animal physiology - breathing and gas exchange Flashcards
pg 39-51
the gas exchange system
- breathe in, air enters through our nose or mouth
- passes down the trachea (windpipe)
-it splits into two tubes called the bronchi, one leading to each lung - each bronchus divides into smaller and smaller tubes called bronchioles
-eventually ending at microscopic air sacs called the alveoli
-this is where gas exchange with the blood takes place and oxygen then diffuses into the blood down the concentration gradient
trachea walls
the walls of the trachea contain rings of gristle or cartilage
- so it can keep its rigid shape and opens up the airways for air to pass through them
thorax
- inside of thorax separated from lungs by two thin, moist membranes (pleural membranes)
-they make up a continuous envelope around the lungs, forming an airtight seal
-between the two membranes is a space called the plural cavity, (filled with a thin layer of liquid called pleural fluid)
-this acts as lubrication so surfaces of lungs don’t stick to the inside of chest wall when breathing
3 common characteristics of exchange surfaces (eg lungs, gills, small intestine)
- large surface area
- good network of blood capillaries to keep steep concentration gradient
-thin walls, only one cell thick
mucus:
some cells secrete a sticky licid called mucus which traps dirt particles and bacteria and prevents it from going into the lungs
explain what happens in the lungs for the process of inhalation to occur
-intercostal muscles contract
-ribs move up and out
-diaphragm contracts/flattens
-volume increases inside the thorax
-pressure decreases
-air is drawn in
adaptation of the alveoli for efficient gas exchange
-large surface area for diffusion
-they are moist to help dissolve gases and increase diffusion rate
- a rich blood supply to maintain a steep diffusion gradient between the alveoli and the blood
-the walls are freely permeable, gaps in between cells, through these substances can move in and out
cilia
tiny-hair like structures called cilia, they beat backward and forward, sweeping mucus and trapped particles out towards the mouth
-dirt and bacteria is prevented from entering the lungs where they might cause an infection
lung conditions caused by smoking
- lung cancer
- chronic bronchitis
-emphysema, breakdown of walls of the alveoli
smoking
tobacco smoke and tar contain chemicals which can cause mutations.
healthy lungs before smoking
-In healthy lungs, the cells lining the bronchi and bronchioles have tiny little hairs on them called cilia.
- There are also cells called goblet cells which secrete mucus.
- The mucus traps bacteria and dust to stop it entering the lungs.
unhealthy lungs/why do smokers get smokers cough
Cigarette smoke contains a chemical named tar which can cause mutations.
The tar damages and paralyzes the cilia.
This results in a build up of bacteria and mucus, and you get more chest infections.
The tar also irritates the lining, encouraging more mucus to be produced, which can’t then be cleared.
Therefore, the smoker develops a heavy cough called a smoker’s cough and in some cases chronic bronchitis which is…
what do the lungs feel like
spongy because of the tiny millions of air sacks
how does the trachea stay rigid and flexible
it has many cartilage rings
why do the bronchi branch out
to let air flow through both lungs
practical 1:comparing the carbon dioxide content of inhaled and exhaled air
-person breayjrd gently in through middle tube
- exhaled air passes through one tube of indicator solution and inhaled through the other
- if limewater used, exhaled will turn cloud before inhaled
- if hydrogen carbonate indicator solution used, it changes from red to yellow
