human exchange surface

Question 1

how does air enter the human system

Answer 1

-air enters the trachea which spilts into two bronchi , then many bronchioles and then alveoli
where gas exchange occurs

Question 2

what are the adaptions of the alveoli

Answer 2

there are many alveoli so a large surface area
alveoli epithelium and capillary endothelium are one cell thick so there’s a short diffusion pathway
there are many capillaries close to the alveoli to maintain good blood supply and a steep gradient
they’re well ventilated to bring fresh air and take away steel air to maintain a steep concentration

Question 3

what is ventilation

Answer 3

to maintain the diffusion of gasses across the alveolar epithelium , the air must be constantly moved in and out of the lungs
aswell as this air always moves from a high to low pressure

Question 4

what happens when you breathe in

Answer 4

the external intercostal muscles contract which moves the ribs up and out
intercostal muscles relax
the diaphragm contracts which makes it flat
the volume of the thorax increases which decreases the pressure below atmospheric pressure
air is then moved into the lungs down a pressure gradient

Question 5

what happens when you breathe out

Answer 5

external intercostal muscles relax
the internal intercostal muscles contact which causes the ribs movement downwards and inwards
the diaphragm relaxes into a dome shape
the volume of the thorax decreases which increases the pressure above atmospheric pressure
air moves out the lungs down a concentration gradient