Respiratory System Flashcards
What does the Upper respiratory tract do?
aids in the passage of air
Moistens the warm air before it reaches our lungs
What makes up the upper respiratory tract
Nasal cavity
Pharynx- nasopharynx, oropharynx and laryngopharynx
Larynx
Describe the nasal cavities structure and function
Internal chambers in the nose
Where air is inhaled, warmed and humidified
Describe the structure of nasal conchae and function
Scroll-shaped bones
That protrude and firn spaces which air passes
Conchae swirl air around allowing time to humidify, warm and clean air before it enters the lungs
Describe the epithelial cilia and mucous membrane function in the nasal cavity
Seromucous, other glands and goblet cells produce mucous that along with cilia traps unwanted large particles which we cough or swallow when it reaches the pharynx
What is the purpose of the epithelial lining
Contains glands/goblet cells which secrete mucus to trap particles
Ciliates cells waft foreign particles towards the pharynx where they can be swallowed
Phagocytotic cells engulf an destroy bacteria and debris trapped by mucus
larynx function
voice box
pharynx function
dual function as passageway for air travelling to and from the lungs and swallowing food and drink down the oesophagus
what happens to the epiglottis when breathing
stays up and air passes freely between laryngopharynx and larynx
what happens to the glottis and epiglottis when eating
when eating glottis closes and epiglottis folds backwards covering the entrance to the larynx so food and liquid don’t enter the trachea to lungs
What makes up the lower respiratory tract?
Bronchial tree:
Trachea
Divides into two primary bronchi
Hilum
Divide into two/right secondary bronchi and three/left
Tertiary bronchi
Bronchioles
Alveoli
Alveolar sacs
Describe the structure of the trachea
Cylindrical tube, has c-shaped cricoid cartilaginous tubes prevent airway collapse
Lined with ciliated epithelial cells containing goblet cells which secrete mucus
Describe the structure of bronchi
Structured by cartilage
Describe the structure of bronchioles
Structured by smooth muscle
Under the control of autonomic nervous system can cause bronchodilation and brochoconstriction
Describe the structure of alveolus
One layer of squamous epithelial cells (type 1 cell) also contains type 2 cells (cuboidal) which secrete pulmonary surfactant, a phospholipid what keeps the membrane moist and the alveolus patent
Covered by a network of pulmonary capillaries, each wall is one cell thick
macrophages line alveolar surface
Describe the relationship between alveolar and the pulmonary blood vessels
The meet point between the walls of the alveolus and wall of capillary is called the respiratory membrane
Gas exchange occurs via diffusion
The large surface area plus very thin wall = efficient gas exchange
describe the pleura and pleural cavity
pleura consists of a closed sac of serous membrane which contains a small amount of serous fluid called pleural fluid
the visceral and parietal pleura refer to the two layers of the pleura cavity
describe the role of pleura
the lungs can expand and recoil within the pleural sac, lubricated by the pleural fluid
describe the conducting zone
from nostril to start of bronchioles
no gas exchange
describe intercostal muscles
11 pairs between 12 pairs of ribs
supplied by intercostal nerves and arranged in two layers: external and internal
describe the function external intercostal muscles
lift the rib cage up and out in inspiration
describe the function of internal intercostal muscles
used when expiration becomes active, i.e. exercise
describe the diaphragm
dome-shaped muscular structure
Describe Inspiration
Active (needs energy), simultaneously, diaphragm contracts and moves downwards and external intercostal muscles contract which expands the thoracic cavity and the rib cage is moved upwards and outwards, causing the lung tissue to be pulled upwards and outwards with the ribs and downwards with diaphragm as pleura membrane is all connected
causes lungs to expand and pressure within alveoli and air passage to decrease, drawing air into lungs
Describe expiration
Passive, diaphragm and external intercostal muscle relax, so downwards and inwards movement of rib cage so volume of thoracic cavity is reduced and pressure inside lungs increases so Air is expelled .
describe how accessory muscles are used in forced inspiration
muscles contract and pull rib cage upwards boosting the action of the external intercostal muscles
describe how accessory muscles are used in forced expiration
shortens the expiration time, increases the speed and force of exhalation and allows respiratory rate to rise
sometimes the abdominal muscles are used, which compress the abdominal organs increasing the upward pressure on diaphragm and helping to force air out of lungs
describe the physiological variables affecting breathing
elasticity: the amount of stretch of the lung and ability to return to normal
compliance: how easy it is for the lungs to stretch
airway resistance: how easy it is for air to move through the airways
describe the role of surfactant
reduce friction and decrease surface tension within the alveoli and makes it easier for the alveoli to expand and contract
describe the mechanics of inspiration
movement of rib cage and flattening of diaphragm increases lung volume
causes drop in airway pressure
air rushes in
lungs expand
max air is lung volume
define tidal volume
amount of air that moves into the lung in one respiratory cycle
define functional residual capacity/ residual volume
amount of air left in the lungs at the end of expiration
describe the mechanics of expiration
relaxed diaphragm relaxes the chest muscles
causes rib cage to compress lungs and decrease space as u breath out
lungs return to original shape due to elastic recoil
define inspiratory reserve volume
extra volume of air over and above the normal tidal volume that can be inhaled into the lungs during max inspiration
define inspiratory capacity
amount of air that can be inspired with max effort
define expiratory reserve volume
additional volume of air that can be expelled over and above the normal tidal volume during max expiration
define peak expiratory flow
measured with peak flow meter and record max speed of air flow during forced expiration
define vital capacity
the max amount of air that can be moved in and out of the lungs
describe the gas exchange taking place during respiration in alveoli and tissues
lungs: high partial pressure of oxygen in alveoli so oxygen binds to haemoglobin in blood
blood: low partial pressure of oxygen in blood so carbon dioxide binds to haemoglobin in blood
describe transport of CO2
10% as dissolved gas
30% combined with Hb
60% as bicarbonate ions
describe neural control of ventilation
receptors (peripheral chemoreceptors, central chemoreceptors and pulmonary mechanoreceptors) > respiratory control centre (medulla, pons) > impulse travels via spinal cord > effectors (respiratory muscles, diaphragm)
describe the central chemoreceptors role
central- brain stem neurons respond to changes in pH in cerebral spinal fluid = levels of CO2 in blood
maintaining stable pH ensures stable CO2 levels
describe the peripheral chemoreceptors role
peripheral- sensitive to pCO2 and low arterial pO2
