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Circulation & Gas Exchange

From Ch. 42

13 July 2009 1Circulation & GasEx.ppt

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13 July 2009 Circulation & GasEx.ppt 2

Animal Life

Four critical processes

Obtain energy and material

Ingest, digest, absorb

Obtain oxygen

Dispose of nitrogenous waste

NH3, urea, uric acid

Dispose of CO2

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Animal Life

Harder for multicellular

organisms

Internal circulation

Coordination,information transfer

Structural maintenance

Movement

Maintenance ofhomeostatic internal

environment


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Circulatory System

Why have a circulatory System? Small animals often dont.

Cnidarians, flatworms, nematodes

Cells get sufficient O2, diffusion from environment

Cells dispose of wastes to environment

Cells get nutrients from gut by diffusion


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Circulatory System

Why have a circulatory System?

Larger animals MUST have circulatory system

Most cells too far from surface and too far from gut

Diffusion would take too long!!!

Circulatory systems bring O2, food, to all tissues

All cells close enough to a capillary

Circulatory systems carry away metabolic wastes

Circulatory systems carry regulatory signaling

molecules


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Circulatory System

Open and closed circulatory systems Open: hemolymph flows through hemocoel

Closed: blood confined to vessels


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Circulatory System

Vertebrate circulatory systems

Amphibians & Reptiles


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Circulatory System

Vertebrate circulatory

systems

Mammalian systems

4-chambered heart Gas exchange in lungs


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Organization of the

Cardiovascular System

Heart = muscular double pump

Blood = circulating fluid tissue

Vessels

Arteries carry blood FROM the heart,

Capillaries distribute O2, nutrient molecules,

and pick up wastes,

Veins return blood TOWARD the heart

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Organization of the

Cardiovascular System

Two circulations

Pulmonary

To and from lungs

Systemic

To and from all other tissues

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The Heart

Ya gotta have heart, miles and miles

and miles of heart.

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The Heart

Mammalian heart

Hollow, muscular

Double pump

Right: Pulmonarycirculation

Left: Systemic

circulation


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The Heart

Location

Thoracic region in

pericardial sac, between

lungs

2/3 of mass left of

midsagittal plane

Apex = lower tip of left

ventricle

Base = flat superior

side, tops of atria.


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The Heart

Chambers

2 Atria

receive venous return

2 Ventricles receive blood from

atria,

pump blood out

through major arteries


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The Heart

Valves direct bloodflow through the heart

2 Atrioventricular

valves Tricuspid Bicuspid or Mitral

2 Semilunar valves

Pulmonary Aortic

Operation of valves


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Vessels

Arteries

Carry blood from heart

Thick muscular wall

Veins Carry blood to heart

This nwall

Capillaries Extremely thin

membrane for

exchange


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Vessels

Blood pressure Systolic

Diastolic


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Vessels

Capillary Exchange

Filtration & bulk flow

Diffusion

Osmosis

Excess fluid picked up

by lymphatic system


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Vessels


Venous return

Low venous pressures

Venous pumps

Muscular pump

Respiratory pump

Valves

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Circ & Gas Ex