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Flashcards in anatomy Deck (25):

function of respiratory system

gas exchange- addition of oxygen to blood and removal of carbon dioxide
acid base balance- regulation of body pH
protection from infection
communication - expiration for speech


breathing through nose..

moistens and warms air - higher SA:V than mouth - gas needs to be in solution for gas exchange to occur
checks for infectious material - contains lymphoid tissue
filters air and traps dust - hairs in nose


where/ how does gas exchange occur?

diffuses across concentration gradient ( in solution) , across thin walls in alveoli and capillaries - walls are thin enough for gas to cross ( other vessel walls are too thick)


Structure of right lung

right lung is bigger - space taken on left for heart
has 3 lobes separated by 2 fissures , and 3 secondary bronchi
3 lobes - superior ( horizontal fissure ) middle ( oblique fissure) inferior
* right primary bronchi articulates to trachea more vertically than left bronchi - aspirated objects more likely to be found in right lung


structure of left lung

smaller than right - space taken up by heart
cardiac notch present
2 lobes separated by 1 fissure, and 2 secondary bronchi
superior ( oblique fissure) inferior


how is patency maintained in the airways?

C shaped rings of cartilage - larynx, trachea, bronchi - hold airways open to allow airflow
Physical forces in thorax - bronchioles and alveoli - no cartilage present**


how can resistance to air flow be altered ?

changing airway diameter - activity of bronchial smooth muscle
contraction decreases diameter - increased resistance to airflow
relaxation increases diameter - reduced resistance to airflow
*large cross sectional area in LRT - decreased resistance to airflow
** greatest resistance in conducting zone ( trachea and bronchi)


structure of alveoli

each cluster of alveoli surrounded by elastic fibres and capillary network - elastic never separates alveoli and capillaries
alveoli- interspersed Type 1 pneumocytes and Type 2 pneumocytes
alveolar macrophages present - ingest foreign material that enters airway
large surface area of alveoli - enhances gas exchange
thin walls - gas exchange
elastic fibres - recoil


anatomical dead space

air in conducting airways (upper airways) - gas cannot participate in gas exchange as walls of airways are too thick


function of type 1 pneumocytes

gas exchange - found in alveoli - simple squamous epithelium
97% of alveoli


function of type 2 pneumocytes

surfactant production - reduces alveolar surface tension in lungs to prevent alveolar collapse ( separates water molecules on inside of alveoli to prevent hydrostatic interaction - alveoli collapsing
reduces work of breathing


progression of lining from nose to alveoli

epithelium becomes more squamous
mucous cells lost
cilia lost


lining of respiratory tract

lymph nodes
blood vessels - nutritive


role of mucous

moisten air
trap particles
provide large SA for cilia to act on


systemic circulation

delivers oxygen form lungs to cells and pick sup CO2


pulmonary circulation

delivers CO2 to lungs and picks up oxygen from the lungs


describe the pleura

lungs and interior thorax covered by pleural membranes
visceral pleural membrane lines lung
parietal pleura lines thorax
continuous at the lung hillux
left and right pleural cavities independent of eachother
pleural cavity filled by pleural fluid
*prevent lungs from collapsing away form the ribs
pleurisy - inflammation of pleura


relationship between pleura and lungs

at rest - elastic tension in ribcage muscles - makes chest want to expand further
held in equilibrium by elastic recoil in lungs - want to relax further
creating a negative pressure inside the pleural cavity
* in health people pressure in pleural cavity is always negative


process of inhalation

external intercostal muscle contract and pull the ribcage up and out
diaphragm contracts and flattens
- volume in thorax increases
- pressure in thorax decreases
sternocleidomastoids and scalenes are accessory inspiratory muscles
* air moves from high pressure to low pressure so air rushes in to fill the lungs
* airways are pulled open by physical forces of inspiration


process of exhalation

diaphragm relaxes and moves up
intercostals relax and chest move down and in
passive at rest - thoracic volume decreases and pressure increases - air is pushed out to empty the lungs
* internal intercostal and abdominal muscles used in exhalation in severe respiratory load - exercise


result of loss of pleura - lung relationship

pneumothorax - if air is allowed to enter the pleural cavity then negative pressure is lost
lung collapses due to elastic recoil


intra-thoracic(alveolar) pressure (PA)

pressure inside thoracic cavity - pressure inside lungs
may be negative or positive


intra-pleural pressure (Pip)

pressure inside pleural cavity
always negative in healthy lungs


trans-pulmonary pressure (PT)

difference between alveolar and intra-pleural pressure
always positive in healthy lungs
PT=Palv - Pip


tidal volume

volume of breath in or out ( not combined )
average 500 ml