Ch 32 & 33 lecture

Copyright © 2009 Pearson Education, Inc..

Lectures by

Gregory AhearnUniversity of North Florida

Chapters 32,33

Circulation and Respiration

Copyright © 2009 Pearson Education Inc.

What Are The Major Features And Functions Of Circulatory Systems? A circulatory system evolved in multicellular

animals to bring the external world to each metabolizing cell in the animal, so that nutrients, oxygen, and waste products could be exchanged.


What Are The Major Features And Functions Of Circulatory Systems? Circulatory systems have three main

components:• Blood• Blood vessels• Heart

Animals have two types of circulatory systems:• Open circulatory system• Closed circulatory system


What Are The Major Features And Functions Of Circulatory Systems? Animals have two types of circulatory

systems (continued).• In an open circulatory system, blood flows

through blood vessels, but at some point, leaves the vessels and moves freely through tissues and a large space called a hemocoel.


What Are The Major Features And Functions Of Circulatory Systems? Open circulatory system

Fig. 20-1a

heart

bloodbathes internal

organs

bloodvessels

hemocoel

openingwith valves

tubularhearts

Open circulatory system(a)


What Are The Major Features And Functions Of Circulatory Systems? Some invertebrates, including earthworms,

and all vertebrates have closed circulatory systems, where blood is confined to blood vessels and flows through them in a continuous circuit.


What Are The Major Features And Functions Of Circulatory Systems? Closed circulatory system

Fig. 20-1b

heart

extracellular fluid

vessels branch ineach organ

heartsvessel

small vessels

Closed circulatory system(b)


What Are The Major Features And Functions Of Circulatory Systems?

PLAYPLAY Animation—Open vs. Closed Circulatory Systems



systems (continued).• In closed circulatory systems of vertebrates,

vessels that carry blood away from the heart are called arteries.

• Arteries carry blood to the smallest blood vessels, called capillaries, which are microscopic vessels that penetrate tissues.



systems (continued).• Dissolved substances in the blood exchange

with those in the fluid surrounding capillaries, which is called extracellular fluid.

• After passing through capillaries, blood moves back toward the heart through vessels called veins.


What Are The Major Features And Functions Of Circulatory Systems? The vertebrate circulatory system transports

many substances.• Transports oxygen from the lungs or gills to

the tissues• Transports carbon dioxide from the tissues to

the lungs or gills• Transports nutrients from the digestive system

to the tissues• Transports waste products and toxic

substances to the liver and the kidney for excretion


What Are The Major Features And Functions Of Circulatory Systems? The vertebrate circulatory system transports

many substances (continued).• Transports hormones from the glands and

organs that produce them to the tissues on which they act

• Helps to regulate body temperature by adjusting blood flow

• Helps to protect the body from bacteria and viruses by circulating the cells and molecules of the immune system


How Does The Vertebrate Heart Work?

The vertebrate heart consists of muscular chambers.• In vertebrate hearts, muscular chambers,

called atria, collect blood. • Blood flows from the atria to the ventricles,

chambers whose contractions circulate blood through the body.

• The number of atria and ventricles differs among different classes of vertebrates.



Fish hearts have two chambers, one atrium, and one ventricle; blood flows through the fish body in a single loop.



Fish heart

Fig. 20-2aFish

gill capillaries

body capillaries

ventricle

atrium

(a)



Amphibians and most reptiles have three-chambered hearts and two circulatory loops, one for the lungs and one for the rest of the body.

Blood from both circuits mixes in the heart; therefore, the two circuits are not completely separate.



Amphibian, and most reptiles’ heart

Fig. 20-2b

Amphibians, most reptiles

lung capillaries

atria

ventricle

body capillaries(b)



In alligators, crocodiles, birds, and mammals, the heart has four chambers, and the two circulatory loops are completely separate.



Mammals and birds’ heart

Fig. 20-2cMammals, birds

lung capillaries

body capillaries

atria

ventricle

(c)



Animation—Vertebrate HeartPLAYPLAY



Four-chambered hearts, like the human heart, can be thought of as two separate pumps.• One pump, consisting of the right atrium and

right ventricle, pumps oxygen-depleted blood to the lungs.

• The other pump, consisting of the left atrium and left ventricle, moves oxygen-rich blood from the lungs and through the aorta to the rest of the body.



The human heart and its valves and vessels

Fig. 20-3

aorta

left atrium

pulmonary artery(to left lung)

semilunar valves

pulmonary veins(from left lung)

atrioventricularvalve

left ventricle

thicker muscleof left ventricle

descending aorta(to lower body)right ventricle

inferior vena cava

atrioventricular valve

superiorvena cava

pulmonary artery(to right lung)

pulmonary veins(from right lung)

right atrium



The atria and ventricles contract in a coordinated way.• The chambers of the heart alternatively

contract and relax.• The two atria contract at the same time,

emptying their contents into the ventricles.• A fraction of a second later, the two ventricles

contract, forcing blood into arteries that exit the heart.

• Both atria and ventricles then relax briefly, and the cycle repeats.



The cardiac cycle

Fig. 20-4

Atria contract, forcingblood into the ventricles

Then the ventriclescontract, forcing bloodthrough the arteries to thelungs and the rest of the body

The cycle endsas the heart relaxes

Deoxygenated blood ispumped to the lungs

Blood fills theatria and beginsto flow passivelyinto the ventricles

Deoxygenatedblood from thebody enters theright ventricle

Oxygenated blood from thelungs enters the left ventricle

Oxygenated bloodis pumped to thebody



Animation—Function of the Human HeartPLAYPLAY



The atria and ventricles contract in a coordinated way (continued).• At a normal resting heart rate, the cycle lasts

about 1 second.• Blood pressure changes as the cycle

proceeds.• Systolic pressure is measured during

ventricular contraction, and diastolic pressure is measured between contractions.



Measuring blood pressure

Fig. 20-5

A stethoscopedetectspulse sounds

The cuff is inflated,putting pressureon the artery

cuff



Animation—Measuring Blood PressurePLAYPLAY



Valves prevent blood from moving in the wrong direction.• When the ventricles contract, blood must

move only out through the arteries and not back into the atria.

• Once blood has left the ventricles and entered the arteries, it must be prevented from flowing back as the heart relaxes.



Valves prevent blood from moving in the wrong direction (continued).• These needs are met by four one-way valves.

• Atrioventricular valves separate the atria from the ventricles.

• Semilunar valves allow blood to enter the pulmonary artery and the aorta when the ventricles contract.



Electrical impulses coordinate the sequence of contractions.• Contractions are coordinated by the

pacemaker, a cluster of specialized heart muscle cells that produce spontaneous electrical signals.

• The heart’s primary pacemaker is the sinoatrial (SA) node, located in the wall of the right atrium.



Electrical impulses coordinate the sequence of contractions (continued).• From the SA node, an electrical impulse

creates a wave of muscular contraction that spreads through the right and left atria until it arrives at the unexcitable tissue between the atria and ventricles.

• There, the excitation is channeled through the atrioventricular (AV) node.



Electrical impulses coordinate the sequence of contractions (continued).• From the AV node, the signal to contract

spreads along excitable fibers to the base of the two ventricles.

• This signal causes the ventricles to contract in unison.

• If the pacemaker fails, uncoordinated irregular contractions, called fibrillation, occurs, and blood cannot be pumped out of the heart.



The heart’s pacemaker and its connections

Fig. 20-6

Unexcitable tissueseparates the atriaand ventricles

AV node

The sinoatrial nodeelectrical signal startsthe atrial contraction

The atrioventricularnode transmits thesignal to the ventricleswith a slight delay

The signal travels tothe base of the ventricles

Excitable fibers transmitthe signals to ventricularcardiac muscle, causingcontraction from the baseupwards

The signal spreads,causing the atria tocontract

excitablefibers



The heart’s contractions result from movement of filaments in muscle cells.• The muscle tissue that makes up the heart

consists of cells known as muscle fibers.• Each muscle fiber contains many myofilbrils,

cylindrical structures that extend from one end of the fiber to the other.

• The myofibrils are composed of subunits called sarcomeres, which are aligned end to end long the length of the myofibril.



A muscle fiber

Fig. 20-7a,b

myofibril

membrane

Cross section of fiber(a)

mu

scle

fib

er

sarcomere

myofibril

thin filament

Z lines

Myofibril and sarcomerethick filament

(b)



Within each sarcomere is a precise arrangement of filaments of the proteins actin and myosin; actin forms the thin filaments, and myosin forms the thick filaments.

Fig. 20-7cThick and thin filaments

thin filament

thick filament(myosin)

cross-bridge

actin

accessoryproteins

(c)



The heart’s contractions result from movement of filaments in muscle cells (continued).• The thin filaments are attached to fibrous

protein bands called Z lines, which separate adjacent sarcomeres.

• During contraction, the myosin filaments make contact with the actin filaments and, using ATP energy, pull the actin strand past the myosin strand, shortening the sarcomere and contracting the muscle.



Muscle contraction

Fig. 20-8

Relaxedmuscle

Contractedmuscle

z line

sarcomere

A sarcomere shortensCross-bridge attachment and release

thick filament

binding sites

cross-bridge

ATP

thin filament

(b)(a)

When bindingsites are exposed,cross-bridgesattach to thebinding sites

The cross-bridges bend,moving thefilaments pastone another andshortening thesarcomere

Using energy fromATP, the cross-bridgesrelease, straighten, andreattach farther along


Muscle Contraction

Suggested Media Enhancement:

Muscle ContractionTo access this animation go to folder C_Animations_and_Video_Filesand open the BioFlix folder.


What Is Blood?

Blood transports dissolved nutrients, gases, hormones, and wastes through the body. • It has two major components:

• A fluid, called plasma• Cellular components—including red blood

cells, white blood cells, and platelets—which are suspended in the plasma

• The cellular components are produced in bone marrow and later move into the blood.


What Is Blood?

Blood cells

Fig. 20-9

platelets

megakaryocyte

neutrophil neutrophil

basophil

monocyte

eosinophil

lymphocyte

red blood cells

Erythrocytes White blood cells

Megakaryocyte forming platelets

(a) (b)

(c)


What Is Blood?

Plasma is primarily water and dissolved substances.• Plasma is 90% water.• Dissolved in the plasma are proteins,

hormones, nutrients, salts, and wastes, such as urea.


What Is Blood?

Red blood cells carry oxygen from the lungs to the tissues.• The most abundant cells in the blood are red

blood cells.• Red blood cells get their red color from

hemoglobin, an iron-containing protein that can bind up to four oxygen molecules.

• Hemoglobin picks up oxygen in the lungs, where oxygen is at high concentration, and releases it in other tissues of the body, where the oxygen concentration is low.


What Is Blood?

White blood cells help defend the body against disease.• White blood cells, or leukocytes, make up less

than 1% of blood cells but play a key role in the body’s resistance to disease.

• There are five types of white blood cells:• Neutrophils • Eosinophils • Basophils • Lymphocytes• Monocytes


What Is Blood?

Lymphocytes are responsible for the immune response against disease.• Neutrophils and monocytes engulf foreign

particles.

Fig. 20-10


What Is Blood?

Platelets are cell fragments that aid in blood clotting.• Platelets are pieces of large cells, called

megakaryocytes, that occur in the bone marrow and enter the blood, playing a key role in blood clotting.

• Blood clotting starts when platelets contact an irregular surface, such as a damaged blood vessel, where they partially block the opening.


What Is Blood?

The platelets and injured tissue initiate a complex sequence of reactions among plasma proteins, which results in a fibrous network, called fibrin, that traps red blood cells and closes the wound.

Fig. 20-11

platelets white blood cell

red blood cell

fibrin strands


What Are The Types And Functions Of Blood Vessels? As it leaves the heart, blood travels from

arteries to arterioles to capillaries to venules to veins, and finally, it returns to the heart.

Copyright © 2009 Pearson Education Inc.Fig. 20-12

jugular vein

aorta

superiorvena cava

carotid artery

lungcapillaries

pulmonaryartery

heart

kidney

femoral vein

intestine

inferiorvena cava

liver

femoral artery


Arteries and arterioles carry blood away from the heart.• These vessels have thick walls embedded

with smooth muscle and elastic connective tissue.

• Arteries branch into vessels of small diameter called arterioles.

precapillarysphincters

arteriole

venule

artery vein

capillaryvalve

smooth muscleconnective tissue

smoothmuscle

crosssection

capillarynetwork

What Are The Types And Functions Of Blood Vessels?

Fig. 20-13


What Are The Types And Functions Of Blood Vessels? Structures and interconnections of blood

vessels

Fig. 20-13

precapillarysphincters

arteriole

venule

artery vein

capillaryvalve

smooth muscle

connective tissue

smoothmuscle

crosssection

capillarynetwork


What Are The Types And Functions Of Blood Vessels? Capillaries are microscopic vessels through

which nutrients and wastes are exchanged.• Diffusion of nutrients and wastes occurs in

capillaries, the smallest of all blood vessels.• Because their walls are only one cell thick,

substances can cross a capillary cell’s plasma membrane and easily move into or out of capillaries.


What Are The Types And Functions Of Blood Vessels? Capillaries are microscopic vessels through

which nutrients and wastes are exchanged (continued).• Capillaries are so narrow that red blood cells

pass through them in single file.• The speed of blood flow drops very quickly as

it moves through this narrow capillary network.• The flow of blood in capillaires is regulated by

tiny rings of smooth muscle, called precapillary sphincters, which surround the junctions between arterioles and capillaries.


What Are The Types And Functions Of Blood Vessels? Red blood cells flow through a capillary.

Fig. 20-14

Red blood cells mustpass through capillariesin single file

Capillary walls are thinand permeable to gases,nutrients, and cellularwastes


What Are The Types And Functions Of Blood Vessels? Venules and veins carry blood back to the

heart.• After picking up carbon dioxide and other

cellular wastes from cells, capillary blood drains into larger vessels called venules, which empty into larger veins.

• To prevent blood from flowing away form the heart, veins are equipped with valves that allow blood to flow in only one direction.


What Are The Types And Functions Of Blood Vessels? Blood pressure is low in veins and

contraction of skeletal muscle during exercise helps return blood to the heart by squeezing the veins and forcing blood through them.


What Are The Types And Functions Of Blood Vessels? Valves direct the

flow of blood in veins.

Fig. 20-15

valveclosed

valveclosed

valveopen

relaxedmuscle

musclecontractioncompressesvein


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system consists of:

• A network of lymph vessels that empty into the circulatory system

• Numerous small lymph nodes• The thymus• The spleen


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system removes excess fluid

and dissolved substances that leak from the capillaries.• It transports fats from the small intestine to the

blood stream.• It defends the body by exposing bacteria and

viruses to white blood cells.

Copyright © 2009 Pearson Education Inc.Fig. 20-16

thoracic duct enters avein to the vena cava

thymus

heart

spleen

thoracic duct

valve preventsbackflow

lymph node

chamberspacked withwhite blood cells

superiorvena cava

lymphvessels

lymphnodes


How Does The Lymphatic System Work With The Circulatory System? Lymphatic vessels resemble the capillaries

and veins of the circulatory system.• The smallest lymph vessels are lymph

capillaries.• Lymph capillary walls have specialized

openings between the cells that act as one-way valves.

• These openings allow large particles to be carried into the lymph capillaries along with fluid.


How Does The Lymphatic System Work With The Circulatory System? Lymphatic vessels resemble the capillaries

and veins of the circulatory system (continued).• Materials collected in the lymph flow into

larger lymph vessels.• The direction of flow in lymph vessels is

regulated by one-way valves.


How Does The Lymphatic System Work With The Circulatory System? Lymph capillary structure

Fig. 20-17

extracellularfluid

lymphvessel

Pressure forcesfluid from plasma atthe arteriole end ofthe capillary network

Extracellular fluidenters lymph vesselsand the venous endsof capillaries

Lymph is transportedinto larger lymph vesselsand back to thebloodstream


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system returns fluids to the

blood.• The lymphatic system collects excess fluid

that leaks out of the blood capillaries and returns it to the blood.

• As extracellular fluid accumulates, its pressure forces the fluid through the one-way opening in the lymph capillary walls.

• Once inside lymphatic vessels, the excess fluid taken up is now called lymph.


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system transports fats from

the small intestine to the blood.• After a fatty meal, the cells of the small

intestine absorb globules of digested fat.• These globules are too large to diffuse into

blood capillaries, but they easily move into openings between lymph capillary cells.

• They are later deposited into the superior vena cava that enters the heart.


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system helps defend the

body against disease.• In the lymph nodes, lymph is forced through

channels that are lined with masses of white blood cells that recognize and destroy foreign particles, such as bacteria or viruses.

• The thymus and spleen are considered part of the lymphatic system.


How Does The Lymphatic System Work With The Circulatory System? The lymphatic system helps defend the

body against disease (continued).• Certain types of white cells mature in the

thymus.• The spleen is another white blood cell-

producing organ, which also filters blood, exposing it to white blood cells that destroy foreign particles and aged red blood cells.


How Are Oxygen And Carbon Dioxide Exchanged In Animal Bodies? The process by which the body acquires

oxygen from the environment and delivers carbon dioxide back to it is called respiration.• Although animal respiration systems are

diverse, they all rely on diffusion of gases across a respiratory surface.

• Respiratory surfaces are large and moist; they must remain moist because gases must be dissolved in water in order to diffuse into or out of cells.


How Are Oxygen And Carbon Dioxide Exchanged In Animal Bodies? Aquatic animals may have gills.

• For some small aquatic animals, gases are exchanged across their body surface.

• Most larger animals have specialized respiratory structures; many have gills, which are elaborately folded to increase their surface area.


How Are Oxygen And Carbon Dioxide Exchanged In Animal Bodies? Aquatic animals may have gills (continued).

• Fish pump oxygen-rich water into the mouth and over the gills, ejecting it through an opening just behind the gills.

• Fish gills have a series of filaments that are covered with capillary-filled lamellae where gases are exchanged.


How Are Oxygen And Carbon Dioxide Exchanged In Animal Bodies? Gills exchange gases with water.

Fig. 20-19

Water flows over gills Gill structure Lamella

waterin

gill arch

water out

(protectiveflapremoved)

gill filament

gill archlamellae

lamella

water flow blood flow

capillaries

deoxygenatedblood

oxygenatedblood

(a) (b) (c)


How Are Oxygen And Carbon Dioxide Exchanged In Animal Bodies? Terrestrial animals have internal respiratory

structures.• In land animals, the respiratory structures are

lungs.• Lungs are chambers containing moist gas-

exchange membranes that are protected within the body, where water loss is minimized.


How Does The Human Respiratory System Work? There are two parts to the human

respiratory system:• The conducting portion• The gas exchange portion


How Does The Human Respiratory System Work? The conducting portion brings air to the

lungs.• Air enters through the nose or mouth, passes

through the nasal cavity or oral cavity into the pharynx, then travels through the larynx.

• Both food and air pass through the pharynx; the epiglottis is a flap of tissue that covers the larynx when food is being swallowed, preventing it from going into the trachea and on to the lungs.


How Does The Human Respiratory System Work? The human respiratory system

Fig. 20-20aHuman respiratory system

diaphragm

nasal cavity

pharynx

oral cavity

epiglottis

larynx

esophagustrachearings ofcartilage

pulmonary vein

pulmonary artery

bronchi

bronchioles

(a)


How Does The Human Respiratory System Work? The conducting portion brings air to the

lungs (continued).• Inhaled air continues past the larynx into the

trachea, which is a flexible tube whose walls are reinforced with semicircular bands of stiff cartilage.

• The trachea splits into two bronchi, which continue to branch more and to get smaller with each branch until they become bronchioles.

• Bronchioles are connected to groups of small air sacs called alveoli.


How Does The Human Respiratory System Work? Alveoli with capillaries

Fig. 20-20bAlveoli with capillaries

bronchiole

pulmonary venule

alveoli

capillarynetwork

pulmonary arteriole

(b)


How Does The Human Respiratory System Work? Gas exchange occurs in the alveoli.

• Both the alveolar wall and the adjacent capillary walls are only one cell thick, so the air in the lungs is extremely close to the blood in the capillaries.

• A thin layer of watery fluid lines each alveolus.


frompulmonaryartery

alveolarmembrane

respiratorymembrane

to pulmonary vein

(air) CO2

O2

capillary

fluid

Oxygen diffusesinto red blood cells

Carbon dioxidediffuses into alveolus

How Does The Human Respiratory System Work? Gases dissolve in this fluid and diffuse

through the alveolar and capillary membranes.

Fig. 20-21


How Does The Human Respiratory System Work? Oxygen diffuses from the air in the alveoli,

where its concentration is high, into the blood, where its concentration is low; the flow of carbon dioxide is opposite to that of oxygen.


Air moves in Air moves out

Rib cagecontracts Lungs

compress

Diaphragmrelaxes upward

Diaphragmcontracts downward

Rib cageexpands Lungs

expand

Inhalation Exhalation(a) (b)

Fig. 20-23

How Does The Human Respiratory System Work? The mechanics of breathing


How Does The Human Respiratory System Work? An overview of

gas exchange

Fig. 20-22

CO2

alveoli(air sacs)

Oxygenated blood

Deoxygenated blood Gases move in and outof the lungs by breathing

O2 andCO2 areexchangedin the lungsby diffusion

Gasesdissolved inblood aretransportedby thecirculatorysystem

O2

left ventricle

O2 and CO2

are exchangedin the tissuesby diffusion

rightatrium

rightventricle

leftatrium

O2

O2

O2

CO2

O2

CO2

CO2

CO2

CO2 CO2

O2


How Does The Human Respiratory System Work?

Animation—Gas ExchangePLAYPLAY


How Does The Human Respiratory System Work? Carbon dioxide and oxygen are transported

in different ways.• Almost all of the oxygen transported in blood

is bound to hemoglobin molecules in red blood cells.

• Hemoglobin only carries about 20% of the carbon dioxide in the blood; the remainder is carried by two processes.• About 10% is dissolved in the plasma.• About 70% is converted to bicarbonate ions

(HCO3–) for transport.


How Does The Human Respiratory System Work? Carbon dioxide and oxygen are transported

in different ways (continued).• Bicarbonate is formed between water and

carbon dioxide in the presence of carbonic anhydrase, which is in the red blood cells:

CO2 + H2O H+ + HCO3–


How Does The Human Respiratory System Work? The lungs are protected in an airtight cavity.

• The chest cavity that surrounds the lungs is airtight.

• It is bounded by neck muscles and connective tissue on top, and by the dome-shaped muscular diaphragm on the bottom.

• Within the wall of the chest, the rib cage surrounds and protects the lungs.


How Does The Human Respiratory System Work? Air is inhaled actively and exhaled

passively.• We breathe in two stages:

• Inhalation, when air is actively drawn into the lungs

• Exhalation, when it is passively expelled from the lungs


How Does The Human Respiratory System Work? Inhalation is accomplished by enlarging the

chest cavity.• The diaphragm muscles contract, drawing the

diaphragm downward.• The rib muscles also contract, lifting the ribs

up an outward.• When the chest cavity expands, the lungs

expand with it and increase their volume, but lower the air pressure inside.

• The air then flows from high pressure outside to low pressure inside.


How Does The Human Respiratory System Work? Inhalation

Fig. 20-23a

Air moves in

Diaphragmcontracts downward

Rib cageexpands Lungs

expand

Inhalation(a)


How Does The Human Respiratory System Work? Exhalation occurs automatically when the

muscles that cause inhalation are relaxed.• The relaxed diaphragm domes upward, and

the ribs move down and inward, decreasing the size of the chest cavity and forcing air out of the lungs.


How Does The Human Respiratory System Work? Exhalation

Fig. 20-23b

Air moves out

Rib cagecontracts Lungs

compress

Diaphragmrelaxes upward

Exhalation(b)


How Does The Human Respiratory System Work? Breathing rate is controlled by the

respiratory center of the brain.• Each contraction of the respiratory muscles is

stimulated by impulses from nerve cells.• The impulses originate in the respiratory

center of the brain, which is located in the medulla, the part of the brain just above the spinal cord.


How Does The Human Respiratory System Work? Breathing rate is controlled by the

respiratory center of the brain (continued).• Nerve cells in the respiratory center generate

cyclic bursts of impulses that cause alternating contraction and relaxation of the respiratory muscles.

• The respiratory rate is regulated to maintain a constant level of carbon dioxide in the blood, as monitored by carbon dioxide receptors in the medulla.

Ch 32 & 33 lecture

Education

types of circulatory

circulatory systemb

vertebrate circulatory

pearson education

major features

smallest blood vessels

blood flows

blood moves