Physiology of Respiration · Inverts living in fluctuating environments like local lakes where O2 in water can be quite high but the animals then travel into anaerobic mudflats where

Physiology of Respiration

• Aerobic Respiration

• Anaerobic Respiration

• Cellular Respiration

Respiratory pigments

• Substances that reversibly binds oxygen

• Increases oxygen carrying capacity of blood

• Conjugated proteins

• Protein combines with metallic group which gives a characteristic

colour on oxygenation

• Impart definite colour to the body fluids

Role of respiratory pigments in different environments

• High PO2 - low affinity pigments –example: Terrestrial mammals: lots of easily

accessible O2 in normal air, no need for thick protective diffusion barrier because no

ionic problems in gas exchange in air, low affinity pigment allows for easier & greater

unloading at cells/tissues and permits high O2 use, easier delivery. Another example is

in marine environments where polychaetes like Sabella have chlorocrourin and the

pigment acts as an emergency store and increases the blood O2 carrying capacity

• High PO2 - High affinity pigment i.e. decapod crustaceans like Spiny lobster from the

marine environment have basic problems with ionic/osmotic balance in marine

environment. Need a high affinity pigment to pick up O2 across thick gill diffusion

barrier that is designed to help control water loss and ion influx from sea water. High

affinity needed to facilitate O2 uptake across thick gill barrier. Unloads only at very

low cell/tissue O2 tensions

Low P O2 - High affinity pigment found in invertebrates that move from high O2 to

areas of low O2 regularly . Inverts living in fluctuating environments like local lakes

where O2 in water can be quite high but the animals then travel into anaerobic mudflats

where the pigment then serves as an O2 reserve during emergency . Under normal

circumstances O2 bound to pigment is not used. Another i.e. is planorbis (pulmonate

snail) uses high affinity pigment to allow for longer dives under water where O2 is low

and will ventilate lung chamber before and after dive where air is stored and pigment

can procure O2 during dive.

Low PO2 - Low affinity pigment i.e. Sipunculid worms (peanut worms) like

Siphonosoma ingens that lives in a marine sediment burrow. Has interesting

circulatory system where blood cells contain heme-erythrin in thick walled tentacles

that emerge from burrow. Harsh water/ion gradients in marine water but they have a

low affinity pigment in tentacles. In body cavity have a high affinity coelomic

pigment that facilitates uptake of O2 obtained by tentacles pigment.

Respiration

The respiratory system is involved in the intake and

exchange of oxygen and carbon dioxide between an

organism and the environment.

Air enters the respiratory systems of insects through a

series of external openings called spiracles. These external

openings, which act as muscular valves in some insects,

lead to the internal respiratory system, a densely networked

array of tubes called tracheae. This network of transverse

and longitudinal tracheae equalizes pressure throughout the

system.

Insects

Aquatic Respiration

Aquatic respiration is the process whereby an aquatic

animal obtains oxygen from water

In most aquatic animals respiration takes place through

gills and also by skin.

The labyrinth fish have developed a special organ that

allows them to take advantage of the oxygen of the air, but

is not a true lung. Fish use the process known as

countercurrent flow, in which water and blood flow in

opposite directions across the gills, maximizing the

diffusion of oxygen.

Fish

Within each lamella, blood flows

opposite to direction of water

movement

◼ Countercurrent flow

◼ Maximizes oxygenation of blood

Fish gills are the most efficient of all

respiratory organs

In a concurrent system, exchange is

inefficient. Equilibrium is reached at

one end.

In a countercurrent system,

equilibrium is not reached, so gas

exchange continues, increasing

efficiency.

Vertebrate

Ventilation in Amphibian

Aves

Mammal

Gases exchange in tissue

• Gas Exchange

O2, CO2

• Acid-base balance

CO2 +H2O←→ H2CO3 ←→ H+ + HCO3-

• Phonation

• Pulmonary defence

• Pulmonary metabolism and handling of bioactive

materials

• Respiratory systems allow animals to move oxygen

(needed for cellular respiration) into body tissues and

remove carbon dioxide (waste product of cellular

respiration) from cells.

Functions of the Respiratory System

Control of Respiration

Respiratory control center in brain: a reverberating circuit.

Primary pacemakers are inspiratory center found in the pons & medula of higher

vertebrates

Send impulses to Diaphram or musces of inspiration via phrenic nerve

Also send impulses to apneustic or expiratory center and stimulate them to

eventually fire and turn off pacemaker cells

Respiratory Adaptations

Hypoxia : lower amount of oxygen available at a higher altitude.

diphosphoglycerate

diphosphoglycerate

Myoglobin increases in body tissue