Circulation

•Chapter 23

Cardiovascular System

•Accepts oxygen, nutrients, and other substances from the respiratory and digestive systems and delivers them to cells

•Accepts carbon dioxide and wastes from cells and delivers them to respiratory and urinary systems for disposal

Chambers of heart

•RIGHT ATRIUM•RIGHT VENTRICLE•LEFT ATRIUM •LEFT VENTRICLE

Basic overview

(a) Pulmonary circuit (b) Systemic circuit

O2-rich bloodO2-poor blood

LungLung

Heart

CO2

CO2

CO2CO2

O2 O2

O2

O2

Figure 23.2

▫One complete trip through the human cardiovascular system: Takes about one minute Requires two passes through the heart

Animation: Path of Blood in Mammals

O2-rich bloodO2-poor blood

Capillaries ofhead, chest,and arms

Capillaries ofabdominal regionand legs

Capillariesof lung

Capillariesof lung

Pulmonaryartery

Pulmonaryartery

Superiorvena cava

Pulmonaryvein

Inferiorvena cava

Pulmonary vein

Left ventricle

Left atriumRight atrium

Right ventricle

Aorta

Figure 23.3-11

O2-rich blood

O2-poor blood

Right atrium Left atrium

Leftventricle

RightventricleFrom

body

Rightlung

Leftlung

Frombody

Tobody

Valves Valves

Figure 23.4

The Cardiac Cycle

▫The heart relaxes and contracts throughout our lives. Diastole is the relaxation phase of the heart

cycle. Systole is the contraction phase.

Blast Animation: Cardiac Cycle Overview

Heart is relaxed.Blood flows in.

Diastole

0.4sec

Atria contract. Blood isforced into ventricles.

0.1sec

Systole

Ventricles contract.Blood is pumped out.

0.3sec

0.8sec

Figure 23.5-3

The Pacemaker and the Control of Heart Rate

▫The pacemaker, or SA (sinoatrial) node: Sets the tempo of the heartbeat Is composed of specialized muscle tissue in

the wall of the right atrium

Blast Animation: Electrical Coordination of the Cardiac Cycle

Pacemaker(SA node)

Rightatrium

AV node

Right ventricle

Wire leadingto SA node

Artificialpacemaker

Heart

Pacemakergenerateselectricalimpulses.

Impulsesspreadthroughatria.

Impulsesreachventricles.

(b) Artificial pacemaker(a) The heart’s natural pacemaker

Figure 23.6

Blood Vessels

▫If the heart is the body’s “pump,” then the “plumbing” is the system of arteries, veins, and capillaries. Arteries carry blood away from the heart. Veins carry blood toward the heart. Capillaries allow for exchange between the

bloodstream and tissue cells.

Blood Flow through Arteries▫The force that blood exerts against the

walls of blood vessels is blood pressure. Blood pressure is the main force driving the

blood from the heart to the capillary beds. A pulse is the rhythmic stretching of the

arteries caused by the pressure of blood forced into the arteries during systole.

Fromheart

Toheart

Smoothmuscle

Connectivetissue

Connectivetissue

Smoothmuscle

Epithelium

Epithelium

Epithelium

Capillary

Arteriole Venule

Artery

Valve

Vein

Figure 23.8

(a) Capillaries (b) Chemical exchange

Capillary

Red blood cell

Tissue cell

Interstitialfluid

Diffusion of

O2 andnutrients outof capillaryand intotissue cells

Diffusion

of CO2 andwastes outof tissuecells andinto capillary

From artery

To vein

To vein

LM

Figure 23.9

Blood Flow through Capillary Beds

▫At any given time, only about 5–10% of the capillaries have a steady flow of blood.

▫The regulation of blood flow through capillaries Is controlled by muscles Reflects shifting

demands by organs of the body

Capillaries▫The walls of capillaries are thin and leaky.

At the arterial end of the capillary, blood pressure pushes fluid rich in oxygen, nutrients, and other substances into the interstitial fluid.

At the venous end of the capillary CO2 and other wastes diffuse from tissue cells into the capillary bloodstream.

Blood Flow in Capillary

▫Blood moves back towards the heart because of: Surrounding skeletal muscles that compress

the veins One-way valves that permit blood flow only

toward the heart

Blood▫An adult human has about 5 L (11 pints) of

blood.▫By volume, blood is about:

45% cells and 55% plasma, consisting of about:

90% water 10% dissolved salts, proteins, and other

molecules

Plasma(55%)

Water (90%of plasma)

Dissolved salts(such as sodium,potassium, calcium)

Substances beingtransported (such as

O2, CO2, nutrients,

wastes, hormones)

Cellularelements (45%)

Red blood cells(erythrocytes)

White blood cells(leukocytes)

Platelets

BloodProteins

Figure 23.11

Blood Cells

•Red blood cells (erythrocytes)▫Contain hemoglobin▫Rapidly transport oxygen (and carbon

dioxide) ▫Have no nucleus when mature

•White blood cells (leukocytes) ▫Tissue maintenance and repair▫Defenses against pathogens

Fig. 34.6, p. 558

• ABOUT 99% OF ALL BLOOD CELLS• FUNCTION TO TRANSPORT

OXYGEN AND CARBON DIOXIDEPICK UP IN LUNGS

DELIVER TO ALL CELLS• CONTAIN IRON RICH PROTEIN

HEMOGLOBIN• MADE IN BONE MARROW

CONTINUOUSLY

Red Blood Cells

• CIRCULATE FOR ABOUT 120 DAYS THEN ARE BROKEN DOWN

• CAN’T REPLICATE - THEY HAVE NO NUCLEUS

• ARE MADE IN THE BONE MARROW

• RBC in capillary

Red Blood Cells

Platelets

•Platelets function in blood clotting

•Platelets and all blood cells arise from stem cells in bone marrow

White Blood Cells• LEUKOCYTES - 1% OF BLOOD CELLS

▫ NORMAL BLOOD -ABOUT 10,000 CELLS/MM3

• MAKE IN THE BONE MARROW• ARE NUCLEATED• HELP BODY DEFEND AGAINST INVADERS• LEUKEMIA CANCER OF WHITE BLOOD CELLS

WBC•5 KINDS OF WHITE BLOOD CELLS

▫NEUTROPHILS-PHAGOCYTOSIS AND PROCESSING

▫LYMPHOCYTES- IMMUNITY▫MONOCYTES-GIVE RISE TO

MACROPHAGES▫EOSINOPILS- ASSOCIATED WITH

ALLERGIES▫BASOPHILS-INTENSIFY

INFLAMMATION

Blood Platelets

•FRAGMENTS OF CELLS•FUNCTION IN CONTROLLING

BLEEDING•FORMED IN THE BONE MARROW

Platelets(bits of membrane-enclosedcytoplasm that aid clotting)

Fibrin

Red blood cell

Co

lori

zed

SE

M

Co

lori

zed

SE

M

Figure 23.12c

ABO Blood Typing

•Helps match blood of donors and recipients to avoid blood transfusion problems (agglutination)

Rh Blood Typing

•Helps prevent problems that may arise when maternal and fetal Rh blood types differ

Circulatory System Disorders

•Atherosclerosis, hypertension (chronic high blood pressure), heart attacks, strokes, certain arrhythmias

•Regular exercise, maintaining normal body weight, and not smoking lower risk for these disorders

Connectivetissue

Smoothmuscle

Plaque

Epithelium

Normal artery Artery partially blocked by plaque

Figure 23.14

Coronary artery(supplies oxygento the heart muscle)

Dead muscletissue

Blockage

Aorta

Figure 23.13