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Anatomy 2 Ch4
Arteries and veins and all that stuff
| Question | Answer |
|---|---|
| Angiogenesis | the growth of new blood vessels |
| Arteries | carry blood from the heart to the tissues. |
| Arterioles | are small arteries that connect to capillaries. |
| Capillaries | are the site of substance exchange between the blood and body tissues. |
| Venules | connect capillaries to larger veins. |
| Veins | convey blood from the tissues back to the heart. |
| Vaso vasorumare | small blood vessels that supply blood to the cells of the walls of the arteries and veins. (supply oxygen to the cells lining larger vessels |
| The functional properties of arteries are... | elasticity and contractility. |
| Elasticity | allows arteries to accept blood under great pressure from the contraction of the ventricles and to send it on through the system. |
| Contractility | allows arteries to increase or decrease lumen size and to limit bleeding from wounds. |
| Do blood vessels relax? | Blood vessels never relax, unless you’re dead. In vasodilation, they don’t contract as much |
| 3 major layers of arteries. | Tunica interna (intima), Tunica media, Tunica externa |
| Tunica interna (intima) | endothelium, basement membrane, internal elastic lamina |
| Tunica media | circular smooth muscle & elastic fibers |
| Tunica externa | elastic & collagen fibers |
| Blood vessels only have _____response. | sympathetic. Vascular smooth muscle is innervated by sympathetic nervous system |
| Sympathetic Innervation | increase in stimulation causes muscle contraction or vasoconstriction: decreases diameter of vessel; decrease in stimulation or presence of certain chemicals causes vasodilation |
| cause vasodilation | nitric oxide, K+, H+ and lactic acid |
| Elastic Arteries | Large arteries w/more elastic fibers&less smooth muscle •Able to receive blood under pressure&propel it onward.•Called conducting arteries because they conduct blood from the heart to medium sized muscular arteries.•They function as a pressure reservoir. |
| Muscular Arteries | Medium-sized arteries with more muscle than elastic fibers in tunica media•Capable of greater vasoconstriction and vasodilation to adjust rate of flow(walls are relatively thick–called distributing arteries because they direct blood flow) |
| Arterioles | Small arteries delivering blood to capillaries•Metarterioles form branches into capillary bed |
| to bypass capillary bed... | precapillary sphincters close & blood flows out of bed in thoroughfare channel |
| vasomotion is | intermittent contraction & relaxation of sphincters that allow filling of capillary bed 5-10 times per minute |
| Post capillary sphincters | don’t exist |
| Microcirculation | Microscopic vessels that connect arterioles to venules•Found near every cell in body but more extensive in highly active tissue (muscles, liver, kidneys, & brain)•Capillary walls composed of a single layer of cells (endothelium) and a basement membrane |
| Continuous capillaries | skeletal & smooth, connective tissue and lungs |
| Fenestrated capillaries | kidneys, small intestine, ciliary process & endocrine glands |
| Sinusoids | liver, bone marrow, & spleen |
| Holes in sinusoids for... | liver and spleen is to take RBC out of circulation to break down ect |
| No capillaries in our joints because | they’d be shredded. Also not in cornea because it would obstruct light |
| Venules | Small veins collecting blood from capillaries•Tunica media contains only a few smooth muscle cells & scattered fibroblasts(porous endothelium allows WBC emigration) |
| Veins | Same three tunics as arteries –thinner tunica interna and media and a thicker tunica externa–less elastic tissue and smooth muscle–thinner-walled than arteries–contain valves to prevent the backflow of blood |
| Vascular (venous) sinuses | veins with very thin walls with no smooth muscle to alter their diameters. •Ex. coronary sinus of the heart |
| Veins have... | Proportionally thinner walls than same diameter artery•Still adaptable to variationsin volume & pressure•Valves are thin folds of tunica interna designed to prevent backflow |
| Anastomoses | Union of 2 or more arteries supplying the same body region–blockage of only one pathway has no effect |
| Collateral circulation | Alternate route of blood flow through an anastomosis |
| end arteries | Arteries that do not anastomose |
| Occlusion of an end artery .. | interrupts the blood supply to a whole segment of an organ, producing necrosis (death) of that segment. |
| Blood Distribution | 60% of blood volume at rest is in systemic veins and venules–functions as a blood reservoir |
| blood is diverted from reservoir in times of need | increased muscular activityproduces venoconstriction•hemorrhage causes venoconstriction to help maintain blood pressure |
| Capillary Exchange | Diffusion, Transcytosis, Bulk flow |
| Diffusion (most important method) | Substances such as O2, CO2, glucose, amino acids, hormones, and others diffuse down their concentration gradients.–all plasma solutes except large proteins pass freely across |
| Transcytosis | passage of material across endothelium in tiny vesicles by endocytosis and exocytosis (large, lipid-insoluble molecules such as insulin or maternal antibodies passing through placental circulation to fetus) |
| Bulk Flow | Movement of large dissolved/suspended material in same direction–move in response to pressure•from area of high pressure to low–faster rate of movement than diffusion or osmosis•Most important for regulation of relative volumes of blood&interstitial fluid |
| Filtration | movement of material into interstitial fluid•promoted by blood hydrostatic pressure & interstitial fluid osmotic pressure |
| Reabsorption | movement from interstitial fluid into capillaries•promoted by blood colloid osmotic pressure |
| balance of hydrostatic,interstituial,blood colloid pressure... | net filtration pressure |
| Net Filtration Pressure | Whether fluids leave or enter capillaries depends on net balance of pressures–net outward pressure of 10 mm Hg at arterial end of a capillary bed–net inward pressure of 9 mm Hg at venous end of a capillary bed |
| About 85% of the filtered fluid is returned to the capillary– | escaping fluid and plasma proteins are collected by lymphatic capillaries (3 liters/day) |
| Edema | An abnormal increase in interstitial fluid if filtration exceeds reabsorption |
| result of excess filtration | increased blood pressure (hypertension)•increased permeability of capillaries allows plasma proteins to escape |
| result of inadequate reabsorption | decreased concentration of plasma proteins lowers blood colloid osmotic pressure |
| Filtration/reabsorption issue | Often not noticeable until 30% above normal |
| Hemodynamics | Cardiac output, blood volume, viscosity, resistance, and elasticity of arteries. |
| As blood leaves the aorta and flows through systemic circulation | its pressure progressively falls to 0 mm Hg by the time it reaches the right atrium |
| Resistance refers to | the opposition to blood flow as a result of friction between blood and the walls of the blood vessels. |
| Vascular resistance depends on | the diameter of the blood vessel, blood viscosity, and total blood vessel length. |
| Systemic vascular resistance(also known as total peripheral resistance) | all of the vascular resistances offered by systemic blood vessels; most resistance is in arterioles, capillaries, and venules due to their small diameters. |
| Blood Pressure | Pressure exerted by blood on walls of a vessel –caused by contraction of the ventricles–highest in aorta (120/80) |
| with distance from left ventricle... | Pressure falls steadily in systemic circulation |
| Pressure entering capillaries | 35 mm Hg |
| Pressure entering the right atrium | 0 mm Hg |
| If decrease in blood volume is over 10%... | BP drops |
| Velocity of Blood Flow | Speed of blood flow in cm/sec is inversely related to cross-sectional area–blood flow is slower in thearterial branches |
| Blood flow in aorta is | 40 cm/sec |
| flow in capillaries is | .1 cm/sec |
| Blood flow becomes faster when ... | vessels merge to form veins |
| Circulation time is time it takes... | a drop of blood to travel from right atrium back to right atrium |
| Venous Return | Volume of blood flowing back to the heart from the systemic veins |
| Venous Return depends on... | pressure difference from venules (16 mm Hg) to right atrium (0 mm Hg)–tricuspid valve leaky andbuildup of blood on venousside of circulation |
| Skeletal muscle pump– | contraction of muscles & presence of valves |
| Respiratory pump– | decreased thoracic pressure and increased abdominal pressure during inhalation, moves blood into thoracic veins and the right atrium |
| Resistance | Friction between blood and the walls of vessels |
| Average blood vessel radius | •smaller vessels offer more resistance to blood flow•cause moment to moment fluctuations in pressure |
| Total blood vessel length | •the longer the vessel, the greater the resistance to flow•200 miles of blood vessels for every pound of fat |
| Systemic vascular resistance (SVR) | blood vessel radius and length total–arterioles control BP by changing diameter |
| Role of cardiovascular center | help regulate heart rate & stroke volume–specific neurons regulate blood vessel diameter |
| Cardiovascular center (CV) | a group of neurons in the medulla that regulates heart rate, contractility, and blood vessel diameter. |
| CV overview | input from higher brain regions&sensory receptors –output from CV flows along sympathetic ¶sympathetic fibers–Sympathetic impulses along cardioaccelerator nerves increase heart rate&contractility–Parasym impulses along vagus nerves decrease heartrate |
| The sympathetic division also continually... | sends impulses to smooth muscle in blood vessel walls via vasomotor nerves. The result is a moderate state of tonic contraction or vasoconstriction, called vasomotor tone. |
| Syncope | Fainting or a sudden, temporary loss of consciousness not due to trauma–due to cerebral ischemia or lack of blood flow to the brain |
| vasodepressor syncope = | sudden emotional stress |
| situational syncope = | pressure stress of coughing, defecation, or urination |
| drug-induced syncope = | antihypertensives, diuretics, vasodilators and tranquilizers |
| orthostatic hypotension = | decrease in BP upon standing |
| Chemoreceptor Reflexes | Carotid bodies and aortic bodies |
| Carotid bodies and aortic bodies... | detect changes in blood levels of O2, CO2, and H+ (hypoxia, hypercapnia or acidosis )–causes stimulation of CV–increases sympathetic stimulation to arterioles & veins–vasoconstriction and increase in blood pressure Also changes breathing rate |
| Renin-Angiotensin-Asldosterone System (RAAS) | A decrease in BP or decreased blood flow to kidney results in a release of renin from kidney which results in the formation angiotensin II (AII) |
| AII | a potent vasoconstrictor (↑ SVR), causes release of aldosterone |
| Aldosterone | increases reabsorption of Na+ in the kidneys which increases H2O reabsorption |
| Epinephrine & norepinephrine | Decreased BP results in a release of epinephrine and norepinephrine from the adrenal medulla–Increases heart rate & force of contraction–Causes vasoconstriction in skin & abdominal organs–Vasodilation in cardiac & skeletal muscle |
| ADH release from posterior pituitary causes | vasoconstriction |
| Atrial natriuretic peptide(ANP) | lowers BP; causes vasodilation & loss of salt and water in the urine |
| Autoregulation | The ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for supply of O2 and nutrients and removal of wastes is called. |
| Local factors cause changes in each capillary bed | important for tissues that have major increases in activity (brain, cardiac & skeletal muscle) |
| Local changes in response to physical changes | warming & decrease in vascular stretching promotes vasodilation |
| Vasoactive substances released from cells alter vessel diameter | (K+, H+, lactic acid, nitric oxide); systemic vessels dilate in response to low levels of O2–pulmonary vessels constrict in response to low levels of O235 |
| Hypovolemic shock | due to loss of blood or body fluids (hemorrhage, sweating, diarrhea)–venous return to heart declines & output decreases |
| Cardiogenic shock | caused by damage to pumping action of the heart (MI, ischemia, valve problems or arrhythmias) |
| Vascular shock | causing drop inappropriate vasodilation -- anaphylatic shock, septic shock or neurogenic shock (head trauma) |
| Obstructive shock | caused by blockage of circulation (pulmonary embolism) |
| Systemic circulation | left side heart to body & back to heart |
| Hepatic Portal circulation | capillaries of GI tract to capillaries in liver |
| Pulmonary circulation | right-side heart to lungs & back to heart |
| Fetal circulation | from fetal heart through umbilical cord to placenta & back |
| External carotid arteries | supplies structures external to skull as branches of maxillary and superficial temporal branches |
| Internal carotid arteries (contribute to Circle of Willis)– | supply eyeballs and parts of brain |
Created by:
Devtemrys
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