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Flashcards in cardiovascular week 4 Deck (37):
1

Describe the trachea

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

2

Describe the epithelium of the trachea

ciliated pseudo stratified with goblet cells in between

3

Describe the trachea bifurcation

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

4

Describe the bronchioli

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

5

Describe the respiratory portion

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

6

What is present between alveoli?

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

7

What are the pleura?

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

8

What are the two major types of pleura?

parietal pleura
visceral pleura

9

Describe the pleural cavity

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

10

What is ventilation?

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

11

What is perfusion (q)

(Q)
the flow of blood through the pulmonary capillaries

12

Why must perfusion and ventilation be matched?

For efficient gas exchange

13

Where is perfusion greater and why?

the bases of the apices due to gravity

14

What are the ways which breathing is controlled?

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

15

What do central chemoreceptors respond to?

only changes in plasma carbon dioxide levels

16

How do central chemoreceptors work?

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

17

How do peripheral chemoreceptors work?

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

18

What is the most important factor in determining breathing rate?

CO2 levels

19

What is a pneumothorax?

the presence of air in the pleural space

20

What can cause pneumothorax?

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

21

What are risk factors for pneumothorax?

smoking
tall stature
presence of apical sub-pleural blebs

22

What types of pneumothorax are there?

closed
open
tension

23

Describe a closed pneumothorax

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

24

Describe open pneumothorax

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

25

Describe a tension pneumothorax

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

26

What is the oxygen capacity of haemoglobin?

the maximum number of oxygen molecules that can be carried

27

What is the saturation of haemoglobin?

The proportion of capacity occupied

28

What happens if tissues start to use more oxygen?

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

29

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

for a given PaO2, the oxygen saturations are lower

30

What can shift the curve to the right?

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

31

What causes left-ward shift of the curve?

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

32

How isCO2 transported in the body?

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

33

What is the reaction between carbon dioxide and water?

CO2 + H2O > H+ + HCO3-

34

Why are investigations of the respiratory system important?

confirms diagnosis
establish severity
assess fitness for treatment

35

What methods of respiratory investigations are there?

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

36

What is type 1 respiratory failure?

low O2

37

What is type 2 respiratory failure?

low O2, high CO2