T1 L1 Intro to the endocrine system Flashcards
What is the endocrine system?
System of ductless glands which secrete chemical messengers into the blood
Describe the nervous system
Cells release a chemical messenger & grow towards each other Rapid Focused Precise Communication between individual cells
Describe the endocrine system
Cells release chemical messenger into carrier medium
Very slow
Sustained contraction
Communication between groups of cells
What does the pineal gland do?
Regulates sleep-wake cycle
What functions does the pancreas have?
Exocrine: secretes digestive enzymes into GI tract
Endocrine: secretes insulin into the blood
What is the medulla involved in?
Stress response
What is the cortex involved in?
Stress
Sodium homeostasis
Glucose homeostasis
Describe the method of steroid hormone receptors
1) Hormone crosses cell membrane
2) Binds to cytoplasmic or nuclear receptor
3) Hormone receptor complex then binds to hormone-response element of DNA
4) Influence gene transcription
Describe the method of G-protein coupled receptors
1) Hormone binds to 7 transmembrane receptor
2) Synthesis of second messenger e.g. IP3 or cAMP
3) Second messengers phosphorylate intracellular regulatory proteins
4) Influence cellular activity e.g. smooth muscle contraction
Describe tyrosine kinase receptors
Membrane-bound enzyme which is a single strand of protein
Often 2 receptors must be present for hormone action (dimerised receptors)
Receptor acts as an enzyme to phosphorylate tyrosine components of intracellular regulatory proteins
What are tyrosine kinase receptors involved with?
Involved with growth & development
Describe the characteristics of peptide hormone
Water soluble Not orally active Rapid onset of action Short plasma half life Short duration of action
Describe the characteristics of steroid & thyroid hormones
Poorly water soluble Orally active Slow onset of action Long plasma half life Long duration of action Crosses cell membrane
What receptors do peptide hormones act on?
Membrane-bound receptors
What receptors do steroid & thyroid hormones act on?
Intracellular receptors
What is TRH?
Thyrotrophin releasing hormone
What is TSH?
Thyroid stimulating hormone
What is CRH?
Corticostrophin releasing hormone
What is ACTH?
Adrenocorticotrophic hormone
What is FSH?
Follicle stimulating hormone
What is LH?
Luteinising hormone
What is GnRH?
Gonadotrophin releasing hormone
What is GHRH?
Growth hormone releasing hormone
What does TRH stimulate?
Secretion of TSH
What does CRH stimulate?
Secretion of ACTH
What does GnRH stimulate?
Secretion of FSH
What does GHRH stimulate?
Growth hormone
What releasing hormones are secreted by the hypothalamus?
TRH
CRH
GnRH
GHRH
What do the releasing hormones from the hypothalamus control?
The secretions produced by the pituitary gland
What hormones are produced by the anterior pituitary gland?
TSH
ACTH
FSH
LH
Describe the effect of TSH
Acts on thyroid gland to produce thyroxine
Describe the effects of ACTH
Acts on adrenal cortex to produce cortisol
Describe the effects of FSH
Acts on ovary to produce oestrogens
Describe the effects of LH
Acts on ovary to produce progesterone
How do thyroid hormones control negative feedback?
Decreased secretion of TRH & TSH
How is the level of cortisol controlled by negative feedback?
Cortisol leads to decreased secretion of CRH & ACTH
How is the level of oestrogens controlled by negative feedback?
Decreased secretions of GnRH & FSH
