Respiration and Circulation Part 1

Biology 155

Krilowicz

Spring 2010

Respiration and Circulation are coupled processes in most animals

The systems function together to exchange gases with the environment and transport them to the tissuesFig. 22.1

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

Fig. 22.2A

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

Fig. 22.2B and 22.3

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

Fig. 22.2 D and 22.6

Ventilation uses tidal flow of air due to density

Fig. 22.8

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 Fig. 22.2C

and 22.4

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