Week 20: (A) Respiratory Physiology recap

Question 1

What are the 5 stages of lung development?

Answer 1

embryonic, pseudoglandular, Canicular, saccular, alveolar

Question 2

What is a way to describe the branching of the lungs?

Answer 2

irregular dichotomous branching

Question 3

How is Cl- initiated to enter the epithelial cells?

Answer 3

Na+ and potassium enter through a transporter (NKCC Co-transporter)
Na leaves through a na/K pump
K+ leaves through a K+ channel (along its electrochemical gradient)
The NKCC links Cl- to enter the cell

Question 4

What is the name of the channel that k+ moves through, out of the cell?

Answer 4

Basolateral K channel

Question 5

What is the concentration of Cl- outside the cell and inside the cell?

Answer 5

blood= 107 mM
inside= 157 mM

Question 6

how does Cl- enter the apical (airway lumen)?

Answer 6

the NKCC moves 2Cl- across its electrostatic gradient

Question 7

What is the effect of Cl- accumulation in the airway epithelial cells?

Answer 7

Causes the membrane potential (Em) to go from -55mV to -90mV

Question 8

How does Cl- exit the cell into the apical?

Answer 8

Through a voltage-activated Cl- channel die due hyperpolaristion. Will cross the apical membrane

Question 9

How does Cl- create an osmotic gradient?

Answer 9

Accumulates in the apical (airway lumen) and creates an osmotic gradient.
Meanwhile Na+ enters through the tight junctions between the cells.
A potent osmotic gradient created and draws water from blood plasma to the airway lumen

Question 10

What stage does the osmotic gradient occur, filling of the lungs (3D structure)?

Answer 10

pseudoglandular

Question 11

How does blood leave the airways?

Answer 11

circulating cortisol binds to a TF glucocorticoid R-alpha.
ENaC genes are transcribed
ENaC subunit expression and increase ENaC membrane trafficking
Increased adrenaline titres
Bind to beta-2Adrenoreceptors
PKA initiates the opening of na channels
Leave the cell into the blood via Na/K channel

Question 12

What do the ENaC subunits make?

Answer 12

Create the Na+ transporter on the apical membrane.

Question 13

What does Cortisol bind to and initiate?

Answer 13

binds to Glucocorticoid R-alpha (TF)
Transcribes ENaC genes
ENaC subunit expressed, increased ENaC membrane trafficking
Creates the na+ transporter on the apical membrane

Question 14

What does adrenaline bind to and initiate?

Answer 14

Binds to B2-adrenoreceptor

induces a protein kinase dependent pathway, increased cAMP, increased PKA

Question 15

What opens the Na+ channels?

Answer 15

PKA
enter cells along its electrochemical gradient
Strong driving force for Na to enter the cell

Question 16

How does Na leave the cell?

Answer 16

A na/K pump
on basolateral gradient
potent osmotic gradient , which weather follows.