Chapter 21 vessels
Arteries
carry blood away from the heart
Veins
carry blood toward the heart
tunica interna, tunica media, tunica externa
blood vessel structure
Tunica interna (tunica intima)
innermost layer; adjacent to lumen; simple squamous endothelial layer that lines the lumen
blood vessel larger than 1mm...
subendothelial connective tissue basement membrane is present
has an internal elastic lamina
tunica interna (tunica intima)
tunica media
middle layer; smooth muscle and elastic fibers
regulated by SNS
tunica media
controls vasodilation/vasoconstriction of vessels which regulatesblood flow and blood pressure
tunica media
tunica externa (tunica adventitia)
outermost layer; elastic and collagen fibers that protect and reinforces vessels
elastic allows them to absorb oressure created by ventricles as they pump blood into the arteries
Artery walls
regulate the vessels diameter
tunica media
Elastic Arteries
conducting arteries
more elastic fibers, less smooth muscle
Elastic arteries
function as pressure reservior by storing mechanical energy during ventricular systole
elastic arteries (conducting arteries)
Muscular arteries
distributing arteries
large diameter
elastic artery
medium artery
Muscular artery (distributing artery)
more smooth muscle, fewer elastic fiber
Muscular arteries
distribute blood to various parts of the body
Muscular arteries
Vasoconstriction
decrease in lumen diameter of the blood vessel due to contraction of the smooth muscle
Vasodilation
increase in diameter of blood vessels due to relaxation of smooth muscle
Anastomosis
union of the branches of 2 or more arteries supplying same region of body
provides alternate route for blood flow in case one artery gets obstructed
Anastomosis
Arterioles
delivers bood to capillaries
greatest collective influence on both local flow and overall blood pressue
arterioles
regulates blood flow into capillaries
arterioles
primary "adjustable nozzles" across which the greater drop in pressure occurs
arterioles
microscopic cessels that usually connect arterioles and venules
capillaries
thin walls-premits the exchange of nutrients and waster between blood and tissue cells
capillaries
Capillary walls
single layer of cells and a basement membrane
Continuous capillaries
most common and abundant in the skin and muscles
adjacent cells are connected with tight junctions
continuous capillaries
constitute the blood-brain barrier
continuous capillaries
have intercellar clefts to allow passage of fluids
continuous capillaries
Fenestrated Capillaries
where active capillary absorption or filtrate formation occurs
ex: small intestines, kidneys, endocrine glands
fenestrated capillaries
greater permeability than other capillaries
fenestrated
endothelium riddled with pores
fenestrated capillaries
Sinusoids
Large lumens; wider and more winding; large fenestrations
liver, spleen, bone marrow, lymphoid tissue, some endocrine organs
sinusoids
allows large molecules (protein and blood cells) to pass between the blood and surrounding tissues
sinusoids
blood flows sluggishly
sinusoids
simple diffusion
most important method of capillary exchange
O2, CO2, glucose, amino acids, some hormones cross capillaries by...
simple diffusion
Filtration
pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid
Reabsorption
pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries
Starling's Law of Capillaries
the volume of fluid and solutes reabsorbed is almost as large as the volume filtered
Edema
due to capillary blood pressure and increase in premeability of capillaries allowing plasma proteins to escape which influence lowers the blood colloid osmotic pressure
swelling in the interstitial due to infiltration exceeding absorption with a result of increase in the interstitial fluid volume
Edema
Metarteriole
formed at the terminal end of an arteriole
Precapillary sphincter
monitors and regulates blood flow into the capillary
formed at the distal of most muscle cells at the metarteriole-capillary junction
precapillary sphincter
Capillary Network
formed by capillary branch throughout the tissues and are found near almost every cell
consist of capillaries and thoroughfare channel
Capillary network
Thoroughfare channepl
provides direct flow from arteriole to venule
bypasses capillaries
thoroughfare channel
distal end of metarteriole; does not have smooth muscle
thoroughfare channel
Blood hydrostatic pressure (BHP)
pressure of blood against capillary walls that tends to force fluids thru capillary walls; 35mmHg
hydrostatic pressure
greater at arteriol end
osmotic pressure
greater at venous end
Interstitial fluid hydrostatic pressure
pushes fluid from the interstitial space into capillaries but is close to zero; 0mmHg
Blood Colloid Osmotic pressure (BCOP)
due to colloid suspension of large plasma proteins that are unable to pass thru fenestrations or gaps between endothelial cells; 26mmHG
Interstitial Fluid Osmotic Pressure (IFOP)
pressure that "pulls" fluid out of capillaries into the interstitial fluid and since only small amount of protein in interstitial fluid value of 1mmHg
Myogenic Response
smooth muscle in arteriole walls that contract more forcibly when stretched and relaxes when stretching lessens
Longer the blood vessel...
greater the resistance
higher the blood viscosity...
the higher the resistance
small diameter arteries...
major determinants of peripheral resistance
the difference between the systolic and diastolic blood pressures
pulse pressure
increase in HR and contractility; increases BP; norepinephrine and epinephrine
Altering Cardiac Output
vasoconstriction: Angiotensin II, ADH; BP increased
vasodilation: ANP, nitric oxide, epinephrine; decrease BP
changing systemic vascular resistance
blood volume increased-aldosterone, ADH-increase BP
blood volume decreased-ANP-BP decreases
Adjusting Total Blood Volume
Shock
failure of the cardiovascular system to deliver enough O2 and nutrients to meet metabolic demands of body cells
due to decrease in blood volume
hypovolemic shock
due to poor heart function
cardiogenic shock
due to obstruction of bood flow
obstructive shock
due to excess vasodilation-seen in anaphylaxis or sepsis
vascular shock
negative feed back; activation of the renin-angiostein-aldosterone system; secretions of ADH; activation of SNS; release of local vasodilators in response to hypoxia
symptoms of shock
Ductus Venosus
where oxygenated blood bypasses the liver and dumps into the inferior vena cava on route to right heart in a fetus
Ductus arteriosus
where the blood remaining in the right hear bypasses the closed lungs in a fetus and is diverted into the left sided circulation
Hepatic portal vein
transfers blood it receives from the capillaries of GI organs and the spleen to the sinusoids of liver
Blood reservoirs
systemc veins and venules at rest
Pressure Reserviors
elastic arteries store mechanical energy during ventricular stroke
Transient Elevations Hypertension
normal and can be caused by fever, physical exertion, and emotional upset
Chronic Elevation Hypertension
major cause of HF, vascular disease, renal failure, and stroke
Secondary Hypertension
due to identifiable disorders including excessive renin secretion, arteriosclerosis, and endocrine disorders
clammy, cool pale skin, tachycardic, weak pulse, sweating, hypotension, altered mental status, decrease urinary output, thirst, acidosis
symptoms of shock
located in aorta, internal carotid arteries of neck, lg arteries of neck and chest
baroceptors
monitor changes in pressure and stretch in wall of the blood vessels
baroceptors
pressure sensitive sensory neurons sends impulses in the glosspharyngeal nerves
baroceptors
Chemoreceptors
monitor the chemical composition of blood
located near carotid and aortic bodies
Chemoreceptors
detects hypoxia. hypercapnia, acidosis
chemoreceptors
causes increase in SNS stimulation causing vasoconstriction and increase in BP
chemoreceptors