Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CHAPTER 50 LECTURE SLIDES To run the animations you must be.

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CHAPTER 50LECTURE

SLIDES

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The Circulatory SystemChapter 50

Blood

• Type of connective tissue composed – Fluid matrix called plasma– Formed elements

• Functions of circulating blood1.Transportation

2.Regulation

3.Protection

3

4

Blood plasma

• 92% water

• Contains the following solutes– Nutrients, wastes, and hormones– Ions– Proteins

• Albumin, alpha () and beta () globulins • Fibrinogen

– If removed, plasma is called serum

5

Formed elements

• Red blood cells (erythrocytes)– About 5 million per microliter of blood– Hematocrit is the fraction of the total blood

volume occupied by red blood cells– Mature mammalian erythrocytes lack nuclei– RBCs of vertebrates contain hemoglobin

• Pigment that binds and transports oxygen

6

Formed elements

• White blood cells (leukocytes)– Less than 1% of blood cells– Larger than erythrocytes and have nuclei– Can migrate out of capillaries into tissue fluid– Types

• Granular leukocytes– Neutrophils, eosinophils, and basophils

• Agranular leukocytes– Monocytes and lymphocytes

7

Formed elements

• Platelets• Cell fragments that pinch off from larger cells

in the bone marrow• Function in the formation of blood clots

8

Formed elements

• All develop from pluripotent stem cells

• Hematopoiesis is blood cell production

• Occurs in the bone marrow

• Produces 2 types of stem cells– Lymphoid stem cell Lymphocytes– Myeloid stem cell All other blood cells

• Erythropoietin stimulates the production of erythrocytes (erythropoiesis)

9

10

Invertebrate Circulatory Systems

• Sponges, Cnidarians, and nematodes lack a separate circulatory system

• Sponges circulate water using many incurrent pores and one excurrent pore

• Hydra circulate water through a gastrovascular cavity (also for digestion)

• Nematodes are thin enough that the digestive tract can also be used as a circulatory system

11


• Nature of the circulatory system in multicellular invertebrates is directly related to the size, complexity, and lifestyle of the organism

• No circulatory system– Sponges and most cnidarians utilize water from the

environment as a circulatory fluid• Gastrovascular cavity

– Nematodes• Use the fluids of the body cavity for circulation• Small or long and thin

12


• Larger animals require a separate circulatory system for nutrient and waste transport

• Open circulatory system– No distinction between circulating and extracellular

fluid– Fluid called hemolymph

• Closed circulatory system– Distinct circulatory fluid enclosed in blood vessels and

transported away from and back to the heart

13

14

Vertebrate Circulatory Systems

• Fishes– Evolved a true chamber-pump heart – Four structures are arrayed one after the

other to form two pumping chambers• First chamber – sinus venosus and atrium• Second chamber – ventricle and conus arteriosus

– These contract in the order listed

• Blood is pumped through the gills, and then to the rest of the body

15

16



• Amphibians– Advent of lungs required a second pumping

circuit, or double circulation– Pulmonary circulation moves blood between

the heart and lungs – Systemic circulation moves blood between

the heart and the rest of the body

17


• Amphibian heart– 3-chambered heart

• 2 atria and 1 ventricle

– Separation of the pulmonary and systemic circulations is incomplete

– Amphibians living in water obtain additional oxygen by diffusion through their skin

– Reptiles have a septum that partially subdivides the ventricle, thereby further reducing the mixing of blood in the heart

18

19


• Mammals, birds, and crocodilians– 4-chambered heart– 2 separate atria and 2 separate ventricles– Right atrium receives deoxygenated blood

from the body and delivers it to the right ventricle, which pumps it to the lungs

– Left atrium receives oxygenated blood from the lungs and delivers it to the left ventricle, which pumps it to rest of the body

20

21

22


Lancelets

Fish Mammals

TurtlesAmphibians

Crocodilians

Squamates Birds

4-chamberheart4-chamber

heart

3-chamberheart

2-chamberheart

The Cardiac Cycle• Heart has two pairs of valves

– Atrioventricular (AV) valves• Maintain unidirectional blood flow between atria and

ventricles• Tricuspid valve = On the right• Bicuspid, or mitral, valve = On the left

– Semilunar valves

• Ensure one-way flow out of the ventricles to the arterial systems

• Pulmonary valve located at the exit of the right ventricle

• Aortic valve located at the exit of the left ventricle

23

The Cardiac Cycle

• Valves open and close as the heart goes through the cardiac cycle

• Ventricles relaxed and filling (diastole)

• Ventricles contracted and pumping (systole)

• “Lub-dub” sounds heard with stethoscope– Lub – AV valves closing– Dub – closing of semilunar valves

24

Right ventricle

1. The atria contract.

Diastole

“Lub” “Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve

2. “Lub”: The ventriclescontract, theatrioventricular (AV)valves close, andpressure in theventricles builds

up until the aortic and pulmonary valves open.

3. Blood is pumped outof ventricles andinto the aorta andpulmonary artery.

5. The ventricles fill with blood.

4. “Dup”: The ventriclesrelax, the pressure inthe ventricles falls atthe end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut.

Time (seconds)

65 mL

130 mL

25


Right ventricle


Diastole

“Lub” “Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve






pressure inleft ventricle

Time (seconds)

65 mL

130 mL

26


Right ventricle


Diastole

“Lub”

1.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







Time (seconds)

65 mL

130 mL

27


Right ventricle


Diastole

“Lub”

1. 2.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







Time (seconds)

65 mL

130 mL

28


Right ventricle


Diastole

“Lub”

1. 2.

3. “Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







Time (seconds)

65 mL

130 mL

29


Right ventricle


Diastole

“Lub”

1. 2.

3.

4.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







Time (seconds)

65 mL

130 mL

30


Right ventricle


Diastole

“Lub”

1. 2.

3.

4.5.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







Time (seconds)

65 mL

130 mL

31


Right ventricle


Diastole

“Lub”

1. 2.

3.

4.5.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







pressurein aorta

Time (seconds)

65 mL

130 mL

32


Right ventricle


Diastole

“Lub”

1. 2.

3.

4.5.

“Dup”

DiastoleSystole

Pre

ssu

re (

mm

Hg

)

0

25

0.10 1.00.90.80.6 0.70.50.40.30.2

50

75

100

125

Pulmonaryvalve

Rightatrium

AVvalves

Leftventricle

Leftatrium

Aorticvalve







pressurein aorta

Time (seconds)

65 mL

130 mL

volume inleft ventricle


33

The Cardiac Cycle

• Heart contains “self-excitable” autorhythmic fibers

• Most important is the sinoatrial (SA) node– Located in wall of right atrium– Acts as pacemaker– Autonomic nervous system can modulate rate

34

The Cardiac Cycle

• Each SA depolarization transmitted– To left atrium– To right atrium and atrioventricular (AV) node

• AV node is only pathway for conduction to ventricles– Spreads through atrioventricular bundle– Purkinje fibers– Directly stimulate the myocardial cells of both

ventricles to contract35

The Cardiac Cycle

• Electrical activity can be recorded on an electrocardiogram (ECG or EKG) – First peak (P) is produced by depolarization of

atria (atrial systole)– Second, larger peak (QRS) is produced by

ventricular depolarization (ventricular systole)– Last peak (T) is produced by repolarization of

ventricles (ventricular diastole)

36

Seconds

R

T wave

1 sec

+1

-1

0

Purkinje fibers

Left atriumRight atrium

Purkinje fibers

AV bundle

SA node(pacemaker)

AV node

AV bundleInterventricularseptum

Left and rightbundle branches

1. The impulse begins at the SA node and travels to theAV node.

InternodalpathwayAV

2. The impulse is delayed at the AV node. It then travels to the AV bundle.

P wave

Mill

ivo

tts

QS


37

Seconds

R

T wave

1 sec

+1

-1

0

Purkinje fibers

AV bundle

Interventricularseptum

3. From the AV bundle, the impulse travelsdown the interventricular septum.

Left and rightbundle branches

5. Finally reaching the Purkinje fibers, the impulse is distributed throughout the ventricles.

4. The impulse spreads to branches from the interventricular septum.

P wave

Mill

ivo

tts

38


QS

The Cardiac Cycle

• Right and left pulmonary arteries deliver oxygen-depleted blood from the right ventricle to the right and left lungs

• Pulmonary veins return oxygenated blood from the lungs to the left atrium of the heart

39

The Cardiac Cycle

• Aorta and all its branches are systemic arteries, carrying oxygen-rich blood from the left ventricle to all parts of the body– Coronary arteries supply oxygenated blood to

the heart muscle

• Blood from the body drains into the right atrium– Superior vena cava drains upper body– Inferior vena cava drains lower body

40

The Cardiac Cycle

• Arterial blood pressure can be measured with a sphygmomanometer

• Systolic pressure is the peak pressure at which ventricles are contracting

• Diastolic pressure is the minimum pressure between heartbeats at which the ventricles are relaxed

• Blood pressure is written as a ratio of systolic over diastolic pressure

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42

Characteristics of Blood Vessels

• Blood leaves heart through the arteries

• Arterioles are the finest, microscopic branches of the arterial tree

• Blood from arterioles enters capillaries

• Blood is collected into venules, which lead to larger vessels, veins

• Veins carry blood back to heart

43


• Arteries and veins are composed of four tissue layers– Endothelium, elastic fibers, smooth muscle, and

connective tissue– Walls too thick for exchange of materials across the

wall

• Capillaries are composed of only a single layer of endothelial cells– Allow rapid exchange of gases and metabolites

between blood and body cells

44

45



• Arteries and arterioles– Larger arteries contain more elastic fibers in their

walls than other blood vessels• Recoil each time they receive blood from the heart

– Contraction of the smooth muscle layer of the arterioles results in vasoconstriction

• Greatly increases resistance and decreases flow• Chronic vasoconstriction can result in hypertension

– Relaxation of the smooth muscle layer results in vasodilation

• Decreasing resistance and increasing blood flow to an organ

46

• Vasoconstriction and vasodilation are important means of regulating body heat in both ectotherms and endotherms

47


• Capillaries– Every cell in the body is within 100

micrometers (μm) of a capillary– Although each capillary is very narrow, so

many of them exist that the capillaries have the greatest total cross-sectional area of any other type of vessel

• Slows blood flow to allow for exchange with extracellular fluid

48


• Veins and venules– Thinner layer of

smooth muscles than arteries

– Venous pump helps return blood to heart

• Skeletal muscle contractions and one-way venous valves

49

The Lymphatic System

• Significant amount of water and solutes in the blood plasma filter through the walls of the capillaries to form the interstitial (tissue) fluid

• Most fluid leaves at the arteriole end of the capillary and returns at the venule end

• Fluid that does not return to capillaries is returned to circulation by the lymphatic system

50

51

Blood pressure

Osmotic pressure

Capillary bedArteriole Venule

a.

b.

Capillary

Direction of blood flow

Filtration

Absorption

Arteriole

Arteriole

Lymphaticcapillary

Interstitialfluid

Lymphaticcapillary

Excess interstitial fluidbecomes lymph

Interstitialfluid

Venule

Bloodflow

Pre

ssu

re

Net filtration due toblood pressure

Net absorption due toosmotic pressure

Venule


The Lymphatic System

• Consists of lymphatic capillaries, lymphatic vessels, lymph nodes, and lymphatic organs (spleen and thymus)

• Excess fluid in the tissues drains into blind-ended lymph capillaries

• Lymph passes into progressively larger vessels with one-way valves

• Eventually drains into subclavian veins

52

Cardiovascular Diseases

• Leading cause of death in the United States• Atherosclerosis

– Accumulation of fatty material within arteries– Impedes blood flow

• Arteriosclerosis – Arterial hardening due to calcium deposition

53

Cardiovascular Diseases

• Heart attacks (myocardial infarctions)– Main cause of cardiovascular deaths in U.S.– Insufficient supply of blood to heart

• Angina pectoris (“chest pain”)– Warning sign that the blood supply to the

heart is inadequate but is still sufficient to avoid myocardial cell death

• Stroke– Interference with blood supply to the brain

54

Blood Flow and Blood Pressure

• Autonomic nervous system modulates heart rhythm and force of contraction

• Cardiac center of the medulla oblongata modulates heart rate– Norepinephrine, from sympathetic neurons,

increases heart rate– Acetylcholine, from parasympathetic neurons,

decreases heart rate

55


• Cardiac output is the volume of blood pumped by each ventricle per minute– Increases during exertion because of an

increase in both heart rate and stroke volume

• Arterial blood pressure (BP) depends on the cardiac output (CO) and the resistance (R) to blood flow in the vascular system

• BP = CO x R

56


• Baroreceptor reflex– Negative feedback loop that responds to blood

pressure changes– Baroreceptors detect changes in arterial blood

pressure – If blood pressure decreases, the number of

impulses to cardiac center is decreased• Ultimately resulting in blood pressure increase

– If blood pressure increases, the number of impulses to cardiac center is increased

• Ultimately resulting in blood pressure decrease 57

58


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• Blood pressure increases with blood volume

• Blood volume is regulated by four hormones– Antidiuretic hormone (ADH)– Aldosterone– Atrial natriuretic hormone– Nitric oxide (NO)

60

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CHAPTER 50 LECTURE SLIDES To run the animations you must be.

Documents

chamber heart slide

blood plasma

deoxygenated blood

blood vessels

mixing of blood

blood cells larger

blood cells erythropoietin

circulatory system chapter