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A&P II Blood vessles
Blood Vessle Whitley
| Question | Answer |
|---|---|
| Blood Vessels | Form a closed system compose of arteries, arterioles, capillaries, vein, venules |
| An artery and a vein | An artery is a vessle taking blood away from the heart A vein is a vessel returning blood to the heart |
| Walls of the arteries and veins have three coats | Tunica intima Tunica media Tunica externa or Tunica adventicia |
| Tunica intima | inside lining 1. Layer of simple squamous epithelium 2. Layer of elastic fibers (found only in artery) |
| Tunica media | Layer of smooth muscle and elastic fibers (veins have more connective tissue fibers mixed with the smooth muscle) |
| Tunica externa or tunica adventicia | Connective tissue located on the outside |
| Arteries Characteristics | 1. Walls are thicker and contain more smooth muscle. 2.Lumen is round (particulary in smaller vessels) 3. Valves are absent |
| Arteries Types | 1. Elastic or conducting arteries 2. Distributing or muscular arteries |
| Elastic or conducting arteries | Large vessels that contain more elastin and muscle fibers. (Aorta and its direct branches) |
| Distributing or muscular arteries | Distributes blood to various parts of the body and is composed of a thick tunica that constricts and dilates |
| Arteriles | Are small arteries that contain all three coats on the arterial end, but are composed of an endothelial lining witha few smooth muscle cells towards the end |
| Capillaries Characteristics | 1. Smallest are 7-10 microns in diameter 2. Walls are composed of a single layer of simple squamous epithelium with basement membrane *3. Amount of blood flowing through a capillary is determined by a precapillary sphincter muscle located at the origin |
| Types of Capillaries | Continuous Fenestrated Discontinuous |
| Continuous | Adjacent endothelial cells closely joined. Located in muscles, lungs, adipose and central nervous system. Contain many pinocytic vesicles. |
| Fenestrated | Capillaries contain large pores covered with the basement membrane. Located in the kidneys, endocrine glands, intestines, and choroid plexus of brain |
| Discontinuous | Larger spaces between the endothelial cells. Located in the liver, spleen, and bone marrow |
| Venules | Capillaries come together to make venules composed of Tunica interna and tunica externa |
| Veins | Vessles that return blood to the heart |
| Veins Characteristics | 1. Have less smooth muscle and more connective tissue 2. Lumen partially collapsed 3. Contains valves |
| Veins Function | 1. Return blood to heart 2. Act as blood reservoirs (approx. 2/3 of blood volume located in veins) not active |
| Anastomosis | Junction between two vessels supplying the same area |
| Collateral circulation | Two vessels supplying the same are and providing an alternate route for blood flow due to an anastomosis |
| End arteries | Vessels that do not anastomos |
| Blood pressure | Pressure blood exerts on any vessel. |
| Factors That Affect Arterial Pressure | Cardiac output Blood volume Peripheral resistance |
| Cardiac output | decrease in stroke volume or heart beat leads to decrease in blood pressure |
| Blood volume | Directly proportional to blood pressure. Anything that increases blood volume increase blood pressure 1. ADH 2. Aldosterone |
| Peripheral resistance | resistance to blood flow by force of friction blood and walls of vessels |
| 1.Any condition that increases viscosity increase blood pressure (affects length) 2. The smaller the diameter of the vessels,the more resistance. 3. The longer the vessel, the more resistance. For each pound of fat, the body makes 200 additional miles | |
| Control of Blood Pressure | Increase in heart rate and muscular contractions increases blood pressure. Factors controlling heart rate and force on contractions also affect blood pressure. |
| Factors action on blood vessels | 1.Vasomotor center in medulla controls diameter of blood vessel. 2. Pressoreceptors in aortic arch and carotid sinus 3. Chemoreceptors in arotic arch and carotid sinus (monitors low oxygen by checking for high H+. High CO2 levels lead to high H+ concent |
| Autoregulation | Oxygen is the principal stimulant. Low oxygen cuases vasodilator substace to be release. Examples are K+, H+, CO2, lactic acid and adenosine. This cause local dilation and relaxationof precapillary sphincter muscles. (high CO2 high H+ causes low 02) |
| Venous Pressure | Highest in venules (16 mm Hg) and lowest at junction of vena cava with right atrium (0 mm Hg) Aids venous blood returning to heart |
| Aids venous blood returning to heart | 1. Pressure differences 2. Sympathetic nerve activity 3. Skeletal muscle pump 4. Pressure difference between thoracic and abdominal cavities. |
| Velocity of blood in inversely related to TOTAL cross-sectional area | A. Aorta, cross-sectional area of 2.5 cm2 and velocity of 40 cm/sec. B. Capillaries, cross-sectional area of 4500-6000 cm2 and velocity of .1 cm/sec. C. Vena cava, cross-sectional area of 8 cm2 and velocity of 5- 20 cm/sec. |
| Distribution of Blood | A. Systemic Veins- 60% 1. Act as blood reservoirs 2. Veins have thinner, less muscular walls, therefore higher compliance. This means that a given amount of blood causes more distenton in veins B. Systemic arteries- 13% C. Capillaries- 7% D. Head and |
| Capillary Exchange | A. Exchange dependent on pressure B. Effective filration pressure- C. Starling's Law of the Capillaries |
| Exchange dependent on Pressure | 1. Blood Hydrostatic pressue 2. Interstitial Fluid Hydrostatic Pressure 3. Blood osmotic pressure 4. Interstitial Fluid Osmotic Pressure |
| Blood Hydrostatic pressure | Blood pressure in capillaries average 35 mm Hg at arterial end and 16mm Hg at venous end. |
| Interstitial Fluid Hydrostatic pressure | Pressure of fluid against cells of tissue and capillaries. Average O mm Hg. |
| Blood Osmotic Pressure | Due to large number of plasma proteins in blood. Moves fluid into capillaries. Average 26 mm Hg at both ends |
| Interstitial Fluid Osmotic Pressue | Due to small number of proteins in interstitial fluid. Averages 1 mm Hg at both ends |
| Effective filtration pressure | Direction of fluid movement Peff=(BHP+IFOP)-(IFHP+BOP). If the calculation equal a positive number, fluid is flowing from teh capillary to the interstitial fluid, but if the calculation equal a negative number fluid is flowing from teh interstitial fluid |
| Starling's Law of the Capillaries | Amount flowing out of the arterial end almost equal the amount flowing in the venous end and the amount flowing into the lymphatic capillary |
| Pulse | Alternate expansion and recoil of artery as blood passes through Average pulse Trachycardia Bradycardia |
| Average pulse | Is 60-80 beats per min |
| Trachycardia | Rapid pulse over 100 beats per minute at rest |
| Bradycardia | Slow pulse, under 50 beats per minute at rest |
| Blood pressure | Pressue of blood in arteries A. Expressed as 120/80 B. Top number represents pressure of blood in arteries during systole. C. Bottom number represents pressure of blood in arteries during diastole D. Difference in two numbers called the pulse pressure |
| Types of Circulation | A. Systemic B. Pulmonary |
| Systemic | All oxygenated blood leaving left ventricle and returning to right atrium 1. Coronary 2. Hepatic portal circulation 3. Circle of Willis 4. Fetal circulation |
| Hepatic portal cirulation | Veins that drain blood from capillaries in intesines, pancreas, spleen, stomach and gall bladder drain into capillaries in liver. The hepatic vein drains blood from liver and empties blood into the inferior vena cava |
| Circle of Willis | Provides alternate pathway for blood to reach brain in case of arterial occlusion. Also aids in equalizing blood pressure to brain. |
| Fetal circulation | special structures associated with fetus |
| Pulmonary | All deoxygenated blood leaving the right ventricle and returning to left atrium |
| Capillaries Characteristics #2 | 4. With few exceptions a capillary should be located within 60-80 microns of any tissue 5. Capillaries contain approx. 250 ml. of blood out the 5000 ml. of blood flowing through the vessels at any time. 6. capillaries function as the area of exchange be |
Created by:
vannessa01
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