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Ch. 21 - A&P II
The Cardiovascular System: Blood Vessels and Hemodynamics
| Question | Answer |
|---|---|
| 3 blood vessel layers. | Tunica interna (a.k.a. tunica intima) Innermost layer, adjacent to lumen. Endothelium. Tunica media Middle layer, smooth muscle and elastic fibers. Tunica externa Outermost layer, adjacent to surrounding tissue. |
| Tunica externa. | Elastic and colagen fibers. |
| Tunica interna. | Simple squamous epithelium tissue. |
| Arteries. | Carry blood away from the heart and distributes it to other organs of the body (tissues). |
| Arterioles (small arteries). | Regulates the blood flow carrying nutrients and oxygen. |
| Capillaries. | Microscopic; smallest blood vessels (5 to 10 µm in dia.). Connect arterioles and venules. Thin walls. Permit the exchange of nutrients, electrolytes, O2 and CO2 gases, ammonia and other solutes b/w blood and and IF; distribute blood to postcap. venules. |
| Venules (little veins). | Small vessels that are formed by the union of several capillaries. Receive blood from capillaries and then empty into the veins of the body to transport carbon dioxide and nitrogenous wastes away from the body cells. |
| Arteries & Arterioles. | Tunica externa, External elastic lamina, Tunica media, Internal elastic lamina, Base membrane, Tunica interna, Valve and Lumen. |
| Arteries. | The walls of the arteries are elastic, which allows them to absorb the pressure created by ventricles of the heart as they pump blood into the arteries. Because of the smooth muscle in the tunica media, arteries can regulate their diameter. |
| Types of Arteries. | Elastic arteries (conducting arteries). Muscular arteries (distributing arteries). |
| Elastic arteries. | Large diameter. More elastic fibers, less smooth muscle. Function as pressure reservoirs |
| Muscular arteries. | Medium diameter. More smooth muscle, fewer elastic fibers. Distribute blood to various parts of the body. |
| Arteries as Pressure Reservoirs. | Elastic aorta and arteries stretch during ventricular contraction. Elastic aorta and arteries recoil during ventricular relaxation. |
| Arteries pressure reservoir process. | 1. Blood flows towards capillaries. 2. Left ventricle contract (systole) and ejects blood. 3. Blood continues to flow towards capillaries. 4. Left ventricle relaxes (diastole) and fills with blood. |
| Anastomoses. | Union of the branches of 2 or more arteries supplying the same region of the body. Provide an alternate route for blood flow. |
| End arteries. | Arteries that do not form an anastomosis. |
| Necrosis. | Can occur if an end artery is blocked and blood cannot get to a particular region of the body. |
| Vesicle. | Structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Form naturally during the processes of secretion (exocytosis), uptake (endocytosis) and transport of materials within the plasma membrane. |
| Capillary walls. | Are composed of a single layer of thin squamous cells and a basement membrane. Cells have pores for substances and fluid to pass through allowing the exchange of substances between the bloodstream and the interstitial fluid. |
| Blood Flow Through Capillaries. | Capillaries branch to form an extensive capillary network throughout the tissues and are found near almost every cell in the body. |
| Capillary exchange. | Substances cross capillary walls by: Diffusion, Transcytosis and Bulk flow. Transfer of substances between the interstitial fluid surrounding each cell and the blood flowing past the cells in the capillaries. |
| Blood flow process. | Nutrient and oxygen-rich blood return low nutrient, but higher in carbon dioxide blood to the heart. |
| Blood flow steps. | Arteries branch into arterioles that divide to become capillaries. that recombine into venules and then to veins. |
| Simple diffusion. | Primary method for exchange where substances such as oxygen, carbon dioxide, glucose, amino acids, and some hormones cross capillary walls. |
| Diffusion (from the bloodstream into the interstitial fluid or vice versa). | Solely dependent upon the substance’s concentration gradient on either side of the vessel wall. |
| Lipid-soluble substances and gases. | Can pass directly through the thin cells of the capillary wall. |
| Lipid-insoluble substances. | Diffuse through pores in the capillaries. |
| Aerobic cellular respiration within each cell. | Changes in diffusion gradients of nutrients, gases and wastes within each cell. |
| Active cells during diffusion. | Consume oxygen during the production of ATP in the mitochondria. |
| Active cells diffusion (into of the cell) . | As more of the intracellular oxygen is used up, its concentration becomes less than that of the surrounding interstitial fluid, causing oxygen to diffuse into the cell. |
| Active cells diffusion (out of capillaries). | As the oxygen level in the interstitial fluid decreases below the concentration in the bloodstream, oxygen diffuses out of the capillaries into the interstitial fluid. |
| Carbon dioxide. | Given off during ATP production. |
| Carbon dioxide diffusion (out of the cell). | When the accumulation of carbon dioxide within the cell exceeds that of the interstitial fluid, the carbon dioxide diffuses out of the cell. |
| Carbon dioxide diffusion (out of the IF). | As the carbon dioxide level in the interstitial fluid increases to a higher concentration than in the bloodstream, the carbon dioxide diffuses into the bloodstream. |
| Transcytosis. | Provides a method to move larger lipid-insoluble molecules(like insulin) and proteins or antibodies cross capillary walls in vesicles. |
| Exocytosis. | then passes out of the opposite side by . |
| Endocytosis. | Forms a vesicle containing the needed protein or antibody. The vesicle seals to enclose the proteins in a double phospholipid membrane which passes unaltered through the cell. |
| Elastic arteries. | Largest arteries in the body. Conducts blood from heart to muscular arteries. Well defined internal elastic lamina. |
| Muscular arteries. | Medium-sized arteries. Distribute blood to arterioles. |
| Arterioles. | Microscopic (15 to 300 µm in diameter). Deliver blood to capillaries and help regulate blood flow from arteries to capillaries. |
| Postcapillary venules. | (10 to 50 µm in diameter). Pass blood to muscular venules; permit exchange of nutrients and wastes between IF and blood. Function in WBC emigration. |
| Muscular venules. | Microscopic (5 to 200 µm in diameter). Pass blood into vein; act as a reservoir for large blood volume accumulation (along with capillary venules). |
| Veins. | Formed from the union of several venules. Range from 0.5 mm to 3 cm in diameter. return blood to heart, facilitated by valves in limb veins. |
| Filtration. | Flow from blood to interstitium. |
| Reabsorption. | Flow from interstitium to blood. |
| Bulk flow is given two names depending on the direction of movement. | Filtration and reabsorption. |
| Blood hydrostatic pressure. | Generated by the pumping of the heart. 35 mm Hg./16 mm Hg. |
| Blood colloid osmotic pressure. | Caused by the colloidal suspension of plasma proteins that are too large to pass through fenestrations or gaps between endothelial cells. |
| BCOP. | This pressure acts as if it pulls fluid into the capillary and promotes reabsorption. Upward pressure. Venous end. |
| BHP. | Promotes filtration by pushing fluid out of the capillary. Downward pressure. Arterial end. |
| BHP /(IFOP) interstitial fluid osmotic pressure combination . | The slight pull of fluids towards the interstitium to promote filtration. |
| BCOP/(IFHP) interstitial fluid hydrostatic pressure combination. | Which is near zero under normal conditions, promote reabsorption. |
| Net filtration pressure. NFP = (BHP + IFOP) - (BCOP + IFHP). | Balance of the filtration and reabsorption forces. Determines whether blood volume remains steady or changes. |
| Force promoting filtration on arterial end of capillary. | BFP=35 mm Hg. IFOP=1mm Hg. BCOP=26 mm Hg. IFHP=0 mm Hg. (NFP={35+1}-{26+0}=10). NFP=10 mm Hg. |
| Force promoting reabsorption on venous end of capillary. | BFP=16 mm Hg. IFOP=1mm Hg. BCOP=26 mm Hg. IFHP=0 mm Hg. (NFP={16+1}-{26+0}=-9). NFP=-9 mm Hg. |
| Lymph. | Not reabsorbed remainder of the fluid volume that is filtered out of the capillary but that drains into lymphatic capillaries. |
| Edema. | Swelling due to abnormal buildup of interstitial fluid. Symptom of increased blood hydrostatic pressure or capillary permeability. Decreased blood colloid osmotic pressure or a problem with normal lymphatic drainage. |
| Blood velocity. | Inversely related to total cross-sectional area; the greater the area, the slower the velocity. |
| BV. | Slows as blood travels away from the heart and increases as blood leaves capillaries and returns to the heart. |
| Arteries and veins. | Lower cross-sectional area than capillaries so blood velocity is greater. |
| Blood Distribution. | Pulmoary vessels 9%, Heart 7%, Systemic arteries and anterioles 13%, Systemic capillaries 7%, Systemic veins and venules (blood reservoirs) 64% at rest. |
| Blood Flow Through Capillaries. | Branch to form an extensive network throughout the tissues and are found near almost every cell in the body. |
| Types of Capillaries. | Continuous, Fenestrated, Sinusoid. |
| Continuous capillaries. | Formed by endothelial cells. |
| Fenestration. | Pore. |
| Sinusoid. | Sinusoid. |
| Bulk flow. | Passive process in which small numbers of ions, molecules, or particles in a fluid move together in the same direction. |
| Bulk flow. | Occurs from an area of higher pressure to an area of lower pressure, and it continues as long as a pressure difference exists. |
| Bulk flow. | Most important regulation of the relative volumes of blood and interstitial fluid. |
| Filtration. | Pressure-driven movement of small fluid and solutes from blood capillaries into interstitial fluid (outward). |
| Filtration. | Promoted by Blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure (IFOP). |
| Reabsorption. | Pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries (inward). |
| Reabsorption. | Promoted by Interstitial fluid hydrostatic pressure (IFHP) and blood colloid osmotic pressure (BCOP). |
| Starling’s Law of the Capillaries. | Under normal conditions, the volume of fluid and solutes reabsorbed is almost as large as the volume filtered. |
| Starling’s Law of the Capillaries. | NFP = (BHP + IFOP) – (BCOP+ IFHP) |
| Net filtration pressure. | Blood hydrostatic pressure + Interstitial fluid hydrostatic pressure – Blood colloid osmotic pressure + Interstitial fluid osmotic pressure. |
| Blood flow. | Volume of blood that flows through any tissue in a given time period (in mL/min). |
| Total blood flow is cardiac output (CO). | Volume of blood that circulates through systemic (or pulmonary) blood vessels each minute. |
| CO. | Heart rate (HR) × stroke volume (SV) |
| CO. | Mean arterial pressure (MAP) ÷ resistance (R) |
| Blood Pressure (BP). | Contraction of the ventricles generates it. |
| BP. | Determined by CO, blood volume, and vascular resistance. |
| The higher the BP. | The greater the blood flow. |
| Vascular Resistance (R). | Opposition to blood flow due to friction between blood and the walls of blood vessels. |
| The higher the R. | The smaller the blood flow |
| R depends on. | Size of the blood vessel lumen, Blood viscosity, Total blood vessel length. |
| Venous Return. | Volume of blood flowing back to the heart through the systemic veins, occurs due to the pressure generated by contractions of the heart’s left ventricle. |
| Venous return is assisted by: | Valves, Respiratory pump, Skeletal muscle pump. |
| Skeletal Muscle Pump. | Proximal valve, distal valve. |
| Velocity of Blood Flow. | Blood flow is inversely related to the cross-sectional area of blood vessels. Aorta, arteries, arterioles, capillaries, venules, veins, venae cavae. |
| CHP (also capillary blood pressure). | Outward force causing filtration. |
| Colloid osmotic pressure (plasma). | Inward force causing reabsorption . |
| Plasma colloid osmotic pressure. | Stays relatively constant throughout the length of the capillary. |
| Blood pressure (CHP). | Diminishes with distance along the blood vessel. |
| CHP drops and becomes less than the plasma COP. | As blood passes through the capillary to the distal end. |
| On the proximal end of the capillaries. | CHP is greatest and becomes the driving force causing filtration of fluid out of the capillaries into the interstitial fluid. |
| Factors that affect BP-1. | High MAP, High CO, High HR, High SV, Decreased parasympathetic impulses, Increased parasympathetic impulses and hormones from adrenal medulla, Increased venous return, Increased blood volume, Skeletal muscle pump, respiratory pump, Venoconsrtiction. |
| Factors that affect BP-2. | High (SVR), High blood viscosity, High total blood vessel lenght, Low blood vessel radius (vasoconstriction), High number of RBC, as in polycythemia, High body size, as in obesity. |
| Cardiovascular center (in medulla oblongata). | Group of neurons that regulate heart rate, contractility, and blood vessel diameter. |
| Input into cardiovascular center (nerve impulses). | From higher brain centers: cerebral cortex, limbic system, hypothalamus. from proprioceptors: monitor joint movements. From baroreceptors: monitor blood pressure. From chemoreceptors: monitor blood acidity (H+), CO2, and O2. |
| Output to receptors (increased frequency of nerve impulses): | Heart: decreased heart rate (vagus nerve-parasympathetic). Heart: increase rate and contractility (cardiac accelerator nerves-sympathetic). Blood vessels: vasoconstriction (vasomotor nerves-sympathetic). |
| Baroreceptors. | Important pressure-sensitive sensory neurons that monitor stretching of the walls of blood vessels and the atria. |
| Negative Feedback Regulation of BP. | |
| Cardiac output (Increased HR and contractility). Increase BP. | Norepinephrine, epinephrine. |
| SVR (Vasoconstriction). Increase BP. | Angiotensin II, antidiuretic hormone (ADH), norepinephrine*, epinephrine+. * acts a an (a) receptor in arterioles of abdomen and skin. + acts a an (b) receptor in arterioles of cardiac and skeletal muscle; (nore) has a much smaller vasodilating effect. |
| SVR (Vasodilation). Decrease BP. | Atrial natriuretic peptide (ANP), epinephrine+, nitric oxide.+ acts a an (b) receptor in arterioles of cardiac and skeletal muscle; (norepinephrine) has a much smaller vasodilating effect. |
| Blood volume Increase. Increase BP. | Aldosterone, antidiuretic hormone (ADH). Increase BP. |
| Blood volume decrease. Decrease BP. | Atrial natriuretic peptide (ANP). |
| Autoregulation. | Ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for delivery of oxygen and nutrients and removal of wastes. |
| Physical and chemical stimuli. | Can lead to autoregulation. |
| Superficial temporal artery. | Medial to ear. |
| Facial artery. | Mandible (lower jawbone) on line with corners of mouth. |
| Common carotid artery. | Lateral to larynx (voice box). |
| Brachial artety. | Medial side of biceps brachii muscle. |
| Femoral artery. | Inferior to inguinal ligament |
| Popliteal artery. | Posterior to knee. |
| Radial artery. | Lateral aspect of wrist. |
| Dorsal artery of foot (dorsalis pedis artery). | Superior to instep of foot. |
| Measurement of BP. | Systolic blood pressure (SBP) and Diastolic blood pressure (DBP). |
| Systolic blood pressure (SBP). | First sound heard. |
| Diastolic blood pressure (DBP). | Last sound heard. |
| Shock. | Inadequate CO that results in failure of the CV system to meet the metabolic demands of body cells. |
| Shock. | Cell membranes dysfunction, cell metabolism is abnormal, and cell death may occur. |
| Types of shock: | Hypovolemic, Cardiogenic, Vascular, Obstructive. |
| Homeostatic Responses to Shock. | Activation of the renin-angiotensin-aldosterone system. Secretion of anti-diuretic hormone. Activation of the sympathetic division of the autonomic nervous system. Release of local vasodilators. |
| Signs and Symptoms of Shock. | Clammy, cool, pale skin, Tachycardia, Weak, rapid pulse, Sweating, Hypotension (SBP <90 mmHg), Altered mental status, Decreased urinary output, Thirst, Acidosis. |
| Circulatory Routes. | Systemic circulation, Pulmonary circulation, Hepatic portal circulation, Fetal circulation. |
| Development of Blood Vessels & Blood. | Blood vessels develop from isolated masses of mesenchyme in the mesoderm called blood islands. |
| Aging and the CV System. | Loss of compliance of the aorta, Reduction in cardiac muscle fiber size, Progressive loss of cardiac muscular strength, Decline in maximum heart rate, Increased systolic blood pressure. |
| Hypertension. | Normal S: Less than 120 D: Less than 80. Prehypertension: S: 120-139. D: 80-89. Stage 1 hypertension: S: 140-159. D: 90-99. Stage 2 hypertension: S: Higher than 160. D: Higher than 100. |
Created by:
Jpereira72
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