Endocrine System Flashcards
What is homestasis
Counteract changes in internal environment dynamic equilibrium
Examples of homeostasis
Cell - regulation ca2+ conc
Tissue - balance between cell proliferation and cell death
Organ - kidney regulates water and ion conc in blood
Organisms - constant body temp
Hormone classifation
Peptide/polypeptide -largest group shirt chains of amino acids
Amines - synthesised from aromatic amino acids
Glycoproteins - large protein molecule - LH FSH TSH
Steroids - derived from cholesterol cortisol aldosterone and testosterone
Major endocrine glands
Hypothalamus
Pituitary gland
Parathyroid
Thymus
Pancreas
Pancrea
Adrenal gland
Ovary and testes
Hormone definition
Chemical signal produce by endocrine gland or tissue that travel ink bloodstream to cause an effect on other tissues
Anterior pituitary gland hormones
Growth hormone prolactin
Trod simulating hormone
Corticotrophin
FSH
LH
Growth hormone
Simulates growth and division of mst body cells
Secretion highest in childhooand adolescence
Release stimulated by GHRH and suppressed by GHRIH
Prolactin
Prepares breast for lactation
Thyroid stimulating hormone
Stimulated release by TRH from hypothalamus
Stimulates growth and activity of thyroid gland
Corticotrophin
Corticotrophin releasing Norma one from hypothalamus promotes synthesis and release of ACTH by anterior pituitary gland
Stimulate growth and activity of adrenal cortex
FSH and LH
On troll secretion of oestrogen and progesterone in menstrual cycle
Posterior pituitary gland hormones
Oxytocin
Antidiuretic hormone
Oxytocin
Releasing increasing amounts of oytocin into the blood responding to increases stimulation of sensory stretch receptors in cervix
Antidiuretic ADH
Reduces urine output
Acts on DCT and collecting ducts of kidney increasing permeability to water
More reabsorption so less urine produced.
Corticosteroids
Exert actions by regulating gene transcription
Readily diffuse across plasma membrane
Bind to glucorticord receptors
Receptors bond to dna sequence
Aldosterone
Regulates gene transcription
Plays central role in regulation for plasma na+ k+ and arterial blood pressure e
In distal convoluted tubule and collecting docs here it promote expression of na+/k+ pump promoting reabsorption of na + and excretion of k+ thereby influencing water retention blood volume and therefore blood pressure
RAAS
Cells in Afferent arterioles release renin in response to sympathetic smlation and low blood volume.
Renin converts angiotensinogen to angiotensinogen 1
Angiotensinogen converting enzyme converts angiotensinogen 1 into 2- a vasoconstrictor = high blood pressure
Angiotensin 2 raised blood potassium levels also stimulate adrenal gland secrete aldosterone which stimulates na and h2o re absorption in kidney increases blood volume and pressure.
- VASOCONSTRICTION
- INCREASES EXPRESSSION OF NA K PUMP EABSORPTION OF NA AND WATER INTO BLOOD
- TRANSLOCATION OF AQUAPORIN CHANNELS ACIDS REABSORPTION OF WATER BACK NTO BLOOD
Cortisol
Regulates gene transcription
Crease protein breakdown in muscle
Increase lipolysis in fat
Resistance in stress
Anti inflammatory effects
Depression of immune response
Androgens
Inner layer f adrenal cortex eceretesandrogens
In males deydroepiandostereme is converted into testosterone in testes
In females adrenal androgens promote libido and converted to oestrogen
Thryoid gland
Lies against and around front larynx and trachea
2 lobes joined by ishmus
Parathyroid and thyroid are distinct glands
Thyroid hormone
Simulate metabolic rate by increases number and size of mitochondria
Glucocorticoid actions on metabolism
Maintain energy balance and responding to stree
cortisol released in bloodstream and binds to receptors
In liver - stimulates gluconeogenesis and helps increase glucose levels
In muscles - reduces uptake of amino acids in muscle cells and increase release in muscle tissue which diverts amino acids to liver where they can be used gluconeogenesis
In fat theybreakdown into fatty acids and glycerol the fatty acids can be used as energy source
Lipid soluble hormones bind to intracllular receptor
Easily pass through membrane
Once infused the cell they bind to intracellular receptors which are located in the cytoplasm or nucleus
This hormone receptor complex then act as as transcription receptor influencing gene expression and protein synthesis
Water soluble hormones bind to cells surface receptors
Bind to surface receptors
Triggers series of intracellular responses
Often involves secondary messages like cAMP
Leads to various cellular responses
Mechanisms of communication via hormones
Aautocrine
Paracrine
Endocrine
Neurone
