Respiratory system Flashcards
Blood pH
pH is the measure of acidity, alkalinity and neutrality
Blood pH needs to be controlled within very narrow linits – 7.35-7.45
Low pH = elevated H+ ion concentration (more acidic)
High pH = more alkaline
Blood pH; Acidosis (respiratory and metabolic)
Respiratory acidosis results from raised CO2 in blood causes increased in H+ ions and therefore increased acidity
Metabolic acidosis from exercise = lactic acid & fasting = ketoacids which enter the blood
Ventilation helps lower the acidity of body fluids via exhalation of CO2.
Blood pH; regulation
Low pH (increase in acidity) is managed in 3 ways;
1) Buffer systems – temporarily bind to H+ removing them from solution (i.e. proteins, bicarbonate)
2) Increased exhalation of CO2
3) Kidney excretion of H+ (slow mechanism, kidneys can synthesis new & reabsorb bicarbonate, influencing pH
Cell respiration
The process of energy production (ATP) within cells.
Metabolic process whereby energy (ATP) is obtained by metabolising carbohydrates, fats and proteins
Glucose is primary molecule metabolised for ATP production. Fats & proteins also used. Energy is produced by either; Aerobic or Anaerobic respiration
Cell respiration; aerobic
Aerobic respiration - requires oxygen to generate ATP. Occurs in mitochondria.
Produces 38 ATP (total yield = net 36)
Requires carbohydrates (usually glucose but also fats and proteins)
Glucose + Oxygen = Water + Carbon Dioxide + ATP
Cell respiration; anaerobic
Anaerobic respiration in the absence of oxygen).
Occurs in the cytoplasm via glycolysis. Produces a total of 2 ATP molecules and lactic acid. Intensive short term activity.
Glucose = Lactic acid + ATP
Cells; Alveolar: cell types and functions
Type 1: Epithelial cells, covering 90% of alveolar surface, very thin (gas exchange)
Type 2: Secrete alveolar fluid that contains pulmonary surfactant – reduces surface tension, preventing alveolar collapse. The fluid allows gasses to diffuse through it.
Alveolar macrophages: Strategically located white blood cells (leukocytes) that engulf & destroy microbes entering the alveoli
Cells; Macrophages
Type of white blood cell that performs phagocytosis and engulfs and digests microbes and dead /worn out cells and stimulates the action of other immune cells
Coughing Reflex
First line of immune defense:
1. Epithelial receptors in the respiratory tract are highly sensitive to mechanical and chemical stimuli. The coughing reflex starts when irritation of the mucous membrane occurs
2. Stimulation sensitive nerve endings in the larynx, trachea, bronchi
3. A nerve impulse is sent via the vagus nerve to the respiratory centre in the brain stem
4. This causes deep inhalation and closure of the glottis (and vocal cords)
5. Contraction of abdominal / respiratory muscles to increase pressure
6. Forced removal if irritation
Deoxyhaemoglobin
Haemoglobin (Hb) that lacks oxygen
Functions of respiratory;
Voice / smell: Voice production & smell
Air; Warming, cooling, moistening of air
Gas exchange; O2 & CO2, O2 is required for cell respiration, CO2 is a waste product of cell respiration. By breathing, we are able to inhale O2 & exhale CO2
Immunity; Removal of inhaled particles (immunity); larger substances in nose & smaller substances in mucociliary escalator. Alveolar macrophages in alveoli
Gas exchange; Alveoli
In alveoli, oxygen and carbon dioxide are exchanged between air and blood. Gas exchange occurs between alveoli and capillaries. O2 moves from the alveoli (after beathing in), into the blood = oxygenated blood, CO2 moves from the blood (having been delivered via the pulmonary artery), into alveoli, to be exhaled. Movement of both gases occurs via diffusion
Alveoli have thin walls, large surface area for exchange and are next to a network of capillaries to help gas exchange
Gas exchange; Diffusion
Exchange of gases down the concentration gradient
Gases
(inhaled and exhaled)
Inspired air contains a large quantity of nitrogen and oxygen. Oxygen has a strong affinity with haemoglobin so will bind to Hb molecules. Nitrogen does not bind with haemoglobin and is not used or created in the body so does not dissolve in the blood.
Inspired:
Oxygen; 21%
Carbon Dioxide; 0.04%
Nitrogen; 78%
Expired:
Oxygen; 16%
Carbon Dioxide; 4%
Nitrogen; 78%
Gases in blood; Carbon Dioxide
Carbon Dioxide diffuses into the blood from respiring cells. Transported by:
70% plasma as HCO3 (bicarbonate (buffer)
23% in RBC (bound to Hb)
7% dissolved in plasma
Gases in blood; Carbon Dioxide – Bicarbonate buffer
Bicarbonate buffer reaction (to control blood pH):
Co2 diffuses down its concentration gradient from tissues into blood
* Because of the high water content of blood, CO2, combines with water to produce carbonic acid (H2CO3)
* As carbonic acid is unstable it decomposes immediately into bicarbonate (alkaline) and H+
* Hydrogen is exhaled and excreted into urine to reduce acidity. In addition, bicarbonate is alkaline, which buffers the acidity of blood to keep pH stable
Carbon dioxide + water = carbonic acid = bicarbonate + hydrogen (reversible reaction)
CO2 + H20 = H2CO3 = HCO3 + H+
Gases in blood; Oxygen
Oxygen is an essential gas in the body, cells use it to create the energy that is required for various processes.
98.5% of Oxygen in the blood is transported by haemoglobin,
1.5% of O2 is dissolved in plasma
Hypoxic
Lack of oxygen
