Week 7 Flashcards
What are the two types of ventilation?
- Involuntary= controlled by CNS (medulla)
- Voluntary= hyperventilation, breath holding, swallowing
What are the two types of pulmonary stretch reflexes?
- Slow adapting- when tidal volume starts to reach the limit of expansion and protects lungs. In airway smooth muscle
- Rapidly adapting- respond to cigarette smoke and cause coughing and sneezing to remove particles
What receptors detect Pressure of oxygen and carbon dioxide
How does exercise lead to an increase in ventilation?
Phase I (neural mechanisms)- as exercise begins
• Muscle afferents
• Central command
• Learnt response
Phase II (chemical mechanisms)- as exercise continues
• PCO2 and pH oscillations
• Plasma K+, catecholamines
• Temperature
• Hypoglycaemia, metabolic rate
What is Dalton’s law?
Daltons Law= the pressure of a gas mixture is equal to the sum of the pressure of the individual gases
what is the atmospheric pressure?
Atmospheric pressure- 760 mmHg
Atmospheric pressure x percentage of gas in air = partial pressure of atmosphere gases
what is the water vapour partial pressure?
Water vapour partial pressure in lungs = 46 mmHg
So..
Partial pressure of atmosphere gases in lungs = (atmosphere pressure – 46) x percentage of gas in air
what is the alveoli diffusion pathway?
- Surfactant
- Epithelium
- Endothelium
- Red blood cells
- Haemoglobin
what affects the rate of diffusion
- The partial pressure difference
- Properties of the gas- solubility
- Surface area
- Temperature
how does pp and concentration differ when the gas achieved equilibrium pressure?
• Gas molecules move between air nd liquid to achieve equibrium of partial pressures
• The partial pressure will become equal but the concentrations can still be significantly different (e.g oxygen is not very soluble to the concentration will be much higher in air than solution even when partial pressure is equal)
What is partial pressure?
the pressure exerted by a gas in a container
what is concentration
the amount of molecules of that gas s
what is haemoglobin
oxygen bromine protein within red blood cells
How does oxygen bind with haemolgobin and how does it dissociate?
- high partial pressure of oxygen in alveoli and low in plasma
- Oxygen diffuses and accumulates reacting with Haemoglobin to form oxygaemoglobin
- Blood transports to tissues
- Low partial pressure of oxygen in tissues and oxygen dissociates from oxyhemoglobin
Hb + 02 <> Hb02
Describe the oxygen oxyhaemolobin curve
Systemic venous - carrying deoxygenated blood back to heart
Systemic arterial- carrying oxygenated blood to body
50% saturation = only 2 oxygen molecules have binded
what happens when curve shifts left
Increased affinity to oxygen
= more likely to bind
What causes the curve to shift left ?
- Decreased acidity
- Low partial pressure of c02
- Low DPG concentration
- Lower temperature
How is c02 carried in the blood
- a lot more soluble than oxygen
What is the equation for increase in oxygen uptake (very important)
What is steady state exercise and what happens to heart rate?
- The level of exercise at which the physiological responses remain relatively stable for an extended period of time
1. Immediate increase in heart rate or minute ventilation
2. Responses begin to increase overtime as the system adapts to exercise
3. Plateau as dependent variable levels out
What determines steady state exercise
- Delivery of oxygen to exercising muscles
- Ability of cells to utilise oxygen
How is mean arterial pressure regulated?
Describe Cardiovascular control system
Phase I: immediate increase
o Too quick to be humoral
o Anticipatory central command
Phase II: exponential increase
o Central neurogenic feedforward
o Peripheral neurogenic feedforward (pressor reflex)
Phase III: plateau/steady state
o Central neurogenic feedforward
o Peripheral neurogenic feedforward (pressor reflex)
o Modified by baroreceptor reflex
Describe the sensory information going to the medulla and the motor information leaving
