SfM - Homeostasis Flashcards
What is a tissue?
groups of cells that share the same characteristics or specialisations
what is an organ?
collections of tissues, usually of different cell types. Link to perform a particular function
what does the cardiovascular system do?
deliver O2 and nutrients to cells, removes waste from cells
role of respiratory system?
acquires O2 (gives oxygen to blood) and disposes of CO2
Gastrointestinal system
acquires nutrients and disposes of waste via faeces
renal system
disposes of waste via urine
musculoskeletal system
sources nutrients, removes us from danger and protects us from threat
immune system
protects us from infection
nervous system
co-ordinates all our bodily systems
endocrine system
co-ordinates other systems, major role in allowing access to nutrients
reproductive system
ensures continuation of life, however, does produce steroid hormones required for metabolism
what is the definition of homeostasis?
as energy demand increases, the supply of substrates required to produce energy must also increase (need enough to meet that demand). Aim to prevent disturbance in the system
what happens when homeostasis isn’t maintained?
Failure to adequately correct imbalances results in illness and disease
what are the common everyday challenges to internal environment?
external temperature
diet
exercise
what are the three mechanisms involved in maintaining homeostasis?
negative feedback
feedforward
positive feedback
how does homeostasis work after eating?
after meal –> blood glucose increased –> insulin released –> increased glucose uptake by cells –> BG concentration falls –> reduced insulin production
what happens in diabetes?
after meal –> blood glucose increased –> no insulin produced/lack of effect –> lack of glucose uptake in cells leads body to perceive starvation –> increased liver production of glucose –> even greater increase in BG
what percentage of the body is water?
60%
How much water to do we gain/lose in a day?
2550
Gained = drinking, eating, metabolic
Lost = insensible loss, sweat, faeces, urine
where is the water spread in our body?
intracellular fluid & extracellular fluid (interstitial fluid + plasma)
what is the purpose of the capillary wall?
separates plasma and interstitial fluid, allows water to move freely but blood products can not
what is the purpose of the cell membrane?
separates intracellular fluid and interstitial fluid, allows water to move freely but no ions can pass w/o channels and transporters
how is water distributed across these compartments?
1/3 ECF (80% interstitial/20% plasma)
2/3 ICF
how do we measure body fluid volumes?
dilution principle
c=mass of contrast/volume
how do we measure compartments?
plasma volume = evans blue or albumin (confine test to plasma)
extracellular volume = inulin, sucrose, mannitol, N+, Cl- (substance can’t cross cell membrane)
total body water = heavy/deuterated water
what is the composition of ECF/ICF?
Na = low ICF/high ECF K = high ICF/low ECF Cl = low ICF/high ECF HCO3 = higher ECF phosphates/sulphates = high ICF/low ECF protein = high ICF/low ECF (comes from plasma in ECF)
how can homeostasis go wrong?
ECF-K+ conc. increases outwith the normal range –> leads to loss of conc gradient between ECF/ICF –> disrupts nerve and muscle function –> ventricular fibrillation and death
ESSENTIAL TO REGULATE ECF K+
Terminology hyper? hypo? aemia? uria? glyc?
hyper = greater than norm hypo = lower than norm aemia = in the blood uria = in the urine glyc = related to glucose
