Chapter 23

Circulation

Standards

CORE:

• I can describe the components and function of blood.

• I can describe structure and function of blood vessels.

• I can compare and contrast systemic and pulmonary systems.

• I can outline blood flow through the heart.

• I can explain why blood pressure is related to overall heath.

• I can compare and contrast adult and fetal circulation.

ADVANCED:

• I can trace a red blood cell through the body and back to its starting point.

• I can describe nervous control of the heartbeat.

How Does Gravity Affect Blood Circulation?

• Few animals seem less alike than the giraffe and the corn snake

• Despite their differences they have many features in common

• What do you think they have in common??

• Most animals have a circulatory system that transports O2 and nutrients to cells and takes away CO2 and other wastes

• The circulatory system of land animals must deal with the problem of gravity

• 23.1 The circulatory system connects with all body tissues

• In many animals, microscopic blood vessels called capillaries form an intricate network among the tissues

• These capillaries are fed by arteries and empty into veins

Capillary

Nuclei of

smooth

muscle

cells

Red

blood

cell

LM

70

0

Figure 23.1A

Hank – circulatory system

STRUCTURE AND FUNCTION OF BLOOD

• 23.13 Blood consists of red and white blood cells suspended in plasma

• Plasma is about 90% water

• And contains various inorganic ions, proteins, nutrients, wastes, gases, and hormones

Plasma (55%)

Constituent Major functions

Water Solvent forcarrying othersubstances

Salts (ions)SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Osmotic balance,pH buffering, andnerve and musclefunction

Plasma proteins

Fibrinogen

Immunoglobulins

(antibodies)

Osmotic balance and pH buffering

Immunity

Clotting

Substances transported by blood

Nutrients (e.g., glucose, fatty

acids,vitamins) Waste products of

metabolismRespiratory gases (O2 and CO2)Hormones

Centrifugedblood

sample

Figure 23.13 (left part)

Bloody Blood!

• Red blood cells (erythrocytes)

• Transport O2 bound to hemoglobin

• White blood cells (leukocytes)

• Function both inside and outside the circulatory system to fight infections and cancer

Centrifugedblood

sample

Cellular elements (45%)

Cell type Number

per L (mm3) of blood

Functions

Erythrocytes

(red blood cells)5–6 million Transport

of oxygen

(and carbon

dioxide)

Leukocytes

(white blood cells)5,000–10,000 Defense

and

immunity

Basophil

Eosinophil

Lymphocyte

Monocyte

Blood clotting250,000–

400,000

Platelets

Neutrophil

Figure 23.13 (right part)

CONNECTION

• 23.14 Too few or too many red blood cells can be unhealthy

• Anemia is an abnormally low amount of hemoglobin or red blood cells

• The hormone erythropoietin regulates red blood cell production

• Some athletes artificially increase their red blood cell production, a dangerous practice – why would they want to do this?? C

olo

rized S

EM

3,4

00

Figure 23.14

THE MAMMALIAN CARDIOVACULAR SYSTEM

• 23.4 The human heart and cardiovascular system are typical of mammals

• The mammalian heart

• Has two thin-walled atria that pump blood into the ventricles

• Has thick-walled ventricles that pump blood to all other body organs

Right

atrium Left

atrium

Semilunar

valve

Semilunar

valve

Atrioventricular

(AV) valveAtrioventricular

(AV) valve

Right

ventricleLeft

ventricleFigure 23.4A

• Blood flow through the human cardiovascular system

Figure 23.4B

1

2 7

8

9

2

3

4

5

6

410

3

9

8

Superior

vena cava

Capillaries of

head, chest, and

arms

Pulmonary

artery

Capillaries

of left lung

Pulmonary

vein

Aorta

Left atrium

Left ventricleAorta

Capillaries of

abdominal region

and legs

Inferior

vena cava

Right ventricle

Right atrium

Pulmonary

vein

Capillaries

of right lung

Pulmonary

artery

• 23.5 The structure of blood vessels fits their functions

• A single layer of epithelial cells forms the walls capillaries

• Arteries and veins have smooth muscle and connective tissue

Figure 23.5

Capillary

EpitheliumBasement

membrane Valve

Epithelium

Smoothmuscle

Connective

tissue

Vein

VenuleArteriole

Artery

Connective

tissue

Smoothmuscle

Epithelium

• Muscle contractions and one-way valves keep blood moving through the veins to the heart

Skeletal

muscle

Direction of

blood flow

in veinValve

(open)

Valve

(closed)

Figure 23.9B

• Capillaries are the sites of exchange between blood and interstitial fluid and are one cell layer thick

Capillary

Interstitial

fluid

Tissue

cell

Diffusion of

molecules

Figure 23.1B

• 23.12 Capillaries allow the transfer of substances through their walls

TE

M 5

,000

Muscle

cell

Cleft between

two epithelial

cells of the

capillary wall

Nucleus of

epithelial

cell

Capillary

wall

Iumen

Interstitial

fluid

Figure 23.12A

CONNECTION

• Not all of our capillaries can be used at the same time – if they are you will go into shock!

• Our body controls entry of blood into capillary networks using sphincters in the arterioles prior to a capillary network

• Apart from avoiding shock, when and why would our bodies want to do this?

Flow of blood through the heart

Heart Beat, Beat, Beat

• During diastole blood flows from the veins into the heart chambers

• During systole

• Contractions of the atria push blood into the ventricles

• Stronger contractions of the ventricles propel blood into the large arteries

• Cardiac output is the amount of blood/minute pumped into the systemic circuit

• Heart valves prevent the backflow of blood

Figure 23.6

Heart is

relaxed.

AV valves

are open.

1 2 Atria

contract.

Systole

Diastole

0.4 sec

0.1sec

0.3 sec 3 Ventricles

contract.

Semilunar

valves

are open.

23.6 The heart contracts and relaxes

rhythmically

• 23.7 The pacemaker sets the tempo of the heartbeat

• The pacemaker (SA node) generates electrical signals that trigger contraction of the atria

• The AV node relays these signals to the ventricles

Figure 23.7

1 2 3 4

Pacemaker

(SA node) AV node

Specialized

muscle fibers

Apex

Right

ventricle

Right

atrium

ECG

ECG / EKG

• An electrocardiogram (ECG) records the electrical changes in the heart

• Heart rate adjusts to body needs

CONNECTION

• 23.8 What is a heart attack?

• A heart attack is damage to cardiac muscle usually resulting from a blocked coronary artery

AortaSuperior

Vena cava

Pulmonary

artery

Left

coronary

artery

Right

coronary

arteryBlockage

Dead

muscle

tissueFigure 23.8A

Atherosclerosis

• In atherosclerosis plaques develop in the inner walls of arteries and can block blood flow

Connective

tissue

Smooth

muscleEpithelium

LM

16

0

LM

60

Plaque

Figure 23.8B

Hypertension

• Is a serious cardiovascular problem

resulting from consistent high blood

pressure in the arteries

• 23.9 Blood exerts pressure on vessel walls• Blood pressure

• Is the force blood exerts on vessel walls

• Depends on cardiac output and the resistance of vessels

• Pressure is highest in the arteries and lowest in the veins

Pre

ssure

(m

m H

g)

120

100

80

60

40

200

Systolic

pressure

Diastolic

pressure

Relative sizes and

numbers

of blood

vessels

Velo

city

(cm

/sec)

50

40

30

20

10

0

Aort

a

Art

eries

Art

eriole

s

Capill

aries

Venule

s

Venae c

avae

Vain

s

Figure 23.9A

CONNECTION

• 23.10 Measuring blood pressure can reveal cardiovascular problems

• Blood pressure is measured as systolic and diastolic pressures

Bloodpressure110 systolic70 diastolic(to be measured)

Rubber cuffinflatedwith air

Artery

1 2 3 4

Artery

closed

Pressurein cuffabove 110

110

Pressurein cuffat 110

110

Pressurein cuffat 70

70

Sounds

stop

Soundsaudible instethoscope

Figure 23.10

• The transfer of materials between the blood and interstitial fluid occurs

• By diffusion

• By pressure flow through clefts between epithelial cells

Tissue cells

Osmotic

pressureArterial

end of

capillary

Interstitial

fluidNet fluid

Movement outNet fluid

Movement in

Blood

pressure

Blood

pressure

Osmotic

pressureVenous

end of

capillary

Figure 23.12B

• Blood pressure forces fluid out of the capillary at the arterial end and osmotic pressure draws fluid at the venous end

• 23.15 Blood clots plug leaks when blood vessels are injured

• When a blood vessel is damaged platelets help trigger the conversion of fibrinogen to fibrin, forming a clot that plugs the leak

Colo

rized S

EM

3,4

00

Figure 23.15B

The blood-clotting process

Epithelium

1 Platelets adhere to

exposed connective tissue

Connective

tissue

PlateletPlatelet plug

2 Platelet plug forms 3Fibrin clot

traps blood

cells

Figure 23.15A

CONNECTION

• 23.16 Stem cells offer a potential cure for blood cell diseases

• Stem cells divide in bone marrow to produce all blood cells and may be used to treat some blood disorders

Figure 23.15B

Stem cells Stem cells

Erythrocytes Basophils

Eosinophils

Neutrophils Monocytes Lymphocytes

Platelets

Fetal Circulation

• The fetus does not use

lungs for acquiring

oxygen.

Why???

Fetal Circulation

Placenta - organ responsible for delivery of nutrients, removal of waste products and delivery of oxygenated blood to the fetus via diffusion and active transport mechanisms.

Fetal Circulation – 4 differencesAKA: The Fetal Four

1. Umbilical cordA. Umbilical vein (1)- A vessel which delivers oxygenated

and nutrient rich blood from the placenta to the fetus.B. Umbilical arteries (2) vessels that carries

deoxygenated blood from iliac arteries out to the placenta.

2. Venous duct - receives blood from the umbilical vein and directs it to the posterior/inferior vena cava. This venous duct acts as a liver bypass and moves blood into the fetal systemic circulation.

Function – to bypass the liver Why bypass the liver??

Fetal Circulation

3. Foramen Ovale - an opening between the right atrium and left atrium

Function – to bypass the lungs

Why bypass the lungs??

Fetal Circulation

4. Ductus Arteriosus - A vessel that connects the pulmonary artery to the aorta.

Function – to bypass pulmonary circuit.

Lymph System

• Is a one way transport system (tissues to blood)

• Takes excess fluid from capillary beds of body and returns it to the blood

• CONSISTS of lymph veins (have valves) and capillaries

• Fluid is called lymph

• Joins blood at subclavian vein

Main Functions of Lymphatic System

1. Take up excess tissue fluid

2. Transport fatty acids (from LACTEAL)

3. Fight infection (lymphocytes)

• lymph system

Parts of Lymphatic System

1. LACTEAL: dead ends of lymph vessels in villi of the small intestine.

2. LYMPH NODES - small oval structures that produce and store lymphocytes, filter the lymph of damaged cells and debris.

3.SPLEEN: stores blood.

4.THYMUS GLAND -production and maturation of some lymphocytes.