chapter 20 blood vessels Flashcards
3 major types of blood vessels
arteries, capillaries and veins
carry blood away from the heart
arteries
the smallest arteries
arterioles
smallest blood vessels
capillaries
receive blood from capillaries
venules
receive blood from venules
veins
structure of blood vessels
- tunica intima
- tunica media
- tunica externa
- innermost tunic
- contains endothelium
tunica intima
- sheets of smooth muscle
- contraction (vasoconstriction) and relaxation (vasodilation)
tunica media
composed of connective tissue
-outermost tunic
tunica externa
central blood filled space of a vessel
lumen
- largest arteries
- range from 2.5cm to 1 cm
- includes aorta and its major branches
- sometimes called conducting arteries
- high elastin content dampens surge of blood pressure
elastic arteries
- lie distal to elastic arteries
- ranges from 1cm to 0.3mm
- unique features ; internal and external elastic laminae
muscular (distributing) arteries
- smallest arteries
- ranges from 0.3mm to 10nm
arterioles
-smallest blood vessels
-ranges from 8-10nm
-site specific functions
lungs ; oxygen enters blood, CO leaves
-S. intestines ; receive digested nutrients
-kidneys ; remove N. waste
capillaries
-most common type of capillary
-occurs in most organs
-tight junctions and desmosomes join epithelial cells
includes intercellular cleft
-allows small molecules in and out of capillaries
continuous capillaries
- joined by tight junctions and desmosomes
- have pores in their endothelium
- occur where high rates of exchange occur
- intestines, glomeruli of kidneys and endocrine glands
fenestrated capillaries
- wide Leakey capillaries found in some organs
- usually fenestrated
- intercellular clefts are wide open
- occur in bone marrow and spleen
- have a large diameter and twisted course
sinusoid capillary
4 routes into and out of capillaries
- direct diffusion
- through intercellular clefts
- through cytoplasmic vesicles
- through fenestrations
- capillaries have complete tight junctions
- no intercellular clefts are present
- vital molecules pass through
- not barrier against ; oxygen ,co2, anesthetics
blood brain barrier
- network of capillaries running through tissues
- regulate the flow of blood to tissues
- tendons and ligaments poorly cascularized
- epithelia and cartilage ; avasucular
precapillary sphincter
-conduct blood from capillaries toward the heart
-blood pressure is lower than in arteries
-smallest veins
venues join to form veins
venous vessels
- structurally different from arteries
- lumens are larger
- 65% of blood in __ at any given time
- tunica externa is thicker
- less elastin in walls
- walls are thinner than those of comparable arteries
veins
- particularly in limbs
- prevent back flow of blood
- not located in veins of thoracic and abdominal cavities
valves
muscles press against thin walled veins
skeletal muscle pump
vessels interconnect to form
-organs receive blood from more than one arterial source
vascular anastomoses
neighboring arteries from
-provide collateral channels
arterial anastomoses
- leaves the right ventricle
- divides into right and left pulmonary arteries
- superior and inferior pulmonary veins
- -carry oxygenated blood into left atrium
- thinner walls than systemic vessels
pulmonary trunk
largest artery in the body
aorta
arises from the left ventricle
-branches coronary arteries
ascending aorta
lies posterior to the manubrium
- branches;
- brachiocephalic trunk
- left common carotid
- left subclavian arteries
aortic arch
continues from aortic arch
-divides into left and right common iliac arteries
descending aorta
in the region of t5-t12 aorta
thoracic aorta
ends at l4 aorta
abdominal aorta
Pairs of arteries supplying head and neck
- branches of subclavian arteries
- vertebral arteries
- throcervical trunk
- costocervical trunk
- located in anterior triangle of the neck
- branches out
- external/internal carotid artery
carotid arteries
external carotid artery branches
- superior thyroid artery
- lingual artery
- facial artery
- occipital artery
- posterior auricular artery
- superficial temporal artery
- maxillary artery
internal carotid artery branches
- ophthalmic artery
- anterior cerebral artery
- anterior communicating artery
- -forms part of the circle of will
- middle cerebral artery
right ; originates from brachiocephalic trunk
left; arises as third branch from aortic arch
subclavian arteries
- supply posterior brain
- join to form basilar artery
vertebral arteries
divides into two posterior cerebral arteries
- posterior communicating arteries
- connect posterior cerebral arteries to middle cerebral arteries
basilar artery
- sends two branches posteriorly over scapulae
- sends one branch anteriorly to the inferior part of the thyroid gland
thyrocervical trunk
- sends a branch superiorly to deep muscles of the neck
- sends a branch inferiorly to intercostal spaces
costocervical trunk
supply anterior thoracic walls
internal thoracic arteries
branches of internal thoracic arteries
anterior intercostal arteries
inferior nine pairs arise form thoracic aorta
posterior intercostal arteries
-enters the axilla after leaving the clavicle/scapulae region
subclavian artery
axillary artery becomes __ at the inferior border of teres major
brachial artery
brachial artery divides into 2 arteries
- radial artery
2. ulnar artery
arteries of the abdominal aorta
- inferior phrenic arteries
- celiac trunk
- superior mesenteric artery
- suprarenal arteries
- renal arteries
- gonadal arteries
- inferior mesenteric artery
- common iliac arteries
arteries of the pelvis and lower limbs
- internal iliac arteries
- external iliac artery
- femoral artery
- popliteal artery
- anterior tibial artery
- posterior tibial artery
returns blood from body regions superior to the diaphragm
superior vena cava
returns blood from body regions inferior to the diaphragm
inferior vena cava
joins the right atrium
superior and inferior vena cava
dural sinuses
- superior and inferior sagitall sinuses
- straight sinus
- transverse sinuses
- sigmoid sinus
- drains blood from brain
- superiorly it lies lateral to the internal carotid artery
- inferiorly it lies lateral to the common carotid artery
internal jugular veins
- tributaries drain scalp
- empty into subclavian vein
external jugular veins
veins of the thorax
- azygos vein
- hemiazygos vein
- accessory hemiazygos vein
- follow the paths of companion arteries
- have the same names as the companion arteries
deep veins
- visibile beneath the skin
- cephalic vein
- basilic vein
- median cubital vein
- median vein of the forearm
superficial veins
used to obtain blood or administer IV fluids
median cubital veins
veins of the abdomen
- lumbar veins
- gonadal veins
- renal veins
- suprarenal veins
- hepatic veins
- specialized part of the vascular circuit
- picks up digested nutrients
- delievers nutrients to the liver for processing
- two capillary beds
hepatic portal system
3 parts of hepatic portal veins
- superior mesenteric vein
- splenic vein
- inferior mesenteric vein
- leads to blockage of liver sinusoids
- raises blood pressure in hepatic portal system and leads to portal hypertension
- portal hypertension leads to emergency anastomoses for portal blood
portal systemic anastomoses
shares the name of the accompanying artery
deep veins
Great saphenous vein
Small saphenous vein
superficial veins
empties into the femoral vein
great saphenous vein
empties into the popliteal vein
small saphenous vein
disorders of blood vessels
- aneurysm
- deep vein thrombosis of the lower limb
- venous disease
- microangiopathy of diabetes
- arteriovenous malformation
- all major vessels in place by month 3 of development
- fetus supplies blood to the placenta
- very little blood is sent through the pulmonary circuit
fetal circulation
umbilical vessels run in the umbilical cord
paired umbilical arteries
unpaired umbilical vein
shunts away from the pulmonary circuit
- foramen ovale
- ductus arteriosus
- begins in youth
- consequences evident in middle to old age
atherosclerosis
