cardiovascular week 4

Question 1

Describe the trachea

Answer 1

wall contains fibrous tissue/ muscle tissue. C shaped hyaline cartilage rings
internal lining - respiratory epithelium
tracheal rings between cartilage contain glands
cartilage surrounded by perichondrium
trachealis muscle - smooth muscle, relaxes on swallowing and inspiration, contraction on coughing

Question 2

Describe the epithelium of the trachea

Answer 2

ciliated pseudo stratified with goblet cells in between

Question 3

Describe the trachea bifurcation

Answer 3

respiratory epithelium
mainly propria with glands
ring-shaped muscular layer
cartilage plates instead of C-shaped rings
lymphatic infiltration in connective tissue

Question 4

Describe the bronchioli

Answer 4

less than 5mm
epithelium decreases in size - cuboidal in terminal branch, cilia tend to disappear
no goblet cells
clara cells - function?
no cartilage
folded lumen

Question 5

Describe the respiratory portion

Answer 5

alveoli open here
often located in clusters opening into alveolar sac
sac-like evaginations of tissue
95% type 1 pneumocytes - thin epithelium
5% `type 2 - produce surfactant
surfactant relieves surface tension of alveoli

Question 6

What is present between alveoli?

Answer 6

alveolar septa - thin connective tissue rich in elastic fibres, extremely vascularised, blood-air barrier

Question 7

What are the pleura?

Answer 7

each plural cavity is lined by a single layer of flat cells, mesothelium, and an associated layer of connective tissue

Question 8

What are the two major types of pleura?

Answer 8

parietal pleura
visceral pleura

Question 9

Describe the pleural cavity

Answer 9

the potential space enclosed between the visceral and parietal pleura. Normally contain a thin layer of serous fluid

Question 10

What is ventilation?

Answer 10

(V)
the movement of gas into and out of the alveoli

Question 11

What is perfusion (q)

Answer 11

(Q)
the flow of blood through the pulmonary capillaries

Question 12

Why must perfusion and ventilation be matched?

Answer 12

For efficient gas exchange

Question 13

Where is perfusion greater and why?

Answer 13

the bases of the apices due to gravity

Question 14

What are the ways which breathing is controlled?

Answer 14

higher cortical centres - modulation of breathing rate or depth
Central and peripheral chemoreceptors - react to a variety of factors in the blood

Question 15

What do central chemoreceptors respond to?

Answer 15

only changes in plasma carbon dioxide levels

Question 16

How do central chemoreceptors work?

Answer 16

Separated from the blood by the blood-brain barrier
only non-polarised molecules can diffuse through the lipid layer
When CO2 diffuses into the CSF it combines with water to form bicarbonate and hydrogen ions.
Chemoreceptors detect H+ ion concentration
Oxygen can diffuse but has no effect

Question 17

How do peripheral chemoreceptors work?

Answer 17

they are located in the arctic arch and carotid body
they respond to changes in the partial pressures of CO2 or H+, or falls in O2

Question 18

What is the most important factor in determining breathing rate?

Answer 18

CO2 levels

Question 19

What is a pneumothorax?

Answer 19

the presence of air in the pleural space

Question 20

What can cause pneumothorax?

Answer 20

spontaneous, iatrogenic injury or trauma to the lung or chest wall

Question 21

What are risk factors for pneumothorax?

Answer 21

smoking
tall stature
presence of apical sub-pleural blebs

Question 22

What types of pneumothorax are there?

Answer 22

closed
open
tension

Question 23

Describe a closed pneumothorax

Answer 23

communication between the airway and pleural space seals off as the lung deflates and does not re-open
pleural pressure remains negative
spontaneous reabsorption of air occurs in days or weeks

Question 24

Describe open pneumothorax

Answer 24

communication fails to seal off and air continues to flow freely between the bronchial tree and pleural space

Question 25

Describe a tension pneumothorax

Answer 25

communication between the airway and pleural spear acts as a one-way valve
air enters the pleural space during inhalation
does not escape during expiration
large amounts of trapped air accumulate
this causes mediastinal displacement towards the opposite side

Question 26

What is the oxygen capacity of haemoglobin?

Answer 26

the maximum number of oxygen molecules that can be carried

Question 27

What is the saturation of haemoglobin?

Answer 27

The proportion of capacity occupied

Question 28

What happens if tissues start to use more oxygen?

Answer 28

the PaO2 only has to drop a little for the saturation to drop a lot - haemoglobin gives lots of oxygen out to the tissues

Question 29

What happens when the oxo-haemoglobin curve is shifted to the right?

Answer 29

for a given PaO2, the oxygen saturations are lower

Question 30

What can shift the curve to the right?

Answer 30

increased temperature, CO2 concentration, H+ concentration
2,3DPG is a molecule produced in RBCs which pushes curve to right in chronic hypoxia - at altitude

Question 31

What causes left-ward shift of the curve?

Answer 31

reduction of other factors
foetus - more efficient at stripping oxygen from the mother

Question 32

How isCO2 transported in the body?

Answer 32

dissolved in plasma
bound to proteins such as carbamino compounds (e.g. haemoglobin)
as a bicarbonate

Question 33

What is the reaction between carbon dioxide and water?

Answer 33

CO2 + H2O > H+ + HCO3-

Question 34

Why are investigations of the respiratory system important?

Answer 34

confirms diagnosis
establish severity
assess fitness for treatment

Question 35

What methods of respiratory investigations are there?

Answer 35

xray - usually first
CT scanning - solid, peruse. affecting other body parts?
bronchoscopy - can be used to take a sample
CT guided biopsy
PET
Spirometry

Question 36

What is type 1 respiratory failure?

Answer 36

low O2

Question 37

What is type 2 respiratory failure?

Answer 37

low O2, high CO2