Respiratory System

Question 1

What is the tidal volume?

Answer 1

the amount of air that passes into and out of the lungs during each respiration.

Question 2

What are the normal tidal volumes for dogs and cats?

Answer 2

15mls/kg (for up to 5kg) and 10mls/kg (for over 5kg)

Question 3

What is the residual volume?

Answer 3

The air that is left In the lungs after the hardest expiration

Question 4

What is total lung capacity?

Answer 4

The Residual volume (i.e. the volume that never leaves) + the expiratory reserve volume (the extra air that can be exhaled with force) + the tidal volume (the normal volume inhaled and exhaled) + the inspiratory reserve volume (the extra air that could be inhaled with force)

Question 5

What is the functional residual capacity

Answer 5

The volume of air left in the lungs after normal expiration

Question 6

What is anatomical dead space

Answer 6

The volume of air inspired that never reaches the alveoli

Question 7

What is the Vital Capacity?

Answer 7

The total amount of air that can be expired after a maximum inspiration

Question 8

What is meant by the functional dead space

Answer 8

Areas of the respiratory system that do not contribute to gas exchange (including anaesthetic tubing etc)

Question 9

Define Inspiratory Reserve Volume

Answer 9

The volume of air inhaled during forced inspiration that’s above the normal inspiration volume

Question 10

Define Expiratory Reserve Volume

Answer 10

The volume of air that exceeds that of normal expiration after a forced expiration

Question 11

Define Inspiratory capacity

Answer 11

Tidal volume + inspiratory reserve volume

Question 12

Define expiratory capacity

Answer 12

Tidal Volume + expiratory reserve volume

Question 13

What is the respiratory rate? And what are the normal values for dogs and cats?

Answer 13

Breaths per minute. Dogs: 10-30bpm. Cats: 20-30bpm

Question 14

What is external respiration?

Answer 14

‘Breathing’. Inspiration and expiration - gas exchange between air and blood

Question 15

What is internal respiration?

Answer 15

Gas exchange between the blood and its tissues through capillary walls

Question 16

Describe the composition of inspired air

Answer 16

79% nitrogen, 21% oxygen and <0.03% CO2. +water vapour and other trace gases

Question 17

Describe the composition of expired air

Answer 17

79% nitrogen, 16% oxygen and 4-5% CO2. +traces of other gases.

Question 18

What 3 ways is CO2 transported?

Answer 18

1. 25% bound to Hb
2. Some dissolved in plasma
3. Most is dissolved in water in red blood cells

Question 19

What is the function of ethmoturbinate bones?

Answer 19

Filter incoming air for any microorganisms and dust particles, by ciliated mucous membrane
Increase the surface area of the nasal cavity
Warms and moistens incoming air

Question 20

What are the four bones that make up the nasal cavity?

Answer 20

Ethmoid bone, palatine bone, incisive bone and maxilla bone

Question 21

What divides the nasal cavity into right and left halves?

Answer 21

Bony septum

Question 22

What are the sinuses of the head and what’ the difference between them ? What are they collectively known as?

Answer 22

Frontal Sinus - ‘true’ sinus
Maxillary Sinus

Collectively known as paranasal sinuses

Question 23

What is the function of the frontal sinus?

Answer 23

Lined with ciliated mucous epithelium to secrete mucous
Mechanical Barrier to foreign material
Reduce the weight of the skull

Question 24

What is the correct term for the nostrils?

Answer 24

External nares

Question 25

What is the first opening of the nasal cavity?

Answer 25

Internal nares

Question 26

What cranial nerve is the olfactory nerve?

Answer 26

1

Question 27

What two structures attach to the hyoid apparatus?

Answer 27

Tongue and the Larynx

Question 28

What is the pharynx?

Answer 28

The portion at the back of the throat where the respiratory and digestive tracts overlap

Question 29

Name the 6 openings of the pharynx

Answer 29

``` Oropharynx Nasopharynx Oesophagus Trachea 2 Eustachian tubes ```

Question 30

What are the two functions of the pharynx?

Answer 30

Regulate passage of air from nasal cavity to trachea | Regulates passage of food from oral cavity to oesophagus

Question 31

How does the trachea enter the mediastinum

Answer 31

Via the cranial thoracic aperture

Question 32

Describe the make up of the trachea

Answer 32

Composed of incomplete C-shaped hyaline cartilage rings. Rest filled up by membrane. The membranous part is dorsal to allow for stretching of the oesophagus above it. The whole thing is surrounded by a fibrous connective tissue.

Question 33

What is the structure of the Larynx

Answer 33

Box-like cartilaginous structure lined by mucous membrane. Mucous membrane in 2 folds: 1. Vocal cords - muscular ligaments 2. Lateral ventricle - hollow cavity where sound is produced

Question 34

What is the epiglottis?

Answer 34

A flap of elastic cartilage that covers the larynx. Falls forward at rest to allow air to reach the trachea. When swallowing, it shuts and covers the larynx to prevent the entry of food into the trachea.

Question 35

Describe the structure of the bronchi

Answer 35

2 branches from trachea Have complete cartilage rings Lined by ciliated epithelium

Question 36

Describe the structure of the bronchioles

Answer 36

Divide from bronchi into these multiple branches Size decreases and have less and less cartilaginous support The smallest bronchioles are called terminal or respiratory bronchioles which have no cilia or cartilage

Question 37

Terminal bronchioles divide to form …?

Answer 37

2 or 3 alveolar ducts, which each terminate in numerous alveolar sacs

Question 38

Describe the structure of the alveolar sacs

Answer 38

``` Very vascular Very thin membrane Very large surface area Can expand Surfactant ```

Question 39

What is surfactant?

Answer 39

Mixture of lipids and proteins secreted into the alveolar space to reduce surface tension and allow the alveoli to expand more easily

Question 40

What are the coverings of the lungs? | What is their purpose?

Answer 40

The lungs are covered in visceral pleura, the thoracic cavity is lined with parietal pleura and in between these 2 layers is the pleural cavity. These layers facilitate friction-free movement of the lungs

Question 41

Name the 3 lobes of the lungs that are present in both right and left lungs (from top to bottom). What Is the name of the extra lobe and what side is it found on?

Answer 41

Apical Lobe Cardiac Lobe Diaphragmatic Lobe Right lobe has an extra accessory lobe between the cardiac and diaphragmatic lobe

Question 42

What are the 2 muscles of respiration and what nerves stimulate them?

Answer 42

Diaphragm - via phrenic nerve | Intercostal Muscles - via intercostal nerve

Question 43

Describe what happens to the thoracic cavity during inspiration and why

Answer 43

Increases the volume of the thoracic cavity: 1. Caudally, due to contraction and flattening of the diaphragm. 2. Laterally, due to the contraction of intercostal muscles causing the ribs to swing out and raise. These contractions create a vacuum, lowering pressure and draws air into the lungs.

Question 44

Describe the process of expiration

Answer 44

Usually a passive process Respiratory muscles relax, diaphragm relaxes and ribs fall. The thoracic volume decreases and air is forced out of the lungs

Question 45

Where are the respiratory centres found?

Answer 45

The hindbrain. The pons contains the expiratory centres (the apneustic and pneumotaxic centres). The medulla oblongata contains the inspiratory centres.

Question 46

What receptors are involved in respiration control?

Answer 46

Baroreceptors in walls of bronchi - detect pressure and stretch. Chemoreceptors in periphery (aorta and carotid arteries) - detect o2, co2 and pH- and central (medulla oblongata) - detect co2 and pH.

Question 47

Describe the Hering-Breuer Reflex

Answer 47

Prevents over-inflation of the lungs Lungs inflate Baroreceptors send signal to medulla via vagus nerve Further inspiration inhibited Expiration stimulated via apneustic centre

Question 48

What would happen if the respiratory rate was too slow?

Answer 48

CO2 wouldn't be expelled fast enough and would build up as carbonic acid. This would lower the pH in the blood and CSF. This would then be picked up by chemoreceptors in the medulla and would trigger the increase in respiratory rate.