- Factors influencing rate of gaseous exchange (diffusion): surface area, concentration gradient, length of diffusion path
- Air Pathway: Nose --> Pharynx --> Larynx --> Trachea --> Bronchi --> Bronchioles
- Nose
- Hair and mucus trap dust, microoraganisms and foreign particles
- Air warmed and moistened
- Sensory cells detect odour molecules
- Trachea
- C-shaped cartilage rings support trachea and keep it open
- Gland cells on epithelium secrete mucus
- Cilia on epithelium sweep mucus particles up pharynx
- Bronchi
- Right: 3 tubes; Left: 2 tubes
- Gland cells
- Divides into bronchioles (smaller tubes)
- Alveoli (air sacs) are adapted for efficient gaseous exchange:
- Thin: Shorter diffusion path, higher rate of diffusion
- Moist: Oxygen dissolves in thin film of moisture to enhance binding to plasma Hb of RBCs
- Extensive blood capillaries: Increased surface area for diffusion
- Membrane permeable to oxygen and carbon dioxide
- Ribs, Diaphragm and Intercoastal Muscles work together to enable breathing:
- During inspiration
- Diaphragm contracts, flattens downwards
- Intercoastal muscles: external muscles contract, internal muscles relax
- Ribs and sternum move up and out
- Volume of thoracic cavity increases, hence pressure decreases. Internal pressure becomes lower relative to atmospheric pressure, hence air diffuses in down the concentration gradient
- The respiratory and circulatory systems are regulated together by plasma carbon dioxide levels
- During physical exertion, heart rate and CO2 level increases
- Higher CO2 stimulates faster rate of inspiration and expiration, taking in O2 and removing CO2 is removed
- Higher heart rates allows oxygenated blood to be transported to muscles more efficiently
You probably are wondering if there will be a follow up with a hack notes on Fishes' Respiratory System. Well we don't have plans to upload any yet, but you sure can get notes and worksheets on the Respiratory System of Fishes if you sign up as a student here :)
