External Respiration

Cellular respiration is the process by which cells harvest chemical energy to form ATP

which am i? water or air

i have good buoyancy, low varible o2 levels and water is freely availbale (lol)

water... hehe

this is ideal for fish gills which can be external or internal structures. the unidirectional flow allows the use of the countercurrent exchange system

air

this is ideal for mammalian lungs as the lungs are internal structures that use the tidal flow system as there is no countercurrent system

air enters nasal passage through NEGATIVE PRESSURE BREATHING

it then goes to pharynx > larynx >trachea > bronchus > bronchioles > terminal bronchioles > respiratory bronchioles with alveioli

exchange of gases takes place in alveoli of lungs

what does the glottis do?

which part of conducting zone is made from cartilagenous rings?

which part of the conducting zone is made from smooth muscle walls?

How many terminal bronchioles in humans?

glottis prevents food from enetering trachea

Bronchus is >1mM made from cartilagenous rings

bronchioles <1mM and made from smooth muscle walls

there are 145, 000 terminal bronchioles in humans

what makes up the conducting zone and the respiratory zone?

where does exchange of gas take place?

conducting zone - pharynx, larynx, trachea, bronchus, bronchioles and terminal bronchioles

Respiratory zone - respiratory bronchioles with alveoli

exchange of gas takes place in the alveoli of the lungs

where is air initially moistened?

how does air enter nasal passages?

air is initially moistened in the nasal cavity

air enters the nasal cavity by negative pressure breathing

what is the diameter of an alveolus?

what is the total respiratory surface area?

diameter of an alveolus 70-300uM

total respiratory surface area = 70m² approximately the same size as a tennis courth

how many million alveoli does the human lung contain?

each alveolus is wrapped in a mesh of capillaries covering approx how much of its area?

what happens to the radius of an alveolus during inhalation

human lung contains 200-300 million alveoli

~70% of alveolus wrapped in fine mesh of capillaries

the radius of an alveolus approximately doubles during inhalation

what are the trachea and bronchi lined with?

what type of cells secrete mucus?

which cells escalate mucus?

trachea and bronchi lined with pseudostratified columnar epithelium containing cillitaed and mucous cells

goblet cells secrete mucous

ciliated cells escalate mucous

what are the 2 cell types that line the 300 million alveoli in the human lung?

what do alveolar macraphages do?

Type I alveolar cells - primary cell lining

Type II alveolar cells AKA granular pneumocytes - secrete liquid surfactant that is needed to expand lungs and it also reduces the surface tension of lungs

alveolar macrophages remove microorganisms and dust from the alveoli

the pleural membranes are doubled walled sac around the lungs. name the layers and say what they attach to.

what is the pleural cavity filled with? what is the function of the pleural cavity?

visceral pleural membrane (inner) adheres to outside of lungs

parietal pleural membrane (outer) attached to the chest wall

pleural cavity (20uM across) filled with lubricating pleural fluid

(-2.5mm Hg)

it transfers negative 'suction' pressure to the lungs

During inspiration

• Diaphragm contracts (active) it depresses thorax floor by 1.5-7cm
• external intercostal muscles contract - moving ribcage up and outwards by 2-10cm
• in strenous exercise acessory muscles like the back and neck can help.
• during inhalition the intrapleural pressure drops to -6mm Hg

due to natural elasticity of lung tissues there is passive recoil of elements of the lungs

diaphragm relaxes (passive) - floor of thorax is raised

internal intercostals contract moving ribcage down and inwards

intrapleural pressure back to -2.5 mm Hg

what is the vital capacity in men and women?

what apparatus can be used to mease lung volumes and capacities?

Vc in men 4.6 litres

Vc in women 3.1 litres

the largest ever lung capacity recorded is 11.7 litres from an olympic rower. woo

A spirometer can be used to measure lung volumes and capacities

define tidal volume

define total lung capacity

the normal volume of air inhaled and exhaled without any extra effort (at rest)

Total lung capacity is the volume in the lungs at maximal inflation

define Residual volume

define expiratory reserve volume

Residual volume is the volume of air remaining in the lungs after maximal exhalation

Expiratory reserve volume is the max volume of air that can be exhaled from the end-respiratory position

define inspiratory reserve volume

define inspiratory capacity

Inspiratory reserve volume is the max volume that can be inhaled from the end inspiratory level

Inspiratory capacity is the sum of tidal volume (TV) and inspiratory reserve volume (IRV)

define inspiratory vital capacity IVC

define vital capacity VC

IVC is the maximal volume of air inhaled from the point of maximum expiration

VC is the total equal to TLC -RV (total lung capacity - residual volume)

consists of air in the conducting zone (trachea, bronchi, bronchioles)

aprrox 150ml of it

not in alveoli so not available for gaseous exchange

Forced Vital Capacity

the forced expiratory volume in 1 second (FEV1) is the amount of air that can be forcibly blown out in one second

75-80%

worked out by FEV1/FVC

forced expiratory volume in 1 second/ forced vital capacity

which aparatus is used by asthma sufferers to measure peak expiratory flow rate?

which aparatus can accurately measure flow rates as well as volume of air breathed in and out and can connect directly to a computer?

a peak flow meter is used to measure peak expiratory flow rate

a modern spirometer with pressure transducer can measure flow rates, volume of air breathed in and out and can connect to computer

Lung volumes are decreased

flow rate is near normal 75-80%

what type of lung disease is Asthma and COPD? 

what happens to lung volume and peak flow rate these conditions?

these are classed as obstructive diseases

lung volumes are normal but flow rates are impeded around 30-40%

Restrictive diseases

Pulmonary fibrosis involves scarring of the lung with alveoli being replaced by fibrotic tissue

fibrotic tissue

pulmonary fibrosis is a restrictive lung disease where lung volumes are decreased but peak flow is near normal 75-80%

Obstructive diseases

most common causes are asthma and smoking

B-adrenegic receptor agonists are used as bronchodilators

given as a combination with corticosteroids and other anti-inflammatories.

corticosteroids are anti-inflammatories