Communication And Homeostasis Flashcards
What are the 4 types of communication, how do they work and examples of each
Autocrine - messenger molecules bind with receptors in the cell where they are produced = chemical messengers
Paracrine - messengers in the extra cellular fluid = clotting factors
Endocrine - secretions into the blood = insulin
Exocrine - secretions into the duct all system to an epithelial surface = ovaries and testes are stimulated by hormones produced by the brain
What is positive feedback
Amplification of signalling
What is negative feedback
The basis of homeostasis
What is an example of positive feedback
Clotting cascade
What is an example of negative feedback
Majority of endocrine hormones
What are hormones
They are molecules which act as chemical messengers
What are the 3 types of hormones
Peptide
Steroid
Amino-acid derivative
What are peptide hormones made of
Peptide hormones are made from short chain amino acids
Where are peptide hormone stored
They are stored in the cell and the released when are needed/signalled
How does a peptide hormone work
They bind to receptors on the membrane
What do peptide hormones produce
They produce a quick response via a secondary messenger cascade
What are examples of peptide hormones
Insulin
Growth hormone
TSH
ADH
Where are steroid hormones synthesised from
Cholesterol
What are the properties of steroid hormones
They are water insoluble
Lipid soluble
So they can cross membranes but they require transport
They require transport proteins in the blood
What happens to a steroid hormone once it is made
A steroid hormone is made within the cell but then diffuses out of the cell once made, so isn’t stored there
How does a steroid hormone work
A steroid hormone can directly affect DNA and alters transcription/translation
What are examples of steroid hormones
Testosterone
Oestrogen
Cortisol
Where are amino-acid derivative hormones synthesised from
They are synthesised from tyrosine
How do amino-acid derivatives work
They work in the same way peptide hormones work
What are examples of amino-acid derivatives
Adrenaline
Thyroid hormones T3+T4
Describe the body fluid compartments
Total volume is 60% of a persons body weight = approx 42L
This is split between extracellular (14L) and intracellular (28L) fluid
Extracellular fluid is split into extra vascular fluid (11L) and intravascular fluid (3L)
Extravascular fluid is then split into interstitial fluid (10.5L) and trans cellular fluid (0.5L)
What is osmosis
The net movement of solvent molecules through a semipermeable membrane to a higher solute concentration
What is osmolality
Concentration of solutes in plasma per kg of solution
What is osmolality
Concentration of solutes in plasma per kg of solvent
What is osmotic pressure
Pressure applied to a solution by a pure solvent required to prevent inward osmosis through a semi permeable membrane
What is oncotic pressure
Form of osmotic pressure exerted by proteins that tend to pull fluid into it solution
Water moves from ISF into plasma
What is hydrostatic pressure
Pressure differences between capillary blood and interstitial fluid
Water and solutes move from plasma to ISF
What creates an osmotic gradient across cell membranes
Osmotically active substances(solutes) in the ICF(potassium) and ECF(sodium, chloride, glucose, urea) create an osmotic gradient
What is the predominant electrolytes in the extracellular fluid
Na+
Cl-
HCO3-
Ca2+
Urea
Glucose
What is the predominant electrolyte in the intracelluar fluid
K+
What is intravascular fluid
Plasma/ circulating extracellular component of blood
What is interstitial fluid
Fluid which surrounds cells but does not circulate
What is transcellular fluid
Trans cellular fluid makes up CSF, digestive juices and mucus
How is water intake achieved
Drinking
Diet
IV fluids
How is water lost
Through kidneys/urine
What hormones regulate water loss
ADH
Aldosterone
Atrial natriuretic peptide
What cause dehydration
Water deprivation
Vomiting
Diarrhoea
Burns
Heavy sweating
Diabetes insipidus
Diabetes mellitus
Drugs
What does dehydration cause
Thirst
Inelastic skin
Sunken eyes
Raised haematocrit
Weight loss
Hypotension
What can cause someone to have excess water
High intake of water
Decreased loss of water
Excess ADH
What consequences can be caused by excess water
Hyponatremia (low sodium levels)
Cerebral over perfusion which causes headache, confusion and convulsions
What is serous effusion
Excess water in the body cavity
What is oedema
Excess water in the intercellular tissue space
What is hypernatremia
High sodium levels
What is hyponatriemia
Low sodium levels
What is hyperkalaemia
High potassium
What is hypokalemia
Low potassium levels
What is hypercalcaemia
High calcium levels
What is hypocalcaemia
Low calcium levels
What is the difference between endoderm and ectotherm
Endoderm is able to regulate their own body temperatures by producing or decreasing the amount of heat
Ectotherm relies on the external environment to regulate their bodies temperature
