module 3 exchange and transport alevel biology

3 main factors that affect the exchange system ?

size

surface area : volume

levels of activity

explain how size affects the exchange system ?

in smaller organisms such as single-celled organisms, diffusion is sufficient for gas exchange due to their high surface area to volume ratio.

Larger organisms require specialized systems to efficiently transport materials across longer distances.

explain how surface area to volume ratio affects the exchange system ?

A higher surface area to volume ratio allows for more efficient diffusion of substances, enabling faster exchange of gases and nutrients.

larger organisms have a lower ratio, necessitating specialized structures or systems to facilitate adequate exchange.

explain how the level of activity affects the exchange system ?

Higher levels of activity increase the demand for oxygen and nutrients, requiring more efficient exchange systems to meet metabolic needs. Active organisms often have adaptations, such as larger respiratory surfaces or enhanced blood flow, to support their energy requirements.

what are the features of a good exchange system ?

large surface area,

thin barriers for diffusion,

a moist environment,

good blood supply to maintain concentration gradients,

ensuring efficient exchange of gases and nutrients.

describe the structure of the mammalian gaseous exchange system ?

the trachea made of rings of cartilage that prevent collapsing during inspiration

trachea branches into the bronchi, leading to bronchioles and alveoli

alveoli walls contain elastic fibres to allow stretch and recoil during inhalation and exhalation

the lungs are protected by the ribcage which are made of intercostal muscles and a diaphragm that aids in ventilation.

The alveoli provide a large surface area for gas exchange and are surrounded by capillaries to facilitate diffusion of oxygen and carbon dioxide.

how is the mammalian gaseous exchange system adapted ?

alveolus one cell thick (squamous epithelium tissue)

capillary walls one cell thick

capillaries are in close contact with alveolus walls

to maximize diffusion efficiency, enhancing gas exchange.

how is a good blood supply maintained within the mammalian exchange system ?

breathing movements ventilate the lungs by bringing in more o2 and removing co2 and ensures

conc of O2 in air of alveolus remains higher than in the blood

conc of CO2 remains lower in alveoli than in the blood

describe inhalation ?

diaphragm contracts down and becomes flattened

external intercostal muscles contract to raise ribcage

volume of thorax increases

thorax pressure decreases below atmospheric pressure

air moves into the lungs

describe exhalation

diaphragm relaxes and becomes dome shaped

external intercostal muscles relax and ribs fall

internal intercostal muscles contract to forcefully push more air out, usually only happens during exercise coughing or sneezing.

volume of thorax decreases

pressure in lungs increases

air moves out of the lungs

what are the tissue in the gaseous exchange system ?

lung tissue have alveoil