Copyright © 2009 Pearson Education, Inc. Giraffes have –Very strong hearts –Higher blood...

Copyright © 2009 Pearson Education, Inc.

Giraffes have– Very strong hearts

– Higher blood pressure

– Sinuses that function like check valves to lower pressure to head when bending down

– Valves in veins of legs to keep blood moving upward

Blood and respiratory gasses are passed Blood and respiratory gasses are passed through which organ system?through which organ system?


Circulatory system

All cells need

– Nutrients

– Gas exchange

– Removal of wastes

Diffusion alone is inadequate for large and complex bodies


◦ A gastrovascular cavity in cnidarians and flatworms serves

– Digestion

– Distribution of substances

◦ Most animals use a circulatory system– Blood

– Heart

– Blood vessels


1. Open circulatory systems– Arthropods and many molluscs

– Heart pumps blood through open-ended vessels

– Cells directly bathed in blood

PoresTubular heart


2. Closed circulatory systems– Vertebrates, earthworms, squids, octopuses

– Blood stays confined to vessels

– A heart pumps blood through arteries to capillaries; veins return blood to heart

Capillary beds

Artery(O2-rich blood)

Arteriole

Artery(O2-poor blood)

HeartVentricleAtrium

Vein

Venule

Gillcapillaries


Land vertebrates have double circulation

– Separate pulmonary (lung) and systemic (body) circuits

– Two circuits that do not mix

– Right side pumps blood from body to lungs

– Left side pumps blood from lungs to body

Lung capillaries

Pulmonarycircuit

VRight

Systemic capillaries

A A

LeftSystemic

circuit

V

Lung capillaries

Pulmonarycircuit

VRight

Systemic capillaries

A A

LeftSystemic

circuit

V

◦Four-chambered hearts

– Crocodilians, birds, mammals

– Two atria and two ventricles

– Higher blood pressure

– Supports more efficient movement of blood


THE HUMAN CARDIOVASCULAR

SYSTEM

Superiorvena cava

Pulmonaryartery

Capillariesof right lung

8

9

2

3

Aorta

4 510

16

Pulmonaryvein

9Right atrium

Inferiorvena cava

Right ventricle

4

8

3

Pulmonaryartery

Capillariesof left lung

Aorta

Pulmonaryvein

Left atrium

Left ventricle

27

Capillaries ofhead, chest, andarms

Capillaries ofabdominal regionand legs


◦The mammalian heart

– Two thin-walled atria that

– Pump blood – To ventricles

– Two thick-walled ventricles that

– Pump blood – To lungs and all

other body regions

Right atrium

To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Left atrium

To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Rightventricle

Leftventricle


◦During diastole, blood flows

Veins heart

◦During systole, blood flows

Atria ventricles

Semilunarvalvesclosed1 Heart is

relaxed.

AV valvesare open.

Diastole

0.4 sec

2 Atriacontract.

Systole0.1 sec

Semilunarvalvesare open.

3 Ventriclescontract.

AV valvesclosed

0.3 sec


◦Cardiac output– Amount of blood/minute pumped into systemic

circuit

◦Heart rate– Number of beats/minute

◦Heart valves– Prevent the backflow of blood

◦Heart murmur– A defect in one or more heart valves


◦The pacemaker (SA node) – Sets the rate of heart contractions

– Generates electrical signals in atria

◦The AV node– Relays these signals to the ventricles

Pacemaker(SA node) AV node

Rightatrium

1 Pacemakergeneratessignalsto contract

2 Signals spreadthrough atriaand are delayedat AV node

ECG

3 Signals relayedto apex of heart

4 Signals spreadthroughventricle

Apex

Specializedmuscle fibers


◦An electrocardiogram (ECG or EKG)– Records electrical changes in heart

◦Heart rate normally adjusts to body needs

◦Abnormal rhythms may occur in a heart attack


A heart attack is damage to cardiac muscle– Typically from a blocked coronary artery

Blockage

Deadmuscletissue

Rightcoronaryartery

Superiorvena cava

Pulmonaryartery

Aorta

Leftcoronaryartery


Stroke– Death of brain tissue from blocked arteries in the

head


Atherosclerosis– Plaques develop inside inner walls of blood

vessels

– Plaques narrow blood vessels

– Blood flow is reducedPlaqueEpithelium

Connectivetissue

Smoothmuscle


Capillaries– Thin walls—a single layer of epithelial cells

– Narrow—blood cells flow in a single file

– Increase surface area for gas and fluid exchange

Nuclei ofsmoothmusclecells

Redbloodcell

Capillary

Diffusion ofmolecules

Capillary

Interstitialfluid

Tissuecell


◦Blood and interstitial fluid exchange substances

– By diffusion

– By pressure flow through clefts between epithelial cells

◦Blood pressure forces fluid out of capillaries at the arterial end

◦Osmotic pressure draws in fluid at the venous end

Capillaries allow the transfer of Capillaries allow the transfer of substances through their wallssubstances through their walls

Tissue cells

Osmoticpressure

Interstitialfluid

Net fluidmovement in

Bloodpressure

Osmoticpressure Venous

end ofcapillary

Arterialend of

capillary

Bloodpressure

Net fluidmovement out


Arteries and veins– Lined by single layer of epithelial cells; smooth

muscle in walls

– Veins have one-way valves that restrict backward flow

Connectivetissue

Capillary

Venule

Smoothmuscle

Arteriole

Artery Vein

Valve

Epithelium

Basal lamina

Epithelium

Smoothmuscle

Epithelium

Connectivetissue


– Pressure from muscle contractions

– Squeezes veins

– One-way valves limit blood flow to one direction, towards heart

Direction ofblood flowin vein

Valve(open)

Skeletalmuscle

Valve(closed)


– Deep Vein Thrombosis (DVT)– Blood pools deep within body- usually lower leg or

thigh – Clot can form- travel to lungs- pulmonary embolism


– Maintain healthy weight– Don’t smoke– Stretch or move legs on long flights or car rides– Compression garments– Blood thinners


◦Blood pressure

– The force blood exerts on vessel walls

– Depends on

– Cardiac output

– Resistance of vessels

– Decreases as blood moves away from heart

Systolicpressure

Diastolicpressure

120100

806040200

Relative sizes andnumbersof bloodvessels

Pre

ssu

re (

mm

Hg

)V

elo

city

(cm

/sec

)

5040302010

0

Ao

rta

Ven

ae c

avae

Art

erie

s

Cap

illar

ies

Ven

ule

s

Vei

ns

Art

erio

les


Blood pressure is – Highest in ________– Lowest in _________

Blood pressure is measured as – Systolic pressure—caused by ventricular

contraction– Diastolic pressure—low pressure between

contractions


Hypertension is a serious cardiovascular problem

– Consistent pressures above either– 140 systolic– 90 diastolic

Typical bloodpressure120 systolic70 diastolic Pressure

in cuffabove 120120Rubber cuff

inflatedwith air

Arteryclosed

Artery

1 2

Pressurein cuffat 120120

Soundsaudible instethoscope

3

70

Soundsstop

4

Pressurein cuffat 70


Hypertension causes– Heart to work harder, weakening heart over time– Increased plaque formation from tiny ruptures– Increased risk of blood clot formation

Hypertension can cause– Heart attacks– Strokes– Kidney failure


STRUCTURE AND FUNCTION

OF BLOOD


Plasma is about 90% water

Plasma contains – Various inorganic ions

– Proteins, nutrients

– Wastes, gases

– Hormones

Plasma (55%)

Constituent

Osmotic balance,pH buffering, andmaintaining ionconcentration ofinterstitial fluid

Solvent forcarrying othersubstances

Water

Ions (blood electrolytes)

Major functions

SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Plasma proteins

ClottingFibrinogen

Osmotic balanceand pH buffering

Defense Immunoglobulins(antibodies)

Substances transported by blood

Nutrients (e.g., glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones

Centrifugedblood

sample


◦Red blood cells (erythrocytes)– Transport O2 bound to hemoglobin

◦White blood cells (leukocytes)– Function inside and outside the circulatory

system

– Fight infections and cancer

◦Platelets

Cellular elements (45%)

Centrifugedblood

sample

Numberper µL (mm3) of blood

Cell type Functions

Erythrocytes(red blood cells) 5–6 million Transport of

oxygen (andcarbon dioxide)

Leukocytes(white blood cells)

BasophilLymphocyte

Defense andimmunity

Eosinophil

5,000–10,000

250,000–400,000

Neutrophil Monocyte

Blood clottingPlatelets

Plasma (55%)

Constituent

Osmotic balance,pH buffering, andmaintaining ionconcentration ofinterstitial fluid

Solvent forcarrying othersubstances

Water

Ions (blood electrolytes)

Major functions

SodiumPotassiumCalciumMagnesiumChlorideBicarbonate

Plasma proteins

ClottingFibrinogen

Osmotic balanceand pH buffering

Defense Immunoglobulins(antibodies)

Substances transported by blood

Nutrients (e.g., glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)Hormones

Cellular elements (45%)

Centrifugedblood

sample

Numberper µL (mm3) of blood

Cell type Functions

Erythrocytes(red blood cells) 5–6 million Transport of

oxygen (andcarbon dioxide)

Leukocytes(white blood cells)

BasophilLymphocyte

Defense andimmunity

Eosinophil

5,000–10,000

250,000–400,000

Neutrophil Monocyte

Blood clottingPlatelets


◦Function:

◦If too few:– Anemia: abnormally low amounts of

hemoglobin or red blood cells

– Causes fatigue due to lack of oxygen in tissues


Function: Clot formation during tissue damage

◦ When a blood vessel is damaged

– Platelets help trigger the conversion of fibrinogen to fibrin

– Fibrin forms a net with cells (clot) that plugs the leak

Platelets adhereto exposedconnective tissue

1

Epithelium

Connective tissue

Platelet


1

Epithelium

Connective tissue

Platelet

Platelet plugforms

2

Platelet plug


1

Epithelium

Connective tissue

Platelet

Platelet plugforms

2

Platelet plug

Fibrin clottrapsblood cells

3

Copyright © 2009 Pearson Education, Inc. Giraffes have –Very strong hearts –Higher blood...

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