HSF LO's: Foundations Flashcards
Fluid compartment percentages and definitions
Extracellular (20% body weight)
Fluid outside of the cell
(plasma and interstitial fluid) – similar makeup
Plasma (20%): fluid portion and has dissolved proteins and ions
→ only in circulatory system
Interstitial fluid (80%): fills the space between cells and body – less dissolved proteins (similar to plasma)
Barriers separate compartment to restrict movement and allow different environments
Plasma:interstitial – capillary wall separation
Interstitial:intracellular – cell membrane
Lower protein, low K+, high Na+ : higher protein, high K+, low Na+
Intracellular (40% body weight)
Fluid inside the cell
Cytoplasm
Very different to ECF
Definition of osmosis
Movement of water molecules across semi permeable barrier to even concentration of dissolved particles
Definition of concentration, osmolarity, tonicity
Concentration
Molar
The number of particular molecule dissolved in volume of solution
Osmolarity
mOsM
The total number of dissolved particles in volume of solution, penetrating non penetrating
Tonicity
Osmotic pressure gradient between two solutions, depending only on non-penetrating solutes (only solute affecting the osmotic pressure gradient)
Definition of different tonicity
Isotonic- normal size
Hypertonic - shrink
Cells lose water by osmosis, inside has higher concentration of solutes
Hypotonic - bloated and burst
Cells increase water by osmosis, outside has higher concentration of solutes
Definition of homeostasis
Maintenance of a stable, internal environment by regulating physiological processes around the set point.
Describe basic reflexes involved in maintaining homeostasis
There are two types of reflexes – negative and positive feedback.
Negative - closed loop and self regulating, oscillating around set point
Example: thermoregulation
Stimulus - body temperature above or below 37 degrees
Sensor - body temperature sensors/thermosensors
Integrating centre - control thermoregulatory in the brain
Target - blood vessels and sweat glands
Response - increased blood flow to skin and sweating
Positive - open loop and amplification used for protection such as birth and blood clotting
Example: birth delivery
Stimulus - baby head pushed against the cervix
Sensor - cervical sensors to nerve impulses
Integrating sensor - pituitary gland in the brain
Target - oxytocin to uterine
Response - increased uterine contractions
The control centres of homeostasis
The hypothalamus - integrator and regulates ANS for neural control. Neurosecretory cells involve oxytocin producing cells (birth delivery), antidiuretic hormone (vasopressin for constriction in blood pressure), tropic releasing hormone (target to endocrine gland) - cells release into the circulatory system but only targets with a receptor will have a response.
Posterior pituitary gland - neurosecretory region
Anterior pituitary gland - tropic hormones (signal to second order endocrine glands)
RH - releasing hormone, stimulate release of tropic hormone from anterior pituitary
IF - inhibitory factor, inhibit release of tropic hormone from anterior pituitary (STATINS)
Chemical signalling molecules also involved such as neurotransmitters
Identify major component of reflex arc
Stimulus → receptor/sensor → afferent pathway – control centre/integrator – efferent pathway → effector → response
Apply negative feedback to understand endocrine responses
check notes
Apply Fick’s Law of Diffusion
Phospholipid is a lipid, hydrophobic barrier. Hydrophobic molecules diffuse the best and passively, followed by small and uncharged polar molecules. Large uncharged polar molecules and ions will NOT diffuse in and need a transporter.
Factors affecting diffusion
Concentration gradient
Barrier permeability (permeability = lipid solubility/molecule size)
Distance to travel
*check notes for equation
