The nose: Breathing in through the nose is beneficial because:
The nose: Breathing in through the nose is beneficial because: (1) The air is filtered by the hairs and the mucous in the nose.
The nose: • Breathing in through the nose is beneficial because: • The air is filtered by the hairs and the mucous in the nose. • It is moistened.
The nose: • Breathing in through the nose is beneficial because: • The air is filtered by the hairs and the mucous in the nose. • It is moistened. • It is warmed as it passes across the nasal passages.
These 3 things make it easier for the air to diffuse from the lungs into the bloodstream.
Pharynx is the part of the throat that begins from behind the nose to the beginning of the voice box and the oesophagus.
It is a common channel that both air and food pass through. • Because of these two functions, the pharynx must open to allow air and food to pass through.
Epiglottis: Because of the need to swallow and breathe there is a flap of tissue called the epiglottis which closes off the trachea when your swallowing and closes off the oesophagus when breathing.
Thererfore when breathing this prevents food and drink entering the trachea (windpipe).
Contains two vocal cords. • These vibrate when we force air across them. • The vibrations produce sound which our tongue and lips convert to speech.
Trachea: • The trachea, bronchi and bronchioles are all made of muscle and elastic fibres and incomplete rings of cartilage. • Rings of cartilage prevents tubes from collapsing as air is drawn in.
Trachea bronchi bronchioles. Bronchioles become narrow during an asthma attack.
Cilia: Sticky. Beat create an upward current. Moves the mucus into the oesophagus to the stomach. Clearing our throats force mucus up and away from the vocal cords.
All of these air pipes are lined with mucous secreting cells and tiny hairs called cilia.
Lungs: • Large spongy structures. • Where gaseous exchange takes place. • Each lung is surrounded by the pleural membrane. • The outer pleura lines the chest wall and diaphragm. • The inner pleura lines the lungs.
The gap between these 2 membranes is the pleural cavity and it is full of liquid. This liquid lubricates the membranes and reduces friction during breathing.
Alveoli: Each bronchus divides into about a million bronchioles. These end in hollow, balloon-like air sacs called alveoli (or alveolus). 700 million alveoli in the 2 lungs. Very large surface area for gas exchange = tennis court
Each alveolus is 1 cell thick. Moist. Enclosed in a network of blood cappilaries (like the villi). When the gases are exchanged they only have to pass through the alveoli membrane and the capillary wall.
Function of the alveoli: Gas exchange.
Gas exchange: Respiration happens in cells to supply energy. Body cells use up oxygen and produce carbon dioxide and water. Eqn: C6H12O6 + 6O2 --- 6CO2 + 6H2O + energy. Enzymes
Gaseous exchange = diffusion!!! CO2 and H2O diffuse out of cells and into the blood because the cytoplasm has a high conc of CO2 and H2O compared with the blood. In the lungs, CO2 and H2O diffuse out of the blood into the alveoli from ↑ conc to ↓ conc.
Diffusion is: the movement from a high conc to a low conc. In the same way, O2 diffuses from the alveoli into the blood and then from the blood into body cells. Exhalation: body cells CO2 plasma (in blood) alveolus exhale. Inhalation: O2 from air alveolus blood body cells.
Transport of gases: (1). O2 is mostly carried by haemoglobin (97%) + 3% carried in the plasma. (2). CO2 is dissolved in plasma and carried in blood. H2O is carried in plasma.
Mechanism of breathing: Normally involuntary. At rest: 15 times per minute. In: inhalation/inspiration. Out: exhalation/expiration.
The process: • Medulla oblongata in the brain controls the rate of breathing. • It sends a message to the diaphragm and intercostal muscles. • Muscles contract = active process.