LU9: HORMONE AND ENDOCRINOLOGY (hormone regulation in insect development…
LU9: HORMONE AND ENDOCRINOLOGY
The Cushing’s syndrome shows collections of external sign or symptom related to cortisol imbalance.
Prolonged exposure of cortisol leads to hypercortisolism.
Some of the symptoms are;
•Weight loss despite increase in appetite
•Increased activity level / Rapid heart rate
•Increased urination / Diarrhea
•Aggression / Nervousness
Frequently caused by excessive concentration thyroxine-a thyroid hormone in the bloodstream
common glandular disorder in cats.
Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine
Endocrine gland hyposecretion (leading to hormone deficiency)
Tumours (benign or malignant) of endocrine glands
Endocrine gland hypersecretion (leading to hormone excess)
Symptoms includes behavioral, physical or physiological changes.
It can be caused by endocrine disease or drugs interaction and if left untreated, can result in serious medical condition.
Unusual level of hormones in bloodstream can leads to hormone disorder.
hormone regulation in insect development
In adult molt, low level of JH allows larva to develop into moth when induced by BH and ecdysone.
But relatively high concentration of JH promote retention of juvenile characteristics and thus supress metamorphosis.
In larval molt and pupal molt, BH and ecdysone promote molting process by inducing development of adult characteristic.
Neurosecretory cells in the brain produce brain hormone (BH).
JH balance the effect of BH and ecdysone.
BH stimulates protoracic gland to secretes ecdysone.
The third hormone – juvenile hormone (JH) - secreted by a pair of small gland (corpora allata) promotes retention of larval characteristic.
Ecdysone induces molting in moth.
control and feedback
hormone feedback mechanisms
metabolisms and growth
stimulus triggers control mechanism that inhibits further change
stimulus triggers control mechanism that amplifies effect
Endocrine glands are activated by other hormones
Most are under control of the sympathetic nervous system
Nerve impulses stimulate hormone release
Changing blood levels of certain ions stimulate hormone release
endocrine vs nervous signalling
Signal type → electrical + chemical
Action → fast, short-lasting response
Transfer → neuron network to target cells
Transfer → blood circulation to whole body
Action → slow, long-lasting response
Signal type → chemical (hormone)
endocrine vs exocrine
lumen ans surfaces
Eg: enzyme & sweat
Each gland contain specialized cells that synthesizes Hormone
A system of ductless glands
class of hormones
activate genes that result in synthesis of new proteins
bind to receptor proteins in nucleus & then bind to DNA as transcription factors
bind to receptor proteins in cytoplasm
activate cellular response
trigger secondary (2°) messenger pathway
hydrophilic & not lipid soluble
function of hormones
Coordinate the organs through action and feedback
A method of communication between one body part to another
definition of hormones
A chemical signal secreted into body fluid (often blood), and communicates regulatory messages within the body