23 lecture presentation

© 2010 Pearson Education, Inc.

• The cardiovascular system of vertebrates consists of the:

– Heart

– Blood vessels


• In the heart the:

– Atrium receives blood

– Ventricle pumps blood away from the heart


• Blood is confined to three main types of blood vessels:

– Arteries carry blood away from the heart

– Capillaries are the site of exchange between blood and interstitial fluid

– Veins return blood back to the heart


The Path of Blood

• Humans and other terrestrial vertebrates have a double circulation system.

• A double circulation system consists of a:

– Pulmonary circuit between the heart and lungs

– Systemic circuit between the heart and the rest of the body


How the Heart Works

• The human heart:

– Is a muscular organ about the size of a fist

– Has four chamberLocated in the thoracic cavity (between the lungs and the sternum)

– s


The Heart

Structure

Chambers: two atrias, two ventricles

Valves

• Two atrioventricular valves: tricuspid and bicuspid (mitral)

• Two semilunar valves: pulmonary and aortic


Pulmonary Circuit: Oxygenation of Blood

Pathway

• Deoxygenated blood through the vena cava to the right atrium

• Deoxygenated blood through the right atrioventricular valve to the right ventricle

• Deoxygenated blood through the pulmonary semilunar valve to the pulmonary trunk and the lungs

• Oxygenated blood through the pulmonary veins to the left atrium

• Oxygenated blood through the left atrioventricular valve to the left ventricle


Systemic Circuit: Delivery of Oxygenated Blood to Tissues and Return of Blood to the Heart

Pathway

• Oxygenated blood through the aortic semilunar valve to the aorta

• Oxygenated blood through branching arteries and arterioles to the tissues

• Oxygenated blood to the capillaries

• Deoxygenated blood from capillaries into venules and veins

• Ultimately to the vena cava and into the right atrium


Frombody Venae

cavae

Rightatrium

Leftatrium

Rightventricle

Leftventricle

Pulmonaryarteries

Pulmonaryveins

Tolungs

Fromlungs

Tobody

Aorta

Figure 23.UN3

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

Pacemaker(SA node)

Rightatrium

AV node

Right ventricle

Pacemakergenerateselectricalimpulses.

Impulsesspreadthroughatria.

Impulsesreachventricles.

(a) The heart’s natural pacemaker

Figure 23.6a

Wire leadingto SA node

Artificialpacemaker

Heart

(b) Artificial pacemakerFigure 23.6b


• In certain kinds of heart disease, the heart fails to maintain a normal rhythm.

• The remedy for this failure of the electrical control of the heart is:

– An artificial pacemaker, a small electronic device surgically implanted near the SA node


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.


• Optimal blood pressure for adults is below 120 systolic and below 80 diastolic.

• High blood pressure, or hypertension, is:

– Persistent systolic blood pressure higher than 140 and/or

– Diastolic blood pressure higher than 90


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

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

Proteins

Figure 23.11a


Red Blood Cells and Oxygen Transport

• Red blood cells (erythrocytes) are:

– Shaped like discs with indentations in the middle

– The most numerous type of blood cell

Red Blood Cells(cells that carry oxygen)

Co

lori

zed

SE

M

Figure 23.12a


Hemegroup

Ironatom

Polypeptide chain

O2 loaded

in lungs

O2 unloaded

in tissues

O2

O2

Figure 23.23

White Blood Cells(cells that fight infection)

Co

lori

zed

SE

M

Figure 23.12b

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


• Each red blood cell contains large amounts of the protein hemoglobin, which:

– Contains iron

– Transports oxygen throughout the body


• Anemia may result from:

– An abnormally low amount of hemoglobin or

– A low number of red blood cells

• The hormone EPO boosts production of red blood cells.


White Blood Cells and Defense

• White blood cells (leukocytes) fight:

– Infections

– Cancer

• .


Platelets and Blood Clotting

• Blood contains two components that aid in clotting:

– Platelets

– Clotting factors released from platelets that convert fibrinogen, a protein found in plasma, into a threadlike protein called fibrin


• Cardiovascular disease:

– Includes all diseases affecting the heart and blood vessels

– Accounts for 40% of all deaths in the United States

– Kills more than 1 million people each year


• Coronary arteries:

– Supply the heart muscle

– Can narrow or close, contributing to a heart attack

Coronary artery(supplies oxygento the heart muscle)

Dead muscletissue

Blockage

Aorta

Figure 23.13


• Atherosclerosis:

– Is a chronic cardiovascular disease

– Results from the buildup of cholesterol and other substances in the walls of arteries

– Gradually narrows arteries throughout the body

Connectivetissue

Smoothmuscle

Epithelium

Normal artery

Figure 23.14a

Plaque

Artery partially blocked by plaqueFigure 23.14b


• Heart disease:

– Involves inherited factors but

– Can be reduced by:

– Not smoking

– Exercising regularly

– Eating a heart-healthy diet


THE HUMAN RESPIRATORY SYSTEM• The human respiratory system has three phases of gas exchange:

– Breathing

– Transport of oxygen from the lungs to the rest of the body via the circulatory system

– Removal of oxygen from the blood and release of CO2 into the blood by cells of the body

Lungs(localized internal organs)

Model of a pair of human lungs

Figure 23.17d

The Structure and Function of the Human Respiratory System• Air moves sequentially from the mouth and nose:

– To the pharynx, where digestive and respiratory systems meet

– To the larynx (voice box) and trachea (windpipe)

– To the bronchi (one bronchus to each lung)

– To the bronchioles, the smallest branches of the tubes within the lungs and

– To the alveoli, the air sacs where gas exchange primarily occurs


Larynx (voice box)

Trachea(windpipe)

(a) Overview of the human respiratory system

Pharynx

Right lung

Bronchus

Bronchiole

Diaphragm

Esophagus

Nasal cavity

Left lung

Heart

Figure 23.19a

(b) The structure of alveoli

Bronchiole

Bloodcapillaries

Fromheart

Toheart

Alveoli

O2-rich

blood

O2-poor

blood

O2CO2

Figure 23.19b


Taking a Breath• Breathing is the alternating process of:

– Inhalation

– Exhalation


• During inhalation, the chest is expanded by the:

– Upward movement of the ribs

– Downward movement of the diaphragm

• Air moves into the lungs:

– By negative pressure breathing

– As the air pressure in the lungs is lowered by the expansion of the chest

Inhalation(Air pressure is

higher in atmospherethan in lungs.)

Exhalation(Air pressure is

lower in atmospherethan in lungs.)

Diaphragmrelaxes(moves up)

Diaphragmcontracts(movesdown)

Rib cageexpands asrib musclescontract

Rib cage getssmaller asrib musclesrelax

Airinhaled

Airexhaled

Lung

Figure 23.20


How Smoking Affects the Lungs• Breathing exposes your respiratory tissues to potentially

damaging chemicals, including one of the worst pollutants, tobacco smoke.


• Tobacco smoke:

– Irritates the cells that line the bronchi and trachea

– Inhibits their ability to remove foreign substances from the airways


• Smoking:

– Kills half of all people who smoke, about 440,000 Americans every year,

– Causes 90% of all lung cancer (one of the deadliest forms of cancer)

– Causes more deaths than the combined total of:

– All accidents

– Alcohol and other drug abuse

– HIV

– Murders

(a) Healthy lungs (nonsmoker)

Lung

Heart

Figure 23.24a

(b) Cancerous lungs (smoker)

Lung

Heart

Figure 23.24b


• The lifestyle choice with the greatest impact on your long-term health is choosing not to smoke.

The Heimlich maneuver:

– Involves quick thrusts to the diaphragm

– Compresses the lungs

– Forces air rapidly out of the chest

– May dislodge food or other objects obstructing the breathing pathway



• The food and air passageways pass through a common tube in the rear of the pharynx.

• Choking results when food or other substances get diverted from the food to the air pathway.


• The common passageway of food and air reflects the remodeling of the food passageway during the evolution of the respiratory system in shallow-water fishes.

• Choking is thus a consequence of the evolutionary remodeling of the throat.

Figure 23.25

Science

23 lecture presentation