Control of Lung Function

Question 1

What are the groups of neurones in the brainstem?

Answer 1

DORSAL RESPIRATORY GROUP(medulla):

• Group of nuclei
• main controller of INSPIRATION

VENTRAL RESPIRATORY GROUP(medulla):

• EXPIRATORY control
• inactive during quiet breathing
• inhibit APNEUSTIC CENTRE

APNEUSTIC CENTRE(pons):

• Srtimulates activity in DRG
• Inhibited by Pulmonary afferents

PNEMOTAXIC CENTRE(pons):

• INSPIRATORY off switch
• regualtes depth and frequency of breathing

Question 2

How do the different respiratory groups and nerve centres interact with eachother in the brainstem?

Answer 2

Dorsal respiratory group -shuts down the ventral respiratory group.

Ventral respiratory group- shuts downt the dorsal respiratory group AND inhibits the Apneustic control (to prevent the dorsal group being activated)

Apneustic Control -activates the Dorsal respiratory group

Pneumotaxic control- inhibits the dorsal respiratory group

Question 3

Describe the image?

Answer 3

The action potential pattern of breathing is in a RAMP pattern.

The frequency of action potentials get higher up to the point where breathing is complete and then it is shut down

At the beginning the APNEUSTIC is activated and then PNEUMOTAXIC at the end to stop the breathing

Question 4

What is the Make up and importance of the Phrenic Nerve?

Answer 4

Spinal nerves C3, 4 and 5 (Motor) combine to form the phrenic nerve

This is the main drive to breath as it innervates the DIAPHRAGM

Question 5

What is the pulmonary plexus?

What is the structure of the pulmonary plexus?

Answer 5

convergence of the autonomic fibres :

parasympathetic-can case airways to narrow

Sympathetic-can cause airways to dialate(fight or flight)

Parasympathetic nerves come from the VAGUS NERVE

Sympathetic nerves come form the UPPER THORACIC AND CERVICAL GANGLIAN

Question 6

What is the difference between capillaries in normal circulation and the blood brain barrier?

Answer 6

Normal - Have GAP JUNCTIONS betweent the endothelial cells that are H2O filled

Blood brain barrier- Have TIGHT JUNCTIONS between the endothelial cells whcoih are supplement by GLIAL CELLS to keepn them in place=prevents the brain being leaky

Question 7

What provides the main stimulus to breath?

Answer 7

Proton Concentration in the CNS

Question 8

How do protons reach the medulla?

Answer 8

• They can’t travel throught he blood brain barrier(look at image) because they are charged and Large)
• Instead C02 travels easily through the blood brain barrier as it is HIGHLY LIPID SOLUBLE and

combines with H20 in the CSF to form H+ and HCO3

Question 9

What happens when the protons reach the medulla?

Answer 9

Interacts with the medulla and sends information to the dorsal respiratory nucleus

Question 10

What receptors are in the trachea and what do they do?

Answer 10

IRRITANT RECEPTORS-afferent receptors within and beneath airway epithelium

These lead to coughing-forceful expiration against closed glotis =suden opening of glottis =high velocity expulsion of air

Question 11

W1hat receptors are in the medium and small airways?

Answer 11

STRETCH RECEPTORS-activated when there is excessive stretching of the lungs

• sends afferent signals to DORSAL RESPIRATORY GROUP and APNEUSTIC CENTRE= inspiration inhibited
• stimulate PNEUMATAXIC CENTE =expiration triggered

Question 12

Whuch receptors are next to the capillaries of the alveoli?

Answer 12

J-RECEPTORS-detect odema and Pulmonary Capillary engorgement (pulmonay capillaries becoming too large)

Question 13

What happens during volitoinal Apnea?

What is the risk?

Answer 13

HOLD BREATH FRO A LONG PERIOD OF TIME- You hyperventilate with oxygen and are therefore able to remove lots of CO2 hence removing the main stimulus to breath(as C02 enters the CSF and combines with water to produce H+ whcih stimulate Dorsal respiratory group(DRS) =inspiration)

Risk of reaching the O2 blackout threshold before CO2 threshold for breathing

Question 14

1. What is an acid?
2. What is a base?

Answer 14

1. Molecule that is a H+ DONAR
2. H+ ACCEPTOR

Question 15

What happens if you are injected with a large qunatity of strong acid and why?

Answer 15

There is a NEGLIGABLE drops in pH

-This is due to the ENORMOUS BUFFERING capacity of the blood and that it reacts almost IMMEDIATELY to imbalances

Question 16

How can you claculate pH using [H+] and vice versa?

Answer 16

pH =log10[H+]

[H+]=10^ -pH

Question 17

What are the definitions of the following terms?

1. Alkalaemia
2. Acidaemia
3. Alkalosis
4. Acidosis

Answer 17

1. higher than normal blood pH
2. lower than normal blood pH
3. Describes circumstances that will decrease blood[H+] and therefore increase pH
4. Describes circumstances that will increse blood[H+] and therefore decrease blood pH

Question 18

What can happen to pH of the blood when lung ventilation rates change?

Answer 18

Change in ventilation=RAPID compensatory response to change CO2 and therefore this changes pH

Question 19

What responses are needed to reverse acidosis and alkalosis?

Answer 19

Acidosis needs ALKALOSIS to correct it

Alkalosis needs ACIDOSIS to correct it

Question 20

How can the kidney affect pH?

Answer 20

can secrete/retain H+ and HCO3- = SLOW compensatory response to increase/decrease kidney function

Question 21

What receptors are in the aortic arch and carotid bodies and what do they do?

Answer 21

PERIPHERAL CHEMORECEPTORS- sensitive to changes in arterial carbon dioxide, oxygen, and pH. The carotid bodies are generally more important in mediating this response and sense lowered levels of oxygen.

Question 22

Match up the images to the labels?

Answer 22

A-Yawning(large inspiration)

B-Talking ( lots of variation)

C-Normal Breathing

D-Laughing(inspiration increases and then gradually decreases in bumpy pattern)

E-Coughing (breath in and spiky patterns of expiration)

Question 23

What things send signals to the medulla during exercise to change breathing?

Answer 23

Efferent nerves from the PRE CENTRAL GYRUS(primary motor cortex) innervate the muscles mainly and a small part innervate the medulla so it can tell the brain to increase breathing for more muscle contraction

PROPRIOCEPTORS from MUSCLE SPINDLES + GOLGI TENDON in the muscle innerevate the medulla which then sends signals to the brain

Question 24

What receptors in the skin effect breathing?

Answer 24

THERMORECEPTORS-have afferent nerves coming from it that will inform us how to breath when temperature changes

Question 26

What happens during cold shock response?

Answer 26

• immersion of 80=90% of body into water less than 10 degrees
• causes Inspiratory Gasp and Hyperventilation
• can cause muscle spasms
• effects heart rate and blood pressure
• can kill you
• due to thermoreceptors