1) Homeostasis Flashcards
Define homeostasis
Homeo = sameness Stasis = standing still
What needs to be kept constant in an internal environment?
- conc. of CO2, O2, salts and other electrolytes
- conc. of nutrients and waste products
- pH
- Temperature
- volume and pressure
What is a negative feedback loop?
A system in which the output reduces, reverses or stops the original stimulus
What is a positive feedback loop?
A system in which the output enhances or exaggeratess the original stimulus
What are the body’s responses to an increase in temperature?
- vasodilation
- sweating
- stretching out
- pilorelaxation
What are the body’s responses to a decrease in temperature?
- vasoconstriction
- piloerection
- shivering
- curling up
Describe the process of blood clotting
1) Break/tear in blood vessel
2) Platelets adhere to to site of tear and release chemicals
3) The chemicals attract more platelets
4) Clotting occurs
5) Feedback ends when clot seals tears
When does positive feedback stop?
When the initiator ceases
When does negative feedback stop?
When the effector ceases
What is core body temperature?
The temperature of the head, neck and torso as they contain the main organs
What is the average core body temperature?
36.5-37.5 degrees celcius
Above what body temperature is classified as a fever?
38.5 degrees celcius
What symptoms are associated with heat exhaustion?
- unconcious/seizures
- headaches
- confused
What symptoms are associated with heat stroke?
- flushed dry skin
- strong bounding pulse
What symptoms are associated with a fever?
- pale sweaty skin
- cramps in stomach, arms & legs
What symptoms are associated with mild hypothermia?
- shivering
- fatigue
- confusion
- forgetfulness
- slurred speech
What symptoms are associated with severe hypothermia?
- shivering stops
- muscles become rigid
- very slow and weak pulse
- severe reduction in response levels
What symptoms are associated with no vital signs?
- unconciousness
- dilated pupils
- pulse undetectable
- appearance of death
What symptoms are associated with no vital signs?
- unconciousness
- dilated pupils
- pulse undetectable
- appearance of death
What is the normal blood pH?
7.35 (arteriole end) - 7.45 (venuole end)
What are the 2 main organs responsible for maintaining acid-base balance?
lungs-respiratory balance
kidney-metabolic balance
What are the 2 main organs responsible for maintaining acid-base balance?
lungs-respiratory balance
kidney-metabolic balance
Between what blood pH does acidosis occur?
7-7.35
Below what blood pH does death occur?
7
Between what blood pH does alkalosis?
7.45-7.8
Above what blood pH does death occur?
7.8
Above what blood pH does death occur?
7.8
What is normal gastric pH?
1.5-3.5
What is the limit of human tissue survival?
pH 6.8-7.8
What is oedema?
Fluid retention
What causes oedema?
There are proteins in the interstitial space causing hydrostatic pressure > osmotic pressure causing water to be driven out into the interstitial space
What is hydrostatic pressure?
Pressure from the heart and blood
What is osmotic pressure?
Pressure of water coming back into the vessel
Where is oedema commonly found?
In the limbs (mainly the ankles)
How much water is needed each day to maintain a healthy adult?
2.5 litres
What is the total body water percentage of a normal man?
60%
What is the total body water percentage of an obese man?
50%
What is the total body water percentage of a lean man?
70%
What does the term isotonic mean?
There is the same amount of water on both sides of the plasma membrae
What does the term isotonic mean?
There is the same amount of water on both sides of the plasma membrane
What does hypotonic mean?
Less water inside of the cell than outside, so water moves in
What does hypertonic mean?
Less water outside the cell, so water moves out
What happens if there is not enough water in the body?
Cells and tissues absorb water from interstitial space
Then abosrb water fromm each other
Then water is absorbed from organs when tissues die
Then water is absorbed from the brain, liver, kidney and heart when the organs die
What is osmolarity?
How much water there is in the urine or plasma
What is oligurea?
Decrease in urea production
What regulates the flow of water in cells?
Amount of glycerol in the cells
Why do IV drips need to be isotonic solutions?
To ensure the Iv fluid has the same oncotic pressure as the blood
How do IV fluids have the same physiological saline concentration as blood?
IV drip includes salts
0.9% NaCl
How do IV fluids have the same physiological saline concentration as blood?
IV drip includes salts
0.9% NaCl
What is osmolality?
The concentration of a solution expressed as the total number of particles per Kg
(units = osmol/L or osmol/Kg)
