Blood Vessels and Circulation

1. Seeley’s
ESSENTIALS OF
Anatomy &
Physiology
Tenth Edition
Cinnamon Vanputte
Jennifer Regan
Andrew Russo
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© 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education.

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Chapter 13
Blood Vessels
and Circulation
Lecture Outline

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Blood Vessels
Blood vessels outside the heart are divided into
two classes:
1. The pulmonary vessels, which transport
blood from the right ventricle of the heart
through the lungs and back to the left atrium
2. The systemic vessels, which transport blood
from the left ventricle of the heart through all
parts of the body and back to the right atrium

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Blood Vessel 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

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Vessel Structures
Arteries:
• 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

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Blood Flow
Blood flows from arteries into arterioles
Arterioles into capillaries
Capillaries into venules
Venules to small veins
Veins return to heart

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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

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Artery and Vein
Figure 13.2
©Ed Reschke/Photolibrary/Getty Images

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Types of Arteries
Elastic arteries:
• largest in diameter
• thickest walls
• Example - aorta and pulmonary trunk
Muscular arteries:
• medium to small size
• thick in diameter
• contain smooth muscle cells
• can control blood flow to body regions

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Arteries
Figure 13.1a,b

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Capillaries
Blood flows from arterioles into capillaries
Capillaries branch to form networks
Blood flow is regulated by smooth muscle cells,
precapillary sphincters

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Capillary Network
Figure 13.3

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Capillary Structure
Figure 13.1d

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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
veins
Large veins:
• contain valves

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Blood Vessel Structure
Figure 13.1

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Valves
Figure 13.4

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Pulmonary Circulation Vessels
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

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Systemic Circulation Vessels
The systemic circulation carries blood from the
left ventricle to the tissues of the body and back
to the right atrium.
Oxygenated blood from the pulmonary veins
passes from the left atrium into the left ventricle
and from the left ventricle into the aorta.
Arteries distribute blood from the aorta to all
portions of the body

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Blood Flow through the Circulation
Figure 13.5

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Parts of the Aorta1
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

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Parts of the Aorta2
Thoracic:
• part of descending aorta that extends through
thorax to diaphragm
Abdominal:
• descending aorta that extends from diaphragm
where it divides at the common iliac arteries

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Major Arteries
Figure 13.6

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Branches of the Aorta
Figure 13.7

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Arteries of the Head and Neck1
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

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Arteries of the Head and Neck2
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

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Arteries of the Head and Neck3
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

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Arteries of the Head and Neck
Figure 13.8

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Cerebral Arterial Circle
Figure 13.10

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Major Arteries of the Head and Thorax
Figure 13.9

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Arteries of the Upper Limbs1
Axillary arteries:
• continuation of subclavian
• supply blood deep in clavicle
Brachial arteries:
• continuation of axillary
• where blood pressure measurements are taken

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Arteries of the Upper Limbs2
Ulnar arteries:
• branch of brachial artery
• near elbow
Radial arteries:
• branch of brachial artery
• supply blood to forearm and hand
• pulse taken here

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Arteries of the Upper Limbs3
Figure 13.11

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Abdominal Aorta Branches1
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

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Abdominal Aorta Branches2
Renal arteries:
• supply blood to kidneys
Hepatic arteries:
• supply blood to liver
Testicular arteries:
• supply blood to testes
Ovarian arteries:
• supply blood to ovaries

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Abdominal Aorta Branches3
Inferior phrenic arteries:
• supply blood to diaphragm
Lumbar arteries:
• supply blood to lumbar vertebra and back muscles

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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

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Major Arteries of the Abdomen and
Pelvis
Figure 13.12

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Arteries of the Lower Limbs1
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

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Arteries of the Lower Limbs2
Figure 13.13

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Veins1
Veins return blood to the heart.
In the systemic circulation, the blood returning
to the heart is deoxygenated.
In the pulmonary circulation, the blood
returning to the heart in the pulmonary veins is
oxygenated.

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Veins2
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

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Major Veins
Figure 13.14

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Veins of the Head and Neck1
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

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Veins of the Head and Neck2
Subclavian veins:
• forms brachiocephalic veins
Brachiocephalic veins:
• join to form superior vena cava

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Veins of the Head and Neck3
Figure 13.15

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Veins of the Upper Limbs1
Brachial veins:
• empty into axillary vein
Cephalic veins:
• empty into axillary vein and basilic vein
Median cubital veins:
• connects to cephalic vein
• near elbow

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Veins of the Upper Limbs2
Figure 13.16

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Veins of the Thorax1
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

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Veins of the Thorax2
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

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Veins of the Thorax3
Figure 13.17

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Veins of the Abdomen and Pelvis1
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

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Veins of the Abdomen and Pelvis2
Internal iliac vein:
• drains blood from pelvic region
• empties into common iliac vein
Renal vein:
• drains blood from kidneys

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Major Veins of the Abdomen and Pelvis
Figure 13.18

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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

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Veins of the Hepatic Portal System
Figure 13.19

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Veins of the Lower Limbs1
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

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Veins of the Lower Limbs2
Figure 13.20

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Blood Pressure
Blood pressure is the measure of force blood
exerts against blood vessel walls.
Systolic pressure: contraction of heart
Diastolic pressure: relaxation of heart
Average Blood Pressure: 120/80

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Measuring Blood Pressure
Figure 13.21

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Pulse Pressure
Pulse pressure is the difference between systolic
and diastolic blood pressures.
• Example - 120 for systolic / 80 for diastolic; pulse
pressure is 40 mm Hg
• pulse pressure points can be felt near large arteries

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Body Locations to Evaluate Pulses
Figure 13.23

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Capillary Exchange1
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

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Capillary Exchange2
Figure 13.24

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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

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Local Control of Blood Flow through
Capillary Beds
Figure 13.25

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Nervous 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

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Hormonal Control of Blood Flow
The sympathetic division also regulates
hormonal control of blood flow through the
release of epinephrine and norepinephrine from
the adrenal medulla.
In most blood vessels, these hormones cause
constriction, which reduces blood flow.
In some tissues, such as skeletal muscle and
cardiac muscle, these hormones cause the blood
vessels to dilate, increasing blood flow.

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Nervous Regulation of Blood Vessels
Figure 13.26

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Mean Arterial Pressure1
An adequate blood pressure is required to
maintain blood flow through the blood vessels of
the body.
Several regulatory mechanisms ensure that
blood pressure remains adequate for this task.
Mean arterial pressure (MAP) is a calculated
value that reflects an average arterial pressure in
various vessels of the body.

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Mean Arterial Pressure2
The body’s MAP is equal to the cardiac output
(CO) times the peripheral resistance (PR).
Cardiac output is equal to the heart rate (HR)
times the stroke volume (SV).
Peripheral resistance is the resistance to blood
flow in all the blood vessels.
MAP = CO × PR

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Mean Arterial Pressure3
The MAP changes in response to changes in HR,
SV, or PR.
The mean arterial pressure changes over our
lifetime.
MAP is about 70 mm Hg at birth.
It is maintained at about 95 mm Hg from
adolescence to middle age, and may reach 110
mm Hg in a healthy older person.

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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

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Baroreceptor Reflex Mechanisms
Figure 13.27

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Baroreceptor Effects on Blood Pressure
Figure 13.28

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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

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Chemoreceptor Reflex Mechanisms
Figure 13.29

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Adrenal Medullary Mechanism1
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

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Adrenal Medullary Mechanism2
Figure 13.30

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Renin-Angiotensin-Aldosterone
Mechanism1
1. Reduce blood flow causes kidneys to release
renin
2. Renin acts on angiotensinogen to produce
angiotensin I
3. Angiotensin-converting enzyme converts
angiotensin I to angiotensin II
4. Angiotensin II causes vasoconstriction
5. Angiotensin II acts on adrenal cortex to release
aldosterone

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Renin-Angiotensin-Aldosterone
Mechanism2
6. Aldosterone acts on kidneys causes them to
conserve sodium and water
7. Result less water lost in urine and blood
pressure maintained

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Renin-Angiotensin-Aldosterone
Mechanism3
Figure 13.31

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Antidiuretic Hormone Mechanism1
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

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Antidiuretic Hormone Mechanism2
Figure 13.32

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Long-Term Control of Blood Pressure
Figure 13.33

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Aging and Blood Vessels
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

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Atherosclerotic Plaque
Figure 13.34