respiration - lecture 1

Question 1

what is primary function of respiration

Answer 1

gas exchange

Question 2

what is inspiration

Answer 2

air rich in oxygen inhaled into lungs

Question 3

what is expiration

Answer 3

carbon dioxide produced during oxidative processes of body is exhaled from lungs

Question 4

which system is closely related to respiratory system

Answer 4

both gases are transported by the blood
both cardiovascular system and respiratory system involved

Question 5

describe respiratory tract

Answer 5

first through nasal turbinates = nose/mouth, filters, catches, dust and particles
common passage of pharynx = air and food which then split = larynx - vocal chords, sound and speech
trachea = cartilage splits into right and left main bronchi then split smaller and smaller to alveolar region = gas exchange
alveoli = small balloons, covered by capillaries = blood comes from heart and becomes oxygenated and goes back = got rid of co2
airway tree = lots of space for gas exchange

Question 6

how do lungs inflate

Answer 6

lungs do not inflate on own - muscles of ribcage and coupling of ribcage and lungs
done by pleural space - v thin
intercostal muscles - allow for inflation

Question 7

what is pleural space

Answer 7

small amount of fluid
parietal pleura = attached to inside ribcage
visceral pleura = attached to alveoli
pleural space = one per lung, not continuous, creates coupling of ribcage and lungs

Question 8

how to visualize pleural surfaces

Answer 8

drop of water between 2 glass microscope slides = the 2 slides can easily slide over each other but cannot be pulled apart - creates suction = how we breathe

Question 9

describe when ribcage enlarges

Answer 9

enlarges size of lungs = coupling
bigger vol = less pressure so air flows inside lungs down pressure gradient

Question 10

describe normal pleural space

Answer 10

p=0 outside
p=0 inside lung
no air in or out since equal pressures
in pleural space p=-5, negative pressure, lungs like balloon, always want to collapse, lungs pull more than ribcage (which wants to spring out, opposing forces so neg)

Question 11

describe pneumothorax pleural space

Answer 11

p=0 in pleural space
accident = hole through ribcage removes coupling so lungs deflate and ribcage expands = pneumothorax, usually only on one lung since pleural spaces discontinuous
removes coupling

Question 12

describe mechanical pump

Answer 12

syringe = pull down plunger = neg pressure = air moves in and expands like balloon
when respiratory muscles contract = diaphragm and intercostals contract = increase size of ribcage so decrease pressure = holds lung open and causes air to move in

Question 13

describe bronchi splitting

Answer 13

right main bronchus - split into 3 lobar bronchi
left = split into 2 lobar bronchi

Question 14

name and describe subdivisions of respiratory system

Answer 14

conducting zone = trachea, bronchi, bronchioles, terminal bronchioles
respiratory zone = respiratory bronchioles (alveoli budding in walls), alveolar ducts (filled with alveoli), alveolar sacs

Question 15

describe acinus

Answer 15

bronchi = have rings then plaques of cartilage
bronchioles = no cartilage
smooth muscle = involuntary, cannot control, holds tone of airways
asthma = contract and constrict airways and decrease air flow

Question 16

name the 4 main functions of conducting airways

Answer 16

defence against bacterial infection and foreign particles
warm and moisten inhaled air
sound and speech
regulation of airflow

Question 17

describe defence against bacterial infection and foreign particles - main functions of conducting airways

Answer 17

epithelial lining of bronchi = has cilia - beat upwards
epithelial glands secrete a thick substance = mucous which lines respiratory passages as far down as bronchioles
foreign particles stick to mucous and cilia sweep mucous up into pharynx = mucociliary defence system
helps swallow or spit out

Question 18

describe sound and speech - main functions of conducting airways

Answer 18

produced by movement of air passing over vocal chords - larynx

Question 19

describe regulation of airflow - main functions of conducting airways

Answer 19

smooth muscle around the airways may contract or relax to alter resistance to air flow - in whole respiratory tract

Question 20

what is function of respiratory zone

Answer 20

site of gas exchange between the air in the alveoli and the blood in the pulmonary capillaries
~300 million alveoli in the human lungs - each alveolus
may be associated with as many as 1000 capillaries

Question 21

describe heart and lungs together

Answer 21

inferior vena cava = mixed venous blood - right side and goes to lungs through left and right pulmonary arteries and then comes back into left heart through left and right pulmonary veins and goes to whole body through aorta and also to airway to get oxygenated

Question 22

how many circulations do lungs have

Answer 22

2 = pulmonary and bronchial

Question 23

describe pulmonary circulation

Answer 23

bring mixed venous blood to lungs
allows for blood to get oxygenated and then to be taken back to heart

Question 24

describe bronchial circulation

Answer 24

supplying oxygenated blood from systemic circulation to tracheobronchial tree = circulation allows airways to get oxygenated

Question 25

describe bronchial artery

Answer 25

from left heart via aorta
is not much blood going to airways - some goes back to venous system - anastomosis with oxygenated blood - mixed venous blood, and goes back to heart

Question 26

name the 3 alveolar cell types

Answer 26

epithelial type 1 and 2 cells
endothelial cells
alveolar macrophages

Question 27

describe epithelial type 1 and 2 cells

Answer 27

line alveoli
little known about specific metabolic activities of type 1 cells
type 2 cells produce pulmonary surfactant = substance that decreases surface tension of alveoli

Question 28

describe endothelial cells

Answer 28

constitute the walls of pulmonary capillaries
may be as thin as 0.1microns

Question 29

describe alveolar macrophages

Answer 29

remove foreign particles that have escaped mucociliary defence system of airways and found way into alveoli

Question 30

describe alveolar capillary membrane

Answer 30

interstitium = space between alveoli and blood vessels

Question 31

describe surface tension - specific

Answer 31

The surface tension of the liquid film lining the lungs is an important contributor to the mechanical properties of the respiratory system
tension arises because the molecules in the surface of the film tend to arrange themselves in the configuration involving the lowest energy
Being more attracted to themselves than to air, they like to “hold hands” rather than freely associate with air molecules
This causes a tension to be generated across the film surface

Question 32

describe surface tension - gen

Answer 32

everything is lined with a bit of water = air water interface with tension, like soap bubble
surface tension at air liquid interface since forces between water molecules greater than forces between water molecules and air

Question 33

describe what happens with surface tension when surface curved

Answer 33

like on inside alveoli
tension can produce a pressure that tends to collapse alveolus
vectors add up to pressure that tends to collapse soap bubbles
need surfactant - tends to collapse all the alveoli

Question 34

describe alveoli modelling - soap bubble

Answer 34

pressure - p - inside soap bubble radius - r - results from surface tensionT = laplace’s law
p=4T/r
the smaller the bubble = smaller r = greater pressure
small would empty into large = bad system

Question 35

describe pulmonary surfactant

Answer 35

decreases tension and smaller alveoli more
small alveoli will collapse, emptying into large ones = prevented from happening by secretion of pulmonary surfactant by alveolar type II cells

Question 36

name the first primary role of pulmonary surfactant

Answer 36

making surface tension inside alveoli change with lung vol = prevents pressure inside small alveoli from exceeding pressure of large = biophysical properties that decrease surface tension to a greater extend in smaller than larger alveoli
surfactant = stacks up in many layers, helps better than being spread thin

Question 37

name the second primary role of pulmonary surfactant

Answer 37

reducing overal surface tension so we can breathe
if surface tension in liquid layer lining was equal to water = would not be able to inflate lungs

Question 38

describe respiratory muscles

Answer 38

lung tissue = elastic but cannot expand or contract by itself
air must be sucked into lungs
function powered by respiratory system muscles of chest wall

Question 39

name the 2 types of respiratory muscles

Answer 39

inspiratory and expiratory

Question 40

describe principal muscles of inspiration

Answer 40

external intercostals = elevate ribs
parasternal intercartilaginous muscles = elevate ribs, when contract = increase cross sectional dimension of ribs
diaphragm = dome descends, increases longitudinal dimension of chest and elevates lower ribs, separates ribcage from abdomen, bucket handle effect, dome down = increase longitudinal but also attached to lower ribs = bucket handle effect - moves lower ribs outwards = increase cross sectional area too

Question 41

describe accesory muscles of inspiration

Answer 41

do not use them = recruit during exercise or disease
sternocleido-mastoid = elevates sternum when contract
scalenus anteior middle and posterior = elevate and fix upper ribs
all increase cross sectional area

Question 42

describe the quiet breathing muscles of expiration

Answer 42

expiration results from passive recoil of lungs
ribcage goes back to original size

Question 43

describe the active breathing muscles of expiration

Answer 43

recruits these =
internal intercostals, except parasternal intercartilaginous muscles = depress ribs and decreases cross sectional area
abdominal muscles = depress lower ribs, compress abdominal contents, recruit and pushes abdomen in and push diaphragm upwards and get back to original position
all lead to expiration = rectus abdominus, external oblique, internal oblqiue, transversus abdominus

Question 44

what is diaphragm innverated by

Answer 44

phrenic nerves from cervical segments 3, 4 and 5

Question 45

why do smokers cough up mucous

Answer 45

cilia get momentarily paralyzed by nicotine

Question 46

when is surfactant produced

Answer 46

late in gestation and if premature = give drugs to mom so can develop lungs of baby, also artificial surfactant available