Circulation and gas

exchange

Salmon gill

Life exists in a friendly, watery medium

• What are the needs of the cell?• What is the fluid that supplies the

needs of the cell? What are its characteristics?

• What keeps that fluid “friendly?”

Overview of circulatory systems• Three (or four) components:

– Fluid bathing cells = interstitial fluid– Circulatory fluid = “hemolymph” or “blood”– Tubes = blood vessels– Muscular pump = heart (usually)

• Pressure produced by the heart moves blood through vessels down a pressure gradient, and the blood eventually returns to the heart

• Two types of circulatory systems– Open– Closed

Open circulatory system• Arthropods and

mollusks• Blood and interstitial

fluid are not separated; they form hemolymph

• Hemolymph pumped through sinuses (spaces around organs) and returned via pores, or ostia

Fig. 42.3a

Closed circulatory system• Blood and

interstitial fluid are separated

• Earthworms, squid, octopus, and vertebrates

• All exchange between blood and tissues happens by diffusion in capillary beds.

Fig. 42.3b

A few more terms

• Cardiovascular system of vertebrates• Hearts are composed of atria (chambers

that receive blood) and ventricles (chambers that pump blood out)

• Arteries contain blood moving away from the heart and towards capillaries

• Veins contain blood moving towards the heart and away from capillaries

• Sinuses are spaces where blood collects• But the thin-walled capillaries are still

where all the real action is.

Circulation in vertebrates• Exchanging oxygen and carbon dioxide

PICK UP OXYGEN

LET OXYGEN GO2 chambers

Single circulation

• Single Circulation Allows only Low Pressure Circulation to the tissues

PICK UP OXYGEN

LET OXYGEN GO2 chambers

PICK UP OXYGEN

LET OXYGEN GO2 chambers 3 chambers

Single circulation;Loses pressure

Double circulation;Maintains pressure

• Three chambered hearts and dual circulation maintain pressure but allow mixing

PICK UP OXYGEN

LET OXYGEN GO2 chambers 3 chambers

Single circulation;Loses pressure

Double circulation;Maintains pressure

O2 mixing?

Dual circulation with a 4-chambered heart: high pressure, no mixing: most efficient

PICK UP OXYGEN

LET OXYGEN GO2 chambers 3 chambers 4 chambers

Single circulation;Loses pressure

Double circulation;Maintains pressure

O2 mixing?

Mammalian cardiovascular system

• Double circulation

• Right: deoxy• Left: oxy

Fig. 42.6

Mammalian heart• Wall

thickness• Valves: AV

& semilunar• Lub-dup =

valves closing

• A heart murmur is a defect in a valve

Fig. 42.7

Where were we?

• Animal Physiology– Circulatory System– Respiratory System

• Needs of the cell - friendly, watery medium• Structure of circulatory systems

– Interstitial fluid– Circulating fluid– Pumping organ– Blood vessels and spaces

• Functions– Transport (of nutrients, oxygen, wastes). The role of

respiratory pigments.– Defense

• Types of circulatory systems– None– Open– Closed

• Circulation in vertebrates– Types of circuit

• Single• Double/three chambered heart• Double/four chambererd heart

• Blood pressure

Blood flow

• Systole vs. diastole

Fig. 42.10

Arteries and veins• Which is which?

Blood vessels• 1 to 3 layers• Endothelium: layer of smooth, flattened cells

Fig. 42.8

ElasticThicker

Thinner

Elastic

Blood• Specialized connective tissue

Fig. 42.14

Hemoglobin

Cardiovascular disease• Heart attacks—death of cardiac muscle due to prolonged blockage

of coronary arteries (which bring oxygenated blood to heart)• Strokes—death of nervous tissue in the brain due to blockage or

rupture of arteries in head• Atherosclerosis—chronic condition often leading to the above

conditions; plaques (fibrous connective tissue + lipids) narrow arteries

Normal Plaque

Gas exchange

• Tracheal systems

• Gills• Lungs

Fig. 42.18

DIFFUSION

Tracheal systems• Life on land

Skin• Moist skin - small aquatic invertebrates, salamanders, frogs

Skin and External Gills

mudpuppy

tadpole

InternalGills

• Water vs. air– 4 – 8 vs. 210 ml O2 per liter– Diffusion speed– Continuously pumping water

Countercurrent exchange• Always maintaining a gradient

Fig. 42.21

Why do fish out of water suffocate?

Lungs• Life on land

Fig. 42.23

Note [02] &veins & arteries

phagocytosis

Gas loading and unloading

• Partial pressures and diffusion