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Chapter 13
Lecture
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Chapter 13-Blood Vessels
Functions
1. Carry blood
2. Exchange nutrients, waste products, gases
within tissues
3. Transport substances
4. Regulate blood pressure
5. Direct blood flow to tissues
Vessel Structures
• Arterties:
- carry blood away from heart
- thick with a lot of elastic
• Veins:
- carry blood toward heart
- think with less elastic
• Capillaries:
exchange occurs between blood and tissue
fluids
Blood Flow
• Blood flows from arteries into arterioles
• Arterioles into capillaries
• Capillaries into venules
• Venules to small veins
• Veins return to heart
Blood Vessel Walls
• Tunica intima:
- innermost layer
- simple squamous
• Tunica media:
- middle layer
- smooth muscle with elastic and collagen
• Tunica adventitia:
- outermost layer
- connective tissue
Types of Arteries
• Elastic arteries:
- largest in diameter
- thickest walls
- Ex. Aorta and pulmonary trunk
• Muscular arteries:
- medium to small size
- thick in diameter
- contain smooth muscle cells
- can control blood flow to body regions
Capillaries
• Blood flows from arterioles into capillaries
• Capillaries branch to form networks
• Blood flow is regulated by smooth muscle
cells, precapillary sphincters
Types of Veins
• Blood flows from capillaries into venules
• Blood flows from venules into small veins
• All 3 tunics are present in small veins
• Medium sized veins: collect blood from
small veins and deliver to large viens
• Large veins:
contain valves
Blood Vessels of Pulmonary Circulation
• Pulmonary circulation:
blood vessels that carry blood from right
ventricle to lungs and back from left atrium of
heart
• Pulmonary trunk:
blood pump from right ventricle towards lung
• Pulmonary veins:
exit lungs and carry O2 rich blood to left
atrium
Parts of Aorta
• Ascending:
passes superiorly from left ventricle
• Aortic Arch:
3 major arteries which carry blood to head and
upper limbs
• Descending:
extends through thorax and abdomen to pelvis
• Thoracic:
part of descending aorta that extends
through thorax to diaphragm
• Abdominal:
descending aorta that extends from
diaphragm where it divides at common iliac
arteries
Arteries of Head and Neck
• Branches of aortic arch:
- brachiocephalic artery
- left common carotid artery
- left subclavian
• Brachiocephalic artery:
- first branch off aortic arch
- supplies blood to right side of head and neck
• Left common carotid artery:
- 2nd branch off aortic arch
- supplies blood to the left side of head and
neck
• Left subclavian artery:
- 3rd branch off aortic arch
- supplies blood to left upper limbs
• Right common carotid artery:
- branches off brachiocephalic artery
- supplies blood to right side of head and
neck
• Right subclavian artery:
- branches off brachiocephalic artery
- supplies blood to right upper limbs
Arteries of Upper Limbs
• Axillary arteries:
- continuation of subclavian
- supply blood deep in clavicle
• Brachial arteries:
- continuation of axillary
- where blood pressure measurements are
taken
• Ulnar arteries:
- branch of brachial artery
- near elbow
• Radial arteries:
- branch of brachial artery
- supply blood to forearm and hand
- pulse taken here
Figure 13.11
Arteries off Abdominal Aorta
• Celiac trunk arteries:
supply blood to stomach, pancreas, spleen,
liver, upper duodenum
• Superior mesenteric arteries:
supply blood to small intestines and upper
portion of colon
• Inferior mesenteric arteries:
supply blood to colon
• Renal arteries:
supply blood to kidneys
• Hepatic arteries:
supply blood to liver
• Testicular arteries:
supply blood to testes
• Ovarian arteries:
supply blood to ovaries
• Inferior phrenic arteries:
supply blood to diaphragm
• Lumbar arteries:
supply blood to lumbar vertebra and back
muscles
Figure 13.7c
Arteries of Pelvis
• Common iliac arteries:
- branches from abdominal aorta
- divides into internal iliac arteries
• External iliac arteries:
- division of common iliac artery
- supply blood to lower limbs
• Internal iliac arteries:
- division of common iliac
- supply blood to pelvic area
Arteries of Lower Limbs
• Femoral arteries:
supply to thigh
• Popliteal arteries :
supply blood to knee
• Anterior and posterior arteries:
supply blood to leg and foot
• Fibular arteries:
supply blood to lateral leg and foot
Figure 13.13
Veins
• Superior vena cava:
- returns blood from head, neck, thorax, and
right upper limbs
- empties into right atrium of heart
• Inferior vena cava:
- returns blood from abdomen, pelvis, lower
limbs
- empties into right atrium of heart
Veins of Head and Neck
• External jugular vein:
- drain blood from head and neck
- empties into subclavian veins
• Internal jugular vein:
- drain blood from brain, face, neck
- empty into subclavian veins
• Subclavian veins:
forms brachiocephalic veins
• Brachiocephalic veins:
join to form superior vena cava
Veins of Upper Limbs
• Brachial veins:
empty into axillary vein
• Cephalic veins:
empty into axillary vein and basilic vein
• Median cubital veins:
- connects to cephalic vein
- near elbow
Veins of Thorax
• Right and left brachiocephalic veins:
drain blood from thorax into superior vena
cava
• Azygos veins:
drain blood from thorax into superior vena
cava
• Internal thoracic veins:
empty into brachiocephalic veins
• Posterior intercostal veins:
- drain blood from posterior thoracic wall
- drains into azygos vein on right side
• Hemiazygos vein:
receives blood from azygos vein of left side
Veins of Abdomen and Pelvis
• Common iliac vein:
- formed from external and internal iliacs
- empty into inferior vena cava
• External iliac vein:
- drains blood from lower limbs
- empty into common iliac vein
• Internal iliac vein:
- drains blood from pelvic region
- empties into common iliac vein
• Renal vein:
drains blood from kidneys
Hepatic Portal System
• Liver is a major processing center for
substances absorbed by intestinal tract.
• Portal system:
- vascular system that begins with
capillaries in viscera and ends with
capillaries in liver
- uses splenic vein and superior
mesenteric vein
Veins of Lower Limbs
• Femoral veins:
drain blood from thigh and empty into
external iliac vein
• Great saphenous veins:
drain from foot and empty into femoral vein
• Popliteal veins:
drain blood from knee and empty into
femoral vein
Figure 13.14
Blood Pressure
• What is it?
measure of force blood exerts against blood
vessel walls
• Systolic pressure:
contraction of heart
• Diastolic pressure:
relaxation of heart
• Normal is 120/80
Pulse Pressure
• What is it?
- difference between systolic and diastolic
pressure
- Ex. 120 for systolic 80 for diastolic pulse
pressure is 40 mm Hg
- pulse pressure points can be felt near
large arteries
Capillary Exchange
• Most exchange across capillary wall’s
occurs by diffusion
• Blood pressure, capillary permeability and
osmosis affect movement of fluids across
capillary walls.
• Net movement of fluid from blood into
tissues
• Fluid gained in tissues is removed by
lymphatic system
Local Control of Blood Flow
• Local control achieved by relaxation and
contraction of precapillary sphincters
• Sphincters relax blood flow increases
• Precapillary sphincters controlled by
metabolic needs of tissues
• Concentration of nutrients also control
blood flow
• Blood flow increases when oxygen levels
decrease
Nervous and Hormonal Control of Blood Flow
• Vasomotor center:
- sympathetic division
- controls blood vessel diameter
• Vasomotor tone:
- state of partial constriction of blood
vessels
- increase causes blood vessels to constrict
and blood pressure to go up
• Epinephrine and norepinephrine (adrenal
medulla) alter blood vessel diameter
Baroreceptor Reflexes
• Baroreceptor reflexes activate responses to
blood pressure in normal range
• Baroreceptors respond to stretch in arteries
due to increased pressure
• Located in carotid sinuses and aortic arch
• Change peripheral resistance, heart rate,
stroke volume in response to blood pressure
Chemoreceptor Reflex
• Chemoreceptors are sensitive to changes in
blood oxygen, carbon dioxide, and pH
• Chemoreceptors are located in carotid
bodies and aortic bodies which lie near
carotid sinuses and aortic arch
• They send action potentials along sensory
nerve to medulla oblongata
Adrenal Medullary Mechanism
1. Stimuli increase sympathetic stimulation
to adrenal medulla
2. Adrenal medulla secretes epinephrine
and norepinephrine into blood
3. This causes increased heart rate and
stroke volume and vasoconstriction
4. Vasodilation of blood vessels in skeletal
and cardiac muscle
Renin-Angiotensin-Aldosterone
Mechanism
1. Reduce blood flow causes kidneys to
release renin
2. Renin acts on angtiotensinogen to produce
angiotensin I
3. Angiotensin-converting enzyme converts
angiotensin I to angtiotensin II
4. Angiotensin II causes vasoconstriction
5. Angiotensin II acts on adrenal cortex to
release aldosterone
6. Aldosterone acts on kidneys causes them to
conserve sodium and water
7. Result less water lost in urine and blood
pressure maintained
Antidiuretic Hormone Mechanism
1. Nerve cells in hypothalamus release
antidiuretic hormone (ADH) when
concentration of solutes in plasma
increases or blood pressure decrease
2. ADH acts of kidneys and they absorb
more water (decrease urine volume)
3. Result is maintain blood volume and
blood pressure
Other Information
• Arteriosclerosis:
makes arteries less elastic
• Atherosclerosis:
- type of arteriosclerosis
- from deposit of materials in artery walls
(plaque)
• Factors that contribute to atherosclerosis:
lack of exercise, smoking, obesity, diet high in
cholesterol and trans fats, some genetics