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
* 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
starling's law
26
* 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
hemodynamics:factors affecting blood flow
27
* Contraction of ventricles generates blood pressure
* Systolic(highest)/diastolic(lowest)
* Pressure falls progressively with distance from left ventricle
blood pressure
28
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
vascular resistance
29
* 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
Velocity of Blood Flow
30
* 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
interconnected negative feedback systems
31
* 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
location of cardiovascular center
32
* 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
function of cardiovascular center
33
1. _Baroreceptors_ – monitor pressure changes and stretch in blood vessel walls
2. _Proprioceptors_ – monitor movements of joints and muscles to provide input during physical activity
3. _Chemoreceptors_ – monitor concentration of various chemicals in the blood
* Output from cardiovascular center flows along neurons of ANS
* Sympathetic (stimulatory) opposes parasympathetic (inhibitory
reflex neural regulation of BP
34
* 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
baroceptor relfexes
35
* 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
chemoreceptor reflexes
36
* 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
hormonal reg of BP
37
* 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)
renin angiotensin aldosterone (RAA) system
38
* **Released by adrenal medulla in response to sympathetic stimulation**
* **Increases cardiac output by increasing rate and force of heart contractions**
epinephrine and norepinephrine
39
* Produced by hypothalamus, released by posterior pituitary
* Responds to dehydration or decreased blood volume
* Causes vasoconstriction which increases blood pressure
ADH or vasopressin
40
* Released by cells of atria
* Lowers blood pressure by causing vasodilation and promoting loss of salt and water in urine
* Reduces blood volume
atrial natriuretic peptide (ANP)
41
* **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**
autoreg of BP
42
* 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
important diff bewtn pulmonary and systemic circulation in autoregulatory response
43
* 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
pulse
44
* 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
blood pressure
45
* 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
1. Hypovolemic – due to decreased blood volume
2. Vascular – due to inappropriate vasodilation
3. Obstructive – due to obstruction of blood flow
shock
46
* \_\_\_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
light; heavy
47
* 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
cardiovascular response to hemmohaging SHORT term
48
* 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
cardiovascular response to heorrhaging LONG term
49
* 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)
special circulation
50
* 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
distribution of blood:general functional patterns
51
* Superior vena cava-Drains blood from the head and neck
* Inferior vena cava-Drains blood from the remainder of the body
systemic veins
52
* Contains substance absorbed by the stomach and intestines
* Delivers these compounds to the liver for
* Storage
* Metabolic conversion
* Excretion
hepatic portal system
53
* 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
placental supply in fetal circulation
54
* No need for pulmonary function in the fetus
* Two shunts bypass the pulmonary circuit
* Foramen ovale
* Ductus arteriosus
fetal circulation of the heart and great vessels
55
* 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
age related changed in blood
56
