homeostasis Flashcards
What are the three types of hormones?
peptide, steroid amino acid derivative
What are some examples of a peptide hormone and how does it differ to the others?
Peptide - insulin, growth hormone, TSH ● From short chain of AA to small proteins ● Some glycoproteins ● Hydrophilic - receptor
Some examples of amino acid derivatives and how they differ?
Amino-acid derivative- adrenaline, T4, T3 ● synthesised from tyrosine
Definition of osmolality and osmolarity
Osmolality - measure of the number of dissolved particles per kg of fluid.
Osmolarity - measure of the number of dissolved particles per L of fluid.
define oncotic pressure
a form of osmotic pressure derived from proteins mostly albumin
What is the homeostasis mechanism of water loss from the extracellular fluid?
Water loss from ECF ●
↑ solute or ↓ fluid results in an ↑ osmolality
● Detected by osmoreceptors in hypothalamus
● Release of antidiuretic hormone (ADH) from posterior pituitary
● ADH acts by increasing water reabsorption in the kidneys ● Dilutes solute and returns ECF water to normal.
What is the homeostasis mechanism of decreased renal blood flow?
Decreased renal blood flow
● ↓ water in ECF results in ↓ circulating volume results in ↓ renal blood flow
● Kidney release of Renin and activation of RAAS
● Angiotensin II and aldosterone increase Na+ reabsorption (exchange K+ and H+) bringing water. Also stimulates ADH
What are three causes of water excess?
high intake
decreased loss
decrease adh
What is oedema and name some types
Oedema - excess water in the intercellular tissue space
inflammatory (leakage), Venous (increased end pressure), Lymphatic (blocked), Hypoalbuminaemic
What is serous effusion?
Excess water inbody cavity
Types of cell communication
Enodcrine
Nervous
Immune
Water distribution in the body
Total is 42L 60% of body weight 40% intracellular 20% extracellular 14L Interstitial 10 Plasma 3 Transcellular 1
What is hypernatraemia
Excess sodium
What is hypercalacaemia
Excess calcium
raas system
renin released from kidney and converts angiotensinogen to angiotensin 1
ace from lungs convertes ang 1 to ang2
ang 2 can activate adh , aldosterone and sympathetic ns
how is raas system activated
when bp decreases , detected by juxtaglomerular cells in afferent arteriole of kidneys
or decrease in nacl detected by macula densa of distal convoluted tube
renin in then released from kidneys
How does raas system increase blood pressure
Ang2 is a vasoconstrictor causes blood vessels to narrow
Ang2 also increases secretion of hormone aldosterone from adrenal cortex
3 modes of communication and how
autocrine- acts on the same cell
paracrine- secrete into ECF acts on neighbouring cells
enodcrine- secretion into blood acts on distant cell
characteristics of peptide hormone
water soluble
binds to cell surface membrane
fast acting
premade and stored in vesicles
what does adh do
act on ap 2 receptors on collecting ducts
increased permeability of collecting ducts , more ecf higher bp
characteristics of steroid hormone
made from lipid cholestrol lipid soluble diffuse through cell surface membrane slow acting oestrogen and testosterone
main intracellular and extracellular ion ion
K+ intra
Na+ extra
role of aldosterone
increase na reabsorption in ascending limb of LOH
obligatory h20 movement
h2o follows na+
