faster than it is absorbed Three primary causes: 1)Increased capillary filtration 2)Reduced capillary absorption 3)Obstructed lymphatic drainage |
| 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 |
| Venous return | the flow of blood back to the heart; relies on: pressure gradient, gravity, skeletal muscle pump, thoracic pump, and cardiac suction |
| Respiratory (Thoracic) pump | Inhalation—thoracic cavity expands and thoracic pressure decreases, abdominal pressure increases, forcing blood upward: Towards Right Atrium Central venous pressure fluctuates 2 mm Hg—inhalation, 6 mm Hg—exhalation Blood flows faster with inhalation |
| Venous pooling | occurs with inactivity Venous pressure not enough to force blood upward With prolonged standing, CO may be low enough to cause dizziness |
| Circulatory shock | any state in which cardiac output is insufficient to meet the body’s metabolic needs |
| Cardiogenic shock | inadequate pumping of heart (MI) |
| Low venous return (LVR): | cardiac output is low because too little blood is returning to the heart |
| 3 principal forms of LVR shock | Hypovolemic shock—most common Loss of blood volume: trauma, burns, dehydration 2. Obstructed venous return shock Tumor or aneurysm compresses a vein 3. Venous pooling (vascular) shock Long periods of standing, sitting, or widespread vasodilation |
| Neurogenic shock | loss of vasomotor tone, vasodilation Causes from emotional shock to brainstem injury |
| Septic shock | Bacterial toxins trigger vasodilation and increased capillary permeability |
| Anaphylactic shock | Severe immune reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability |
| Compensated shock | Several homeostatic mechanisms bring about spontaneous recovery Example: If a person faints and falls to a horizontal position, gravity restores blood flow to the brain |
| Decompensated shock | When compensation fails Life-threatening positive feedback loops occur Condition gets worse causing damage to cardiac and brain tissue |
| Hypercapnia | CO_2 levels increase in brain, pH decreases, triggers vasodilation |
| Hypocapnia | raises pH, stimulates vasoconstriction Occurs with hyperventilation, may lead to ischemia, dizziness, and sometimes syncope |
| Transient ischemic attacks (TIAs)— | brief episodes of cerebral ischemia Caused by spasms of diseased cerebral arteries Dizziness, loss of vision, weakness, paralysis, headache, or aphasia |
| Stroke, or cerebral vascular accident (CVA) | 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 |
| hypoxia | low oxygen levels in infected or damaged areas of lung |
Created by:
tnrogan
Popular Physiology sets