Physiology

Question 1

Which systems can be involved in shortness of breath?

Answer 1

Respiratory

Cardiovascular

Haem (anaemia)

Endocrine (DKA)

Psychiatric (anxiety)

many more causes

Question 2

Shortness of breath may be ___ or ___.

Answer 2

acute or chronic

Question 3

What are some respiratory causes of shortness of breath?

Answer 3

Asthma

COPD

Pneumonia

Lung cancer

Pulmonary embolism

Pulmonary fibrosis

Interstitial lung disease

…

Question 4

What are some cardiovascular causes of shortness of breath?

Answer 4

Ischaemic heart disease (angina > MI spectrum)

Hypertension

Valvular disease

Cardiomyopathy

Arrhythmias

Question 5

Where generally are the body’s respiratory centres found?

Answer 5

Brainstem

Question 6

Neurons in which parts of the brainstem control the

a) rhythm of respiration
b) inspiration / expiration modifications?

Answer 6

a) Medulla

b) Pons

Question 7

Which group of receptors detects the H+ concentration of the CSF?

Answer 7

Central chemoreceptors

Question 8

Which group of receptors detect the oxygen, CO2 and H+ concentrations of the blood?

Where are they found?

Answer 8

Peripheral chemoreceptors

Common carotid arteries and Arch of the aorta

Question 9

What is an increase in CO2 concentration called?

Answer 9

Hypercapnia

Question 10

How does CO2 reach the central chemoreceptors?

Answer 10

Via blood brain barrier

Question 11

In what form do the central chemoreceptors detect CO2 in the CSF?

Answer 11

H+

Question 12

Which chemoreceptors detect the oxygen concentration of the blood?

Answer 12

Peripheral chemoreceptors

Question 13

Which receptors detect

a) hypercapnia via an increased H+ conc. in the CSF

b) hypoxia via a decreased O2 conc. in the blood?

Answer 13

a) Central chemoreceptors

b) Peripheral chemoreceptors

Question 14

What is the main driver of respiration?

Answer 14

Effect of increased [CO2] on central chemoreceptors

Question 15

The central chemoreceptors are the main drivers of respiration.

What are two peripheral chemoreceptor drivers of respiration?

Answer 15

Hypoxic drive

H+ drive

Question 16

At which partial pressure of oxygen do the peripheral chemoreceptors trigger an increased rate of respiration - hypoxic drive?

Answer 16

< 60 mm Hg

Question 17

Which muscles control the inflation and deflation of the lungs?

Answer 17

Respiratory muscles

Question 18

How do signals reach the respiratory muscles from the chemoreceptors?

Answer 18

Peripheral nerves to intercostal muscles

Phrenic nerve (C3,4,5) to diaphragm

Question 19

Contraction of which muscle increases the vertical dimensions of the thorax?

Answer 19

Diaphragm

C3,4,5

Question 20

Contraction of which muscles increases the horizontal diameter of the thorax?

Answer 20

External intercostal muscles

Question 21

What are the major muscles of respiration?

Answer 21

Diaphragm

External, internal and innermost intercostal muscles

Question 22

What are some accessory muscles of respiration?

Answer 22

SCM

Scalenus anterior

Pectoralis major

Pectoralis minor

Latissimus dorsi

Question 23

___ pressure is usually greater than ___ pressure.

(intra-pleural , intra-alveolar)

Answer 23

Intra-alveolar pressure > Intrapleural pressure

i.e the pressure WITHIN the airways is > the pressure in the pleural cavity

Question 24

What is the difference between intra-alveolar and intrapleural pressure called?

Answer 24

Transmural pressure gradient

Question 25

Why is maintaining the **transmural pressure gradient** important? What can cause it to be **abolished**?

Answer 25

**Allows lungs to stick to pleura during thorax expansion and collapse** **Pneumothorax**

Question 26

What is a **pneumothorax?**

Answer 26

**Air within the pleural space** Abolishes the transmural pressure gradient

Question 27

Which substance is produced by **Type II pneumocytes** and **opposes alveolar surface tension**?

Answer 27

**Pulmonary surfactant**

Question 28

What is the main factor contributing to **airway resistance?**

Answer 28

**Airway radius**

Question 29

**Airway \_\_\_** is the main determinant of **resistance to air flow.**

Answer 29

**Airway radius**

Question 30

What causes **bronchoconstriction?**

Answer 30

**Parasympathetic impulses**

Question 31

What causes **bronchodilation?**

Answer 31

**Sympathetic impulses**

Question 32

During **inspiration**, the diaphragm moves **(up / down).**

Answer 32

**down** to increase vertical dimensions of the thorax reducing intra-alveolar pressure encouraging air to move into the lungs from the greater atmospheric pressure, down the pressure gradient

Question 33

During **expiration**, the diaphragm moves **(up / down).**

Answer 33

**up** to decrease vertical dimensions of the thorax increasing intra-alveolar pressure encouraging air to move out of the lungs to the atmosphere, down the pressure gradient

Question 34

What is the **normal force** which is applied to the airways by **increasing intra-pleural pressure** during expiration?

Answer 34

**Dynamic airway compression**

Question 35

**Dynamic airway compression** is the normal force applied to the airways by increasing intrapleural pressure during expiration. In which patients does this pose a problem?

Answer 35

**Patients with obstructed airways / reduced lung elasticity** i.e those with COPD, fibrosis

Question 36

What is **pulmonary compliance**?

Answer 36

**Effort required to inflate the lungs**

Question 37

Which disease **reduces pulmonary compliance?**

Answer 37

**Pulmonary fibrosis**

Question 38

What are a) **Type I pneumocytes** b) **Type II pneumocytes**?

Answer 38

**a) Alveoli** **b) Cells which produce pulmonary surfactant**

Question 39

Which structures **accept oxygen from** and **transfer carbon dioxide to** the alveoli?

Answer 39

**Pulmonary capillaries**

Question 40

What is found **between** the alveoli and pulmonary capillaries?

Answer 40

**Interstitial space** Affected in **interstitial lung disease**, which impairs compliance and gas exchange

Question 41

**Pulmonary capillaries** branch from the **pulmonary (arteries / veins).**

Answer 41

**pulmonary arteries**

Question 42

The ___ \_\_\_ of **CO2** is **20x that of oxygen**.

Answer 42

**diffusion coefficient** i.e how readily it passes across membanes

Question 43

What is the equation for **cardiac output**?

Answer 43

**CO = HR x SV**

Question 44

How is **stroke volume** calculated?

Answer 44

**SV = EDV - ESV**

Question 45

The **stroke volume** depends on the **\_\_\_** given to the heart's muscle fibres by the **venous return**.

Answer 45

**preload**

Question 46

Up to an optimal length, **\_\_\_ \_\_\_** is directly proportional to **preload.**

Answer 46

**stroke volume is directly proportional to preload** Frank-Starling Law of the heart

Question 47

Which cardiovascular disease shifts the **Frank-Starling curve** to the **right**?

Answer 47

**Heart failure**

Question 48

\_\_\_-\_\_\_ **heart failure** is a common cause of shortness of breath.

Answer 48

**Left-sided heart failure** or **Cor pulmonale**

Question 49

Which disease results in an **impaired ability for the blood to transport oxygen?**

Answer 49

**Anaemia** reduced number of circulating red blood cells, which contain haemoglobin, which binds oxygen

Question 50

What are some **core** **investigations** for **shortness of breath**?

Answer 50

**FBC, ABG** **ECG, Troponin T** **CXR**

Question 51

What is a **tidal volume**?

Answer 51

**Volume of air entering/leaving the lungs during a single breath**

Question 52

What is **inspiratory reserve volume?**

Answer 52

**Volume of air which can be inspired on top of a normal tidal volume**

Question 53

What is **inspiratory capacity?**

Answer 53

**Inspiratory capacity = Tidal volume + Inspiratory reserve volume**

Question 54

What is **expiratory reserve volume?**

Answer 54

**Volume of air which can be expired after a normal tidal volume**

Question 55

What is **residual volume?**

Answer 55

**Volume of air left in the lungs after a full expiration**

Question 56

What is **vital capacity**?

Answer 56

**Max volume of air which can be expired after a maximal inspiration**

Question 57

What is **FEV1?** What is **FVC?**

Answer 57

**FVC** - a forcefully expired vital capacity **FEV1** - volume of FEV1 which can be expired in the first second

Question 58

A normal **FEV1/FVC ratio** is \> \_\_\_%.

Answer 58

**\> 75%**