2.2: Adaptations in gas exchange

Metabolic

Rate of energy usage in the body.

Glottis

Opening that connects lungs to the mouth in amphibians.

Gills

Respiratory surface in fish and some amphibians.

Gill arches

Four of these make up a gill.

Gill filaments

Line gill arches, are thin and flat. One cell thick.

Gill lamallae

In the folds of gill filaments, a network of capillaries that oxygen diffuses into. One cell thick.

Gill rakers

At the top of gill arches and filter debris and particles from the water.

Ventilation

Process of moving the respiratory medium (water or air) against the respiratory surface.

Opercular

Valve that keeps water in the fish’s mouth, allowing it to move against the gills.

Opercular

Cavity where water moves in expiration before exiting the lungs.

Buccal

Cavity also known as the mouth cavity, where water flows into.

Pharyngeal

Cavity where the gills are.

Parallel

Flow of water against gills used by cartilaginous fish, where water flows the same direction as the blood. Least efficient method, only takes up 50% of oxygen

Countercurrent

Flow of water against gills used by bony fish, where water flows the opposite direction of the blood. Most efficient method, takes around 80% of oxygen.

Spiracles

Holes along an insect’s body where respiration takes place, surrounded by hairs and in some insects can open and close using valves.

Tracheae

Inside an insect and attached to the spiracles. Made out of rings of chitin.

Tracheoles

Smaller tubes that branch off the tracheae, leads directly to muscle fibres, where gas exchange takes place.

Lactic acid

Fluid used by insect cells to increase gas exchange during activity.

Anaerobic

Type of respiration that increases lactic acid, causes the osmotic potential of the cell to lower and more gas exchange to occur in insects.

Aerobic

Respiration that occurs during rest, where there is no lactic acid and therefore less gas exchange.

Photosynthesis

Occurs only in plants during the day, when carbon dioxide is taken in and oxygen produced. Most oxygen is diffused out through leaves, but some can be used in respiration.

Stoma

Holes in the epidermis and wavy cuticle of a plant, where gases diffuse through. They can open and close.

Epidermis

Transparent outer layer of a plant that provides protection, also surrounded by a waxy cuticle.

Palisade mesophyll

Elongated cells containing chloroplasts, which rotate to allow for maximum sunlight absorption.

Spongy mesophyll

Cells that contain chloroplasts with air spaces to allow for diffusion of gases.

Potassium ions

Decrease osmotic potential of the guard cells to allow them to become turgid.

Malate

Converted from starch and used to decrease the osmotic potential of guard cells.

Guard cells

Cells that surround a stoma, which expand to open the stoma. Thicker inner wall to allow for this expansion.

Thorax

Airtight compartment which surrounds the lungs.

Lungs

Human breathing surface, also used in other mammals. Made from elastic-like tissue.

Pleural membranes

Double membrane, outer attached to the ribcage and inner covers the lungs.

Intercostal muscles

Muscles between the ribs that contract to increase lung capacity.

Diaphragm

Dome-shaped sheet of muscle which separates the thorax from the abdomen. Contracts to increase lung capacity.

Trachea

Flexible airway which brings air to the lungs. Made from smooth muscle to allow for contraction and expansion to increase or decrease volume.

Bronchus

A left and right one, branch off from the trachae and directly connect to the lungs.

Bronchioles

Branch off from a bronchus, a network inside the lungs.

Alveoli

Air sacs at the end of bronchioles where gas exchange takes place. Walls made out of squamous epithelium and are coated with pulmonary surfectant.

Pulmonary surfactant

Coats alveoli inner surfaces made of protein and phospholipids. It has a low surface tension, preventing alveoli collapse during exhalation due to low pressure and reduces effort needed for lung expansion. Allows allows for gases to dissolve pre-diffusion.

Expiration

Process of breathing out with lungs.

Inspiration

Process of breathing in with lungs.

20

Average concentration of oxygen in air.

0\.04

Average concentration of carbon dioxide in air.

Asthma

Can be chronic or acute, occurs when smooth muscles tighten unnecessary. Can have triggers and lead to mucus build-up.

Emphysema

Condition where air sacs are unable to contract due to pulmonary surfectant damage. Causes breathlessness.

Spirometer trace

Measure done to calculate lung capacity for inspiration and expiration.

Tidal volume

Breathing at rest, shown on a spirometer.

Gill pouches

On cartilaginous fish only, spaces that hold five gills.

Gill slits

On cartilaginous fish only, how gill pouches open.