Cardiovascular System Blood Vessels - Anatomy 10Amtsacanatomy10abrenda.weebly.com/uploads/7/7/9/4/...Cardiac cycle Atrial systole begins: Atrialcontraction forces a small amount of

Cardiovascular System

Blood VesselsBlood Vessels

Chapter 22

Cardiac Contractions

Cardiac cycle consists of alternate periods of

contraction and relaxation

• Contraction is the systolic pressure

– Blood is ejected into the ventricles– Blood is ejected into the ventricles

– Blood is ejected into the pulmonary trunk and the

ascending aorta

• Relaxation is the diastolic pressure

– Chambers are filling with blood

Cardiac contractions

Contractions are coordinated by conducting

cells:

• Sinoatrial node (SA node)

– Also called cardiac pacemaker – Also called cardiac pacemaker

– Located in the posterior wall of the right atrium

– Generates 80-100 action potentials per minute

• Atrioventricular node (AV node)

– Located within the floor of the right atrium

Summary of Cardiac Events

1. Impulse travels from SA node to AV node

– Atrial contration occurs

2. Impulse travels from AV node to AV bundle

3. The AV bundle travels along the 3. The AV bundle travels along the interventricular septum and then divides to form the right and left bundle branches

4. The bundle branches send impulses to the purkinje fibers

– Ventricle contraction occurs

Figure 21.11 The Conducting System and the Cardiac Cycle (3 of 8)

Components of the Conducting System

Sinoatrial

(SA) nodecontains pacemaker cells that initiate the electricalimpulse that results in a heartbeat

Internodal

pathwaysare conducting fibers in the atrial wall that conductthe impulse to the AV node while simultaneouslystimulating cardiac muscle cells of both atria

Atrioventricular

(AV) nodeslows the electrical impulse when it arrives from

the internodal pathways

© 2015 Pearson Education, Inc.

(AV) node the internodal pathways

AV bundle conducts the impulse from the AV node to thebundle branches

Left bundle

branchextends toward the apex of the heart and then radiatesacross the inner surface of the left ventricle

Right bundle

branchextends toward the apex of the heart and thenradiates across the inner surface of the right ventricle

Moderator

bandrelays the stimulus through the ventricle to thepapillary muscles, which tense the chordae tendineaebefore the ventricles contract

Purkinje

fibersconvey the impulses very rapidly to the contractilecells of the ventricular myocardium

Figure 21.11 The Conducting System and the

Cardiac Cycle (4 of 8)

Movement of Electrical Impulses through the Conducting System

Time = 0 Elapsed time = 50 msec Elapsed time = 150 msec Elapsed time = 175 msec Elapsed time = 225 msec

1 2 3 4 5


SA node AV node

AV bundle

Bundlebranches

Moderatorband

Purkinjefibers

The SA node depolar-izes and atrial activa-tion begins.

Depolarization spreadsacross the atrial surfacesand reaches the AV node.

Atrial contraction begins. The AV node delays thespread of electricalactivity to the AV bundleby 100 msecs.

Impulses travel along theAV bundle within the interven-tricular septum to the apex ofthe heart. Impulses alsospread to the papillarymuscles of the right ventricleby the moderator band.

The impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed and ventricular contraction begins.

Cardiac

cycle

Atrial systole begins: Atrial

contraction forces a small amount of

blood into the relaxed ventricles.

Atrial systole ends;

atrial diastole begins:

Atrial diastole continues

until the start of thenext cardiac cycle.

Ventricular systole—

first phase: Ventricular

contraction pushes the

Start

800

msec

0

msec

100

msec

cycle


contraction pushes theAV valves closed butdoes not create enoughpressure to open thesemilunar valves.

Ventricular systole—

second phase: As ventricular

pressure rises and exceedsthe pressure in the arteries,the semilunar valves openand blood is ejected.Ventricular diastole—early: As the

ventricles relax, the ventricular blood pressure

drops until reverse blood flow pushes the

cusps of the semilunar valves together. Blood

now flows into the relaxed atria.

Ventricular diastole—late:

All chambers are relaxed.The AV valves open and theventricles fill passively.

370

msec

Internal Anatomy and Organization of

the Heart

• Valve Function during the Cardiac Cycle

– Papillary muscles relax

– Due to the pressure in the atria, the AV valves

openopen

– When the ventricles contract, pressure causes the

semilunar valves to open

– Also upon contraction, the blood forces the AV

valves closed, thus resulting in blood going

through the semilunar valves

Histology of Blood Vessels

• Characteristics of the Three Layers

– Intima (innermost layer)

• Also called tunica intima

• Makes up the endothelium of the vessel

– Media (middle layer)– Media (middle layer)

• Also called tunica media

• Consists of smooth muscle

• Involved in vasoconstriction and vasodilation

– Adventitia (outermost layer)

• Also called tunica adventitia or tunica externa

• Fibers of the adventitia anchor the blood vessels

Figure 22.1 The Structure of Blood Vessels (4 of 8)

Adventitia

Smooth

Media

Intima

Lumenof vein

Adventitia

Media

Intima

Histological Comparison of Arteries and Veins

AV bundle

The internal elasticmembrane is a network of

elastic fibers located between

Smooth muscle


Lumenofartery

Endothelium

Smoothmuscle

Endothelium

ARTERY VEINLM × 60Artery and Vein

elastic fibers located betweenthe intima and the media.

The media is separated fromthe adventitia by the external elastic membrane, a band

of elastic tissue.

Elastic fiber

Distinguishing Arteries from Veins

• Arteries carry blood away from the heart

• Walls are thicker

• Arteries maintain their circular shape when cut

• Veins carry blood toward the heart

• Walls are thinner

• Veins collapse when cut

• Veins do not have circular shape when cut

• Endothelial lining of arteries have pleated folds

• Blood travels from heart to elastic arteries, muscular arteries and arterioles

• Veins do not have pleated folds

Arteries

• Elastic Arteries

– Large vessels up to 2.5 cm diameter, resilient

– Aorta, Brachiocephalic, Pulmonary trunk, common carotid, subclavian, common iliac

• Muscular Arteries • Muscular Arteries

– Medium-sized arteries up to 0.4 cm diameter

– Examples are: radial and ulnar, external carotid, brachial, femoral, mesenteric

• Arterioles

– 30 micros diameter

– Poorly defined adventitia

– Control blood flow between arteries and capillaries

ARTERY

VEIN

Artery

Tunica externa

Inner elastic

membrane of

tunica intima

Tunica media

Tunica externa

Vein

Tunica intima

Tunica media

Aorta

Tunica intima

Tunica media

Aorta

Tunica intima

Tunica media

Figure 22.1 The Structure of Blood Vessels (2 of 8)

Large veins include the superior and inferior

venae cavae (also termed the great veins) and

their tributaries within the abdominopelvic

and thoracic cavities.

Structural Differences between Arteries and Veins

VEINS ARTERIES Start

Large Vein7

Adventitia

Media

Endothelium

Intima

Medium-sized veins, such as the radial and ulnarveins, range from 2 to 9 mm in internal diameter andcorrespond in general size to muscular arteries. Inthese veins the media is thin,

Medium-Sized Vein6

Elastic Artery 1

The walls of elastic arteries, such as the aorta and

brachiocephalic arteries, are not very thick relative to the

vessel diameter, but they are extremely

resilient. The media of these vessels

contains relatively few smooth

muscle cells and a high density

of elastic fibers.

Internal elasticlayer

Endothelium

Media

Adventitia

Intima

Muscular Artery 2

A typical muscular artery has a diameter of

approximately 4 mm (0.15 in.). Muscular arteries, such

as the radial and ulnar arteries, have a thicker media

with a greater percentage of smooth


and it contains relatively fewsmooth muscle cells.

Adventitia

Media

Endothelium

Intima

Venules, the smallest veins, collect blood fromcapillaries. They vary widely in diameter andcharacter, and the small venules are bothinnumerable and unnamed. The smallestvenules resemble expanded capillaries,

and venules smaller than 50 µµµµm intotal diameter lack a mediaaltogether.

Venule5

Adventitia

Endothelium

Capillaries4

Fenestrated capillaries arecapillaries that contain “windows,” or pores intheir walls, due to anincomplete orperforated endotheliallining.

Fenestrated Capillary

Pores

Endothelialcells

Basal lamina

with a greater percentage of smooth

muscle cells than elastic arteries.

Adventitia

Media

Endothelium

Intima

Arteriole 3

Arterioles have an average diameter of about 30 µµµµm. They

are considerably smaller than muscular arteries, and they

are both innumerable and unnamed. Arterioles have a

poorly defined adventitia, and the media

consists of scattered smooth muscle cells that

may not form a complete layer.

Smooth muscle cells

Endothelium

Basal lamina

Continuous Capillary Continuous capillaries are found

in most regions of the body. In

these capillaries the endothelium

is a complete lining, and the

endothelial cells are connected by

tight junctions and desmosomes.

Endothelialcells

Basal lamina

Capillaries

• Smallest and most delicate vessels

• Thin walls permit exchange of gases between

blood and interstitial fluid

• 8 micron diameter• 8 micron diameter

• Two types: Continuous and fenestrated

• Capillary beds: interconnected network of

capillary vessels connecting arterioles with

venules

Basal lamina

Nucleus

Endothelial cell

Figure 22.2ab Structure of Capillaries and Sinusoids


Fenestrations,or pores

Endosomes

Endosomes

Boundarybetween

endothelialcells

Boundarybetween

endothelialcells

Basallamina

Basallamina

Capillaries continued

• There four mechanisms regarding the passage

of material:

1. Material can diffuse across endothelial lining

2. Material can diffuse through gaps between 2. Material can diffuse through gaps between

adjacent cells

3. Material can diffuse through pores

4. Material can diffuse via endocytosis

Collateralarteries

Arteriole

Smoothmuscle cells

Metarterioles

Vein

Venule

Thoroughfarechannel

Section of

precapillarysphincter

Capillaries

Figure 22.3a Organization of a Capillary Bed


Arteriovenousanastomosis

Precapillarysphincters

Consistentblood flow

Variable

blood flow

KEY

Smallvenule

Veins

• Veins transport blood from tissues back to heart from:

• Capillary beds

• Capillaries

• Venules• Venules

– Smallest veins, lack or have thin tunica media

• Medium-sized veins

– The adventitia (tunica externa) is the largest of the layers, contains elastic fibers

• Large veins

– All three layers are relatively thick

– Examples: Superior Vena Cava and Inferior Vena Cava

Figure 22.4 Function of Valves in the Venous System

Valveclosed

Valve opens above

contracting muscle


Valve closes belowcontracting muscle

Valveclosed


Large veins

18%

Large venous

networks (liver,

bone marrow, skin)

21%

Figure 22.5 The Distribution of Blood in the Cardiovascular System

Venules and

medium-sized veins

25%

Two group 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 – Blood goes to the rest of the body and back to the

heart

Blood goes to both circuits at the same time with

each heart beat

Figure 22.6 An Overview

of the General Pattern

of Circulation

RA

LA

Brain

Pulmonary

circuit

(arteries)

Pulmonary

circuit

(veins)

Lungs

Systemic

circuit

(arteries)

Systemic

circuit

(veins)

Left

ventricleRight

ventricle

Upper limbs


Lower limbs

Kidneys

Spleen

Digestive

organs

Liver

Gonads

Figure 22.7a The Pulmonary Circuit

Ascending aorta

Pulmonary trunk


CO2

O2

Alveolus

Capillary

Figure 22.9 Aortic AngiogramRight common

carotid artery

Left commoncarotid artery

Thyrocervical trunk

Right subclavianartery


Left subclavianartery

Aortic arch

Descendingaorta

Internal thoracicartery

Ascending aorta

Brachiocephalictrunk


Radial

Ulnar

Vertebral

Right subclavian

Brachiocephalictrunk

Celiac trunk

Brachial

Aortic arch

Ascendingaorta

Right common carotid

Left common carotid

Left subclavian

Axillary

Pulmonary trunk

Descending aorta

Diaphragm

Renal

Superior mesenteric

Gonadal

Inferior mesenteric

Common iliac

Internal iliac

Figure 22.8 An Overview of the Systemic Arterial System

Palmararches

Externaliliac

Femoral

Deepfemoral

DescendinggenicularPopliteal

Dorsalis pedis

Posterior tibial

Anterior tibial

Fibular

Plantar arch

Subscapular

Rightthyrocervical

trunkRight

vertebral

Thoracic aorta

Left subclavian

Right vertebral

Left ventricle

Ascending aorta

Aortic arch

Brachiocephalic

trunk

Right common

carotid Left

common

carotid

Left

subclavian

Right subclavian

Right axillary

Right brachial

Right thyrocervical trunk

Right internal thoracic

See Figure 22.12

Deep brachial

Intercostals

Figure 22.10a Arteries of the Chest and Upper Limb

Inferior ulnar collateral

Abdominal aorta

Right

radial

Right

ulnar

Superiorulnar

collateral

Deep palmararch

Superficialpalmar arch

Digital arteries

Maxillary

Superficial temporal

Occipital

Basilar

Cerebral arterial circle

Vertebral

Facial

Lingual

Figure 22.12a Arteries of the Neck and Head

Carotid sinus

Vertebral

Inferior thyroid

Thyrocervical trunk

Suprascapular

Axillary

Internal thoracic

Abdominal Aorta

• Inferior phrenic arteries

• Celiac trunk

• Superior mesenteric artery

• Suprarenal arteries

• Renal arteries• Renal arteries

• Gonadal arteries

• Inferior mesenteric artery

• Lumbar arteries

• Right and left common iliac arteries

Internal thoracic

Common carotid

Axillary

IntercostalTHORACIC AORTA

Left subclavian

Vertebral

Thyrocervical trunk

Aortic arch

Pericardial

Celiac trunkInferior phrenic

Superior phrenic

Figure 22.14 Major Arteries of the Trunk

Diaphragm

Common hepatic

Lumbar

External iliac

Internal iliac

Inferior mesenteric

Terminal segmentof the aorta

Right common iliac

Left gastric

Renal

Suprarenal

Median sacral

Celiac trunk

Splenic

Superiormesenteric

Gonadal

Celiac Trunk

– Branches to form the left gastric artery

• Supplies the stomach

– Branches to form the common hepatic artery

• Supplies liver, gall bladder, duodenum• Supplies liver, gall bladder, duodenum

– Branches to form the splenic artery

• Supplies the spleen, stomach, pancreas

Superior Mesenteric Artery

• Branches to supply:

• Pancreas

• Duodenum

• Small intestine• Small intestine

• Large intestine

Inferior Mesenteric Artery

• Branches to supply:

• Terminal portion of the large intestine

• Rectum

Paired Arteries of Abdominal Aorta

• Inferior phrenic arteries – Supply inferior portion of esophagus and diaphragm

• Suprarenal arteries– Supply suprarenal glands

• Renal arteries • Renal arteries – Supply Kidneys

• Gonadal arteries– Supply testes, scrotum, ovaries, uterine tubes, uterus

• Lumbar arteries – Supply vertebrae, spinal cord, abdominal wall

Arteries of the Pelvis and Lower Limbs

• Common iliac arteries form:

• Internal iliac artery

– Supplies the urinary bladder, walls of the pelvis,

external genitalia, and the medial side of the thighexternal genitalia, and the medial side of the thigh

• External iliac artery

– Supplies blood to the legs

LiverCeliac trunk

Right gastric

Inferior vena cava

Left gastric

Right gastroepiploic Left gastroepiploic

PancreaticPancreas

Superior mesenteric

Inferior mesenteric

Stomach

Superior

pancreaticoduodenal

ABDOMINAL AORTA

Duodenal

THORACIC AORTA

Splenic

Spleen

Common hepatic

Hepatic artery proper

Cystic

Gastroduodenal

Figure 22.15a Arteries of the Abdomen

Ileocolic

Left common iliac

Rectal

Sigmoid colon

Rectum

Right external iliac

Inferior

pancreaticoduodenal

Sigmoid

Small intestine

Ascending colon

Duodenal

Right internal iliac

Left colic

Middle colic (cut)

Right colic

Intestinal

Deep femoral

Popliteal

Femoral

Common iliac

Internal iliac

External iliac

Figure 22.16a Major Arteries of the Lower Limb, Part I

Anterior tibial

Fibular

Posterior tibial

Dorsalis pedis

a

Medial femoral

circumflex

Lateral

femoral

circumflex

Adductor andobturatormuscles, hip joint

Quadricepsmuscles, hipand kneejoints


(see Fig. 22.15)

Femoral

(see Fig. 22.16)

Thigh

Deep femoral

(see Fig. 22.16)

Hip joint, femoral head,

deep muscles of the thigh

Descending genicular

Skin of leg; knee joint

Figure 22.17 Major Arteries of the Lower Limb, Part II

Fibular

Skin of leg; knee joint

Popliteal

Leg and foot

Posterior

tibial

Anterior

tibial

Connected by anastomoses

of dorsalis pedis, dorsal

arch, and plantar arch,

which supply distal portionsof the foot and the toes

Systemic Veins

• Veins collect blood from body tissues and return

it to the heart

• Blood returns to the heart from the lower

extremities

– Via the inferior vena cava

• Blood returns to the heart from the upper

extremities

– Via superior vena cava

• Blood returns to the heart from the lungs

– Via the pulmonary veins to left atrium

Superior Vena Cava & Inferior Vena Cava

Receives blood from:

• The head

• Neck

Receives blood from:

• Neck

• Chest

• Shoulders

• Upper limbs


Median cubital

Palmar venous arches

Left and rightcommon iliac

Lumbar

Superior vena cava

Ulnar

Brachiocephalic

Internal jugular

Vertebral

External jugular

Subclavian

Axillary

Cephalic

Brachial

Basilic

Hepatic

Radial

Median antebrachial

Intercostal

Inferior vena cava

Renal

Gonadal

External iliac

Internal iliac

Figure 22.18 An Overview of the Systemic Venous System

Palmar venous arches

Great saphenous

Popliteal

Small saphenous

Fibular

Dorsal venous arch

Posterior tibial

Femoral

Deepfemoral

Digital

Superficial veins

Internal iliac

Anterior tibial

Plantar venous arch

KEY

Deep veins

Superior

sagittal sinus

Inferior

sagittal sinus

Temporal

Maxillary

Figure 22.19a Major Veins of the Head and Neck

Internal thoracic

Right brachiocephalic

Superior vena cava

Internal jugular

Vertebral

External

jugular

Axillary

Right

subclavian

Clavicle

Left brachiocephalic

Superiorsagittal sinus (cut)

Internal

Figure 22.19b Major Veins of the

Head and Neck© 2015 Pearson Education, Inc.

Internaljugular

KEY

Subclavian

Brachiocephalic

Cephalic

Superficial veins

Deep veins

SUPERIOR

VENA CAVA

Figure 22.20 The Venous Drainage of the Trunk and Upper Limb

Cephalic

Palmar venous

arches

Digital

KEY

Superficial veins

Deep veins

Median cubital

SUPERIOR

VENA CAVA

Subclavian

Brachiocephalic

Axillary

Basilic


Palmar venous

arches

Digital

Cephalic

Ulnar

Basilic

Superior Vena Cava

• Receives blood from Azygos Veins

• Brachiocephalic Veins

– Brachiocephalic veins receive blood from

• Subclavian veins • Subclavian veins

• Internal thoracic veins

KEY

Brachiocephalic

Superficial veins

Deep veins

SUPERIOR

VENA CAVA

Azygos

Internal

thoracic


Inferior Vena Cava

• Receives blood from

• Hepatic veins

• Gonadal veins

– The right gonadal vein drains into the inferior vena – 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

• Lumbar veins

• Common Iliac veins

KEY

Superficial veins

Deep veins

Lumbar

Gonadal

Hepatic


Common

iliac

Right common

iliac

Superior gluteal


Femoral circumflex

Femoral

Great saphenous

Internal iliac

Inferior gluteal

Internal pudendal

Lateral sacral

Obturator

Deep femoral

Collects blood

from the thigh

External Iliac

Femoral

Small saphenous

Collects blood from

superficial veins of

the leg and foot

Figure 22.21a The Venous Drainage of the Lower Limb

Small saphenous

Fibular

Popliteal

Posterior tibial

Anterior tibial Fibular

The dorsal and plantar venous

arches collect blood from the

foot and toes

Dorsal venous arch

Plantar venous arch

Digital

KEY

Superficial veins

Deep veins

External Iliac

Femoral

Internal pudendal

Superior gluteal

Inferior gluteal

Obturator

Femoral

circumflex

Deep femoral

Femoral

Great saphenous

Collects blood from

the superficial veins

of the lower limb

Figure 22.21b The Venous Drainage of the Lower Limb

Popliteal

Posterior tibial

Fibular

The dorsal and plantar venous

arches collect blood from the

foot and toes

Dorsal venous arch

Plantar venous arch

Digital

Small

saphenous

Anterior tibial

KEY

Superficial veins

Deep veins

Anterior tibial

Hepatic Portal System

Blood from the small intestine, large intestine, stomach, and pancreas flows into the hepatic portal system

• Inferior mesenteric vein drains a portion of the large intestinelarge intestine

• Splenic vein drains the spleen, lateral border of the stomach, and the pancreas

• Superior mesenteric vein drains a portion of the stomach, small intestine, and a portion of the large intestine

The hepatic portal system

• From the hepatic portal veins, venous blood

enters into:

• Liver sinusoids

• Hepatic veins• Hepatic veins

• Inferior vena cava

• Right Atrium

Inferior vena cava

Hepatic

Hepatic portal

Liver

Superior mesenteric

Pancreas

Left colic

Stomach

Pancreatic

Left gastric

Right gastric

Figure 22.22 The Hepatic Portal System

Superior mesenteric

Intestinal

Inferior mesenteric

Superior rectal

Fetal cardiovascular system

• Fetal lungs are nonfunctional

• Fetal digestive system not fully functioning

• All fetal nutritional and respiratory needs are

provided by diffusion across the placentaprovided by diffusion across the placenta

• Blood in the fetal internal iliacs enters the

umbilical arteries then enters umbilical cord,

then placenta

Blood leaving the Placenta

• Blood leaves the placenta

• Enters the umbilical vein

• Enters the ductus venosus

• Enters the fetal liver• Enters the fetal liver

• Enters the inferior vena cava

• Enters the fetal right atrium

Foramen ovale (open)

Aorta

Ductusarteriosus(open)

Pulmonarytrunk

Figure 22.23a Changes

in Fetal Circulation at Birth© 2015 Pearson Education, Inc.

Umbilical vein

Liver

Placenta

Umbilicalcord

Inferior vena cava

Umbilicalarteries

Ductus venosus

Ductus arteriosus

(closed)

Pulmonary

trunk

Foramen ovale

(closed)

Right

atrium

Left

atrium

Left

Figure 22.23b Changes in Fetal

Circulation at Birth © 2015 Pearson Education, Inc.

Inferior

vena cava

Right ventricle

Left

ventricle

b


Superior vena cava General systemic circulation

Right ventricle

Right atrium Left atriumForamen ovale

An opening in theinteratrial septumthat permits someblood to flow directlyinto the left atrium Left ventricle

FETAL HEART

Ductus arteriosus

Lungs

Minimalblood flow

Ductus venosus

A shunt that permits most

blood to bypass the fetal

liver so as to directly enter

the inferior vena cava and

Inferior vena cava

Figure 22.23c Changes in Fetal Circulation at Birth

Ductus arteriosus

A vessel that shunts bloodfrom the pulmonary trunk,away from the pulmonarycircuit, into the aortic arch

General systemic circulation Aorta

Umbilical arteries Internal iliac arteries

Flowchart for circulatory patterns in the fetus and newborn infant.

PLACENTA

Umbilical vein

Transports oxygen-rich,nutrient-rich blood fromplacenta to fetal liver

the inferior vena cava and

then the right atrium

c

KEY

Oxygen-rich blood

Mixed blood

Oxygen-poor blood

Aging and the Cardiovascular System

• Age-related changes in the cardiovascular system

– Blood changes

• Decreased hematocrit

• Thrombi and emboli form more easily

• 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

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Cardiovascular System Blood Vessels - Anatomy 10Amtsacanatomy10abrenda.weebly.com/uploads/7/7/9/4/...Cardiac cycle Atrial systole begins: Atrialcontraction forces a small amount of