Systems of distribution

Outline Distribution of respiratory gases, and in blood Respiratory systems - transport of oxygen to tissues - radically different designs in mammals, birds, insects Vertebrate hearts - different hearts for different taxa Extreme vertebrates: respiration and circulation in diving mammals

Respiratory systems CHO+O 2 H 2 O+CO 2 burning carbohydrates requires oxygen burning carbohydrates produces carbon dioxide oxygen must be carried to tissues carbon dioxide must be carried away

Respiration is process that results in the exchange of gases

3 steps in respiration 1. Moving air or water into contact with a damp surface of the body 2. Gases exchanged at this respiratory surface 3. Transport between respiratory surface and tissue (if necessary)

Why do the surfaces need to be wet? Respiratory gases (oxygen, carbon dioxide) can cross membranes ONLY IF they are dissolved in water.

Where is my respiratory surface? only works for small animals

Why is body surface insufficient as a respiratory surface for larger animals? simple geometry All the oxygen and CO 2 for the animal s VOLUME, must be exchanged across its SURFACE, which is an AREA.

one box has 2x the linear dimensions of the other 2 1 1 2 2 1 we want to compare their volumes and surface areas

2 1 1 1 volume=1 surface= 6 1+1+1+1+1+1 S/V=6 2 2 volume=8 surface=24 4+4+4+4+4+4 S/V=3

Larger organisms need more surface area for gas exchange

A second physical factor: direction of blood flow

Fish gills illustrate both... 1. the expanded surface area of the respiratory surface and 2. the importance of the directions of flows

Compare countercurrent and parallel flows

countercurrent water and blood flow in opposite directions

parallel currents both water and blood flow in same direction maximum blood % is 50% 50% left in water

countercurrent exchange is more effective maximum blood % is 90% minimum water % is 15%

Air is an easier fluid environment extract oxygen from than water. 1. the amount of oxygen dissolved in air is 20X that in water 2. Diffusion rate of oxygen is 100,000x faster in air than water

the respiratory system of insects takes advantage of this difference

Air ducts, called tracheae, branch through the insect s body

Oxygen is delivered to each cell by fine branches of tracheae. CO 2 diffuses out of cells into tracheae

In insects, the respiratory surface is at the tissue Their circulatory system does not carrying respiratory gases!

In insects, the circulatory system is open the circulatory system is OPEN

If the respiratory surface is far from most tissues,. respiratory surface then the gases must be carried to and from the tissue by the circulatory system. tissues

CLOSED circulatory system : the circulatory system delivers oxygen to cells

gas exchange between blood and air/water takes place in the lung/gills

gas exchange between blood and cells takes place in tissue in capillary beds

Vertebrates lungs have tidal flow

the bird variation Birds have air sacs in addition to lungs Air sacs are not used for gas exchange

follow the blue air inhalation moves air into posterior air sac exhalation moves air into lung next inhalation moves air into anterior air sacs next exhalation moves air out of anterior air sacs

no dead space!

some birds fly @ 27,000 ft Airplane cabins pressurized @12,000 ft

What are main differences between air and water? What is selected for in respiratory systems as we move through evolutionary lineages?

Different arrangements of respiratory surface(s) and hearts in vertebrates

Fish Heart - 2 chambers Gills heart pumps only venous blood

Lungfish gills AND lungs two atria - one receives venous blood from body the other receives oxygenated blood from the lung

Where did lungs come from?

Adult Amphibian no gills ventricle has 2 separate exits circulation to the lung is partly separated

Mammals and Birds 2 completely separate pumps and circulations one is the circuit to the lungs, and the other is to the body

Adult amphibian Lungfish Compare: advantage?

Lungfish Major evolutionary Adult amphibian trend(s)?

Pushing the limits of vertebrate systems: diving mammals

Pushing the limits of vertebrate systems: diving mammals dive 1 km deep, for about an hour

Blood transport of oxygen Red blood cells contain hemoglobin, which binds oxygen Hemoglobin picks up oxgyen when the concentration is high, releases it when the concentration is low LUNG - oxygen is picked up by hemoglobin TISSUES - oxygen released from hemoglobin

Muscles have high oxygen demand Myoglobin binds oxygen in muscle Myoglobin has higher affinity than hemoglobin O H 2 M

Two sources of oxygen while holding your breath (with deflated lungs) oxygen bound to hemoglobin oxygen bound to myoglobin

how seal physiology is modified for diving (1) THEY STOCKPILE OXYGEN 2x as much blood/kilogram as non-diving mammal = more total hemoglobin spleen stores blood (24 L) higher concentration of myoglobin

how seal physiology is modified for diving (2) THEY CONSERVE OXYGEN heart rate slows blood circulation restricted - goes mainly to brain, nervous system

Bottle-nosed whale made 19 dives > 1/2 mile and the maximum was nearly 1 mile

Key Concepts Respiratory systems size matters counter current exchange transport of oxygen to tissues in air and blood extreme performance: how the design of bird lungs increases respiratory efficiency Vertebrate heart design related to location of respiratory surface(s) Respiratory and circulatory modifications enable deep ocean diving in mammals