Gas Exchange Flashcards
(31 cards)
RESPIRATORY SYSTEM IN MAMMALS
reasons for its necessity (3)
- surface area to volume ratio too large for transport of O2 by diffusion alone
- presence of protective outer surface prevents diffusion of gases, alternative respiratory surface needed
- increased metabolic rate = more O2 needed
conditions for effective diffusion (4)
- large surface area
- ventilation mechanism, to maintain conc. gradient
- good blood supply to transport away O2 quickly and maintain concentration gradient
- presence of a haem protein to increase O2-carrying capacity of the blood.
size of gas exchange surface in humans
70-75 m2
TRACHEA features present (4)
- cartilage
- goblet cells
- cilia
- smooth muscle
TRACHEA function of cartilage
prevents the trachea from collapsing into itself, particularly when a large bolus of food passes through the oesophagus
how is air entering the lungs warmed up?
from the heat of blood passing through the capillary system in the nose
MUCUS function (2)
moistens air and traps fine dust particles
what type of air is needed to protect the alveolar lining?
warm, moist and as free of dust and foreign bodies as possible
CILIA
function
back-and-forth movement beats mucus stream into the buccal cavity, where it is swallowed
TRACHEA
arrangement of cartilage
regular (incomplete) C-shaped rings
BRONCHI + LARGE BRONCHIOLES
arrangement of cartilage
irregular tiny plates or rings
BRONCHI + LARGE BRONCHIOLES
role of smooth muscle & cartilage
prevent collapse (eg. from sudden reductions of pressure that occur with a powerful inhale of air). smooth muscles also regulate the size of the smaller airways by contracting & relaxing
SMALLER BRONCHIOLES
structure
no cartilage, very few goblet cells. smooth muscle is the major component of their walls. become progressively narrower as they branch.
PLEURAL FLUID
source
made from blood plasma, secreted by internal surfaces of the thorax
PLEURAL FLUID
function
provides the surface tension that holds lungs to ribcage and protects the lungs from friction during breathing movements
water loss from the lungs
10-15% of total loss (3L)
MUCUS
structure of goblet
upper part swollen with mucin droplets. rest of the cell contains a Golgi body, some rER, mitochondria and a nucleus. the lower part of the cell is very thin, so the cell looks like a goblet.
role of macrophages in defending lungs
engulf bacteria and fine dust particles.
STRUCTURE OF ALVEOLI
role of elastic muscle fibres
stretch with alveolar walls during inspiration and recoil during expiration. the recoil restores alveoli to regular shape and aids expulsion of air.
STRUCTURE OF ALVEOLI
thickness of wall
one cell thick (formed by squamous epithelium)
STRUCTURE OF ALVEOLI function of thin walls
v. low distance (2-4 micrometers) for diffusion of gases = rapid gas exchange
name of bronchiole connecting alveoli to rest of lungs
terminal bronchiole
% saturation of O2 in blood coming from pulmonary artery
~70%
partial pressure of O2 in blood coming from pulmonary artery
5.3 kPa
