3.1.1 exchange surfaces Flashcards
(37 cards)
why do organisms exchange things with their environments
to take in things for metabolic reactions and to excrete waste products from these reactions
how do we calculate surface area to volume ratio
SA:V = SA/V
why do multicellular organisms need specialised exchange surfaces
there is too big of a distance between most internal cells and the environment so diffusion directly would take too long
multicellular organisms have a high metabolic rate so they use up oxygen and glucose faster
how does a large surface area improve efficiency of an exchange surface
it increases the rate of diffusion as there is a bigger area for the exchange to happen so more can happen at once
how does thickness effect efficiency of an exchange surface
a thin exchange surface is more efficient as there is less diffusion distance so it takes less time to take place
how does a good blood supply effect efficiency of an exchange surface
it maintains concentration gradients making exchange more efficient
what are the exchange organs in mammals
lungs
what is the structure of the lungs
trachea branches into two bronchi one bronchus leading to each lung.
the bronchi split into smaller tubes called bronchioles which end in small sacs called alveoli.
what is the function of goblet cells in the gaseous exchange system
they secrete mucus which traps microorganisms and dust particles inhaled stopping them reaching alveoli
what is the function of cilia in the gaseous exchange system
they beat the mucus which moves it up and away from the alveoli towards the throat to avoid infections
what is the function of elastic fibres in the gaseous exchange system
allow the parts of the lung to stretch when inhaling and recoil when exhaling
what is the function of smooth muscle in the gaseous exchange system
allows the diameter of the tubes in the lungs to be controlled e.g. it relaxes during exercise making tubes wider so air moves in easier
what is the function of the rings of cartilage gaseous exchange system
it provides support. it is strong and flexible and stops the trachea and bronchi collapsing when you inhale and pressure drops
which parts of the lungs contain cartilage
trachea (large C shaped pieces)
bronchi (smaller pieces)
which parts of the lungs contain smooth muscle
trachea, bronchi and larger bronchioles
which parts of the lungs contain elastic fibres
trachea, bronchi, bronchioles and alveoli
which parts of the lungs contain goblet cells
trachea, bronchi and larger bronchioles
which parts of the lungs contain cilia
trachea, bronchi and larger bronchioles
what is inspiration
air flowing into the lungs, it is an active process
how does inspiration happen
external intercostal muscles and diaphragm contract causing the ribcage to move upwards and outwards and the diaphragm to flatten. this increases the volume of the thorax, this decreases the pressure this causes air to flow into the lungs
what is expiration
air flowing into the lungs, it is an passive process but can be forced actively
how does expiration happen
external intercostal muscles and diaphragm relax causing the ribcage to move downwards and inwards and the diaphragm to curve. this decreases the volume of the thorax, this increases the pressure this causes air to be forced out of the lungs
in forced expiration the intercostal muscles contract to pull the ribcage down and in
what is the tidal volume
the volume of air in each breath
( average tidal volume is about 0.4dm3)
what is the vital capacity
the maximum volume of air that can be breathed in or out
