Lecture 12- Blood Vessels

pulmonary circuit

blood to and from lungs, relatively short distance

systemic circuit

blood to the rest of the body and back to the heart, longer distances

3 layers if vessel walls

adventitia, media, intima

vasa vasorum

blood vessels within wall of thick vessels

Intima

innermost layer, tunica intima, made of endothelium of vessel

media

middle layer, tunica media, made of smooth muscle, involved in vasoconstriction and vasodilation

adventitia

outermost layer, tunica adventitia, made of connective tissue, anchor blood vessels

thickness of vessel walls

artery walls thicker, have more smooth muscle

lumen of vessel

arteries have circular shape, veins collapse when cut

vessel lining of arteries

endothelial lining, has pleated folds, thin elastic membranes in media and intima

valves of veins

one way valves, prevents backflow

types of arteries

elastic, muscular, arterioles

elastic arteries

large vessels, elastic membranes in media and intima, very resilient, recoil during diastole (aorta, pulmonary trunk)

muscular artieries

medium sized, thicker media, diameter under control of ANS (radial and ulnar arteries)

arterioles

smallest arteries, very thin adventitia, control blow flow between arteries and capillaries

capillaries

smallest of all vessels, most delicate, lack adventitia and media, where nutrient and waste exchange occurs

continuous capillaries

complete endothelial lining, most common

fenestrated capillaries

endothelial lining not complete, have pores

sinusoidal/discontinued capillaries

endothelial ling not complete, have pores and large gaps

Mechanisms for passage of materials across capillary walls

diffuse across endothelial cells

diffuse through gaps between adjacent endothelial cells

diffuse through pores/gaps in fenestrated capillaries

move via vesicular transport

capillary beds

interconnected network of capillaries, consists of vessels connecting arterioles and venules, contracting or relaxing smooth muscle determines blood flow

capillary beds in brain, heart, stomach

continuous and rich blood flow, more than one artery supplies, if one blocked another will supply, collateral arteries

arterial anastomosis

collateral arteries fused together

capillary beds in joint and visceral organs

blood flow through vessels may be hindered due to body movement, direct connection between arterioles and venules needed, arteriovenous anastomosis

arteriovenous anastomosis

direct connection between arterioles and venules

thoroughfare channels

connect arterioles with venules

metarterioles/precapillary sphincters

guard entrances to capillaries in mesentaries

veins

collect blood from tissues and return it to heart, travels through venules, mediums sized veins and large veins

venules

smallest veins, collect blood from capillaries, lack or have thing tunica media

medium sized veins

adventitia largest layer, elastic fibers, one way valves, alongside muscular arteries

venous valves

blood in veins from lower extremities has to go against gravity, valves in medium veins assist, compartmentalize blood to prevent backflow

large veins

adventitia thickest layer, some smooth muscle, no valves

blood distribution

35% in arteries and capillaries, 65% in veins

capacitance vessels

veins, act as blood reservoirs

venoconstriction of veins

shifts blood toward arterial side of circulation

Blood pressure in 2 systems

higher in systemic, thicker vessel walls

Pulmonary circuit process

oxygen poor blood from RV through pulmonary valve to pulmonary trunk

enters L and R pulmonary arteries

in lungs drops carbon dioxide and picks up oxygen

returns to heart through pulmonary veins into left atrium

systemic arteries circuit

oxygenated blood leaves LV through aortic valve

enters ascending aorta

enters aortic arch

branches into 4 different vessels

brachiocephalic trunk

blood to right side, branches to right carotid and right subclavian

left common carotid artery

middle vessel off aortic arch, blood to left side of head and brain

left subclavian artery

blood to left arm, brain, spinal cord

right carotid artery

blood to right side of head and brain

right subclavian artery

blood to right arm, head, brain, and spinal cord

subclavian arteries

form 3 branches, continue to form axillary arteries

thyrocervical trunk

supplies tissues of neck, shoulder, upper back

internal thoracic artery

supplies pericardium and anterior wall of chest

vertebral artery

supplies brain and spinal cord

flow of blood from subclavian to arm

axillary artery, brachial artery, deep brachial artery, radial and ulnar arteries, anastomose at wrist to form superficial and deep palmar arch, digital arteries

digital artieries

blood to digits

common carotid arteries

ascend the neck, divide to internal and external carotids

carotid sinus

at base of internal carotid, contains baroreceptors and chemoreceptors

external carotids

supply neck and outside of skull, branch to form lingual/facial/occipital/superficial temporal

internal carotids

enter skull to deliver blood to brain, branch to form ophthalmic/anterior cerebral/middle cerebral

ophthalmic artery

supplies eyes

anterior cerebral artery

supplies frontal and parietal lobes

middle cerebral artery

supplies midbrain and lateral surfaces of cerebrum

blood in vertebral arteries reaches brain via…

basilar artery, posterior cerebral and communicating arteries, cerebral arterial circle

basilar artery

right and left vertebral arteries fused, branches many times in pons area

posterior cerebral and communicating arteries

connect basilar artery to internal carotids

cerebral arterial circle

circle of Willis, ring like anastomosis between basilar and carotid arteries

descending aorta

continuation of aortic arch, divided by diaphragm into superficial thoracic aorta and inferior abdominal aorta

Thoracic aorta

forms visceral and parietal branches

visceral branches

supply organ of chest, bronchial/pericradial/mediastinal/esophogeal

parietal branch

supply chest wall, intercostal/superior phrenic

abdominal aorta

celiac trunk, superior and inferior mesenteric arteries, inferior phrenic arteries, adrenal arteries, renal arteries, gonadal arteries, lumbar arteries, R and L common iliac arteries

Celiac trunk

supplies liver, esophagus, stomach, gallbladder, duodenum, pancreas, spleen

left gastric artery

supplies stomach

splenic artery

supplies spleen

left gastro-epiploic artery

supplies stomach

pancreatic arteries

supply pancreas

common hepatic artery

branches from celiac trunk

hepatic artery proper

supplies liver

right gastric artery

supplies stomach

cystic artery

supplies gallbladder

gastroduodenal artery

supplies duodenum

superior mesenteric artery

branches to supply pancreas, duodenum, small and large intestine

inferior pancreaticoduodenal artery

supplies pancreas and duodenum

intestinal arteries

supply small intestine

arteries that supply large intestine

right colic, middle colic, ileocolic

inferior mesenteric artery

branches to supply terminal large intestine and rectum

arteries that supply terminal large intestine

left colic and sigmoid

rectal arteries

supply rectum

5 paired arteries

inferior phrenic, adrenal, renal, gonadal, lumbar

inferior phrenic arteries

supply inferior portion of esophagus and diaphragm

adrenal arteries

supply adrenal glands

renal arteries

supply right and left kidneys

gonadal arteries- Testicular and Ovarian

supply testes, scrotum, ovaries, uterine tubes, uterus

lumbar arteries

supply vertebrae, spinal cord, abdominal wall

arteries of pelvis and lower limbs

abdominal aorta branches to R and L common iliac arteries, split at terminal segment of aorta to internal and external iliac arteries

internal iliac artery

supplies urinary bladder, walls of pelvis, external genitalia, medial side of thigh

external iliac artery

supplies blood to legs

arteries of iliac arteries

exit through abdominal wall to form deep femoral artery

branch to medial and lateral circumflex arteries

femoral artery become popliteal artery, bifurcates to anterior and posterior tibial artery

posterior tibial forms fibular artery

arteries of the foot

anterior tibial artery to dorsalis pedis artery

posterior tibial artery to medial and lateral plantar arteries

superior vena cava

receives blood from head, neck, chest, shoulders, upper limbs

venous return from cranium

superficial cerebral veins into dural sinuses

sinuses converge and L and R transverse sinuses at confluence

confluence darins to sigmoid sinus, then into jugular veins

straight sinus

drains internal cerebral veins and great cerebral vein

cavernous sinus

drain petrosal sinuses

vertebral veins

drains from posterior skull and cervical spinal cord, then into brachiocephalic veins

temporal vein and maxillary veins

drains into external jugular vein, then subclavian

facial vein

drains into internal jugular vein, then subclavian