Human gas exchange Flashcards
how does oxygen enter the capillary?
-oxygen diffuses from the alveoli
-down its concentration gradient
-across the alveolar epithelium
-across the capillary endothelium
-into the blood
how does carbon dioxide enter the alveoli?
-carbon dioxide diffuses from capillary
-down concentration gradient
-across the capillary endothelium
-across the alveloi epithelium
-into the alveoli
why is ventilation needed?
-maintains concentration gradient
-brings in air containing a higher concentration of oxygen
-removes air with low concentration of oxygen
what are the essential features of the alveolar epithelium?
large SA:V ratio
-fast diffusion
thin walls
-short diffusion distance
good blood supply from network of capillaries
-maintains concentration gradient
permeable walls, moist lining
Describe the mechanic of breathing in (inspiration)
-external intercostal muscles contact
-rib cage moves up and out
-diaphragm contracts (moves down) flatten
-increase volume in thoracic cavity
-decrease pressure in thoracic cavity
-air moves down pressure gradient in lungs
-active process
Describe the process of breathing out (expiration)
-internal intercostal muscles contract, external intercostal muscles relax (antagonistic)
-Ribcage moves down and in
-Diaphragm relaxes, moves upwards
-Increase volume in thoracic cavity
-Air moves out of lungs down pressure gradient
-passive process
Define tidal volume
Volume of air in each breath
Define ventilation rate
Number of breaths per minute
Define forced expiratory volume
Maximum volume of air that can be breathed out in 1 second
Define forced vital capacity
Maximum volume of air possible to breathe forcefully out of the lungs after a deep breath in
Describe what fibrosis is and its effects
-scar tissue in lungs → scar tissue thicker, less elastic
- diffusion distance increased → rate of diffusion decreased
-faster ventilation rate to get oxygen into lungs/blood
-reduced tidal volume
-reduced forced vital capacity
Describe what asthma is and its effect
-inflamed bronchi
-asthma attack → smooth muscle lining in bronchioles contract
- constriction of airways
-FEV reduced
-less oxygen enters the alveoli
- reduced rate of gas diffusing in alveoli → less oxygen diffuse into blood → cells receive less oxygen → rate of aerobic respiration reduced → less energy released → fatigue
Structure of the human gas exchange system
-trachea
-splits into 2 bronchi
-each bronchi split into smaller tubes called bronchioles
-bronchioles end in air sacs called alveoli
