Endocrine Flashcards
what are homeostatic mechanisms?and whats homeostasis
and where de thes mechanisms exist?
- homeostatic mechanisms act to counteract changes in internal environment
- homeostasis = dynamic equilibrium
- cell = e.g regulating ca2+ conc
- tissue = balance beween cell proliferation and cel death
- organ = kidney regulates ion concs
- organism = temp control
characteristics of a control system diagram
- communication:
- endocrine and nervous system
- hormones released locally are under paracrine control
- or self effecting once they release substances like autocrine control
- peripheral nervous system divided into afferent (“going to brain; sensory) branch and efferent (going away from brain; motor)
- control centre:
- determine the reference set point
- 2 control centres ; hypothalamus and the the medulla oblongata in the brain stem
- hypothalamus controls the endocrine system whilst medulla oblongata controls ventillation and CVS
- receptors:
- detect stimuli and pass info through afferent pathways
- effector:
- agents that cause change and they are communicated by the efferent pathway
- feedback:
- has an effect on the control centre (reference set point)
- in negative feedback: change from normal causes series of changes that return state back to norm
- positive feedback: causes an increase in effect
what controls our biological rhythm?
when our clocks dont match up whats that called?
suprachiasmatic nucleus is the natural biological clock , (bunch of neurones). in controls our 24 hour cycle but it is affected by our Zeitgebers (environmental cues like like)
mismatch in environmental clock and biological clock causes jet lag
hormone melatonin released by pineal gland is importnt for setting clock
examples of biological rhythm
- temp changes throughout the day
- cortisol levels are highest when you wake up and low at midnight (decrease throughout the day) so write the time it was taken
- menstural cycle
set point
can vary like core body temp
what cells secrete hormones? and what are the cells that hormones act on called?
- endocrine gland
- target cells
if hormones are secreted what is the factor that controls whethere they are effective or not?
what does lipophilic hormones mean?
how is this different for lipophilic hormones?
whats the conc of hormone in the blood
blood concentration of the hormone
steroid based + thyroid hormone
they bind specifically or non-specifically to proteins in the blood and so in this case its the free hormone conc that matters
10^-10 and 10^-9 M
hormones from the heart liver stomach placenta placenta adipose kidney
- ANP BNP
- IGF1
- GASTRIN GHRELIN
- INHIBIN, PLACENTAL LACTOGEN
- LEPTIN
EPO RENIN CALCITRIOL
are some hormones neurotransmitters
yes
classificationS of hormones
- peptides ( insulin/glucagn/Grwth hormone)
- amino acid derivatives (amines) ; adrenaline/nor (tyrosine)/thyroid(tyrosine)/melatonin (tryptophan) {all water soluble but thyroid hormone is lipid soluble and travels using thyroxine-binding globulin TBG}
- glycoprotein ; large protein molecules w carbohydrate side chain e.g. LH/FSH/TSH water soluble
- steroid: derived from cholesterol, sterogenic tissue converts cholesterol to different hormones: (cortisol/testerstone/oestrogen/aldosterone) all lipidsoluble and need transporters
how are peptide, and steroid hormones stored and give examples?
also which hormone doesnt follow this pattern?
peptide
- store their hormones in discrete storage vesicles within the cell prior to secretion:
- just like insulin: which once synthesised is marginated into vesicles and only released via exocytosis in response to kATP channels closing(d high ATP)
- noradernaline stored
- *steroid
- steroid producing tissue dont store the hormone they store the precursor CHOLESTEROL as cholesterol esters in the form of lipid droplets
the thyroid hormone is an exception ; because its stored outside the cell in the form of protein colloid
how are protein and steroid hormones transported
protein are water soluble so travel in the blood okay but steroid hormones aren’t and so require specific carriers
what form is active
- freeform is bioogiall active
hormone level factors
- rate of production -rate of delivery - rate ofdegradation
conc hormones in the blood and give example
v low - thyroxine = 10-30pmol/L
where do water soluble receptors bind and give examples
- cell surface - AD/NR coupled adenylal cylase - Insulin /Tyrosine kinase wc udergoes dimerisation (except insulin since already dimerised, then undergo autophosphorylation , recruitment of adapter P and signalling complex, activate PK, phosphorylate target P
when does the development of the Endocrine System? and what describe the development of the pituitary gland?
- at 4 weeks gestation there are no endocrine glands
- at 5 weeks they begin to develop;
1. pituitary gland develops from the neurohypophyseal bud and hypophyseal pouch
