Ch21 Flashcards
1
Q
- Arteries – carry blood AWAY from the heart
- Arterioles
- Capillaries – site of exchange
- Venules
- Veins – carry blood TO the heart
A
blood vessel types
2
Q
- Inner lining in direct contact with blood
- Endothelium continuous with endocardial lining of heart
- Active role in vessel-related activities
A
tunica interna(intima) of blood vessel
3
Q
- Muscular and connective tissue layer
- Greatest variation among vessel types
- Smooth muscle regulates diameter of lumen
A
tunica media
4
Q
- Elastic and collagen fibers
- Vasa vasorum
- Capillaries that supply blood to tissues of the vessels
- Helps anchor vessel to surrounding tissue
A
tunica externa
5
Q
- has 3 layers of a typical blood vessel
- thick muscular to elastic tunica media
- smooth muscle
- provides for vasoconstriction-decrease in lumen diameter
- vasodialtion- increase in lumen diam
A
arteries
6
Q
- Largest diameter artery but walls relatively thin
- Function as pressure reservoir
- Help propel blood forward while ventricles relaxing
- Also known as conducting arteries
A
elastic arteries
7
Q
- Tunica media contains more smooth muscle and fewer elastic fibers than elastic arteries
- Walls relatively thick
- Capable of great vasoconstriction/ vasodilatation to adjust rate of blood flow
- Also called distributing arteries
A
muscular arteries
8
Q
- Union of the branches of 2 or more arteries supplying the same body region
- Provide alternate routes – collateral circulation
A
anastomoses
9
Q
- Abundant microscopic vessels
- Metarteriole has precapillary sphincter which monitors blood flow into capillary
- Sympathetic innervation and local chemical mediators can alter diameter and thus blood flow and resistance
- Vasoconstriction can raise blood pressure
A
arterioles
10
Q
- smallest blood vessels conecting arterial outflow and venous return
- microcirculation
- exchange vessels
- capillary beds arise form single metarteriole
A
capillaries
11
Q
Flow from metarteriole through capillaries and into postcapillary venule
A
microcirculation(capillaries)
12
Q
- Primary function is exchange between blood and interstitial fluid
- Lack tunica media and tunica externa
- Substances pass through just one layer of endothelial cells and basement membrane
A
exchange vessels(capillaries)
13
Q
– arise from single metarteriole
- Vasomotion – intermittent contraction and relaxation
- Throughfare channel – bypasses capillary bed
A
capillary beds
14
Q
- Continuous-Endothelial cell membranes form continuous tube
- Fenestrated-Have fenestrations or pores
- Sinusoids-Wider and more winding;Unusually large fenestrations
A
types of capillaries
15
Q
- Thinner walls than arterial counterparts
- Postcapillary venule(Smallest venule)
- Form part of microcirculatory exchange unit with capillaries
- Muscular venules have thicker walls with 1 or 2 layers of smooth muscle
A
venules
16
Q
- Structural changes not as distinct as in arteries
- very thin walls in relation to total diameter
- Same 3 layers as arteries
- Tunica interna thinner with little smooth muscle
- Tunica interna thinner than arteries
- Tunica externa thickest layer
- Not designed to withstand high pressure
- Valves – folds on tunica interna forming cusps
- Aid in venous return by preventing backflow
A
veins
17
Q
- Largest portion of blood at rest is in systemic veins and venules
- Blood reservoir
- systemic arteries and arterioles
- pulmonary vessels
- systemic capillaries
- heart
A
blood distribution(greatest to least)
18
Q
Movement of substances between blood and interstitial fluid basic methods include diffusion, transcytosis, and bulk flow
A
capillary exchange
19
Q
- Substances move down their concentration gradient
- O2 and nutrients from blood to interstitial fluid to body cells
- CO2 and wastes move from body cells to interstitial fluid to blood
- Can cross capillary wall through intracellular clefts, fenestrations or through endothelial cells
- Most plasma proteins cannot cross
- Except in sinusoids – proteins and even blood cells leave
- Blood-brain barrier – tight junctions limit diffusion
A
Diffusion:Most important method
20
Q
- Small quantity of material
- Substances in blood plasma become enclosed within pinocytotic vessicles that enter endothelial cells by endocytosis and leave by exocytosis
- Important mainly for large, lipid-insoluble molecules that cannot cross capillary walls any other way
A
transcytosis
21
Q
- Passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction
- Based on pressure gradient
- Diffusion is more important for solute exchange
- Bulk flow more important for regulation of relative volumes of blood and interstitial fluid
- Filtration – from capillaries into interstitial fluid
- Reabsorption – from interstitial fluid into capillaries
A
bulk flow
22
Q
balance of 2 pressures
NFP= (BHP + IFOP) – (BCOP + IFHP)
A
net filtration pressure
23
Q
- Blood hydrostatic pressure (BHP) generated by pumping action of heart
- Falls over capillary bed from 35 to 16 mmHg
- Interstitial fluid osmotic pressure (IFOP)
- 1 mmHg
A
pressures that promote filatrion
24
Q
- Blood colloid osmotic pressure (BCOP)
- Due to presence of blood plasma proteins too large to cross walls
- Averages 36 mmHg
- Interstitial fluid hydrostatic pressure (IFHP)
- Close to zero mmHg
A
Pressures that promote reabsorption
25
Q
- Nearly as much reabsorbed as filtered
- At the arterial end, net outward pressure of 10 mmHg and fluid leaves capillary (filtration)
- At the venous end, fluid moves in (reabsoprtion) due to -9 mmHg
- On average, about 85% of fluid filtered out of capillaries is reabsorbed
- Excess enters lymphatic capillaries (about 3L/ day) to be eventually returned to blood
A
starling’s law
26
Q
- total blood flow equals cardiac output
- CO= heart rate X stroke volume
Distribution of CO depends on:
- Pressure differences that drive blood through tissue
- Flows from higher to lower pressure
- Resistance to blood flow in specific blood vessels
- Higher resistance means smaller blood flow
A
hemodynamics:factors affecting blood flow
27
Q
- Contraction of ventricles generates blood pressure
- Systolic(highest)/diastolic(lowest)
- Pressure falls progressively with distance from left ventricle
A
blood pressure
28
Q
Opposition to blood flow due to friction between blood and walls of blood vessels depending on:
- size of lumen
- blood viscosity
- total blood vessel length
A
vascular resistance
29
Q
- Speed in cm/sec is inversely related to cross-sectional area
- Velocity is slowest where total cross sectional area is greatest
- Blood flow becomes slower farther from the heart
- Slowest in capillaries
- Aids in exchange
- Circulation time – time required for a drop of blood to pass from right atrium, through pulmonary and systemic circulation and back
A
Velocity of Blood Flow
30
Q
- Control blood pressure by adjusting heart rate, stroke volume, systemic vascular resistance, and blood volume
- Some act faster that others
- Some shorter- or longer-term
A
interconnected negative feedback systems
31
Q
- In medulla oblongata
- Groups of neurons regulate heart rate, contractility of ventricles, and blood vessel diameter
- Cardiostimulatory and cardioinhibitory centers
- Vasomotor center controls blood vessel diameter
- Receives input from both higher brain regions and sensory receptors
A
location of cardiovascular center
32
Q
- Helps regulate heart rate and stroke volume
- Controls neural, hormonal, and local negative feedback systems that regulate blood pressure and blood flow to specific tissues
A
function of cardiovascular center
33
Q
- Baroreceptors – monitor pressure changes and stretch in blood vessel walls
- Proprioceptors – monitor movements of joints and muscles to provide input during physical activity
- Chemoreceptors – monitor concentration of various chemicals in the blood
- Output from cardiovascular center flows along neurons of ANS
- Sympathetic (stimulatory) opposes parasympathetic (inhibitory
A
reflex neural regulation of BP
34
Q
- Pressure-sensitive receptors in internal carotid arteries and other large arteries in neck and chest
- Carotid sinus reflex helps regulate blood pressure in brain
- Aortic reflex regulates systemic blood pressure
- When blood pressure falls, baroreceptors stretched less, slower rate of impulses to cardiovascular center
- Cardiovascular center decreases parasympathetic stimulation and increases sympathetic stimulation
A
baroceptor relfexes
35
Q
- Receptors located close to baroreceptors of carotid sinus (carotid bodies) and aortic arch (aortic bodies)
- Detect hypoxia (low O2), hypercapnia (high CO2), acidosis (high H+) and send signals to cardiovascular center
- Cardiovascular center increases sympathetic stimulation to arterioles and veins, producing vasoconstriction and an increase in blood pressure
- Receptors also provide input to respiratory center to adjust breathing rate
A
chemoreceptor reflexes
36
Q
- Hormones
- Renin-angiotensin-aldosterone (RAA) system
- Epinephrine and norepinephrine
- Antidiuritic hormone (ADH)
- Atrial natriuretic peptide (ANP)
- Action
- Help regulate BP and blood flow by
- Altering CO
- Changing systemic vascular resistance
- Adjusting total blood volume
A
hormonal reg of BP
37
Q
- Renin(released by kidney when blood volume falls or blood flow decreases) and angiotensin converting enzyme (ACE) act on substrates to produce active hormone angiotensin II
- Raises BP by vasoconstriction and secretion of aldosterone (increases water reabsorption in kidneys to raise blood volume and pressure)
A
renin angiotensin aldosterone (RAA) system
38
Q
- Released by adrenal medulla in response to sympathetic stimulation
- Increases cardiac output by increasing rate and force of heart contractions
A
epinephrine and norepinephrine
39
Q
- Produced by hypothalamus, released by posterior pituitary
- Responds to dehydration or decreased blood volume
- Causes vasoconstriction which increases blood pressure
A
ADH or vasopressin
40
Q
- Released by cells of atria
- Lowers blood pressure by causing vasodilation and promoting loss of salt and water in urine
- Reduces blood volume
A
atrial natriuretic peptide (ANP)
41
Q
- Ability of tissue to automatically adjust its blood flow to match metabolic demands
- Demand of O2 and nutrients can rise tenfold during exercise in heart and skeletal muscles
- Also controls regional blood flow in the brain during different mental and physical activities
- Types of stimuli
- Physical – temperature changes, myogenic response
- Vasodilating and vasoconstricting chemicals which alter blood vessel diameter
A
autoreg of BP
42
Q
- Systemic blood vessel walls dilate in response to low O2 to increase O2 delivery
- Walls of pulmonary blood vessels constrict under low O2 to ensure most blood flows to better ventilated areas of lung
A
important diff bewtn pulmonary and systemic circulation in autoregulatory response
43
Q
- Alternate expansion and recoil of elastic arteries after each systole
- Strongest in arteries closest to the heart
- Becomes weaker further from the heart
- Normally same as heart rate
- Tachycardia – rapid resting heart or pulse rate
- Bradycardia – slow resting heart or pulse rate
A
pulse
44
Q
- Pressure in arteries generated by left ventricle during systole and the pressure remaining in the arteries when the ventricle is in diastole
- Pulse pressure=Difference between systolic and diastolic pressure
A
blood pressure
45
Q
- Failure of the cardiovascular system to deliver enough O2 and nutrients to meet cellular needs
- Causes characterized by inadequate blood flow to body tissues
Types
- Hypovolemic – due to decreased blood volume
- Vascular – due to inappropriate vasodilation
- Obstructive – due to obstruction of blood flow
A
shock
46
Q
- ___exercise results in
- Extensive vasodilation
- Increased venous return
- A rise in cardiac output
- __ exercise results in
- Increased blood flow to skeletal muscles
- Restriction of blood flow to nonessential organs
A
light; heavy
47
Q
- Carotid and aortic reflexes increase CO and peripheral vasoconstriction
- Sympathetic nervous system elevates blood pressure
- E and NE increase cardiac output and ADH enhances vasoconstriction
A
cardiovascular response to hemmohaging SHORT term
48
Q
- Decline in capillary blood pressure recalls fluids from interstitial spaces
- Aldosterone and ADH promote fluid retention
- Increased thirst promotes water absorption across the digestive tract
- Erythropoietin ultimately increases blood volume and improves O2 delivery
A
cardiovascular response to heorrhaging LONG term
49
Q
- The Brain-Four arteries which anastomose insuring constant blood flow
- The Heart-Coronary arteries arising from the ascending aorta
- The Lungs-Pulmonary circuit, regulated by local responses to O2 levels;Opposite other tissues (declines in O2 cause vasodilation)
A
special circulation
50
Q
- Peripheral distribution of arteries and veins is generally symmetrical
- Except near the heart
- Single vessels may have several names as they cross anatomical boundaries
- Arteries and corresponding veins usually travel together
A
distribution of blood:general functional patterns
51
Q
- Superior vena cava-Drains blood from the head and neck
- Inferior vena cava-Drains blood from the remainder of the body
A
systemic veins
52
Q
- Contains substance absorbed by the stomach and intestines
- Delivers these compounds to the liver for
- Storage
- Metabolic conversion
- Excretion
A
hepatic portal system
53
Q
- Fetal blood flow to the placenta is supplied via paired umbilical arteries
- A single umbilical vein drains from the placenta to the ductus venosus
- Collects blood from umbilical vein and liver &Empties into the inferior vena cava
A
placental supply in fetal circulation
54
Q
- No need for pulmonary function in the fetus
- Two shunts bypass the pulmonary circuit
- Foramen ovale
- Ductus arteriosus
A
fetal circulation of the heart and great vessels
55
Q
- Decreased hematocrit
- Constriction or blockage of peripheral veins by a thrombus
- Pooling of blood in the veins of the legs
- Vessels are less elastic, prone to Ca2+ deposits and thrombi formation
- The aging heart has reduced output, decreased activity, and scarring
A
age related changed in blood
56
Q
A
