Hormonal Processes Flashcards
biological characteristics of hormonal control (6)
- physiological regulators
- effective in minute quantities
- synthesized by cells which may/may not be located in a gland
- secreted and transported into bloodstream
- act on specific target cells (receptors present)
- trigger specific responses
hypothalamus neuroendocrine site and pituitary (2)
- control of many physiological mechanisms
- important to reproduction
hypothalamus (3)
- connect nervous-endocrine system
- produces peptides and amines
- controls part of the autonomic nervous system
pituitary gland (2)
- anterior
- posterior
posterior pituitary
- deposit site for molecules from the hypothalamus
anterior pituitary
- a gland that receives stimulation from portal vessel and releases to general circulation
hypothalamic portal vessel system
- connects to the anterior pituitary
which reproductive hormones are regulated by the hypothalamus (4)
- gonadotropin releasing hormone (GnRH)
- prolactin-inhibiting or prolactin-releasing hormone (PIH/PRH)
- oxytocin
- melatonin
characteristics of GnRH (4)
- small and simple structured polypeptide (only amino acids)
- produced by hypothalamus
- initiates a lot of things in gonads
- commercially available due to its ability to be synthesized easily
GnRH function
- stimulates release of FSH and LH
what can we conclude from the GnRH amino acid sequence across species (2)
- vastly different species all have some form of GnRH
- its conservation across species shows its functional importance as a molecule
oxytocin function (3)
- induces uterine contractions
- induces milk ejection
- facilitates gamete transport
melatonin function
- affects species reproductive cycles, making them seasonal
PIH/PRH function
- inhibits or stimulates prolactin release
which reproductive hormones are regulated by the anterior pituitary (3)
- follicle stimulating hormones (FSH)
- luteinizing hormones (LH)
- prolactin (PRL)
which reproductive hormones are regulated by the posterior pituitary
- oxytocin
what is a characteristic of hormones regulated by the hypothalamus (3)
- polypeptides
- relatively small
- peptide based hormones
what is a characteristic of hormones regulated by the hypothalamus (2)
- glycoproteins
- peptide based hormones
luteinizing hormone (LH) (2)
- relatively large glycoprotein (amino acids and carbohydrate residues) with alpha and beta chains
- molecule is difficult to synthesize
which cells do LH target (2)
- leydig cells
- theca and granulosa cells
LH function (2)
- stimulates follicular growth in female and spermatogenesis in male secretion
- targets leydig cells and theca/granulosa cells
LH alpha and beta chain (2)
- alpha chain AA sequences similar between hormones within and between species
- beta chain AA sequence diverse between species; accounting for hormone and species specificity
follicle stimulating hormone (FSH) (3)
- relatively large glycoprotein with alpha and beta subunits
- carbohydrate residue higher compared with LH
- generally conserved structure across species
what cells do FSH target (2)
- sertoli cells
- granulosa cells
FSH function (2)
-stimulates ovulation and luteinization of ovarian follicles (CL) in females
- stimulates testosterone secretion in men
hormone carbohydrates chains
- content
- most important monosaccharide
- CHO content increases molecular weight (12 [LH] - 24% [FSH] of molecule)
- sialic acid
carbohydrate chains
- sialic acid (2)
- essential for biological activity and extending half life
- higher sialic acid content increases half-life of hormone
1/2 life of steroid hormones: proteins (3)
- steroid hormones bound to protein carriers in blood because they are lipophilic
- binding to proteins increases half-life of steroids
- only 5-10% of hormones present in unbounded form
prolactin structure (3)
- large molecular weight
- no CHO residues
- contains disulfide bonds (loop configuration) and cysteine residues
which cells do prolactin target (2)
- leydig cells
- sex glands
prolactin function (2)
- promotes lactation
- promotes maternal behaviour
gonadal steroids (4)
- produced by testis and ovaries
- similar biosynthesis pathway as lipids
- cholesterol based hormones
- effective orally as it is not digested
structure of steroid hormones (2)
- 4 rings with slight differences
- same cholesterol backbone
how does the structure of steroid hormones effect function
- steroid hormones can easily switch between forms
structural biological variation in steorid hormones (4)
- # of double bonds in the A ring
- ketone vs hydroxyl group at C3
- C10 methyl group present or missing
- C17 attachment of 2 C atoms or hydroxyl groups
structural biological variation in steroid hormones (4)
- # of double bonds in the A ring
- ketone vs hydroxyl group at C3
- C10 methyl group present or missing
- C17 attachment of 2 C atoms or hydroxyl groups
characteristics of hormones secreted by reproductive organs (2)
- fat-related hormones
- cholesterol based
hormones secreted by reproductive organs (4)
- estrogen
- progesterone
- testosterone
- prostaglandin (PG)
prostaglandin (PG) structure (2)
- unsaturated fatty acid
- contains double bonds that bend molecule
prostaglandin (PG) characteristics (3)
- secreted by most body tissues as its precursor is present in all cells
- paracrine and endocrine action; can enter bloodstream or affect adjacent cells
- very short half life
PG function (3)
- causes uterine contractions
- assists sperm in transport in female tract
- causes regression of corpus luteum (luteolysis)
androgen binding protein (ABP)
- structure
- large glycoprotein
ABP location
- sertoli cells
what is ABP production important for (3)
- binds testosterone to increase concentration in seminiferous tubules
- initiation of spermatogenesis
- puberty in young animals
schematic mechanism of steroid hormones (2)
- normally crosses cell membrane from blood vessel as its lipophilic
- nucleus receptor allows steroid to enter nucleus
schematic mechanism of protein hormones (2)
- does not cross membrane
- attaches to receptor from blood vessel that triggers a secondary messenger pathway that signals to nucleus to produce something
example of protein hormone activity (2)
- LH molecule binds to receptor on Leydig cell
- triggers secondary messenger pathway that signals nucleus to produce testosterone
schematic mechanism of nerve pathway example (3)
- teat stimulation triggers nerve pathway to hypothalamus
- oxytocin stored in posterior pituitary from hypothalamus is released into bloodstream
- oxytocin stimulates muscles in teat to eject milk
receptors and 2nd messenger pathways (2)
- hormones dock on receptors and trigger conformation changes to the receptor
- triggers changes to cAMP, protein kinases and phosphorylation pathways
G protein coupled receptor (4)
- 7 trans-membrane domains
- normally linked with adenylate cyclase (AC)
- converts ATP to cAMP
- protein kinase A or C pathway leads to phosphorylation/ transcription
steroid receptors (3)
- nuclear or cytoplasmatic
- associated with chaperones (HSP)
- upon binding, steroid is transferred to nucleus
