Blood Vessels Flashcards
arteries/arterioles
conduct blood away from the ventricles of heart to capillaries
venules/veins
return blood from capillaries to atria of heart
arteries
- strong, elastic vessels that carry blood away from heart under high pressure
- subdivide and branch into arterioles
structure of arterial wall
- 3 distinct layers
1. tunica internal (intima)- layer of simple squamous epithelium, elastic
2. tunica media- bulk of wall, smooth muscle fibers, tough elasticity
3. tunica external (adventitia)- thin layer of connective tissue with irregular elastic and collagenous fibers
what changes the diameter of arteries and arterioles and what does it affect
- greatly impacts BP
- sympathetic brances of autonomic nervous system innervate smooth muscle in artery and arteriole walls which cause vasoconstriction and vasodilation
arterioles details
- microscopic continuations of arteries
- branch into smaller metarterioles that join with capillaries
- muscle fibers of wall of arterioles and metarterioles adapted for vasodilation/vasoconstruction to help control blood flow in capillaries
endothelium
- barrier between vessel lumen and surround tissue allows blood cells and platelets to flow through blood vessels
- helps proper hemostatic balance
- prevents blood clotting
- regulates blood flow by secreting substances that can dilate or constrict vessel
- endothelium damage can play a big role in cardiovascular disease
substance secreted by endothelium that can dilate vessel
- nitric oxide
- prostacyclin
substance secreted by endothelium that can constrict vessel
- endothelin
- thromboxane A2
- angiotensin II
- superoxide
details of capillaries
- smallest diameter
- intercellular channels in walls determine permeability and vary from tissue to tissue
what is the arrangement of capillaries
- high tissues rate of metabolism = denser capillary network
- low metabolism = lack of capillaries
what is the regulation of blood flow of capillaries
- precarpillary sphincters are smooth muscles that surround the entrances of capillary networks and control distribution of blood flow
- sphincters respond to demands of cells that capillary supplies and if the cell is in low oxygen and nutrients, it relaxes and blood flow increases
exchange in capillaries
-occurs through diffusion, filtration, osmosis, reabsorption
diffusion in capillaries
- blood rich oxygen and nutrients within systemic capillaries enters tissue fluid
- CO2 and other wastes enter capillary blood from tissue
- substances that diffuse easily are dependent upon solubility in lipids
- proteins that are too large to diffuse through membrane pores or slitlike openings within endothelial cells remain in blood, which helps maintain osmotic oncotic pressure
filtration in capillaries
- hydrostatic pressure forces molecules through a membrane
- occurs primarily at arteriolar ends of capillaries
- blood pressure higher and opposes the action of plasma colloid osmotic pressure
reabsorption in capillaries
- colloid osmotic pressure pulls fluid into capillaries and/or prevents fluid from leaving
- occurs at venular end
- colloid osmotic pressure unchanged, blood pressure decreased due to resistance through capillary
venules
-microscopic vessels that continue from capillaries and merge to form veins
veins
- carry blood back to the atria
- there are semilunar valves that project inward from interior lining of vessel that aid in returning blood to heart
- function as blood reservoirs in times of blood loss
blood pressure
-most commonly refers to pressure in arteries
systolic pressure
max pressure achieved in arteries during ventricular contraction
diastolic pressure
lowest pressure achieved in arteries before next ventricular contraction
what is a pulse
expanding and recoiling of arterial wall
-used to determine heart rate
what is the order that blood pressure is greatest in
arteries > arterioles > arteriolar end of capillary > venular end of capillary
what are the factors that influence blood pressure
- heart action
- blood volume
- resistance to flow
- blood viscosity: great viscosity, greater resistance to flow
what is the top number when taking blood pressure represent
systolic
what is the bottom number when taking blood pressure
diastolic
what is the normal blood pressure
systolic: less than 120
diastolic: less than 80
what is the prehypertension blood pressure
systolic: 120-139
diastolic: 80-89
what is the high blood pressure stage 1 blood pressure
systolic: 140-159
diastolic: 90-99
what is the high blood pressure stage 2 blood pressure
systolic: 160 or higher
diastolic: 100 or higher
what is hypertensive crisis blood pressure
systolic: higher than 180
diastolic: higher than 110
what role does the aortic root play in aortic circulation`
- contains aortic cusps, aortic sinus, coronary ostia
- aortic bodies that are within lining of aortic sinuses contain chemoreceptors that sense blood concetrations of oxygen and CO2
what role does the ascending aorta play in aortic circulation
- first part of aorta
- emerges from LV posterior to pulmonary trunk and ends at the level of angle where then become the aortic arch
details of aortic arch within aortic circulation
- 4-5cm in length
- emerges from pericardium posterior to sternum
- ends b/w 4 & 5th thoracic vertebral to then become the thoracic aorta
- contains baroreceptors that detect changes in blood pressure
what are the three main arteries that originate from the aortic arch
- brachiocephalic
- left common carotid
- left subclavian
brachiocephalic artery
- aka innominate artery
- supplies blood to tissue of upper limb, head, neck, and thoracic wall
- first branch from arch and rises through mediastinum
- branches into right common carotid and right subclavian
what does the right common carotid supply
-carries blood to the right side of head and neck
what is the external carotid artery
- divided from RCC and LCC
- major blood source to all structures of head except brain
what is the internal carotid artery
- divided from RCC and LCC
- gives rise to multiple branches inside cranial cavity and terminates as anterior cerebral arteries
what is the circle of willis
- also know as cerebral arterial circle
- arrangement of blood vessels @ base of brain
- composed of anastomosis of L and R internal carotid arteries
- equalizes blood pressure in brain
- provides alternate routes for blood flow to brain
what is anastomoses
-important bc occur normally in the body in the circulatory system, serving as backup routes for blood flow if one link is blocked or otherwise compromised
thoracic aorta
-begins b/w 4 and 5th thoracic vertebrae
what branches from thoracic aorta
- visceral branches: arteries to internal organs
- parietal branches: arteriess to body wall structures
- bronchial arteries
what is the abdominal aorta
- continuation of thoracic aorta after passes through diaphragm
- ends at common iliac arteries
- gives off visceral and parietal branches
- unpaired and paired visceral branches
what are the unpaired visceral branches of the abd aorta
- celiac trunk
- superior mesenteric
- inferior mesenteric
what are the paired visceral branches of the abd aorta
-suparenal, renal, gonadal arteries
vessels in liver
- has double blood supply: systemic circulation & hepatic portal circulation
- 20% cardiac output
- portal triad: portal field, portal area, portal trunk
where do the hepatic arteries branch from
celiac trunk of abd aorta
common hepatic artery
supplies liver, gallbladeder, stomach, small intestine and pancreas
-branches off into proper hepatic artery and left heaptic artery
what is the portal triad
- portal field, portal area, portal trunk
- composed of proper hepatic artery, hepatic portal vein, common bile duct, lymphatic vessels, and branch of vagus nerve
venous circulation
- veins return blood to heart
- superficial or deep: superficial veins do not correspond to those of arteries, deep veins do
what are SVC, IVC, and coronary sinus
-systemic veins that drain deoxygenated blood into heart
SVC
receives blood from veins superior to diaphragm
IVC
receives blood from veins that are inferior to diaphragm
where do most blood passing through the head drain into
-internal jugular, external jugular, and vertebral veins
internal jugular
drains brain, bones of cranium, muscles, tissues of face and neck
external jugular
drains scalp of head and neck
vertebral veins
drains cervical vertebrae, cervical spinal cord, deep muscles in neck
veins of the thorax
- most of thoracic structures drain by azygos system (R thoracic wall, thoracic viscera, posterior abdominal wall)
- all drain into SVC
- may serve as bypass for IVC bc many small veins link azygos system with IVC
- provides an alternate route for venous return if the IVC or hepatic portal vein becomes obstructed
veins of abd and pelvis
-blood returns to heart via IVC
where does the IVC not receive blood from
- GI tract
- spleen
- pancreas
- gallbladder
what is hepatic portal circulation
formed from joining of superior mesenteric and splenic veins
-receives blood from left gastric vein, right gastric vein, splenic vein, and superior mesenteric vein
when the deoxygenated blood travels out of the pulmonary artery goes to the lungs, where does the gaseous exchange happen?
capillaries
what is a right dominant heart
PDA come off of RCA
what is a left dominant heart
PDA comes off of LCA
what is a co dominant heart
PDA comes off of RCA and LCA
systolic blood pressure is measured when….
when the ventricles contact
which of the blood vessels is most often used to find the arterial systolic pressure?
radial artery
what is a branch off of the brachiocephalic trunk?
right subclavian artery
which arteries enter the brain through the foramen magnum?
vertebral
the basilar artery are formed by the union of which arteries?
vertebral
from the femoral arteries, blood flows into where
the popliteal artery
blood reaches the cell that make up blood vessels by way of tiny capillaries called the ___ in the outer layer of the vessel
vasa vasorum
pressure due to the presence of water in the capillary blood results in
blood hydrostatic pressure
endothelium makes up the layer of artery called the
tunica interna
Capillaries in which the basement membrane is incomplete or absent and have large spaces between the endothelial cells are called
sinusoids
he most important blood reservoirs are the
veins the abdominal organs
If your total blood volume is 5 liters, the volume in your veins and venules is
3 liters
Velocity of blood flow is fastest in the
aorta
Circulation time in an average resting human is about
one minute
If a tube is decreased to 1/2 its diameter, it will increase its resistance to fluid flow
4 times
Most of the tissues and organs in the thorax are drained by the
azygous system and veins
At the back of the knee, the anterior and posterior tibial and small saphenous veins drain blood into the
popliteal vein
