Chapter 20 Flashcards
what vessels carry blood away from the heart
arteries
what vessels carry blood back to the heart
veins
what vessels connect smaller arteries to smallest veins
capillaries
what is the innermost layer of the vessel wall
tunica interna
what layer of the blood vessel lines the blood vessel and is exposed to blood
tunica interna
define endothelium when pertaining to the vessel wall
simple squamous epithelium overlying basement membrane and sparse layer of loose connective tissue
the tunica international acts as what and of barrier
selectively permeable barrier
what layer of the vessel wall secretes chemicals that stimulate dilation or constriction of the vessel
tunica interna
When tissue around vessel is inflamed, the endothelial cells produce cell-adhesion molecules that induce __ to adhere to the surface in the tunica interna
leukocytes
what does the tunica media consist of
smooth muscle, collagen, and elastic tissue
what layer of the vessel wall prevents blood pressure from rupturing them
tunica media
what layer of the vessel wall regulates the diameter of the blood vessel
tunica media
what are some functions of the tunica externa
anchors the vessel and provides passage for small nerve, lymphatic vessels
what is the name for the small vessels that supply blood to the outer part of the larger vessels
vasa vasorum
what are the three types of arteries
conducting, distributing, and resistance arteries
what are the biggest arteries
conducting
what are some examples of conducting arteries
aorta, common carotid, subclavian, pulmonary trunk, and common iliac
conducting arteries expand during _and recoil during __
ventricular systole, diastole
what arteries contain the internal and external lamina
conducting
what are the medium arteries called
distributing
what is the role of distributing arteries
distributes blood to specific organs
what are some examples of distributing arteries
Brachial, femoral, renal, and splenic arteries
what are the smallest category of the three arteries
resistance
what arteries are too variable to be given names
resistance
what are the smallest arteries
arterioles
what is the role of arterioles
to control the amount of blood to various organs
what arteries link arterioles to capillaries or bypass directly to a venule
metarterioles
what is an aneurysm
a weak point in the artery heart or wall
what are the most common sites of aneurysms
abdominal aorta, renal arteries, and arterial circle at base of brain
aneurysms can rupture causing a
hemorrhage
what are some causes of aneurysms
congenital weakness of blood vessels, trauma, or bacterial infections , but most common cause is atherosclerosis and hypertension
what are some arterial sense organs
carotid sinuses, carotid bodies, and aortic bodies
what kind of receptors are carotid sinuses and their functions
baroreceptors, they monitor blood pressure and Transmit signals through glossopharyngeal nerve
what kind of receptors are carotid bodies and their functions
chemoreceptors, they Monitor blood chemistry, Transmit signals through glossopharyngeal nerve to respiratory centers, and Adjust respiratory rate to stabilize pH, CO_2, and O_2
what kind of receptors are aortic bodies and their functions
chemoreceptors, Same structure and function as carotid bodies, but innervation is by vagus nerve
what vessels are the site where gasses, nutrients, wastes, and hormones pass between the blood and tissue fluid
capillaries
what is known as the business end of the cardiovascular system
the capillaries
what are the three types of capillaries
continuous, fenestrated, a nd sinusoids
where are continuous capillaries found
in most tissues
what type of capillaries allow passage for solutes such as glucose
continuous
where are fenestrated capillaries found
in the kidneys, small intestine, and choroid plexuses
what are filtration pores in capillaries called
fenestrations
where are sinusoids found
in the liver, bone marrow, and spleen
what type of capillaries allow proteins (albumin), clotting factors, and new blood cells to enter the circulation
sinusoids
what are capillary beds
networks of 10-100 capillaries
capillary beds are usually supplied by
a single arteriole or metarteriole
At distal end, capillaries transition to __ or drain into a throroughfare channel (continuation of metarteriole
venules
Most control of flow involves constriction of __ that are upstream from the capillaries however, Within the capillary bed, __control flow
arterioles, precapillary shincters
what are the smallest veins called
post capillary venules
__ are more porous than capillaries so they also exchange fluid with surrounding tissues
post capillary venules
muscular venules are up to __mm in diameter
1
medium veins are up to __ in diameter
10mm
Tunica interna forms __along with surrounding muscle forms the skeletal muscle pump; Varicose veins result from the failure
venous valves
most named veins are
medium veins
what are venous sinuses
Veins with especially thin walls, large lumens, and no smooth muscle
Dural venous sinuses of the brain and coronary sinus of the heart
are venous sinuses capable of vasomotor responses
no
large veins are __mm
larger than 10
smooth muscle is found where in large veins
all three tunics
what are some examples of large veins
Venae cavae, pulmonary veins, internal jugular veins, and renal veins
what are varicose veins
Blood pools in the lower legs of people who stand for long periods stretching the veins, Cusps of the valves pull apart in enlarged superficial veins, further weakening vessels, Blood backflows and further distends the vessels, their walls grow weak and develop into varicose veins
what promotes varicose veins
Hereditary weakness, obesity, and pregnancy
what are hemorrhoids
varicose veins of the anal canal
what is the simplest pathway of the circulatory route
heart, arteries, capillaries, veins, and heart
where can portal systems be found
Between hypothalamus and anterior pituitary,In kidneys, Between intestines to liver
what is anastomosis
convergence point between two vessels other than capillaries
where can anastomosis be found
In coronary circulation and around joints
define blood flow
the amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min.)
define blood perfusion
the flow per given volume or mass of tissue (mL/g/min)
what is the cardiac output measurement
5.25 L/min
what are hemodynamics
the physical principles of blood flow
define blood pressure
the force that blood exerts against a vessel wall
where is blood pressure measured and with what tool can it be measured
Measured at brachial artery of arm using sphygmomanometer
what are the two blood pressures that are recorded
systolic and diastolic pressure
what is systolic pressure
peak arterial BP taken during ventricular contraction
what is diastolic pressure
minimum arterial BP taken during ventricular relaxation
what is the normal value of blood pressure in a young adult
120/75 mm Hg
what is pulse pressure
difference between systolic and diastolic pressure; driving force on circulation and of stress exerted on small arteries by pressure surges generated by the heart.
what is the mean arterial pressure
the mean pressure one would obtain by taking measurements at several intervals throughout the cardiac cycle; Diastolic pressure + (one-third of pulse pressure)
what is the blood pressure measurement that most influences the risk level for edema, fasting, atherosclerosis, kidney failure, and aneurysms
MAP
what is hypertension
high blood pressure
what Is resting BP
140/90
what is Atherosclerosis
build up of lipid deposits that become plaques
what is Arteriosclerosis
stiffening of arteries due to deterioration of elastic tissues of artery walls
what is hypotension
low blood pressure
what is hypotension caused by
blood loss, dehydration, anemia
Blood pressure is determined by
cardiac output, blood volume (regulated by kidneys), and resistance to flow
blood volume is regulated by
the kidneys
what is peripheral resistance
cardiac output, blood volume (regulated by kidneys), and resistance to flow
__ and __ concentration elevate viscosity the most
RBC count, albumin
Decreased viscosity with __and __ speed flow
anemia, hypoproteinemia
Increased viscosity with __ and __ slow flow
polycythemia, dehydration
The farther liquid travels through a tube, the more __ it encounters
cumulative friction
what is the Only significant way of controlling resistance
vessel radius
what are Vasoreflexes
changes in vessel radius
__ markedly affects blood velocity
Vessel radius
Laminar flow: flows in layers, faster in the
center
Blood flow (F) proportional to the fourth power of
radius
what is the typical lumen diameter of the aorta
2.5 cm
what is the typical lumen diameter of the arterioles
20-50um
what is the typical lumen diameter of the capillaries
5-9um
what is the typical lumen diameter of the venules
20um
what is the typical lumen diameter of the inferior vena cava
3cm
__are most significant point of control over peripheral resistance and flow
Arterioles
what are the two purposes of vasomotion
general control of BP and routing blood from one body region to another
what are the three way fo controlling vasomotor activity
local control, neural control, and hormonal control
what are the four ways of local control
auto regulation, vasoactive chemicals, reactive hyperemia, and angiogenesis
what is autoregulation
the ability of tissues to regulate their own blood supply
what is the Metabolic theory of autoregulation:
If tissue is inadequately perfused, wastes accumulate, stimulating vasodilation which increases perfusion
what are vasoactive chemicals
substances secreted by platelets, endothelial cells, and perivascular tissue to stimulate vasomotor responses
what vasoactive chemicals stimulate vasodilation
histamine, bradykinin, and prostaglandins
as a result of vasoactive chemicals, the Drag of blood causes endothelial cells to secrete __ and __ (vasodilators)
prostacyclin, nitric oxide
what is reactive ehyperemia
If blood supply cut off then restored, flow increases above normal
what is angiogenesis
growth of new blood cells
where does angiogenesis occur
regrowth of uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors
Vasomotor center is the integrating center for what three autonomic reflexes
baroreflexes, chemoreflexes, and medullary ischemic reflex
what are baroreflexes
automatic, negative feedback response to change in blood pressure
what are chemoreflexes
an automatic response to changes in blood chemistry
what are medullary ischemic reflexes
automatic response to a drop in perfusion of the brain
what are some examples of hormones used in hormonal control for regulation of blood pressure and flow
angiotensin 2, aldosterone, atrial natriuretic peptide, ADH, epinephrine and norepinephrine
what does angiotensin 2 do
it is a potent vasoconstrictor, promotes Na^+ and water retention by kidneys, and Increases blood volume and pressure, raising blood pressure
what does aldosterone do
Salt retaining hormone, Promotes Na+ retention in kidney promoting, water follows osmotically, raising blood pressure
what does atrial natriuretic peptides do
increases urinary sodium excretion, Reduces blood volume and promotes vasodilation, Lowers blood pressure
what does ADH do
promotes water retention, Pathologically high concentrations also a vasoconstrictor, raises blood pressure
what do E and NE do
In most blood vessels of smooth muscle does vasoconstriction, In cardiac muscle blood vessels does vasodilation
The most important blood in the body is in the
capillaries
what is Capillary exchange
two-way movement of fluid between the bloodstream and tissues across capillary walls
what contents are used in capillary exchanges
Water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, carbon dioxide, ammonia
Chemicals pass through the capillary wall by of what three routes
- Through endothelial cell cytoplasm
- Intercellular clefts between endothelial cells
- Filtration pores (fenestrations) of the fenestrated capillaries
what mechanisms are involved in capillary exchange
diffusion, transcytosis, filtration and reabsorption
__ is the most important form of capillary exchange
Diffusion
Lipid-soluble substances for capillary diffusion
Steroid hormones, O_2, and CO_2 diffuse easily through plasma membranes
what are some water soluble substances for diffusion
Glucose and electrolytes must pass through filtration pores and intercellular clefts
what is transcytosis
endothelial cells pick up material on one side of their membrane by pinocytosis or receptor-mediated endocytosis, transport vesicles across cell, and discharge material on other side by exocytosis
what is transcytosis important for
fatty acids, albumin, and some hormones
what do hydrostatic pressures do
drive fluid out of capillary.
High on arterial end of capillary, low on venous end
what does colloid osmotic pressure do
draws fluid into capillary, Opposes hydrostatic pressure, Osmotically draws water into the capillary at venous end
__ capillaries in Kidneys are devoted to filtration
Glomeruli
__ capillaries in lungs are devoted to absorption
Alveolar
what is edema
accumulation of excess fluid in a tissue
what are the three main causes of edema
increased capillary filtration, reduced capillary reabsorption, and obstructed lymphatic drainage
what are some causes of increased capillary filtration
kidney failure, histamine, old age, poor venous return
what are some causes of reduced capillary reabsorption
Hypoproteinemia, liver disease, dietary protein deficiency
what are some causes of obstructed lymphatic drainage
Surgical removal of lymph nodes interferes with drainage from tissues
what is venous return
the flow of blood back to the heart
what are some things that venous return relies on
pressure gradient, gravity, skeletal muscle pump, thoracic pump, and cardiac suction
the pressure gradient has Higher pressure in __, lower pressure in __
venules, venae cavae
When you inhale, abdominal pressure __ while thoracic pressure __
increase, decreases
what are some ways exercise increases venous return
- Heart beats faster and harder, increasing CO and BP
- Vessels of skeletal muscles, lungs, and heart dilate and increase flow
- Increased respiratory rate, increased action of thoracic pump
- Increased skeletal muscle pump
venous __ occurs with inactivity
pooling
what is circulatory shock
any state in which cardiac output is insufficient to meet the body’s metabolic needs
what two categories fo circulatory shock fall into
cariogenic and low venous return
what is cariogenic shock
inadequate pumping of heart
what is low venous return
cardiac output is low because too little blood is returning to the heart
what are the three principal forms of LVR shock
hypovolemic, obstructed venous return shock, and venous pooling shock
what principal form of LVR shock is most common
hypovolemic
what causes hypovolemic shock
Loss of blood volume: trauma, burns, dehydration
what causes obstructed venous return shock
Tumor or aneurysm compresses a vein and impedes blood flow
what causes venous pooling shock
Long periods of standing, sitting, or widespread vasodilation
what happens to blood vessels during shock
they dilate causing blood pressure to drop
what are three additional types of circulatory shock
neurogenic, septic, and anaphylactic
what is neurogenic shock and its causes
Loss of vasomotor tone causes vasodilation, Can result from emotional shock to brainstem injury
what is septic shock
Bacterial toxins trigger vasodilation and increased capillary permeability
what is anaphylactic shock and its results
Severe immune (allergic) reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability
what is compensated shock
Several homeostatic mechanisms bring about spontaneous recovery
Example: If a person faints and falls to a horizontal position, gravity restores blood flow to the brain
what is decompensated shock
When compensation fails
Life-threatening positive feedback loops occur
Condition gets worse causing damage to cardiac and brain tissue
