18 - anatomy of ventilation

Question 1

pulmonary ventilation definition:

Answer 1

the physical movement of air into and out of the respiratory tract

Question 2

function of breathing:

Answer 2

to ensure constant supply of oxygen

to prevent build up of CO2 and therefore maintain pH

Question 3

inspiration

Answer 3

expiration

Question 4

inhilation

Answer 4

exhalation

Question 5

what two principles does pulmonary ventilation rely on?

Answer 5

• Boyles law (pressure of a gas is inversley proportional to its volume (and so the containers volume) at a constant temperature)
• Air flows from an are of low pressure to an area if high pressure

Question 6

In a syringe

Answer 6

• plunger pulled back
• volume inside increases
• pressure decreases
• fluid/gas moves in

Question 7

air will enter the lungs when

Answer 7

atmospheric pressure is greater than pressure within the lungs (intraalveolar pressure or intrapulmonary pressure)

Question 8

air will leave the lungs when

Answer 8

atmospheric pressure is less than pressure in the lungs

Question 9

how do we change the pressure in the lungs?

Answer 9

by changing the volume of the lungs and thoracic cavity

Question 10

atmospheric pressure is

Answer 10

760mmHg

Question 11

pressure in the lungs differs by how many mmHg during inspiration and expiration

Answer 11

-1=759

+1=761

Question 12

Thoracic volume can be increased by:

Answer 12

-increasing the vertical diameter (diaphragm)
-increasing the anterior posterior diameter (ribs)
-increasing the transverse diameter (up and out) (ribs)
not horizontal diameter

Question 13

contracting the diaphragm

Answer 13

• flattens the diaphragm
• causes vertical diameter to increase
• increases thoracic capacity by 75%

Question 14

Elevation of the ribs

Answer 14

• increases the AP diameter and the transverse diameter

- responsible for 25% of thoracic capacity increase

Question 15

How is AP diameter increased

Answer 15

• pump handle action of the ribs

- elevation of the ribs at the sternal end causes them to become horizontal instead of B\F

Question 16

How is the transverse diameter increased

Answer 16

The bucket handle - ribs tend to dip in the middle like a sagging bucket handle - during inspiration pick the bucket handle up so its horizontal - this increases the diameter from left to right

Question 17

How does the thoracic cavity size effect lung size?

Answer 17

The parietal pleura is stuck to the thoracic wall and diaphragm.
the visceral pleura is stuck to the surface of the lungs and moves with the parietal pleura due to surface tension cause by the serous fluid (fills cavities) in the cavity between the two membranes

Question 18

the pressure in the pleural cavity is

Answer 18

always lower than atmospheric and intrapulmonary pressure because the elastic fibres in the lung tissue are always trying to pull back and cause recoil, causing negative pressure in the pulmonary cavity

Question 19

If air gets between lung and _____ pleura

Answer 19

• parietal pleura the lung will succeed on pulling back and come free from the pleura and collapse - pneumothroax
• occurs as a result of injury - disease or puncture wound

Question 20

what causes pneumothorax

Answer 20

• accumulation of air in pleural cavity resulting from disease or puncture wound
• loss of negative intrapleural pressure
• lung collapse

Question 21

on x-rays what is

• black
• white
• imbetween

Answer 21

• air is black
• connective tissues come up faintly grey
• if the whole lung space is a solid black colour the lung has collapsed
• bone is white
• everything else is imbetween

Question 22

when one lung collapses

Answer 22

it can push the mediastinum to the other side and cause the other lung to collapse

Question 23

what to do when someones lung collapses

Answer 23

put a tube into the pleural cavity and put the other end of the tube into water so the air from the space will start bubbling into the water and the lung will re-inflate

Question 24

what is used in quiet inspiration

Answer 24

active process

• diaphragm 75%
• external intercostal muscles 25%

Question 25

what is used in forced inspiration

Answer 25

- pectoralis major - pectoralis minor - scalenes - serratus anterior - sternacloidamastoids -used by unhealthy people as normal inspiration

Question 26

external intercostal muscles

Answer 26

go downwards and forwards. start on one rib and go down onto the next one. lift the ribs like you would lift weights from squats

Question 27

pec minor

Answer 27

pec minor is attached on the shoulder and comes down to the ribs - it pulls ribs 3-5 up and down to help with AP diameter

Question 28

scalenes

Answer 28

are in the neck come from the cervical vertebra onto the ribs fixes the first rib in place so the external intercostal muscles can work more effectively

Question 29

serratus anterior

Answer 29

comes round the side from the spine and helps pull ribs out at the side

Question 30

sternocleidomastoid

Answer 30

is between the sternum and the clavicle | helps fix the first rib and pulls the sternum out at the front

Question 31

pec major

Answer 31

fixes your humorous so you can move the ribs up and out

Question 32

whats used in quiet expiration

Answer 32

nothing its a passive process | relax the diaphragm and external intercostal muscles

Question 33

whats used in forced expiration

Answer 33

- active process - internal intercostal muscles - abdominal muscles - compress contents of abdomen and therefore push them up against the diaphragm to force air out

Question 34

neural control of ventilation

Answer 34

chemoreceptors | -central and peripheral

Question 35

chemoreceptors

Answer 35

- detect changes in pH ppO2 and ppCO2 | - send information via afferent pathways to the brain via the vagus nerve and glossopharyngeal nerves

Question 36

where do the signals from the chemo receptors get sent

Answer 36

- through afferent pathways through vagus and glossopharangeal nerve - to the respiratory centres in the brain stem - down the efferent pathways down the the phrenic and intercostal nerves

Question 37

which nervous system controls the diaphragm

Answer 37

signals sent to skeletal muscle so somatic nervous sytsem

Question 38

central chemo receptors

Answer 38

- respond to changes in pH and CO2 - DONT RESPOND TO O2 - found in the medulla in the brain stem

Question 39

peripheral chemoreceptors

Answer 39

- respond to ppO2 ppCO2 and pH - found near baroreceptors - some called aortic bodies found in aortic arch - stimulate? vagus nerve - some called carotid bodies found in the common carotid artery

Question 40

groups of neurons in the respiratory centres

Answer 40

- medullary rhythmicity area | - pneumotaxic area (pons)

Question 41

medullary rhythmicitary area

Answer 41

dorsal (back) respiratory group - sets rhythm, stimulates muscles of quiet inspiration ventral (front) respiratory group - involved in forced expiration and inspiration

Question 42

pneumotaxic area

Answer 42

influences the dorsal respiratory group by regulating the duration of inspiration

Question 43

Hering breuer reflex

Answer 43

prevents the over inflation of the lungs - stretch receptors in the visceral pleura, bronchioles and alveoli - impulses sent to the pneumotaxic area via the vagus nerve - duration of inspiration shortened