Respiratory system III

Question 1

Ventilation

Answer 1

• Air to the alveoli for gases to
  exchange

Question 2

Perfusion

Answer 2

• The circulatory system needs to ensure blood gets to the
  alveolar

Question 3

Gas Exchange

Answer 3

• Respiratory membranes are between air and blood
• Respiratory bronchioles and alveolar ducts and alveoli
• Perfusion for those that have emphysema

Question 4

Gas exchange

Thickness of membrane

Answer 4

• O2 exchange affected before CO2
• O2 diffuses through the respiratory membrane less easily than does CO2

Question 5

Gas exchange

Total surface area of the respiratory membrane

Answer 5

• Less surface area reduces gas exchange

Question 6

Gas exchange

Partial pressure of gases across the membrane

Answer 6

• Pressure exerted by a specific gas in a mixture of gases PO2, PCO2
• Gases in the air dissolve in the liquid
• Until partial pressure in liquid = to the partial pressure in air
• Gases in liquid and air diffuse from areas of higher partial pressure toward areas of lower partial pressure until equal

Question 7

step 1

Process of gas exchange

tissues to alveoli

Answer 7

• Blood from tissues has a lower Po2 and a higher Pco2 compared to alveolar air
• O2 diffuses from the alveoli into the pulmonary capillaries
• CO2 diffuses from pulmonary capillaries into the alveoli

Question 8

Step 2

Process of gas exchange

venous end of capillaries

Answer 8

• Pressures equal because of diffusion
• The blood carries O2 away by bulk flow
  to the tissues where O2 is required
• Mixing with deoxygenated blood =
  lower PO2 than in capilaries

Question 9

Step 3

Process of gas exchange

Diffusion to cells

Answer 9

• Oxygen diffuses out of the blood and
  into the interstitial fluid then into cells
• Carbon dioxide diffuses from cells into
  the interstitial fluid and from the interstitial fluid into the blood and equalibrium is reached

Question 10

How is oxygen stored in the body

Answer 10

• As a gas in the lungs
• Dissolved in tissue fluids
• As oxyhaemoglobin in blood
• As oxymyoglobin in muscle

Question 11

Oxyhaemoglobin
Dissociation Curve

Answer 11

• Hemoglobin to bind to O2
  depends on the Po2
• High Po2, haemoglobin binds to
  O2
• Low Po2, hemoglobin releases
  O2
• In the lungs the ppO2 is usually high heam holds most O2
• At tissues the ppO2 is usually low heam relases the O2

Question 12

Factors that effect Oxyhaemoglobin
Dissociation Curve

Answer 12

• Low Po2,
  *high Pco2
  *low pH
  *high temperature
  *Physical Exercise

Question 13

Transport of Carbon Dioxide

Answer 13

• Transported as CO2 dissolved in the plasma
• Transported bound to blood proteins, primarily haemoglobin
• As bicarbonate ions

Question 14

Gas exchange in Tissues

Answer 14

• CO2 diffuses into plasma and
  RBC
• Forms carbonic acid catalysed by carbonic anhydrase found inside RBC and on capillary
  epithelium
• Increase uptake of CO2 by red blood cells

Question 15

Gas exchange in tissues

Answer 15

• Capillaries of the lung CO2 diffuses from RBC to alveoli
• HCO3 dissociates to produce H2CO3
• Carbonic anhydrase catalyses formation
  of CO2 and H20 from H2CO3
• The CO2 diffuses into the alveoli and is
  expired

Question 16

pH importance of carbon dioxide

Answer 16

• CO2 levels increase, the blood pH decreases
  because CO2 reacts with H2O to form H2CO3
• H+ that results from the dissociation of H2CO3 is responsible for the decrease in pH
• Blood levels of CO2 decline, the blood pH increases

Question 17

Regulation of pH

Answer 17

• Chemical acid base buffer system
• The respiratory centre - lungs
• Kidney which takes hours

Question 18

Control of Respiration

Answer 18

• Rate of breathing dependant on number of times repiratory muscles are stimulated
• Spontaneously initiated within the central nervous system
• Increase in the depth of breathing is dependant on more stimulation and stronger contractions of muscle fibre

Question 19

Rhythmic breathing

Starting inspiration

Answer 19

• Neurons are continually active stimulating the repiratory centre caused by blood gas lavels muscle movement
• When threashold is reached somatic nervous system neurons stimulate respiratory muscles and inspiration starts

Question 20

Rhythmic breathing

Increasing inspiration

Answer 20

• Increase in neurone activation therefore stonger stimulation of respiratory muscles which last 2s

Question 21

Rhythmic breathing

Stopping inspiration

Answer 21

• Neurones that stimulate inspiratory muscles also stimulate medullary neurones that stop inspiration
• Receive input from the pontine respiratory neurons stretch receptors in the lungs
• When inputs exceed threashold levels it causes neurone respiratory muscles to be inhibited
• Leads to relaxation and expiration

Question 22

Key functions of Respiration

Answer 22

• Maintainance through involantary controls through regular rhythmic breathing
• Tidal volume and breathing frequency so that ventilation is mantained for gas exchange
• Adjust breathing pattern depending on activity

Question 23

Pons

Answer 23

• Pontine respiratory group
• Controls switches between inspiration
  and expiration

Question 24

Medulla Dorsal respiratory group

Answer 24

Diaphragm

Question 25

Medulla Ventral respiratory group

Answer 25

- Intercostals * Abdominals * Inspiratory and expiratory

Question 26

Hering- Breuer reflex

Answer 26

- Limits the extent of inspiration * As the muscles of inspiration contract the lungs fill with air * Sensory stretch receptors located in the lungs are stimulated * Action potentials sent to the medulla oblongata - Inhibition of respiratory centres causes expiration

Question 27

Chemical control of breathing

Answer 27

- Increase of CO2 in the blood urgue to breath increases with CO2

Question 28

3 Control pathways

Answer 28

- PCO2 is the principle pathway, controlling the rate and depth of breathing on a breath-by-breath basis - Acclimatization to altitude, the PO2 pathway can override the PCO2 pathway - Allows talking, swallowing and coughing to break through the normal pattern of breathing and try to match breathing to the expected voluntary or behavioural activity

Question 29

Central chemoreceptors

Answer 29

- PaCO2 rises causing a rapid increase in H+ ions - Causes the pH level to fall - Causes the central chemoreceptors to transmit a signal to increase ventilation - PaCO2 and CO2 decrease and when balance is restored, ventilation will decrease

Question 30

Types of chemoreceptors

Answer 30

- Central Medulla oblongata - Peripherally Carotid bodies and Aortic bodies

Question 31

Controlling the breathing rate

Answer 31

- CO2 levels of the blood decrease causing the pH to increase - Medullary chemoreceptors signal decrease inbreathing rate keeps CO2 in the blood - Increase CO2 in the blood causes H+ levels to increase and blood pH decreases

Question 32

Globullar innervation | Airways

Answer 32

- Innervated by the vagus nerve – Parasympathetic causing bronchoconstriction

Question 33

Respiratory muscle innervation

Answer 33

- Intercostal (motor) nerves * Phrenic nerve innervates the diaphragm

Question 34

Parasympathetic nervous system

Answer 34

- Acetylcholine is the effector neurotransmitter - The muscarinic M1 to M5 - Most important receptor M3 for airways

Question 35

Muscarinic receptors

Answer 35

- Stimulation causes the contraction of bronchial smooth muscle * Muscarinic receptors located in many glands help to stimulate secretion

Question 36

Sympathetic nervous system

Answer 36

- Noradrenaline effector with adrenergic receptors - Beta1 receptors – Heart Stimulation increases rate and force - Beta2 receptor smooth muscle of bronchioles stimulation (Agonist) causes relaxation