Communication and Homeostasis Flashcards
Define 4 types of communication with examples?
Autocrine- messenger molecules bind with
receptors in cell where they are
produced
- E.g. Cytokine Interleukin
Paracrine- messenger in ECF
- E.g. Clotting factors, prostaglandins
Endocrine- secretions into blood
- E.g. Insulin
Exocrine- glands secrete through ducts
- E.g. Sweat, salivary
Define positive feedback and give examples?
Amplification of signal
E.g. clotting cascade, oxytocin, labour
Define negative feedback and give examples?
Return normal
E.g. Thyroid
Define and state 3 hormones?
Molecules act as chemical messengers
Peptide
Steroid
Amino-acid derivative
State how peptide: made, stored, works
Made short chain amino acids
Stored- cell, released when needed
Binds receptor membrane
Provide quick response- secondary messenger cascade
E.g. Insulin, growth hormone, TSH, ADH
State how steroid: made, stored, works
Synthesised cholesterol
Water insoluble, lipid soluble
Need transport proteins in blood
Intracellular receptor target
Made by cell and diffuses NOT STORED
Slow response as affects DNA- alters transcription/translation- proteins need made
E.g. Testosterone, oestrogen, cortisol
State how amino acid derivative: made, stored, works?
Synthesised from tyrosine
Act same peptide
E.g. adrenaline, thyroid hormones
Define osmosis?
Net movement of solvent molecules through a semipermeable membrane to higher solute concentration
Higher to lower water conc
Define osmotic pressure?
minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane
Define oncotic pressure?
Oncotic pressure: form of osmotic pressure exerted by protein that tends to pull fluid into its solution – water moves from ISF into plasma.
Define hydrostatic pressure?
pressure exerted by a fluid on the walls
Hydrostatic pressure: pressure difference between capillary blood (plasma) and interstitial fluid – water and solutes move from plasma into interstitial space
Define osmolarity?
Concentration of solutes in plasma per L of solution
Define osmolality?
Concentration of solutes in plasma per kg of solvent
State methods of water intake and loss?
Intake- drink, diet, IV
Loss- kidneys
Insensible and sensible water loss?
Insensible- not easily measured
- sweat, resp, vomiting
Sensible- measured
- urine, faeces
What hormones regulate water control?
ADH- causes kidneys to release less water
Aldosterone- regulates salt and water balance
increasing retention of sodium
and water
Atrial natriuretic peptide- ANP
- regulates salt-water
balance, promote
sodium and water
excretion
What counters ADH?
ANP
Causes and consequences of dehydration?
Causes- water dep, vomit, diarrhoea, burns,
sweating, diabetes insipidus, drugs
Conseq- thirst, inelastic skin, raised
haemocrit, weight loss, hypotension
Causes and consequences of water excess?
Causes- high intake/decreased water loss,
excess ADH
Conseq- hyponatremia, cerebral over
perfusion- high blood volume- high
pressure- headaches, confusion,
convulsions
Define dysfunctions:
Serous effusion
Oedema
Inflammatory
Serous effusion- excess water in body cavity
Oedema- excess water in intercellular tissue
space
Inflammatory- proteins leak out due increased vascular permeability- bring in water- dilute toxins- fibrinogen polymerises form fibrin mesh- immunoglobulins collect
Explain inflammatory leakage?
Proteins leak out due increased vascular permeability
Bring in water which dilutes toxins
Fibrinogen polymerises and form fibrin mesh Immunoglobulins collect
Define:
Venous pressure
Lymphatic
Hypoalbuminemia
Venous– end- increased venous pressure or
venous obstruction from a thrombus
Lymphatic (blocked)– obstructions from
tumour /parasite
Hypoalbuminemia– lower oncotic pressure
Does ECF osmolality or volume lead to a rapid change?
ECF osmolality change- rapid response, tight
regulated
ECF volume change- slower response
High and low sodium called?
Hypernatremia- high sodium
Hyponatremia- low sodium
High and low potassium called?
Hyperkalaemia- high potassium
Hypokalaemia- low potassium
High and low calcium called?
Hypercalcaemia- high calcium
Hypocalcaemia- low calcium
Body fluid compartment for 70kg man?
K+ ICF
Na+ ECF
What is main electrolyte in ECF?
Na
What is main electrolyte in ICF?
K
What state do fluid compartments in body exist in?
Osmotic equilibrium
