CHAPTER 19: BLOOD VESSELS Flashcards

Question

DESCRIBE THE SPECIFIC BLOOD PRESSURES IN THE ARTERIAL BLOOD PRESSURE (hint, one of them is pulse pressure)

Answer 1

Systolic blood pressure: the highest pressure in the aorta during ventricular contraction. The left ventricle pumps blood into the aorta, making kinetic energy that stretches the aorta, the average is 120 mm/Hg Diastolic blood pressure: is the lowest pressure in the aorta when the heart is at rest. Average is 70-80 mm/Hg Pulse pressure: is the difference between the systolic and diastolic pressures.

Answer 2

PP= SP (Systolic blood pressure) - DP (diastolic blood pressure)

Answer 3

is the pressure that exerts blood to the tissues. It is also the average BP within the cardiac cycle (the beginning being at the aorta and the end being the right atrium) . The heart spends twice as much time in diastole then in systole. So it's measuring the difference in time between the 2.

Answer 4

MAP= diastole + ⅓ Pulse pressure (PP)

Answer 5

How much elastic arteries close so that the heart can stretch AND Volume of blood forced into them at any time

Answer 6

Venous blood pressure (15 mm/hg) typically isn’t adequate to push blood back to the heart, this is because of the cumulative effects of peripheral resistance which converts blood pressure energy into heat energy.

Answer 7

1) Muscular pump: This is done through the contraction and relaxation of skeletal muscles. This action basically milks the blood back up to the pump. As the blood moves up previous venous valves will close to prevent backflow. 2) Respiratory pump: pressure changes brings blood flow back to the heart by forcing abdominal veins to constrict when thoracic veins expand during breathing. 3) Sympathetic venoconstriction: under control of the sympathetic nervous system, it will cause smooth muscles in the veins to contract, forcing blood to move towards the hea

Answer 8

basically, by rearanging a bunch of formulas we go from F= ΔP/TPR CO= ΔP/TPR ΔP= CO x TPR MAP= CO X TPR AS WELL AS MAP= HR X SV X TPR (because CO is equal to SV x HR) basically, cardiac output, total peripheral resistance, and MAP are directly proportional, if one increases, the rest will.

Answer 9

adequate blood distribution to organs in response to demands, and maintaining mean arterial pressure by increasing or decreasing diameter of blood vessels.

Answer 10

chemoreceptor reflex, baroreceptor reflex, higher brain centre, cardiovascular centre of the medulla

Answer 11

chemoreceptors located in the aortic arch and large arteries of the neck detect changes including increased Carbon dioxide, and decreased oxygen and Ph. It will send signals to the cardioacceleratory center to increase CO, and signals to the vasomotor center to increase vasoconstriction

Answer 12

reflexes that influence blood pressure are found in the medulla. The hypothalamus and the cerebral cortex are also able to alter arterial blood pressure by sending signals to the medulla. The hypothalamus can increase BP in response to stress, and control blood distribution during exercise and temperature changes.

Answer 13

is located in the medulla, and is composed of clusters of sympathetic fibers. It has a cardioacceleratory and cardioinhibitory center as well. It also consists of the vasomotor center which sends sympathetic impulses to the blood vessels.

Answer 14

Stimulus: is changes to MAP (the stretch in blood vessels due to that) Location: walls of large arteries in the neck and thorax, carotid sinuses, aortic arch The receptors themselves increase blood pressure, but by inhibiting them it lowers blood pressure. MAP increasing (high BP) inhibits baroreceptors, and MAP decreasing (low BP) triggers baroreceptors. Baroreceptors will work to either stimulate or inhibit the works of the vasomotor center (sympathetic) , cardioacceleratory center (sympathetic) and cardioinhibitory center (parasympathetic).

Answer 15

Adrenal medulla hormones: epinephrine and norepinephrine cause increased vasoconstriction and cardiac output, this increases BP. Angiotensin II: causes increased vasoconstriction, which increases BP. Atrial natriuretic peptide: antagonizes antidiuretic hormone, this cause generalized vasodilation and decreased blood volume, causing decreased BP Antidiuretic hormone: stimulates the kidneys to conserve water, this causes vasoconstriction which in turn increases BP.

Answer 16

Increased MAP, causes increased BP which causes increased stretch in blood vessels → baroreceptors in the aortic arch and carotid arteries are stimulated → afferent pathway to the integration center: cardiovascular center → vasomotor center is inhibited, cardioacceleratory center is inhibited, cardioinhibitory center is stimulated → sympathetic impulses to heart cause decreased HR, decreased CO, and decreased Contractility → impulses from vasomotor center cause vasodilation= decreased TPR → blood pressure goes back to normal

Answer 17

Decreased MAP, causes decreased BP which causes decrease stretch in the blood vessels → baroreceptors in the aortic arch and carotid arteries are stimulated → afferent pathway to the integration center: cardiovascular center → vasomotor nerves are stimulated, cardioacceleratory center is stimulated, cardioinhibitory center is inhibited → sympathetic impulses to heart cause increased HR, increased CO, and increased contractility → impulses from vasomotor center cause vasoconstriction=increased TPR → blood pressure goes back to normal

Answer 18

is done independently of hormones. For example, when blood pressure is low the kidneys will conserve more water, causing increased blood volume and increased blood pressure. Increased blood pressure will have the kidneys excrete more water into the urine, causing decreased blood volume and blood pressure.

Answer 19

renin-angiotensin aldosterone mechanism: decreased MAP will trigger the kidneys to release an enzyme renin into the bloodstream → renin converts angiotensinogen into angiotensin I → angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II

Answer 20

Potent vasoconstrictor which increases blood pressure Stimulates release of aldosterone which triggers kidneys to conserve Na and water Stimulates release of antidiuretic hormone from the posterior pituitary which works with aldosterone to conserve water from kidneys Triggers the hypothalamic thirst center to increase thirst thus causing increased water intake

Answer 21

is controlling the blood flow within tissues. It is involved during gas exchange, nutrient/waste exchange, nutrient absorption, and urine formation. The rate of tissue perfusion depends on the metabolic needs of the organ, it is no more or less and is supply and demand based.

Answer 22

Intrinsic (autoregulation/local control): Blood flow is controlled locally by the organ itself. The arterioles of the organs are able to modify their own diameter, so the organ controls blood flow by varying resistance in their own arterioles. It is referred to as autoregulation because nerves and hormones are not involved

Answer 23

Myogenic (physical) Vasoconstriction: stretch Metabolic (chemical) Vasoconstriction: endothelins (potent vasoconstrictor) Vasodilation: decreased O2, increased CO2, K+,H, as well as nitric oxide (potent vasodilator), prostaglandins, aldosterone

Answer 24

Neural Vasoconstriction: increased sympathetic tone Vasodilation: decreased sympathetic tone Hormonal Vasodilation: atrial natriuretic hormone Vasoconstriction: epinephrine, norepinephrine, antidiuretic hormone, angiotensin II

Answer 25

Blood flow in the brain MUST be kept constant (around 750 ml/min) because the brain is intolerant to ischemia. Myogenic controls: increased MAP causes cerebral vessels to dilate, decreased MAP causes cerebral vessels to constrict (MAP below 60 mm/hg causes fainting, MAP above 160 mm/hg causes edema) Metabolic controls: decreased Ph or increased Co2 causes vasodilation of the arterioles. Nitric oxide also causes vasodilation.

Answer 26

1) Supplying nutrients to skin cells: autoregulated based on O2 needs 2) Temperature control: controlled by nervous system – hot: hypothalamic signals reduce vasomotor stimulation of skin vessels, causing them to dilate, warm blood is rushed to capillaries and heat radiates off the skin. – cold: superficial skin vessels strongly constrict, this can cause blood to get trapped in the vessels. 3) Acts as a blood reservoir: controlled by nervous system

Answer 27

The pulmonary circuit is strange, the arterioles/arteries are more like veins/venules (thin walls and large lumens), the arterial Bp is also much lower compared to the systemic, averaging around 24/10 mm/Hg Autoregulatory functions are opposite: Low O2 causes vasoconstriction, high O2 causes vasodilation. This is so blood can flow to O2 rich areas of the blood.

Answer 28

Blood flow in the heart is regulated by aortic pressure and ventricular pumping. During ventricular systole coronary muscles compress, this causes Myocardial blood flow ceases Myoglobin provides sufficient oxygen During diastole, high aortic pressure forces blood into the coronary circulation

Answer 29

Blood flow is dependent on fiber type and activity, during rest neural and myogenic controls predominate, however during activity, metabolic control is proportional to blood flow.

Answer 30

As blood flows throughout the systemic circulation, it will change in velocity as well. Blood flow is slowest in the capillaries and is fastest in the arteries. This is because velocity is inversely proportional to cross-sectional area. Blood flow is slowest in the capillaries to provide adequate time for exchange of materials.

Answer 31

1) Pass directly through endothelial cells: ex. Lipid soluble molecules like respiratory gasses 2) Pass through intercellular clefts: ex. Water soluble molecules Pass through 3) fenestrations. Ex. water soluble molecules 4) Pass through active transport by vesicles via endocytosis or transcytosis: ex. Large molecules like protein

Answer 32

Fluid in the capillaries is forced out at the arterial end and return back at the venous end, this is very important to determine relative fluid volume in the blood and interstitial space. Bulk flow in the capillaries causes continuous mixing of plasma and interstitial fluid, maintaining the interstitial environment.

Answer 33

hydrostatic pressure, and colloid osmotic pressure

Answer 34

Capillary hydrostatic pressure: pressure that forces fluids through the capillary walls, is usually greater on the arterial end (35 mm/hg) compared to the venous (17 mm/Hg). FLUID LEAVES CAPILLARY Interstitial fluid hydrostatic pressure: pressure that forces fluid back into the capillary, is usually assumed to be ) because lymphatic vessels drain interstitial fluid. Pressure is 0 mm/hg. FLUID ENTERS CAPILLARY

Answer 35

Capillary colloid osmotic pressure (oncotic pressure, OPc): is a sucking pressure created by non-diffusible plasma proteins that sucks water into the capillary. Is around 26 mm/hg. FLUID LEAVES CAPILLARY Interstitial fluid colloid osmotic pressure (OPif): is inconsequential because the protein content in interstitial fluid is very low, is around 1 mm/hg. FLUID ENTERS CAPILLARY

Answer 36

Net filtration pressure (NFP): compromises all forces acting on the capillary bed Formula: NFP= (HPc + OPif) - (HPif + OPc) basically NFP= (forces pushing out) - (forces pushing inside) Positive number=filtration= usually at arterial end Negative number= reabsorption= usually at venous end

Answer 37

The pulmonary circulation is shorter and the systemic is longer, traveling between the heart and the lungs. The roles of arteries and veins are also flipped, arteries carry deoxygenated and veins carry oxygenated. Both pathways carry both deoxygenated and oxygenated blood.