Gas Exchange (Semester 1)

type 1 pneumocytes function

extremely thin epithelium cells that line the inner surface of alveoli.

Type 2 pneumocytes function

Surfactant production (decrease surface tension): prevents alveoli from sticking together.

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

epiglottis definition

A flap of tissue that seals off the windpipe and prevents food from entering.

Example of gas exchange in fish

Fish take in fresh water through the mouth and pump it over their gills, water moves out though gill slits. It's a one way flow: oxygen goes into blood carbon dioxide goes out.

Properties of gas exchange surfaces in living organisms

Permeable, large, moist, and thin.

How are gasses exchanged?

simple diffusion

Diffusion requires a maintained ______________.

concentration gradient

Maintained concentration gradient example

There's a higher concentration of O2 in the air inside alveoli than blood so O2 diffuses into blood and its lower concentration gradient: It flows continuously through blood vessels to maintain this. It's all a part of cellular respiration.

Ventilation in humans

Air in alveoli exhaled and replaced with fresh air

Ventillation rate

number of breaths per minute determined by CO2 concentration in blood. More ATP = higher ventalation

Mamilian adaptations for gas exchange

Both capillaries + alveoli = single layer of cells

Cover a large surface area

Left lung

Ventilation: Inspiration

external intercostal muscles contract, ribs move up and out, abdomen muscles relax, and diaphragm contracts: Thorax cavity volume raises, pressure lowers, air is drawn in.

Ventillation: Expiration

Internal intercostal muscles contract, ribs move down and in, abdomen wall muscles contract, diaphragm relaxes, thoracic cavity volume lowers, pressure raises, air is pushed out.

Tidal volume

Amount of air that moves in and out of the lungs during a normal breath

Inspiratory Reserve Volume (IRV)

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

expiriatory reserve volume

Volume of air that can be exhaled after a normal exhalation

Viral Capacity

measurement of the volume of air that can be exhaled after maximum inspiration

Waxy Cuticle function and adaptation

reduces water, loss and a low permeability to gases, holding on to them.

Epidermis (plant)

a tissue made up of a single layer of cells which covers the top and bottom of a leaf, and the outside of the stem and root

Stomatal Guard Cells

Found in the epidermis, changes shape to open/close pores allowing C02 and O2 to be exchanged with the atmosphere.

spongey mesophyll

Site of gas exchange/moisture exchange, containing air spaces connected to the atmosphere through stomata

veins (in plants)

In plants, a vascular bundle containing xylem for H20 transport to leaf cells

Where does photosynthesis occur?

palisade mesophyll

Transpiration

Evaporation of water from the leaves of a plant through the stomata

factors affecting transpiration

1. Temperature: more heat

2. Humidity (water vapor in air): a rise in humidity