Homeostasis, pH, core body temperature and bodily fluids Flashcards
(39 cards)
Define homeostasis
The process whereby cells. tissues and organism maintain the status quo
Explain negative and positive feedback loops
Feedback loops are cycles, they are made up of —
- Receptors which monitor,
- Control systems which evaluate,
- Effectors which create changes
Negative feedback loops reverse changes in controlled conditions, end when effector ceases.
Positive feedback loops strengthen changes in controlled conditions until initiator ceases.
Normal body temperature range
36.5-37.5
What happens when core body temp is low
Hypothalamus detects low core body temp,
Skeletal muscles begin shivering to generate heat,
Peripheral arterioles going towards skin contract restricting blood flow, reducing heat loss from skin,
Piloerection: Arrector pili contract causing hair on skin to stand up to trap warmer air
Curling up: reduces surface area.
What happens when core body temp is high
Hypothalamus detects high core body temp,
Sudorific glands secrete sweat which removes heat when water evaporates.
Vasodilation: Arterioles going towards dilate to increase blood flow to skin to increase heat loss.
Pilorelaxation: Arrector pili relax causing hair on arms to lay down and trap less warm air.
Stretching out: increase surface area
What needs to be maintained in the bodies internal environment.
Concentration of -O2 -CO2, -salt -electrolytes(Na,K,Ca) -Nutrients -Waste products, pH Temperature, volume and pressure of water/fluids
Normal pH range
7.35-7.45
What maintains acid base balance
Lungs-respiratory balance
Kidneys-metabolic balance
What happens if gastric acid gets in the oesophagus and why?
Oesophagitis-inflammation of lining of oesophagus
stricture-narrowing of the urethra restricting urine
Oesophagus has no goblet cells that secrete mucus to protect itself from stomach acid pH(1.5 to 3.5)
What happens if stomach loses its mucus lining?
Gastric ulceration and perforation
What does pH 5.8 indicate?
Cancer
What happens if pH changes by 0.3?
[H+] changes by a factor of 2
What do the intracellular buffer systems include?
Sodium Phosphate buffering system regulates intracellular pH and transport systems
Protein buffer systems- Haemoglobin(RBC only),
-amino acid buffers
What do the extracellular buffer systems include?
Carbonic acid-bicarbonate used in blood pH regulatory using erythrocytes as an intermediary (removes CO2)
Plasma protein buffers
Amino acid buffers
Do all the buffer systems regulate water?
Yes
Calcium’s relevance to buffer systems?
Its alkali so it raises pH
Clinical relevance of buffer systems
Antacids neutralise acid
Solubility is a factor (dont wanna mess with osmolality so insoluble is best eg aluminium hydoxide)
How do we find imbalances?
Arterial blood gas analysis
Too much water equals?
toxicity, metabolic failure (everything too diluted) and cell, tissue and organism death
Because:
-osmotic pressures too high,
-cells absorb water and swell till they burst,
-enzymes and proteins stop working.
Too little water equals?
Dehydration, cell, tissue and organism death
How much water is required?
2.5L
Avg water to everything else constitution of the avg male
1avg male=0.4 solids + 0.6 fluids
0.6fluid=2/3intracellular fluid+1/3extracellular fluid
1/3extracellular fluid=0.75 interstitial fluid+ 0.25plasma
What happens when there is not enough water
Cells/tissues absorb water from interstitial spaces
From each other
Once tissues dead water absorbed from organs
Once they’re water is absorbed from brain, liver, kidney and heart.
Causes, symptoms and result of dehydration
Hot humid weather, excessive sweating, vomiting, diarrhoea and burns.
Thirst, dryness, water loss, osmolarity then ADH increase, oliguria(urine output is below 400ml/day )
Plasma volume decrease
