respiration Flashcards
what’s Internal Respiration
-Within the cell, CO2 produced – Glycolysis Krebs Cycle
-O2 consumed – Oxidative Phosphorylation.
-end stages of respiration
whats External Respiration
-Ventilation
-Exchange and transport of gases around the body
-how we get gas from air to cells
overview of respiratory system
-respiratory and cardiovascular system work together with transportation
-diffusion of gases out if the lungs into capillaries
-heart pumping oxygen around body
-haemoglobin carries O2
-lost of CO2 carried back as carbonate
what are the two sections of the lungs branches
-conducting zone- provide pathways to get air to and from respiratory zone- no gas exchange taking place
-respiratory zone- where gas exchange takes place
whats the Conducting Zone
-Nose
-Nasopharynx
-(Mouth) Oropharynx
-Pharynx
-Larynx
-Trachea
-Bronchial Tree
-as you breathe in you filter air using structures inside nose using nasal hair- large particles are filtered
what air is gas more soluble in
-cold
whats the Structure of Bronchial Wall
-Reinforced with cartilage
-smooth muscle
-mucous glands
-elastic tissue
-bronchi help structure from not collapsing
what does The Respiratory Epithelium consist of
-Ciliated epithelia
-Goblet cells - secrete mucous
-Sensory Nerve Endings - pick up chemicals e.g. smoke
what do the bronchioles consist of
-Lack cartilage support
-Lined by respiratory epithelium
-Proportionately more smooth muscle
-more prone to collapsing as less cartilage
what do the alveoli consist of
-large SA
-Fed from terminal bronchiole
-Thin walled
-where gas exchange takes place
-very thin cells- epithelia
-optimised for gas exchange
whats The Air Blood Barrier
-A ‘sandwich’ created by flattened cytoplasm of type I pnemuocyte and the capillary wall
-For gas exchange to take place multiple barriers have to be crossed
-Large surface area for gas exchange (50-100m2
-alveoli surrounded by a network of capillaries
-air needs to pass 5 biological membranes- am, bm, 2 capillary , then alveoli membrane
what are the two processes of ventilation
-Inspiration
-Expiration
-Both of these processes can be quiet (at rest) or forced (when active e.g. during exercise).
-Importantly the movement of air occurs down pressure gradients.
-During inspiration: Patmos > Palv so air moves into the lungs
-During expiration: Palv>Patmos so air moves out of the lungs
whats Quiet inspiration
-Quiet inspiration involves the primary muscles of inspiration
-The diaphragm and The external intercostals
-Effect – increase thoracic and lung volume
-Air movement follows principles of Boyle’s Law. The increase in volume, leads to a reduction in pressure. Air moves into the lungs down the pressure gradient
-intercostal muscle lie between ribs and hence can lift the ribcage up and down
whats forced inspiration
-As well as the primary muscles, Accessory (or Secondary) muscles of inspiration are used.
-Scalenes- in your neck to the top of your ribs- helps pull ribcage up when exercising
-Sternocleidomastoids
-Neck and back Muscles
-Upper respiratory tract muscles.
whats quiet expiration
-Quiet expiration is a passive process using elastic recoil
-There are no primary muscles of expiration.
-Relaxation of external intercostal muscles
-Recoil of the lungs (elastic forces returning lungs to original size)
-Diaphragm relaxes
whats forced expiration
-Accessory muscles
-Internal intercostals
-Abdominal muscles- forced diaphragm back up
-Neck and back muscles
whats the pleura
-Pleural cavity filled with secretions
-Prevents lungs from sticking to the chest wall
-Enables free expansion and collapse of lungs
what happens during At rest elastic forces in lungs and chest balance
-Elastic nature of lungs would tend to cause them to collapse inwards
-The chest wall would tend to expand.
-At rest these inward and outward forces balance – as a result the pressure in the intrapleural space is less than atmospheric pressure.
compliance equation
c= change in V/ change in P
what does low compliance mean
more work required to inspire
what does high compliance mean
-often also involves more difficulty expiring (loss of elastic recoil)
Components of Elastic Recoil in the Lung
-Two major components to the Elastic Recoil of the Lungs.
-‘Anatomical’ component – elastic nature of cells and extracellular matrix.
-Elastic recoil due to surface tension generated at air-fluid interface
whats surface tension
-Due to difference in the forces on water molecules at the air/water interface a surface tension develops.
-In a gas bubble there is a balance between the pressure exerted by the gas and the surface tension at the gas/water border.
-Relationship described by Laplace’s equation
P=2T r -In the lung, many air sacs of different volumes. Because of Laplace’s equation, the pressure in the larger sacs is lower than smaller sacs. Air will flow from smaller alveoli to larger, leading to their collapse.
whats surfactant
-The problem of smaller alveoli collapsing is overcome by the production of surfactant.
-Surfactant produced by Type II pneumocytes. It is composed of a number of lipids and proteins
what do Surfactant (lipoprotein) Type II cells do
-prevents alveolar collapse by decreasing the surface tension
-Alveolar size regulation –spread of surfactant slows rate of inflation
-Increases compliance -allows lung to inflate much more easily
-production decreases (pneumonia) harder to inflate
-Prevents Oedema- reduces fluid entering alveoli
how is lung volume measured
-spirometer
-except residual lung volume
whats Dead Space
-Anatomical dead space - volume of conducting airways
At rest approximately 30% of inspired air volume(150ml)
-Physiological dead space – volume of lungs not participating in gas exchange
conducting zone + non-functional areas of respiratory zone
Normally the two values are almost identical
whats the airflow in the lungs like
-The flow of air into or out of the lungs is proportional to the pressure gradient and inversely proportional to the resistance.
- v= change in P/R= (P(alv)-P(atm))/R
-R= 8/pie . nl/r4
-Importantly small changes in airway diameter have a big impact on the resistance and hence flow rate.
whats poiseuilles law
-Airway resistance is proportional to gas viscosity and the length of the tube but is inversely proportional to the fourth power of the radius
whats Airway resistance through the lung like
-Pharynx-Larynx - 40%
-Airways >2mm diameter – 40%
Factors that impact on airway resistance.
-Airway Diameter:
-Increased mucus secretion will effectively reduce airway diameter – increased resistance.
-Oedema – increased fluid retention in the lung tissue will cause swelling and narrowing of the airways – increased resistance.
-Airway collapse – for example during forced expiration, narrows airway, increased resistance.
how is Bronchial Smooth Muscle controlled
-Autonomic Nervous System:
=Parasympathetic: acetylcholine is released from the vagus, acts on muscarinic receptors leads to CONSTRICTION
=Sympathetic: release of norepinephrine from nerves – weak agonist leads to DILATION
-Humoral factors: Epinephrine circulating in the blood – better agonist leads to DILATION
Histamine – released during inflammatory processes – leads to CONSTRICTION.
