Lecture 2: Fluid Balance and Cardiovascular control Flashcards
Describe the relationship between cells, tissues, organs and organ systems
cells - basic unit of living organisms that differentiate for specialised roles
tissues - made up of cells with similar structure and function, 4 types
organs - made up of different tissue types and have functional units
organ systems - organs that work together to perform a particular function
Define homeostasis and the feedback mechanism that is used to maintain it
maintenance of the bodys mileu interier in a steady state
negative feedback control
What ways can homeostasis be disrupted in the body? Give examples
- Internal stimuli: change in blood glucose levels
- External stimuli: exercise, physical insults, psychological stresses
Define negative and positive feedback and explain what both aim to achieve
negative feedback - response elicited in the body that aims to reverse the response elicited by the stimulus, hence shutting down the response loop EG. blood pressure changes
positive feedback - response amplifies/reinforces the stimulus/change in the controlled condition to increase the response and bring the body further away from setpoint. EG. contractions, clotting
set point is target value
What four elements does negative feedback require?
sensor, ability to compare to referene, sufficient gain, effector mechanism
What is meant by the gain of a control system?
the degree of effectiveness with which a control system in the body is able to maintain homeostatic conditions
Gain is only applicable in negative feedback
What is the formula for Gain
correction/error
How is homeostasis related to ECF?
ECF is termend as the “internal environment of the body/milieu interieur” hence the body tried to maintian the ECF in constant condition
What does ECF consist of
blood plasma, interstitial fluid and transcellular fluid
Describe water distribution in males and females
male
TBW 60% body weight (42L)
- ICF 60% TBW
- ECF 40% TBW
female
TBW 50% body weight (35L)
- ICF 60% TBW
- ECF 40% TBW
Describe the differences and similarities of the location and compostion (solutes and volume) of fluid compartments in the body
ECF
- high sodium, low potassium, high chloride
- blood plasma 3l, interstitial fluid 13l, transcellular fluid 1l (17 total)
ICF
- high potassium, low sodium, low chloride
- intracellular fluid 25l
SAME OSMOLARITY
Why are differences in ECF and ICF solutes important?
- sets up membrane potential
- generates electrical activity (action potentials)
- muscle contractions
- nutrient uptake via secondary active transport
- generation of intracellular signalling cascades
Describe the difference between the movement of solutes and water
solutes - passive or active, proteins in membrane, ATPases
water - driven by the movement of solutes, passive, bulk movement by aquaporins, transcellualr or paracellular
trans (apical to basal)
para (between tight junctions)
Define osmosis
net diffusion of water across a semipermeabel membrane from a region of high water concentration to low water concentration
1 osmole is equal to what?
1 mole of solute particles = amount equal mol weight of solute
1 mol of NaCl = 2 osmole (bc two ions), 1 mol = 58.5 g = 2 osmoles
