Respiration and Circulation

Biology 155A.Russo-Neustadt

Respiration and Circulation are coupled processes in most animals

The systems function together to exchange gases with the environment and transport them to the tissues

I. Types of Respiratory Exchange “Organs”:

A. The Body Surface –

1. Requires no respiratory system

2. Animal must be small or thin

3. Must have low oxygen /energy requirements

4. Diffusion alone accounts for gas exchange

Oxygen

Carbon Dioxide

Animals who use their body surface for respiratory exchange include

Sponges Jellyfish Flatworms (previous slide) Sea stars

B. Gills –

1. Evaginations from the body surface

2. Used by aquatic animals

Gill arch

(In mouth to oral cavity over gills and out slit)

Muscles in oral cavity serve as pump for one-way water flow, due to density of water

Animals who use gills for respiratory exchange include

Marine worms Clams and mussels Lobsters and shrimp Vertebrate fishes

(previous slide)

C. “Lungs”

Used by terrestrial animals Invaginations from the body surface to

decrease water loss Two major types –

True lungs – used by snails and slugs, vertebrates from amphibians to mammals

Tracheal system of insects

a. True lungs – localized exchange surface where oxygen is loaded into the bloodstream

Trachea with cartilaginous rings

bronchuslungBronchial tree

alveolus

oxygen Carbon dioxide

Ventilation uses tidal flow of air due to density

b. Trachea = system of air filled tubes that branches throughout body

Tracheole delivers oxygen to individual cells

Note unique uncoupling between respiratory and circulatory systems

D. All Respiratory Systems have the Following Things in Common –

Large surface area to maximize gas exchange

Thin exchange surfaces to maximize the rate of gas exchange

D. All Respiratory Systems have the Following Things in Common –continued Gills and true lungs are also –

Ventilated = use muscle pumps to keep oxygen rich medium in contact with the exchange surface

Perfused = use muscle pumps to move blood through the vessels at the exchange surface to keep oxygen depleted blood in contact with the exchange surface

Together these processes ensure a large concentration gradient for oxygen diffusion

II. Circulation:

A. Components-

1. The cardiovascular system = heart + blood vessels

Function = Circulates the blood to and from the tissues

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

Right atrium To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Left atrium

To lung

From lung

Semilunarvalve

Atrioventricular(AV) valve

Rightventricle

Leftventricle

2. The lymphatic system = lymph vessels + lymph nodes

Functions –

-immune defense

- returns some fluid from the tissues

Return of excess fluid from the tissues via the immune system

B. Functions of the Circulatory System1. Transport – oxygen, carbon dioxide,

nutrients, wastes and hormones in blood

2. Blood clotting – to seal breaks in vessels, uses platelets and clotting proteins

3. Protection – internal defense using the white blood cells and the lymphatic system

C. Types of Circulatory Systems

1. None –a. Only used by small animals and/or those

with low rates of oxygen use

b. Circulation occurs due to simple diffusion through the body tissues

Examples of Animals That Lack a Circulatory System

sponges (not shown) jellyfish flatworms sea stars

2.

3.

(Pump)Few vessels

(Tissue sinuses)Few vessels

Blood leaves vessels, loses pressure, thus low flow, low oxygen demand system

large vessels (arteries, arterioles)

Capillaries in tissues for exchange

(pump)

large vessels (veins)

Blood stays in vessels, thus high pressure, high flow system for high oxygen demand

Examples of Animals with an Open Circulatory System clams Crayfish, shrimp,

lobsters (not shown) insects as exception

to low oxygen use rule (remember the tracheal system)

Examples of Animals with a Closed Circulatory System vertebrates from fish

to mammals

D. The Vertebrate Circulatory System -1. Blood consists of–

a. Plasma = fluid with dissolved substances (examples – nutrients, hormones and most carbon dioxide)

b. Cells and cell fragments –1) White blood cells – defense

2) Red blood cells – oxygen transport

3) Platelets – blood clotting

2. Vertebrate hearts and circulatory patterns -Note that the evolution of the four-

chambered heart of the mammals and birds allows blood to be returned to the heart after exchanging gases at the lungs and to be pumped a second time before traveling to the tissues, needed for high oxygen demand associated with high body temperatures

Mammals and

aorta

Vena cava

Atrium = receiving chamber

Ventricle = pump

Two-chambered heart with blood pumped once; lower pressure, lower flow system

And thus blood is pumped twice for a higher pressure, higher flow system

arteries

(Pressure declines)

CO2

O2

O2CO2

Pulmonary artery

Pulmonary vein

aorta

Vena cava

Left atriumRight ventricle

Right atrium

CO2

O2

CO2

O2

Copyright © 2009 Pearson Education, Inc.

23.4 The heart contracts and relaxes rhythmically

During diastole, blood flows– From veins– Into heart chambers

During systole, blood flows– From atria– Into ventricles

Semilunarvalvesclosed1 Heart is

relaxed.

AV valvesare open.

Diastole

0.4 sec

Semilunarvalvesclosed1 Heart is

relaxed.

AV valvesare open.

Diastole

0.4 sec

2 Atriacontract.

Systole0.1 sec

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

3. Generation of the heart beat – note that all cardiac cells are autorhythmic and contract on their own

Pacemaker (fastest rate of contraction) =

Electrical signals = action potentials pass due to intercalated discs

(Holds signal before passing to ventricles, connective tissue between atria and ventricles prevents immediate passage of signal