Homeostasis Flashcards
What is homeostasis? (with latin meaning)
Latin means similar condition (not identical/STATIC) the body operates within normal ranges/parameter. to stay In a normal state. The body maintains in these similar but not identical ranges.
What does homeostasis require the integration of?
Integration of organ systems:
Nervous, endocrine, musculoskeletal to seek supply and access nutrients.
respiratory for o2,
alimentary to break down food etc,
cardio to transport 02 and nutrients + transport waste
respiratory + alimentary + renal to dispose of waste.
What systems coordinate and control other systems for homeostasis
Nervous and endocrine
Why do these systems (Nervous and endocrine ) need to integrate effectively for homeostasis
in order to maintain an optimum internal environment and ultimately produce energy = homeostasis
What level of regulation is needed for homeostasis?
Cellular level, tissue level and system level.
What is pathology (Latin meaning)
Pathology [latin pathos means suffering]:
body not tolerant of substantial changes in the internal environment (ph, fluid, temperature, hormone concentration). Failure to adequately correct imbalances results in illness and disease or pathology.
Define the study of physiology
how all different systems in the body: Respiratory, Cardiovascular, GI system, work together to maintain a constant internal environment which all processes work optimally
Explain Negative feedback (key mechanism and most common way homeostasis maintained.)
when condition homeostatically disturbed. e.g. temperature disturbed = shiver/sweating. negative feedback = condition that triggered the response is removed or switched off by the homeostatic response. the response is proportional to the disturbance.
Example of negatvie feedback
Negative feedback: hot and working outside –> loses body water by evapouration –> body fluid more concentrated–> internal receptor sense change in internal concentration–> thirst pathway stimulated –> person seeks and drinks water –> water added to body fluid decrease concentration
Characteristics of Negative feedback system
- oscillation around the set point
- restored regulated condition AFTER its initial disturbance, but CANNOT PREVENT it happening. promote response to correct
explain feed-forward (more sophisticated)
can predict change. additional receptors permit system to anticipate change and therefore activate a response earlier
Example of feed-forward system
Kidneys detect body fluid concentration and PRE-EMPTS a state of dehydration. Responds by producing smaller volumes of urine. Kidney reabsorbs more water, higher concentration urine.
Explain Positive feedback mechanisms
Opposite to negative feedback:
(aims to restore disturbance to optimum)
sets off a chain of events leading to greater disturbance.
leads to instability often - common in pathophysiology, rare in normal physiology
Example of positive feedback normal physiology
for normal nerve function ovulation sexual behaviour
In action potential - initial trigger positive Na in nerve-cell take charge with. inside cell positive = depolarisation. makes the membrane more permeable to na+ to take in more positive (cycle builds more reaction) until trigger an action potential.
Example positive feedback in pathophysiology
Blood glucose in diabetes. mean ingested - increased blood glucose –> pancreas doesn’t respond. –> cell doesn’t break down glucose. -> body triggers starvation –> liver produces glucose –> increase blood glucose further.. cycle increase blood glucose.
why is Water balance critical for life?
water balance
the process that is homeostatically controlled.
makes up 60% body weight
maintenance critical as affects the concentration of everything else in the body -
everything in the body is dissolved in an aqueous solution.
average daily waterbalance in adult male in thermoneutral environment (neurtal temperature)
GAIN Drinking 1,200 ml Eating 1000 Metabolic 250 Total = 2550ml LOSS Insensible - 900ml (from skin and lungs) Sweat 50 - (up to 3l hr) Faeces - 100 Urine 1500 (o.5L –> 20L/day) Total ml 24 hour = 2550ml
Which processes are regulated in order to maintain water?
Input - regulated thirst mechanism Output - regulated by kidney function (urinary loss)
What other processes alter water balance but control is not aimed at maintaining water balance?
other processes e.g. sweat temperature regulation, the conflict between water and temp regulation. (kidney problems)
Where is water contained in our body?
3 compartments 1. intracellular fluid - water inside cells 2. interstitial fluid - between cells 3. plasma - fluid component of blood *Fluid not water now as other nutrients are mixed in the water.
What compartment(s) make up extracellular fluid?
Interstitial fluid (ISF)
plasma
Can water move freely between 3 compartments? ISF, ICF, P
YES
through osmosis
The body can survive only as long as the composition of ____ is maintained in a state compatible with the survival of ______ (homeostasis)
The body can survive only as long as the composition of Extracellular fluid (interstitial fluid + Plasma) is maintained in a state compatible with the survival of its individual cells. e.g. liver functions ions on either side of the membrane. depends on water availability.
Explain the 3 compartments and what differs in composition.
plasma contains blood vessels
interstitial fluid found OUTSIDE blood vessels and BETWEEN cells
intracellular fluid - inside cells
composition plasma and interstitial are ALMOST identical - only thing NOT found in the interstitial fluid that IS found in plasma is a PROTEIN and BLOOD CELLS
