Respiratory System Lecture 5- Mechanics Of Ventilation 1

Front 1

thoracic cavity

Back 1

mechanical source of ventilation (through changes in thoracic volumes.
cavity lined by pleura

Front 2

thoracic cavity bounded by

Back 2

ribcage and intercostal muscles
sternum
thoracic vertebra
diaphragm
thoracic inlet

Front 3

pleura

Back 3

serous membrane covering all surfaces within thoracic cavity
forms mediastinum between two pleural cavities

Front 4

pulmonary or visceral pleura

Back 4

covers surface of all organs and vessels within thorax

Front 5

parital plura

Back 5

lines inner walls of thoracic cavity
named according to region
continous with plulmonary pleura

Front 6

sternopericardial ligament

Back 6

folds of pleura attaching heart to sternum

Front 7

plica venae cava

Back 7

fold of pleura suspending caudal vena cava

Front 8

pleural cavities

Back 8

two complete sacs
air tight cavities containing only small amount of fluid

Front 9

mediastinum

Back 9

encloses thymus, heart, trachea, major thoracic vessels and nerves

Front 10

cranial mediastinum

Back 10

cranial to heart

Front 11

middle mediastinum

Back 11

containing heart

Front 12

caudal mediastinum

Back 12

caudal to heart

Front 13

Back 13

Front 14

Back 14

Front 15

diaphragm

Back 15

principle muscle of inspiration- used during normal breathing
separates thoracic cavity from abdomen
thin sheet of muscle and tendon

Front 16

diaphragmatic attachments

Back 16

transverse processes of the first 2-3 lumbar vertebrae
interal aspect of ribs bear costal arch
caudal end of sternum

Front 17

external intercostal and scalaneus muscles

Back 17

only used during forced inspiration

Front 18

external intercostal muscles run

Back 18

caudoventrally between adjacent ribs

Front 19

scalenus muscles originate

Back 19

on the transverse process of cervical vertebrae and inset on first few ribs

Front 20

calenus and external intercostal muscles function

Back 20

draw ribs cranially and laterly-- expansion of throax

Front 21

expiration
normal

Back 21

normal expiration is passive
utilises elastic recoil of lungs
explusion of air continues until contraction of thorax reaches point of equilibrium between elastic recoil of lung tissue and resistance to stretching of inspiratory muscles.

Front 22

expiration
active

Back 22

occurs when requirment for ventilation elevated
contraction of internal intercostal and abdominal muscles reduces thoracic volume below equilibrium volume

Front 23

internal intercostal muscles run

Back 23

caudodorsally between adjacent ribs and callpase thoracic cavity

Front 24

abdominal muscles

Back 24

move viscera cranially, pressure on diaphragm

Front 25

Back 25

Front 26

Back 26

Front 27

diaphragm innervated by

Back 27

phrenic nerve which orginates from spinal cord in 5th-7th cervical nerves

Front 28

other respiratory muscles innervated by

Back 28

intercostal nerves

Front 29

gas flows from an area of

Back 29

high pressure to an area of low pressure

Front 30

atmospheric pressure

Back 30

760 mm Hg

Front 31

alveolar pressure

Back 31

760 mm Hg when muscles of ventilation realxed or fixed and glottis open

Front 32

alveolar pressure decreases during

Back 32

inspiration

Front 33

alveolar pressure increases during

Back 33

expiration
muscles compress thorax against closed glottis

Front 34

intrapleural thoracic pressure

Back 34

756 mm Hg

Front 35

transmural pressure gradient

Back 35

difference between alveolar and intrapleural pressure

Front 36

inspiration steps

Back 36

1. contraction of diaphram, increase volume of thorax
2. expansion of throax- increase volume of pleural cavity
3. drop in pressure in plueral cavity (754 mm Hg)
4. expansion of lungs and drop in intra alveolar pressure
5. airflow down pressure gradient into lungs ( until pressure is equal to atmospheric)

Front 37

expiration steps

Back 37

1. relxation of insipratory muscles
2. decrease in thoracic and lung volume
3. increased intra alveolar pressure (761 mm Hg) due to increase gas molecules
4. airflow down pressure gradient out of lungs

Front 38

contraction of accessory muscles of inspiration together with diaphgram causes an

Back 38

increase in thoracic volume above resting volume and therefore a greater drop in intra alveolar pressure and greater pressure gradient

Front 39

contraction of muscles of expiration along with relaxation of diaphragm causes

Back 39

a reducing in thoracic and lung volume below resting level and therefore a greater increase in intra alveolar pressure and a greater pressure gradient, and a faster and more complete emptying of lungs

Front 40

pneumothroax

Back 40

entery of air into pleural space due to trauma to lung or thoracic wall

Front 41

airflow into throax results in

Back 41

loss of partial vaccum and lung collapse

Front 42

respiratory dead space

Back 42

the volume of airways that does not participate in gas exchange

Front 43

anatomical dead space

Back 43

not anatomically adapted for gas exchange ( all airways from nose to terminal bronchioles- conducting airways)

Front 44

physiological dead space

Back 44

total volume of airways not participating in gas exchange
includes anatomical dead space plus volume of any alevoli with inadquate circulation
virtually identical to anatomical dead space in healthy animals

Front 45

pulmonary minute ventilation (ml/min)=

Back 45

tidal volume (ml/breath) X respiratory rate (breaths/min)

Front 46

alveolar ventilation =

Back 46

(tidal volume- dead space)X respiratory rate
volume of air entering of leaving alveoli in one minute

Front 47

it is more beneficial to .... .... ventiliation by.... .... .... than by... .... rate ( because all additional air taken in is available for gas exchange

Back 47

increase pulmonary ventiliation
increasing tidal volume
increasing respiratory