Download Chapter 20 Blood Vessels

LECTURE OUTLINE CHAPTER 20 Marieb
The Cardiovascular system; Vessels and Circulation
Lecture Outline
I. Introduction - blood is carried throughout the body in a series of vessels,
alternating between being oxygenated in the lungs and sent to the rest of the
body.
II. Histology of vessels
A. Tunica interna (intima) = endothelium, lines all blood vessels, varying
amounts of elastic tissue deep to endothelium
1. arteries - most elastic tissue
2. veins - very little tissue
3. capillaries - no elastic layer
B. Tunica media - elastic fibers & smooth muscle – permits vasoconstriction,
changing blood flow and pressure
1. arteries - varies by location
2. veins - thin
3. capillaries - no media
C. Tunica externa - epithelium (adventia) -thick, collagen, anchors vessel to
surroundings
1. arteries - relatively thick
2. veins - relatively thick
3. capillaries - very delicate
III. Vessels
A. Arteries – ALWAYS carry blood away from heart
1. structure
a. tunica interna
b. tunica media
c tunica externa
2. types
a. elastic arteries - largest, conducting arteries – lead directly
from heart, subject to high pressures
b. muscular arteries - distributing arteries- lots of muscle,
medium sized
c. arterioles- small arteries -incomplete tunica media, control local
blood flow
B. Capillary
1. only endothelium
2. variably permeable –
i. continuous - simple squamous epithelium with basement
membrane, somewhat permeable
ii. fenestrated- perforations, permit exchange of larger molecules
iii. sinusoids - very thin basement membrane, similar to
fenestrated
C. Capillary beds
1. plexus / bed, group of capillaries supplying an area,
2. precapillary sphincter - closes bed temporarily to redistribute blood
flow
3. metarteriole - shunt-preferred channel through a capillary bed
4. anastomosis - interconnections , alternative routes of supply
D. Veins – ALWAYS return blood to heart, contain about 2/3 body's
blood at any given time
1. structure—similar to arteries, but minimal smooth muscle
a. tunica externa - adventia, see arteries
b. tunica media – thinner than in arteries, less elastic
c. tunica interna - intima - endothelium
d. one way valves in extremities, assist blood return by muscle
"milking"
e. lumen is larger than in corresponding arteries
f. venules – small diameter
g. sinus or sinusoid = no smooth muscle or elastic tissue in walls
h. venous reserve or reservoir - see above
IV. Circulatory System - Arterial portion
A. Pulmonary circuit
1. blood leaves right ventricle past pulmonary valve into pulmonary trunk
2. pulmonary arteries lead to lungs
3. returns by way of 4 pulmonary veins to left atrium
B. Systemic circuit - all of this arises from aorta in priority order
1. coronary circulation has been discussed ( See heart)
2. cephalic circulation - off top of aortic arch, high pressure
a. first branch off aorta is right brachiocephalic artery which gives
rise to
b. right common carotid artery and right subclavian artery
c. second branch is left common carotid artery
d. third branch is left subclavian artery
e. common carotids split into external carotid and internal carotid
arteries
f. external carotids - supply the face and scalp
g. internal carotids - enter cranium by way of carotid canal and
foramen lacerum to lie beside sphenoid bone
h. subclavian artery. give rise to vertebral arteries which ascend
through the transverse foramina of cervical vertebrae and enter the
cranium by the foramen magnum where they anastomose to form the
i. basilar artery which then joins the two internal carotids to form
the
j. cerebral arterial circle (of Willis) supplying the cerebrum and
cerebellum
3. arm circulation a. subclavian artery give off
b. thyrocervical trunk -supplies neck, shoulder, etc.
c. axillary artery - supplies chest and shoulder, becomes
d. brachial artery supplies upper arm, becomes
e. radial and ulnar arteries - supply lower arm and anastomose to
form
f. palmar arches which supply digital arteries
4. descending aorta - thoracic area
a. bronchial arteries - supply bronchi and lungs
b. pericardial arteries - supply pericardium
c. mediastinal arteries - supply mediatinal structures
d. esophageal arteries - supply esophagus
e. paired intercostal arteries- thoracic wall
f. superior phrenic arteries - supply diaphragm
(abdominal region - in order from aorta)
g. inferior phrenic arteries - supply diaphragm
h. celiac artery - 3 branches i. splenic -pancreatic and left gastroepiploic
ii. gastric - stomach and esophagus
iii. hepatic - hepatic proper, right gastric, cystic,
gastroduodenal, duodenal, right gastroepiploic, and superior
pancreaticoduodenal branches
i. superior mesenteric artery - pancreas and duodenum, small
intestine and colon
j. paired suprarenal - supply adrenal glands
k. paired renal arteries - supply kidneys
l. paired gonadal arteries - supply testes or ovaries
m. inferior mesenteric - supplies terminal colon and rectum
n. paired lumbar arteries - supply body wall
5. legs and pelvis
a. aorta splits into common iliac arteries which split to become
b. internal iliac - supply pelvic area
c. external iliac artery - crosses hip joint to become
d. femoral - supplying anterior thigh and gives off
e. deep femoral - supplies hamstring muscles
f. popliteal - behind knee, splits to become
g. anterior tibial - supplies front of leg and
h. posterior tibial - supplies back of leg. Gives rise to
i. peroneal artery - supplies lateral part of leg
j. dorsal pedis artery from anterior tibial and
k. plantar arches from posterior tibial , both of which give rise to
l. digital arteries - supply toes
V. Venous return
A. Cephalic 1. superior sagittal sinus - drains into transverse sinus
2. internal cerebral veins and cavernous sinus - drain into straight sinus
which meets
3. transverse sinuses - drain to become sigmoid sinuses which empty
from the cranium by way of
4. internal jugular vein
5. external jugular vein drains face and scalp - both drain into
6. vertebral veins drain into subclavian veins
7. subclavian veins which meet and become
8. superior vena cava
B. Arm
1. superficial palmar arch drains into
2. antebrachial , basilic (ulnar side) (hidden) and cephalic veins (radial
side) which interconnect by way of
3. median cubital vein
4. deep palmar arches drain into
5. radial and ulnar veins which become the brachial which becomes
6. axillary into which the basilic and cephalic drain
7. subclavian as it passes under the clavicle, meets the internal and
external jugulars and becomes the
8. brachiocephalic veins which join to become the
9. superior vena cava
10. azygous and hemiazygous veins drain from the lumbar region to enter
the superior vena cava
C. Inferior vena cava - collects blood from
1. intercostal veins
2. esophageal veins
3. paired renal veins - from kidneys
4. paired gonadal veins - from ovaries or testes
5. paired lumbar veins - from body wall
6. hepatic veins - from liver
7. suprarenal veins - from adrenal glands
8. phrenic veins - from diaphragm
D. From pelvis and lower limbs
1. digital veins - drain toes into
2. plantar veins which drain into
3. anterior tibial vein
4. posterior tibial vein and
5. peroneal vein which merge to become
6. popliteal vein which becomes
7. femoral vein and collects blood from
8. deep femoral before they become
9. external iliac veins
10. dorsal venous arch drains into
11. great saphenous ( medial side) and lesser saphenous vein ( lateral
side) - superficial veins . lesser saphenous drains into
12. popliteal vein - then as above
13. great saphenous joins the femoral just before becoming external iliac
vein
14. internal iliac veins join externals to become
15. common iliac veins which then join to form the
16. inferior vena cava
VI. Hepatic Portal System
A. Drains digestive viscera into liver where blood is detoxified and
nutrient balance adjusted
B. Vessels involved
1. left colic vein & superior rectal veins join to form
2. inferior mesenteric vein - drains colon and meets the
3. splenic vein -draining spleen, stomach, and pancreas
4. right gastroepiploic v. , intestinal v, pancreaticoduodenal v,, and
ileocolic veins merge to form the
5. superior mesenteric vein which joins with the splenic v to from the
6. hepatic portal vein leading into the liver which in turn is drained by the
7. hepatic veins into the inferior vena cava
VII Fetal circulation
A. Reasons for differences
1. lungs not functioning
2. maternal regulation of blood content of wastes & nutrients
B. Fetal blood flow patterns
1. blood enters umbilical vein from placenta
2. blood bypasses liver by ductus venosus
3. blood passes from right atrium directly into left atrium by foramen ovale ,
opening in interatrial septum
4. blood leaving right ventricle passes from pulmonary trunk into aorta bypassing
the lungs by way of ductus arteriosus
5. blood returns from fetus to placenta by 2 umbilical arteries
C. Changes at birth
1. no blood coming from placenta
2. ductus venosus becomes ligamentum venosus (ligamentum teres)
3. foramen ovale closes & becomes the fossa ovale
4. ductus arteriosus closes and becomes the ligamentum arteriosum
5. umbilical arteries degenerate