BCR TBL 13: Control of Breathing, Pulmonary Circulation & Hypoxaemia

What is hyperpnoea

Increased Breathing to match metabolic needs

What is Tachypnoea

Increased Respiratory rate above normal

What is Hyperventilation

Breathing in excess of metabolic needs

What is apnoea

Absence of airflow due to lack of respiratory effort or obstruction

What is dyspnoea

Shortness of breath

What can involuntary breathing be overridden by

Swallowing or reflex

When we say neural humeral control what do we mean

Hormone release due to neural stimulation

When we say humoral control what do we mean

Hormone release due to changes in physiological condition

What would a change in ion level cause, Neural humeral control or humeral control

Humeral Control

Where does the PSNS originate from

Medulla

What CN controls the PSNS

Vagus nerve

What CN is the Vagus nerve

10

What does the vagus nerve do to smooth muscle cells near the lungs in PSNS

Constriction of airways

What does the vagus nerve do to blood vessels near the lungs in PSNS

Vasodilation

What does the vagus nerve do to Bronchial epithelial glands near the lungs in PSNS

Increase Secretion

Where does the SNS originate from

Thoracic and Lumbar region of spinal cord

What does the SNS do to smooth muscle cells in reference to airways

Relaxes airways

What does the SNS do to blood vessels in reference to airways

Vasoconstriction

What does the SNS do to Glandular cells in reference to airways

Decreased Secretion

What special receptor is there on airway smooth muscle cells abundantly which mediates bronchodilation

Beta 2 Adrenergic Receptors

What activates beta 2 adrenergic receptors

Circulating Catecoleamines

APs are send to inspiratory muscles until what point

Reaches Threshold

After reaching the threshold for APs what happens

Inspiratory muscles relax and passive expiration occurs

When do expiratory APs get fired

Exercise or Forced Expiration

Where are the respiratory rhythm and pattern are automatically generated from where?

Pons and Medulla

How many main groups of neurones/respiratory centres control minute by minute breathing

3

What are the three respiratory centres (just say name not centre)

Medullary Respiratory Apneustic Pneumotaxic

What 2 subgroups is the Medullary Respiratory Centre split into

Dorsal and Ventral Respiratory Group

What does the DRG mainly deal with

Inspiration

What does the VRG mainly deal with

Expiration

Where is the Pre-Botzinger Complex located

VRG

What does the Pre-Botzinger Complex Do

Produces Impulses to determine respiratory rate and rhythm

What part of the brainstem is the DRG and VRG

Medulla

What part of the brainstem is the Apneustic Pneumotaxic part of

Pons

Where does the DRG send impulses (What muscles)

Diaphragm External Intercostal Muscles

What part of the pons is the Apneustic centre in

Lower

What kind of effect does the apneustic centre have on the inspiratory part of medulla (Excitatory or inhibitory)

Excitatory

What does the apneustic centre do to the APs

Prolong

Where is the pneumotaxic centre located in the pons

Upper

What does the pneumotaxic centre control in the pons

Apneustic centre

What can the pneumotaxic centre do to inspiration

Switch off or inhibit

Can normal breathing rhythm happen without the pneumotaxic centre

Yes

What are the two main classes of chemoreceptors

Central and Peripheral

Where are the carotid body peripheral chemoreceptors located

Bifurcation of common carotid arteries

Where are the Aortic body peripheral chemoreceptors located

Above and below Aortic arch

Where are the Paraganglia body peripheral chemoreceptors located

Along length of vagus nerve

What type of cell is a glomus cell (Type 1 or 2)

1

What type of cell is a sustentacular cell (Type 1 or 2)

2

What do type 1 cells in carotid bodies look like under a flourescent micorscope

Intense glow

What is the type 1 cells in carotid bodies glow due to

High Dopamine

Peripheral Arterial Chemoreceptors (PAC) increase fire rate due to 4 conditions. What are they

Hypercapnia Hyperkalaemia Hypoxia Acidosis

What is hypercapnia

Increased Arterial PCO2

What is Hyperkalaemia

Increased Arterial [K+]

What is Hypoxia

Decreased Arterial PO2

What is Acidosis

Decreased Arterial pH

What are the 6 main steps of glomus cell response to hypoxia

Inhibition of K+ channel
Depolarisation of Cell
Firing AP
Opening Voltage Operated Ca2+

Increase in [Ca2+]

Secrete Neurotransmitter

Stimulate afferent nerve fibre

What are the 5 main neuromodulators in hypoxic chemotransduction

Dopamine AcH ATP ROS Cytokines

What are the 4 types of hypoxia (First name only)

Hypoxic Stagnant Anaemic Histotoxic

What is Hypoxic Hypoxia

Insufficient O2 to lungs

What is stagnant Hypoxia

Failure to transport O2 due to Inadequate blood flow

What is anaemic Hypoxia

Reduced Hb so reduced O2 carrying capacity

What is Histotoxic Hypoxia

Impaired Oxygen use by tissues

What are 4 Main reasons for Hypoxic Hypoxia

Low Alveolar PO2 Diffusion impairment Shunts Ventilation-Perfusion Mismatch

Up until about how much pressure are peripheral chemoreceptors sensitive to oxygen

500mmHg

After which point in terms of pressure is there relatively low response by the peripheral chemoreceptors when dealing with oxygen

70mmHg

What is the normal arterial PO2 roughly

100mmHg

If PCO2 is increased, does the Hypoxic Response curve move up or down

Up

At what point do we have a robust response to hypoxia (What pressure)

60-70mmHg

What are central chemoreceptors involved in to do with respiration

Minute by Minute ventilation

What are central chemoreceptors surrounded by instead of lots of blood

Brain Extracellular fluid

What are the six sites at which there are Central Chemoreceptors

VRG Ventro-Lateral Medulla Caudal Raphe Pons NTS RTN

What does NTS stand for

Nucleus Tractus Solitaris

What does RTN stand for

Retro Trapezoid Nucleus

What is CSF seperated from blood by

BBB

How permeable to CO2 is the BBB

Very Permeable

How permeable to [H+] is the BBB

Impermeable

How permeable to HCO3- is the BBB

Impermeable

What converts CO2 and H2O into H2CO3

Carbonic Anhydrase

What does an increase in CO2 do to ventilation

Stimulates it

What does an decrease in CO2 do to ventilation

Decreases it

What is the normal blood pH range

7.35-7.45

If you have prolonged Hypercapniaa what moves through the BBB slowly to remove H+ in ECF and CSF

Bicrabonate Ions

Why is the CSF more sensitive to changes in pH

Reduced Buffering

What percentage of the ventilatory response is due to peripheral chemoreceptors

10-30%

What percentage is tidal volume reduced by during sleep

25%

What happens to PaCO2 in sleep

Increases

What happens to PaO2 in sleep

Decreases

What happens to pharyngeal muscle tone during sleep

decreases

What happens to pharyngeal resistance in sleep

Increases

What is respiratory failure

Gas exchange Fails

What is the PaO2 value for Respiratory Failure

<60mmHg

What is the PaCO2 value for respiratory failure

>50mmHg

In Hypoxaemic Respiratory Failure what are your PaO2 and PaCO2 like

<60mmHg Normal or Low

What are the three common forms for Hypoxaemic Respiratory Failure

Pulmonary Oedema Pneumonia Pulmonary Haemorrhage

What type of respiratory failure is hypoxaemic respiratory failure (type 1 or 2)

1

What type of respiratory failure is hypercapnic respiratory failure (type 1 or 2)

2

What is your PaCO2 in hypercapnic Respiratory Failure

>50mmHg

What is the range of pressures for the right atrium

0-25mmHg

What is the range for PAP

8-25mmHg

What is PVP

8mmHg