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Blood vessels
Circulatory System
Question | Answer |
---|---|
What are the 3 types of blood vessels | Arteries, capillaries, and veins |
Arteries function | Carry blood away from the heart to tissues. Delivers to capillary beds for gas, nutrient, and waste exchange. Thick walls that withstand high BP. NO VALVES. (15% of blood volume) (blood flow is slower) |
Capillaries function, location, type of tissue, what layers does it have | Connect smallest arteries to smallest veins. Location of exchange between blood and interstitial fluid. Simple squamous ET tube. No tunica media/externa. |
Veins function | Carry blood from tissues back to the heart. Thin, non-elastic, walls that can't withstand much pressure, but thicker than arteries. CONTAIN VALVES. (60% of volume at rest) |
What are the three layers in the vessel walls from deep to superficial | 1. Tunica interna (intima), 2. Tunica media 3. Tunica externa (adventitia) |
Tunica interna (intima) | Deepest layer, includes endothelial simple squamous lining, basement membrane , sparse layer of loose CT. Also has a thick layer on outer margin, internal elastic membrane (only arteries) |
Tunica media | Middle layer, sheets of smooth muscle in loose CT. |
Tunica externa (adventitia) | Outer layer,anchors vessel to adjacent tissues. In large veins and arteries it contains Vasa vasorum (blood supply for large vessels) |
What are the 3 types of arteries | Elastic (conducting/large), Muscular (distributing/medium), and Arterioles (small) |
Elastic (conducting/large) arteries | Tunica media: many elastic fibers, few muscle cells. Contains Vasa Vasorum. Ex: pulmonary trunk, aorta, common carotid, subclavian, common iliac |
Vasa Vasorum | Found in large veins/arteries. Serves as blood supply and nourishment for tunica adventitia and outer part of tunica media |
Muscular (distributing/medium) arteries | Make up majority of arteries. Tunica media has many muscle cells. Many are named after internal organ it feeds; Ex: external carotid, brachial, and femoral |
Arterioles | Smallest branches of arteries. Delivers blood to capillaries. Have little or no tunica externa. Has thin or incomplete tunica media |
What are the 3 types of capillaries | Continuous, fenestrated, and sinusoid |
Continuous capillaries | Complete basement membrane on outside with tunica intima inside. Intercellular cleft. Ex: skeletal/smooth muscle, and CT. |
Fenestrated Capillaries | Complete basement membrane on outside, tunica intima has small holes called fenestration's. Ex: kidney's, small intestine, choroid plexus |
Sinusoid Capillaries | Incomplete basement membrane, tunica intima has intercellular gaps for blood cells to pass through. Ex: Liver, bone marrow, spleen, anterior pituitary. |
What are the 3 types of veins from smallest to largest | 1. Venules, 2. Medium, and 3. Large |
Venules | Smallest veins that carry blood away from capillaries |
Medium sized veins | Thin tunica media (few muscle cells.) Thin tunica externa (horizontal bundles of elastic fibers.) Contains valves. EX: Radial, Ulnar, small/great saphenous |
Large sized veins | Tunica externa is very thick and tunica media is very thin. Ex: Inferior/superior vena cava, pulmonary, internal jugular. |
Hepatic portal circulation | Superior/inferior mesenteric and splenic veins pass blood flow into liver and through 2nd capillary bed. Then from the liver the hepatic vein returns to the inferior vena cava |
BP definition | Force exerted by blood on blood vessel walls |
What is BP measured in | Millimeters of mercury (mmHg) |
Systolic pressure | Maximum pressure exerted on blood vessel walls (first # in BP reading) |
Diastolic pressure | Minimum pressure exerted on blood vessel walls (second # in BP reading) |
Hemodynamics | Factors affecting circulation - velocity/volume of blood flow, and blood pressure |
Varicose veins | Twisted, dilated, superficial veins. Cause by leaking of valves of veins. Help with blackflow and pooling of blood. |
What is the most common circulatory route | Heart -> artery -> arteriole -> capillaries -> venules -> veins |
Portal system | Blood flows through 2 consecutive capillary networks before returning to heart -3 total in body - (hypothalamus/anterior pituitary, kidneys, intestine/liver) |
Why can't we have artery anastomoses all over our body like in the brain/heart | We could not regulate our BP |
BHP | "Blood Hydrostatic pressure" - Pressure exerted by the pumping of your heart which drives fluid OUT of the capillaries (high on arterial end, low on venous end) |
BCOP | "Blood colloid osmotic pressure" - A form of osmotic pressure exerted by plasma proteins (albumins) that pulls fluids INTO capillaries (same on arterial and venous ends) |
Where are plasma proteins produced | Liver (except globulins) |
IFHP | "Interstitial fluid hydrostatic pressure" - Pressure in interstitial fluid that pulls fluid into the capillaries (always 0 no matter where - set point) |
IFOP | "Interstitial fluid osmotic pressure " - A form of osmotic pressure in the interstitial fluid that drives the fluid out of the capillaries (but is very low compared to BCOP and BHP) |
NFP equation | "Net Filtration Pressure" - factors pushing out-> (BHP + IFOP) - (BCOP + IFHP) <- factors pulling in |
What do arterial pressures promote in capillary exchange | Filtration |
What do venous pressures promote in capillary exchange | Reabsorption |
To calculate the Net Hydrostatic Pressure along the whole capillary what do you do | NFP result (artery) + NFP result (vein) = Net Hydrostatic Pressue. Ex: 10+(-9)=1 |
What happens to escaping fluid out of your capillaries | Interstitial fluid and plasma proteins are collected by lymphatic capillaries (about 3 liters a day) |
Diffusion in capillary exchange | Easily moves things across capillaries that are lipid soluble (O2/CO2.) Larger proteins will be help back (channels, clefts, fenestration's) |
Transcytosis in capillary exchange | Moves material across in tiny vesicles by endocytosis/exocytosis (large lipid soluble molecules like insulin, albumin) |
Filtration & absorption in capillary exchange | Movement of bulk flow in large amounts, move in response to pressure, high -> low, faster than diffusion |
Consequences of edema | Circulatory shock, tissue necrosis, pulmonary edema (suffocation), cerebral edema (headache, seizure, coma) |
Blood flow becomes _______ when vessels merge to form _____________ | Faster/veins |
What is venous return dependent on | Skeletal muscle pump |
The __________ the vessel the greater the __________ which ___________ blood pressure | Longer/friction/increases |
___ miles of vessels for 1 pound of _____ | 200/fat (High BP in obese people) |
Why do longer vessels produce higher BP | The blood is having to use more pressure to increase the velocity of blood flow and length it needs to travel |
What happens if you have an increase in blood viscosity (thickness) | You will have increase in friction, decrease of flow resulting in increase in BP (dehydration & polycythemia) |
What happens in smaller radii of vessels | The smaller the radius the more friction and resistance. The average velocity of blood flow will also be lower and slower (fluctuations in BP) |
What controls BP by changing its diameter | Arterioles |
What are 3 reasons the blood flow from the aorta to the capillaries decreases | 1. Greater distance = greater friction, 2. Smaller radii of arteriole and capillaries, 3. The farther from the heart, the greater the cross section |
What are 2 reasons the blood flow from the capillaries to the vena cava increases | 1. Large amount of blood forced into smaller channels, 2. Never regains velocity of large arteries |
The skeletal muscle pump process | Muscles contract, squeeze veins, valves make blood go in one direction pushing it into the next set of valves. |
Thoracic pump | Thoracic cavity expands when you breath, increasing the volume and decreasing the pressure, abdominal pressure increases, forcing blood upward |
Venous pooling (vascular shock) can cause | Neurogenic shock, loss of vasomotor tone, vasodilation (emotional shock - brain stem injury) |
Angiotensinogen | Pro-hormone released by liver which stimulates the release of Renin (kidney enzyme for low BP) and they together activate angiotensin 1 |
Angiotensin 1 | ACE (angiotensin-converting enzyme in lungs, which blocks the enzyme lowering BP) converts angiotensin 1 into angiotensin 2 |
Angiotensin 2 | Very potent vasoconstrictor, derives from angiotensin 1 |
What hormones help control BP/flow | Angiotensin, aldosterone, ADH, Epinephrine & norepinephrine, atrial natiruretic factor |
Atrial Natiruretic Factor Hormone and BP | Increase urinary sodium excretion for generalized vasodilation (raise BP) |
Aldosterone and BP | Promotes Na+ and water retention by the kidneys, increases blood volume and pressure (activated by angiotensin 2) |
ADH and BP | Water retention, vasoconstrictor (activated by angiotensin 2) |