The Cardiovascular System: Vessels and Circulationcherylchowbiology.weebly.com/uploads/1/7/1/7/17179396/15._blood... · © 2012 Pearson Education, Inc. 22 The Cardiovascular System:

© 2012 Pearson Education, Inc.

22 The Cardiovascular

System: Vessels and

Circulation


Introduction

• There are two groups of blood vessels

• Pulmonary circuit

• Blood goes to and from the lungs

• Systemic circuit

• Blood goes to the rest of the body and back to the

heart

• Blood goes to both circuits at the same time

with each heartbeat


Histological Organization of Blood Vessels

• The walls of the vessels consist of three

layers

• Intima (innermost layer)

• Media (middle layer)

• Adventitia (outermost layer)

• The layered walls give the vessels tremendous

strength


Figure 22.1 Histological Comparison of Typical Arteries and Veins

ARTERY VEIN

Adventitia

Media

Intima

Smooth

muscle Internal elastic

membrane

External

elastic

membrane

Endothelium

Elastic

fiber

Lumen

of

artery

Lumen

of vein

Artery and vein LM 60

Adventitia

Media

Intima

Smooth

muscle

Endothelium



• Intima (innermost layer)

• Consists of two sublayers

• Endothelial lining

• Underlying layer of connective tissue

• Arteries consists of a thick layer of elastic

fibers giving the lining a “wavy” appearance



• Media (middle layer)

• Consists of smooth muscle

• When stimulated by sympathetic nerves, the

muscles contract resulting in vasoconstriction

• Relaxation of the smooth muscle results in

vasodilation



• Adventitia (outermost layer)

• Forms a connective sheath around the vessel

• Composed of collagen fibers

• Anchors the blood vessels in position


Figure 22.1 Histological Comparison of Typical Arteries and Veins

ARTERY VEIN

Adventitia

Media

Intima

Smooth

muscle Internal elastic

membrane

External

elastic

membrane

Endothelium

Elastic

fiber

Lumen

of

artery

Lumen

of vein

Artery and vein LM 60

Adventitia

Media

Intima

Smooth

muscle

Endothelium



• Distinguishing Arteries from Veins

• Most arteries and veins run parallel to each

other

• Arteries carry blood away from the heart and veins

carry blood toward the heart

• Walls of arteries are thicker than veins

• Arteries maintain their circular shape and veins

typically collapse when cut

• Endothelial lining of an artery has pleated folds


Figure 22.2 Histological Structure of Blood Vessels

Large Vein

Medium-Sized Vein

Venule

Capillaries

Arteriole

Muscular Artery

Elastic Artery

Adventitia

Media

Endothelium

Intima

Adventitia

Media

Endothelium

Intima

Adventitia

Endothelium

Pores

Endothelial cells

Basal lamina

Endothelial

cells

Basal lamina

Endothelium

Basal lamina

Smooth muscle cells

(Media)

Endothelium

Intima

Media

Adventitia

Adventitia

Media

Endothelium

Intima

Internal

elastic layer

Fenestrated Capillary Continuous Capillary



• Arteries

• As blood leaves the heart, it travels through:

• Elastic arteries

• Muscular arteries

• Arterioles

• Capillaries

• Capillary beds



• Capillaries

• Walls are thin enough to permit exchange of

gases between the blood and the interstitial

fluid

• The diameter is about 8 microns

• A red blood cell diameter is also about 8

microns

• Fenestrated capillaries contain pores


Figure 22.3b Structure of Capillaries

This diagrammatic

view of a fenestrated

capillary details the

structure of the wall.

Basal lamina

Endothelial cell

Nucleus

Endosomes

Boundary between

endothelial cells

Basal

lamina

Fenestrations,

or pores



• Capillaries (continued)

• There are four mechanisms regarding the

passage of material across the walls of

capillaries

• Material can diffuse across the endothelial lining

• Material can diffuse through gaps between

adjacent cells of the lining

• Material can diffuse through pores

• Material can move via endocytosis



• Capillary Beds

• This is an interconnected network of

capillaries

• The capillary bed consists of vessels

connecting arterioles with venules

• There are precapillary sphincters involved in

regulating blood flow through the capillaries


Figure 22.4a Organization of a Capillary Bed

Basic organization of a typical capillary bed.

The pattern of blood flow changes continually

in response to regional alterations in tissue

oxygen demand.

KEY

Variable

blood flow

Consistent

blood flow

Small

venule

Arteriovenous

anastomosis

Precapillary

sphincters

Section of

precapillary

sphincter

Smooth

muscle cells

Thoroughfare

channel

Collateral

arteries

Arteriole

Metarterioles

Vein

Venule

Capillaries



• Capillary Beds (continued)

• In areas such as the brain, heart, and

stomach, a continuous, rich flow of blood is

required

• In these areas, more than one artery supplies a

specific area

• These arteries (collateral arteries) typically fuse

forming an arterial anastomosis

• If one arteriole is blocked, the other one will supply

blood to the capillary bed



• Capillary Beds (continued)

• In areas such as the joints or visceral organs,

blood flow through some vessels may be

hindered due to body movement

• In order to accommodate this, there must be a

direct connection between arterioles and venules

• This direct connection is called an arteriovenous

anastomosis


Figure 22.4a Organization of a Capillary Bed

Basic organization of a typical capillary bed.

The pattern of blood flow changes continually

in response to regional alterations in tissue

oxygen demand.

KEY

Variable

blood flow

Consistent

blood flow

Small

venule

Arteriovenous

anastomosis

Precapillary

sphincters

Section of

precapillary

sphincter

Smooth

muscle cells

Thoroughfare

channel

Collateral

arteries

Arteriole

Metarterioles

Vein

Venule

Capillaries



• Veins

• Veins collect blood from tissues and return the

blood to the heart

• As blood leaves the tissue and travels to the

heart, it travels through the following vessels:

• Capillary beds

• Capillaries

• Venules

• Medium-sized veins

• Large veins



• Blood in the veins returning to the heart

from the lower extremities has to go against

gravity

• To assist in this process, many veins have

valves (venous valves)

• These valves compartmentalize the blood in

the veins thus acting as one-way valves

• If the venous valves do not close properly,

varicose veins may occur


Figure 22.5 Function of Valves in the Venous System Valves

Valve

closed

Valve

closed

Valve opens above

contracting muscle

Valve closes below

contracting muscle


Blood Vessel Distribution

• Blood vessels can be divided into two

circuits

• Pulmonary circuit

• Composed of arteries and veins that transport blood

between the heart and the lungs

• Arteries and veins travel relatively short distances

• Systemic circuit

• Composed of arteries and veins that transport

oxygenated blood between the heart and all other

tissues

• Arteries and veins travel longer distances


Figure 22.7 An Overview of the General Pattern of Circulation

Brain

Upper limbs

Lungs

Pulmonary

circuit

(arteries)

Pulmonary

circuit

(veins)

RA

LA

Right

ventricle

Left

ventricle

Systemic

circuit

(veins)

Systemic

circuit

(arteries)

Kidneys

Liver

Spleen

Gonads

Lower limbs

Digestive

organs



• There are functional and structural

differences between the vessels in the two

circuits

• Blood pressure in the pulmonary circuit is lower

than in the systemic circuit

• Walls of the pulmonary arteries are thinner than

the walls of systemic arteries


Blood Vessel Distribution Vessel Distribution

• Functional patterns of the pulmonary and

systemic circuits

• The distribution of arteries and veins is the

same on the left side of the body as it is on the

right side of the body except for the venae

cavae and the aorta

• A single vessel will have different names

according to specific anatomical boundaries



• The Pulmonary Circuit

• Blood leaves the heart by passing through the pulmonary valve

• Blood enters the pulmonary trunk

• Blood enters the left and right pulmonary arteries

• Blood arrives at the lungs to drop off carbon dioxide and pick up oxygen

• Blood returns to the heart via the pulmonary veins

• Blood enters the left atrium of the heart


Figure 22.8a The Pulmonary Circuit

Anatomy of the pulmonary circuit. Blue arrows

indicate the flow of deoxygenated blood; red arrows

indicate the flow of oxygenated blood. The breakout shows the

alveoli of the lung and the routes of gas diffusion into and out of

the bloodstream across the walls of the alveolar capillaries.

Descending aorta

CO2

O2 Inferior vena cava

Right pulmonary

veins

Right pulmonary

arteries

Right lung

Trachea

Superior vena cava

Ascending aorta

Aortic arch

Pulmonary trunk

Left lung

Left pulmonary arteries

Left pulmonary veins

Alveolus

Capillary



• The Systemic Circuit

• Blood leaves the heart by passing through the

aortic valve

• Blood enters the ascending aorta and then the

aortic arch and then it branches into:

• Brachiocephalic trunk (then the right common

carotid and right subclavian arteries)

• Left common carotid artery

• Left subclavian artery

• Descending aorta


Figure 22.9 An Overview of the Systemic Arterial System (Part 1 of 2)

Right subclavian

Brachiocephalic trunk

Aortic arch

Ascending aorta

Celiac trunk

Brachial Renal

Superior mesenteric

Gonadal

Inferior mesenteric

Diaphragm

Pulmonary trunk

Descending aorta

Axillary

Left subclavian

Left common carotid

Right common carotid Vertebral


Figure 22.9 An Overview of the Systemic Arterial System

Vertebral

Right subclavian

Brachiocephalic

trunk

Aortic arch

Ascending

aorta

Celiac trunk

Brachial

Radial

Ulnar External

iliac

Palmar

arches

Popliteal

Posterior tibial

Anterior tibial

Fibular

Plantar arch

Dorsalis pedis

Descending

genicular

Femoral

Deep

femoral

Renal

Superior mesenteric

Gonadal

Inferior mesenteric

Common iliac

Internal iliac

Diaphragm

Pulmonary trunk

Descending aorta

Axillary

Left subclavian

Left common carotid

Right common carotid



• The Systemic Circuit (continued)

• Ascending aorta • Begins at the aortic valve

• Aortic arch

• Brachiocephalic trunk gives rise to the right

common carotid artery (supplies blood to the right

side of the head and brain) and to the right

subclavian artery (supplies blood to the right arm)

• Left common carotid artery (supplies blood to the

left side of the head and brain)

• Left subclavian artery (supplies blood to the left

arm)


Figure 22.10 Aortic Angiogram

Thyrocervical trunk

Right common carotid artery

Right subclavian artery

Internal thoracic artery

Ascending aorta


Left common carotid artery

Left subclavian artery

Aortic arch

Descending aorta



• The Systemic Circuit (continued)

• The subclavian arteries

• Give rise to the 3 branches vertebral arteries

• Thyrocervical trunk (supplies muscles of the neck, head,

and upper back)

• Internal thoracic artery (supplies the pericardium and

anterior wall of the chest)

• Vertebral artery (supplies the brain and spinal cord)

• Give rise to the axillary arteries

• Brachial artery divides to form the radial and ulnar

arteries

• at the wrist, forming the superficial palmar arch and deep

palmar arch


Figure 22.11a Arteries of the Chest and Upper Limb

Arteries originating along the aortic

arch shown branching into the chest

and right upper limb

Thyrocervical trunk

Right common carotid

Left common carotid

Vertebral


Left subclavian

Aortic arch

Ascending aorta

Thoracic aorta

Heart

Internal thoracic

Abdominal aorta

Suprascapular

Right subclavian

Thoracoacromial

Axillary

Lateral thoracic

Anterior humeral circumflex

Posterior humeral circumflex

Subscapular

Deep brachial

Intercostal

Brachial

Superior ulnar

collateral

Inferior ulnar

collateral

Anterior ulnar

recurrent

Posterior ulnar

recurrent

Radial

Anterior

interosseous

Ulnar

Deep palmar

arch

Superficial

palmar arch

Digital arteries


Figure 22.11b Arteries of the Chest and Upper Limb

A flowchart showing

the arterial distribution

from the aortic arch.

Thick arrows show

major pathways of

blood flow; thin arrows

show distribution to

secondary or terminal

pathways.

Right thyrocervical

trunk

Right vertebral Right

common

carotid

Left

common

carotid

Left

vertebral

Left

thyrocervical

trunk Left

subclavian

Brachiocephalic

trunk Right

subclavian

Right internal

thoracic Right axillary

Right brachial

Right radial Right ulnar Left

ulnar

Left

radial

Left

brachial

Left

axillary

Left

internal

thoracic

LEFT

VENTRICLE Connected by anastomoses

of palmar arches that supply

digital arteries

Forearm,

radial side

Forearm,

ulnar side

To structures

of the arm

Muscles of the

right pectoral

region and axilla

Skin and muscles of

chest and abdomen,

mammary gland (right

side), pericardium

Muscles, skin,

tissues of neck, thyroid

gland, shoulders, and

upper back (right side)

Spinal cord, cervical vertebrae

(right side); fuses with left vertebral,

forming basilar artery after entering

cranium via foramen magnum

AORTIC

ARCH

ASCENDING

AORTA

THORACIC AORTA

(see Fig. 22.19)

ABDOMINAL AORTA

(see Fig. 22.19)



• The Carotid Arteries

• The common carotids ascend the neck

• Divide to form the internal carotids and

external carotids


Figure 22.13a Arteries of the Neck and Head

General circulation pattern of arteries supplying the

neck and superficial structures of the head; this is

an oblique lateral view from the right side.

Brachiocephalic

trunk

Common carotid

Carotid sinus

External carotid

Lingual

Facial

Maxillary

Ophthalmic

Middle cerebral

Anterior cerebral

Internal carotid

Vertebral

Inferior thyroid

Thyrocervical

trunk

Transverse cervical

Suprascapular

Subclavian

Axillary

Internal thoracic

Second rib

Occipital

Basilar

Posterior cerebral

Carotid canal

Cerebral arterial circle

Superficial temporal



• The internal and external carotid arteries

• External carotids supply the neck and outside

of the skull

• Internal carotids enter the skull to deliver blood

to the brain

• Internal carotid branches to form:

• Ophthalmic artery (supplies the eyes)

• Anterior cerebral artery (supplies frontal and

parietal lobes of the brain)

• Middle cerebral artery (supplies the midbrain and

lateral surfaces of the brain)


Figure 22.13b Arteries of the Neck and Head

Spiral 3-D volume rendered scan of the arteries supplying

the neck and head. [Courtesy of TeraRecon, Inc.]

Anterior cerebral

External carotid

Facial

Common carotid Vertebral

Carotid sinus

Internal carotid artery

Vertebral artery

after entering skull

Basilar

Posterior cerebral

Middle cerebral

Internal carotid artery

where it enters the skull



• The Descending Aorta

• A continuation of the aortic arch

• Divided into thoracic aorta and abdominal aorta


Figure 22.15 Major Arteries of the Trunk Vertebral

Thyrocervical trunk


Aortic arch

Internal thoracic

Esophageal

Pericardial

THORACIC AORTA

Superior phrenic

Inferior phrenic

Diaphragm

Common hepatic

Suprarenal

Renal

Lumbar

Right common iliac

External iliac

Internal iliac Median sacral

Terminal segment

of the aorta

Inferior mesenteric

Gonadal

ABDOMINAL

AORTA

Superior

mesenteric

Splenic

Left gastric

Celiac trunk

Intercostal

Mediastinal

Bronchial

Axillary

Left subclavian

Common carotid



• The Abdominal Aorta

• Branches to form the following vessels:

• Celiac trunk

• Superior mesenteric artery

• Inferior mesenteric artery

• Suprarenal arteries

• Renal arteries

• Gonadal arteries

• Lumbar arteries

• Right and left common iliac arteries


Figure 22.15 Major Arteries of the Trunk Vertebral

Thyrocervical trunk


Aortic arch

Internal thoracic

Esophageal

Pericardial

THORACIC AORTA

Superior phrenic

Inferior phrenic

Diaphragm

Common hepatic

Suprarenal

Renal

Lumbar

Right common iliac

External iliac

Internal iliac Median sacral

Terminal segment

of the aorta

Inferior mesenteric

Gonadal

ABDOMINAL

AORTA

Superior

mesenteric

Splenic

Left gastric

Celiac trunk

Intercostal

Mediastinal

Bronchial

Axillary

Left subclavian

Common carotid



• The Celiac Trunk

• Branches to form the left gastric artery

• Supplies the stomach

• Branches to form the splenic artery

• Supplies the spleen

• Branches to form the common hepatic artery

• Supplies the liver



• Arteries of the Pelvis

• The common iliac arteries

• Branch to form the internal iliac artery

• Supplies the urinary bladder, walls of the pelvis,

external genitalia, and the medial side of the thigh

• Branches to form the external iliac artery

• Supplies blood to the legs


Figure 22.9 An Overview of the Systemic Arterial System (Part 2 of 2)

Radial

External

iliac

Palmar arches

Popliteal

Posterior tibial

Anterior tibial

Fibular

Plantar arch

Dorsalis pedis

Descending

genicular

Femoral

Deep femoral

Common iliac

Internal iliac Ulnar



• Arteries of the Leg

• External iliac arteries form the: • Femoral artery

• The femoral artery continues to form the

popliteal artery, and then splits to form the

anterior tibial artery and posterior tibial artery

• Deep femoral artery


Figure 22.17a Major Arteries of the Lower Limb, Part I

Anterior view of the arteries supplying the right

lower limb

Plantar arch

Medial plantar

Dorsal arch

Lateral plantar

Dorsalis pedis

Fibular

Anterior tibial

Posterior tibial

Descending

genicular

Popliteal

Femoral

Lateral femoral

circumflex

Deep femoral Medial femoral

circumflex

Obturator Internal pudendal

Lateral sacral

External iliac

Internal iliac

Common iliac

Superior

gluteal

Inguinal

ligament

Iliolumbar



• Arteries of the Foot

• The anterior tibial artery forms the dorsalis

pedis artery

• The posterior tibial artery forms the medial and

lateral plantar arteries



• Systemic Veins

• Veins collect blood from the body tissues and

return it to the heart

• Blood returns to the heart from the lower

extremities via the inferior vena cava to the

right atrium

• Blood returns to the heart from the upper

extremities via the superior vena cava to the

right atrium

• Blood returns to the heart from the lungs via the

pulmonary veins to the left atrium



• Venous Return from the Cranium

• All of the cerebral veins drain into the internal

jugular vein

• The internal jugular vein & vertebral vein drain

into the brachiocephalic veins


Figure 22.21a Major Veins of the Head and Neck

An oblique lateral view of the head and neck

showing the major superficial and deep veins

Axillary

Right

subclavian

Clavicle

External

jugular

Vertebral

Occipital

Sigmoid

sinus

Occipital sinus

Petrosal sinuses

Straight sinus

Great cerebral

Right transverse sinus

Inferior sagittal sinus

Superior

sagittal sinus

Superficial

cerebral veins Temporal

Deep cerebral

Cavernous sinus

Maxillary

Facial

Internal jugular

Right brachiocephalic

Left brachiocephalic

Superior vena cava

Internal thoracic



• Venous Return from the Head • Veins from the head converge to form the:

• Temporal vein

• Facial vein

• Maxillary veins

• The temporal and maxillary veins drain into the

external jugular vein

• The facial vein drains into the internal jugular

vein



• Venous Return from the Neck

• Vessels in the neck drain into the external

jugular vein

• The external jugular vein drains into the

subclavian vein


Figure 22.21a Major Veins of the Head and Neck

An oblique lateral view of the head and neck

showing the major superficial and deep veins

Axillary

Right

subclavian

Clavicle

External

jugular

Vertebral

Occipital

Sigmoid

sinus

Occipital sinus

Petrosal sinuses

Straight sinus

Great cerebral

Right transverse sinus

Inferior sagittal sinus

Superior

sagittal sinus

Superficial

cerebral veins Temporal

Deep cerebral

Cavernous sinus

Maxillary

Facial

Internal jugular

Right brachiocephalic

Left brachiocephalic

Superior vena cava

Internal thoracic



• Venous Return from the Upper Limb

• Blood return to the heart from the hands in the

following sequence:

• The superficial palmar veins drain into the

cephalic vein

• Median cubital vein

• Basilic vein

• Axillary vein

• Subclavian vein

• Brachiocephalic vein

• Superior vena cava

• Right atrium



• Venous Return from the Upper Limb

• Blood can also return to the heart from the

hands in the following sequence:

• The deep palmar veins drain into the radial and

ulnar vein

• Those veins will unite to form the brachial vein

• Axillary vein

• Subclavian vein

• Brachiocephalic vein

• Superior vena cava

• Right atrium


Figure 22.22 The Venous Drainage of the Trunk and Upper Limb

KEY

Deep veins

Superficial veins

Digital

Palmar venous arches

Ulnar

Basilic

Medial sacral

Median antebrachial

Radial

Anterior interosseous

Cephalic

Median cubital

Suprarenal

Phrenic

Basilic

INFERIOR VENA CAVA

Intercostal

Brachial Hemiazygos

Accessory hemiazygos

Cephalic

Axillary

Brachiocephalic

Highest intercostal Subclavian

Internal jugular Vertebral

Mediastinal

SUPERIOR VENA CAVA

Internal thoracic

Esophageal

Azygos

Hepatic

Renal

Gonadal

Lumbar

Common iliac

Internal iliac

External iliac

External jugular


Figure 22.22 The Venous Drainage of the Trunk and Upper Limb (Part 1 of 2)

KEY

Deep veins

Superficial veins

Mediastinal

SUPERIOR VENA CAVA

Internal thoracic

Esophageal

Azygos

INFERIOR VENA CAVA

Intercostal

Brachial

Hemiazygos

Accessory hemiazygos

Cephalic

Axillary

Brachiocephalic

Highest intercostal

Subclavian

Internal jugular

Vertebral

External jugular



• Venous Return from the Abdominal Area • The following veins drain into the inferior vena

cava or the superior vena cava, which drains

into the right atrium

• Lumbar veins go superior and drain into the

superior vena cava

• Gonadal veins: the right gonadal vein drains into

the inferior vena cava, the left gonadal vein drains

into the left renal vein and then into the inferior vena

cava

• Hepatic veins drain into the inferior vena cava


Figure 22.22 The Venous Drainage of the Trunk and Upper Limb (Part 2 of 2)

KEY

Deep veins

Superficial veins

Hepatic

Renal

Gonadal

Lumbar

Common iliac

Internal iliac

External iliac

Digital

Palmar venous arches

Ulnar

Basilic

Medial sacral

Median antebrachial

Radial

Anterior interosseous

Cephalic

Median cubital

Suprarenal

Phrenic

Basilic



• Venous Return from the Lower Limb

• Blood leaves the foot and returns to the heart

via the following veins

• Plantar veins

• Drain into the anterior tibial, posterior tibial, and

fibular veins

• Popliteal vein

• Femoral vein

• Common iliac vein

• Inferior vena cava

• Right atrium



• Venous Return from the Lower Limb

• Blood also leaves the foot and returns to the

heart via the following veins

• Dorsal venous arch

• Great saphenous vein

• Femoral vein

• External iliac vein

• Common iliac vein


• Right atrium


Figure 22.24b The Venous Drainage of the Lower Limb

Anterior view showing the veins of the

right lower limb

Superficial veins

Deep veins

KEY

Digital

Plantar venous arch

Dorsal venous arch

Small saphenous

Fibular Posterior tibial

Anterior tibial

Popliteal

Great saphenous

Femoral

Obturator

Lateral sacral

Internal pudendal

Inferior gluteal

Internal iliac

Right common

iliac

Superior gluteal

External iliac

Femoral circumflex

Deep femoral


Figure 22.24c The Venous Drainage of the Lower Limb

Superficial veins

Deep veins

KEY

Posterior view showing the veins of the

right lower limb

Posterior tibial

Anterior tibial

Fibular

Small

saphenous

Popliteal

Great saphenous

Deep femoral

Femoral

Inferior gluteal

Superior gluteal

Right external

iliac

Internal pudendal

Obturator Femoral

Femoral

circumflex



• Venous Return from the Hepatic Portal

System

• Blood in the inferior mesenteric, splenic, and

superior mesenteric veins drains into the

hepatic portal system

• Liver sinusoids

• Hepatic veins


• Right atrium


Figure 22.26 The Hepatic Portal System

Inferior vena cava

Liver Stomach

Pancreas

Hepatic

Cystic

Hepatic portal

Pancreaticoduodenal

Middle colic

(from transverse colon)

Superior mesenteric

Right colic

Ascending colon

Ileocolic

Intestinal

Superior rectal

Sigmoid

Small intestine

Descending colon

Spleen

Inferior mesenteric

Left colic

Pancreatic

Splenic

Right gastroepiploic

Left gastroepiploic

Right gastric

Left gastric

Aorta

Esophagus


Cardiovascular Changes at Birth

• The fetal cardiovascular system differs from

the adult cardiovascular system

• The fetal lungs are nonfunctional

• The fetal digestive system is nonfunctional



• All fetal nutritional and respiratory needs are

provided by diffusion across the placenta

• Blood in the right atrium can pass through the

heart via the following methods:

• Through the tricuspid valve to the right ventricle

• Through the foramen ovale to the left atrium

• From the pulmonary trunk through the ductus

arteriosus to the aortic arch


Figure 22.27a Changes in Fetal Circulation at Birth

Circulation pathways in a

full-term fetus. Red indicates

oxygenated blood, blue indicates

deoxygenated blood, and violet

indicates a mixture of oxygenated

and deoxygenated blood.

Liver

Aorta

Ductus

arteriosus

(open)

Pulmonary

trunk

Inferior vena cava

Ductus venosus

Umbilical

arteries

Umbilical

cord

Umbilical vein

Foramen ovale (open)

Placenta


Figure 22.27b Changes in Fetal Circulation at Birth

Blood flows

through the heart

of the newborn.

Right ventricle

Left

ventricle

Left

atrium

Inferior

vena cava

Right

atrium

Foramen ovale

(closed)

Pulmonary

trunk

Ductus arteriosus

(closed)



• Upon birth:

• Smooth muscles of the ductus arteriosus

contract forming the ligamentum arteriosum

found in the adult heart

• Pressure in the left atrium increases, thus

closing the valvular flap of the foramen ovale,

forming the fossa ovalis found in the adult

heart


Aging and the Cardiovascular System

• Age-related changes in the cardiovascular system

• Blood changes

• Decreased hematocrit

• Pooling of blood in veins of the leg

• Heart changes

• Reduced efficiency and elasticity

• Atherosclerosis of coronary vessels

• Scar tissue forms

• Blood vessel changes

• Loss of elasticity

• Calcium deposits damage vessel walls

Documents

The Cardiovascular System: Vessels and Circulationcherylchowbiology.weebly.com/uploads/1/7/1/7/17179396/15._blood... · © 2012 Pearson Education, Inc. 22 The Cardiovascular System: