Physiology Flashcards
What is an inert gas?
A gas the body doesn’t use
Describe the flow of blood through the heart
Flows from vena cava into right atrium
Flows from right ventricle to lungs via pulmonary artery
Becomes oxygenated and flows to left atrium via pulmonary vein
Flows from left ventricle to body via aorta
What is Henry’s Law?
When the pressure increases, more gas will dissolve into liquid
If the pressure is decreased, gas will come out of the liquid
What factors contribute to DCS?
Age Fat (slow tissue) Alcohol Dehydration Injuries/ illness Heavy exercise CO2 build up (skip breathing) Cold water Flying
Type 1 DCS
Pain only - limbs/ joints/ skin rashes
Type 2 DCS
Identified as having life threatening symptoms involving brain, nervous system and lungs
Numbness, paralysis, weakness, nausea, unconsciousness
First aid for DCS
Give O2 (lowers alveolar nitrogen + raises blood O2 to help with blood flow to tissues blocked by bubble)
Lie in recovery position on left side (keeps blood flow to brain and helps keep airway clear)
Call emergency services
How are lung over expansion injuries caused?
Holding breath during ascent
Diving with a cold
Blockage of lungs due to surfactant (excessive smoking)
Expanding air over inflates lungs causing rupture
What is an AGE?
Arterial gas embolism
Air enters bloodstream, can flow through carotid arteries and cause cerebral air embolism
S+S similar to stroke
What is a pneumothorax?
Air from rupture goes between lung and chest
Causes lung to collapse
Causes pain and SOB, haemoptysis
What is a mediastinal emphysema?
Air from rupture accumulates in chest over heart
Central chest pain, SOB
What is a subcutaneous emphysema?
Air from rupture accumulates in soft tissue in neck
Feeling of fullness in neck, voice change, crackly skin
Treatment for overexpansion injuries
O2, recompression chamber
DCS vs DCI
DCS - nitrogen coming out of body too fast
DCI - DCS plus over expansion injuries
What are silent bubbles?
Some nitrogen forms v small bubbles in pockets in the body but then dissolve into air - harmless
What is apnea?
Breath holding
What is the carotid sinus reflex?
Carotid sinus receptors monitor pressure of arterial blood
Tight neck seal can imitate high blood pressure, causing bradycardia
What is hypocapnia?
Caused by hyperventilation
S+S of CO poisoning?
Headache
Confusion
Narrow vision
Cherry red lips
O2 toxicity symptoms
Tinnitus
Visual disturbances
Tingling
Seizures
Pulmonary toxicity
Caused by prolonged exposure to elevated O2
Burning chest pain and irritated cough
Ear anatomy
Ossicles connect to cochlea at oval window, which flexes with vibrations
Round window on cochlea flexes the opposite way to the oval window to compensate
How do the ears react to pressure?
During descent, pressure increases on ear drum
Diver equalises by forcing air up the Eustachian tube into middle ear
Expanding air exits through Eustachian tube on ascent
What is barotrauma?
Injury due to increasing pressure in body space
What is middle ear squeeze?
Failure to equalise (potentially due to congestion)
What causes vertigo after ear drum rupture?
Cold water on the vestibular canals
What is reverse squeeze?
Ear equalises on descent but congestion forms so cannot equalise on ascent causing ear drum to flex outwards
Usually caused by decongestants wearing off
What is a round window rupture?
Caused by delayed equalisation followed by forceful valsalva movement (increases thoracic and cochlea pressure causing rupture)
Heat exhaustion S&S?
Weak rapid breathing Weak rapid pulse Cool clammy skin Profuse sweating Nausea Dehydration When body is working to reduce temperature
What is heat stroke?
Cooling has failed
Pulse strong and rapid
No sweating
Skin flushed and hot to touch
Describe the path of the coronary arteries
Left and right branch off aorta
Split into anterior descending and circumflex arteries
What are the papillary muscles?
Attach to lower portion of interior wall of ventricles
Connect to the chorda tendinae which attaches to tricuspid valve in right ventricle and mitral valve in left ventricle
Contraction of papillary muscles causes opening of mitral and tricuspid valves
Valves of the heart
Tricuspid valve separates RA and RV
Pulmonary valve separates RV and pulmonary artery
Mitral valve separates LA and LV
Aortic valve separates LV and aorta
