Week 4 - Vessels & Hemodynamics Flashcards
Identify structural differences between arteries and veins
Arteries have thick elastic muscular walls
Veins have thin non-elastic walls
Veins contain valves to prevent back-flow
Identify structural differences & similarities between veins and lymphatic vessels
Lymphatic vessels are lined with smooth muscle
Lymphatic vessels interconnect with lymph nodes
Lymphatic vessels contain valves to prevent back-flow
Identify structural differences between elastic arteries and muscular arteries
elastic arteries contain elastic fibers in the tunica media layer
muscular arteries contain smooth muscle tissue in the tunica media layer to allow for vasoconstriction
Arterioles are small ____ deliverying ____ to ______
The tunica media of arterioles contains _____
arteries
blood
capillaries
a few layers of muscle
Metarterioles form branches into ______
To bypass capillary bed, _____ close and blood flows _____
capillary bed
precapillary sphincters
out of bed into thoroughfare channel
Vasomotion is intermittent ________ that allows _______at a rate of _____
intermittent contraction and relaxation of sphincters
filling of capillary bed
5-10 times / minute
Continuous capillaries are found in what tissue(s)?
skeletal/smooth muscle, connective tissue, LU
Fenestrated capillaries are found in what tissues(s)?
KD, SI, choroid plexuses, ciliary process, endocrine glands
Sinusoid capillaries are found in what tissue(s)?
LV, bone marrow, SP, anterior pituitary, parathyroid gland
Capillaries are lacking in what tissue(s)?
epithelia, cornea and lens of eye, cartilage
The function of capillaries is _______
exchange of nutrients and waste between blood and tissue fluid
Describe the structure of a capillary
single layer of simple squamous epithelium and its basement membrane
What are the types of capillary exchange?
diffusion
transcytosis
bulk flow
Describe bulk flow
filtration and reabsorption
movement of large amount of dissolved or suspended material in same direction
Bulk flow is more important for regulation of ______
relative volumes of blood and interstitial fluid
Filtration is movement of material into _________ and is promoted by ______
interstitial fluid
blood hydrostatic pressure and interstitial fluid osmotic pressure
Reabsorption is movement from ________ into ________ and is promoted by _______
interstitial fluid
capillaries
blood colloid osmotic pressure and interstitial fluid hydrostatic pressure
Net filtration pressure is defined as _______
(BHP + IFOP) - (BCOP + IFHP)
Blood colloid osmotic pressure is formed by ______ proteins, namely _______
plasma
albumin, globulin, fibrinogen
Net filtration pressure in arterial end of capillary is generally ____ while in the venous end it is generally ______
10mmHg
-9mmHg
As a result of net filtration pressure about ___% of filtered fluid is returned to the capillary. Escaping fluid and plasma proteins are collected by ______
85%
lymphatic capillaries
Edema is _______ and can be a result of _________
abnormal increase in interstitial fluid if filtration exceed reabsorption
excess filtration, inadequate reabsorption
Excess filtration can be caused by _________
increased BP
increased permeability of capillaries allows plasma proteins to escape
Inadequate reabsorption can be caused by _________
decreased concentration of plasma proteins lowers blood colloid osmotic pressure (LV malfunction, burns, malnutrition, KD disease)
What factors affect circulation?
- pressure differences that drive blood flow (blood velocity, blood volume, BP)
- resistance to flow (afterload)
- venous return
How are speed of blood flow and cross-sectional area related? Blood flow becomes _____ when vessels merge to form veins.
inversely related
faster
Cardiac output is influenced by ______
blood pressure
resistance due to friction between blood cells and blood vessel walls
Systemic vascular resistance is determined by _______
average blood vessel radius
blood viscosity
total blood vessel length
There are ____ miles of blood vessels for every pound of fat. HBP can therefore be caused by ______
200
obesity
Arterioles control BP by changing _______
diameter
Venous return is _______. Describe the pumps that facilitate venous return?
volume of blood flowing back to HT from systemic veins
skeletal muscle pump - contraction of muscles & presence of valves
respiratory pump - decreased thoracic pressure and increased abdominal pressure during inhalation, moves blood into thoracic veins and the right atrium
Inputs to the cardiovascular center include _______
higher brain centers - cerebral cortex, limbic system, hypothalamus
proprioceptors
baroreceptors
chemoreceptors - acidity, CO2, O2
Describe the baroreceptor reflexes
carotid sinus reflex - swellings in internal carotid artery wall, CN IX to cardiovascular center in medulla, maintains normal BP in brain
aortic reflex - receptors in wall of ascending aorta, CN X to cardiovascular center in medulla, maintains general systemic BP
Which hormone causes vasoconstriction? Where is it produced?
ADH
hypothalamus
What is the hormonal response to a decrease in BP or decreased blood flow to KD?
release of renin -> formation of angiotensin II, systemic vasoconstriction, causes release of aldosterone (H2O + Na+ reabsorption)
Atrial natriuretic peptide lowers BP by ______
causing vasodilation and loss of salt and water in the urine
The _____ nerve speeds up the heart rate via _____ stimulation. The _____ nerve slows down heart rate via ______ stimulation
cardiac accelerator
sympathetic
vagus (CN X)
parasympathetic
Describe the functions of chemoreceptor reflexes of carotid bodies and aortic bodies
- detect changes in blood chemistry (O2, CO2, H+)
- causes stimulation of CV center
- increases sympathetic stimulation to arterioles & veins
- vasoconstriction and increase in blood pressure
___% of blood in the body is out of circulation. What can push this blood back into circulation?
60%
epinephrine, norepinephrine
To regulate blood pressure locally, vasoactive substances such as ______ are released from cell to alter vessel _____
K+, H+, lactic acid, nitric oxide
diameter
______ vessels dilate in response to low levels of O2
______ vessels constrict in response to low levels of O2
systemic
pulmonary
Shock is _______
failure of cardiovascular system to deliver enough O2 and nutrients
What mechanisms attempt to return cardiac output & BP to normal in response to shock?
activation of renin-angiotension-aldosterone
secretion of ADH
activation of sympathetic nervous system
release of local vasodilators
