Hypothalamus

undefined
undefined
undefined
undefined
undefined
undefined
undefined
undefined
undefined
undefined
GHRH (+), Ghrelin (+) GHIH (-)
undefined
undefined
undefined
(-)
(-)
undefined
TRF (+) Dopamine (-)/Somatostatin (-)
(-)
undefined
(-)
(+) Thyroid follicle cells
(+)
Zona Glomerulosa cells
undefined
(-)
undefined
Males
undefined
undefined
(-)
(-)
undefined
Hypothalamus
Anterior Pituitary
Acidophils
Somatotrophs: GH
Lactotrophs: PRL
Basophils
Thyrotrophs: TSH
Corticotrophs: ACTH
Gonadotrophs: FSH
Gonadotrophs: LH
Posterior Pituitary
SON cells: ADH
PVN cells: Oxytocin
Factors:
GHRH (+)/Somatostatin (GHIH) (-)
GH
TRF (+) Dopamine (-)/Somatostatin(-)
PRL
TRH (+)
TSH
CRF (+)
ACTH
GnRH (+)
FSH/LH
ADH
Oxytocin
Stimuli: 1) Partuition 2) Nipple stimulation 3) Hypertonicity
Uterine Contraction
Let-down reflex
Mammary glands: causes milk to be let down into subareola sinus
Important for cervical dilation at birth
Osmolarity (1-5%) sensed in the hypothalamus
Blood volume (15-20%): sensed by baroreceptors & relayed via brain stem
V1 receptors: G-protein linked
Arterial smooth muslce constriction
Hepatocytes: glycogenolysis
Pituitary cells: ACTH secretion
V2 receptors: G-protein linked
Act at kidney through cAMP & adenylate cyclase to increase H20 reabsorption
Growth Hormone
Liver
ANP(-)
IGFs
(+) amino acid uptake
(+) protein synthesis
Decreased plasma [amino acid]
(-) glucose uptake in cells
(+) glycogenolysis --> (+) plasma [glucose]
Stimuli: exercise, stress, sleep (all +)
(+) lipolysis: TAG --> FFA + Glycerol (+) plasma [FFF]
Negative feedback
Other cells
Bone (+ growth)
Fat (+)
Muscle (+ growth)
Stimulates proliferation, differentiation, metabolism
Stimuli: suckling, sleep, stress
Prolactin
(+) Leydig cells to produce testosterone
(+) Mammary glands & milk production
(-) [Oestrogen] & [Testosterone]
*Responsible for loss of menstruation in lactating women
TSH
Thyroid
T4
T3
Increase plasme [T4]/[T3]
T4/T3 are transcription-activation factors when bound to receptors located in almost all tissues.
(+) Growth
(+) CNS development
(+) CVS: C.O, blood flow, rate, strength, resp via up regulation of beta adrenoceptors
(+) Metabolism: mitochondria, Na+ absorption, gluconeogenesis, glucogenolysis, lipolysis, BMR, protein synthesis
(+) TRF
Stimulus: (+) Cold (-) Anxiety
Glucocorticoids: Cortisol
Metabolic:
Carbs: (+) gluconeogenesis, glycogen synthase (-)
Lipids: (+) Lipolysis, free fatty acids
Proteins: (+) catabolism, (-) amino acid uptake, (-) fibroblast function (+) caloric intake
Haematopoietic:
(-) lymphocytes, eosinophils, monocytes
(-) T cell function (IL-1, IL-2, TNF)
(-) B cell activation
Increases apoptosis
Sundry:
Bone: (+) bone reabsorption, (-) osteoblatic function
CNS: neuronal & glial function reg.
Electrolytes: increase GFR, renal K+ secretion
Promotes cellular differentiation (in fetus)
Inhibits growth
Inflammation:
Potent anti-inflamm effects
Increases susceptibility to infection
Deficiency can result in uncontrolled inflamm. response
Free cortisol: only free is excreted in urine & measuring gives measure of plasma levels that day
Therapeutic uses:
Addison's Disease = low cortisol. Symptoms = weight loss, vomiting, depression, loss of appetite
Inflammatory diseases: asthma, rheumatic disorders, allergic disorders, crohn's dx, thyroiditis
Stimulus: (+) K+ & (+) Renin-Angiotensin system
ACTH
Minerocorticoids: Aldosterone
(+)Distal tubule reabsorption of Na+
LH
CRF (+) ADH (+)
Testosterone
(+) Spermatogenesis
(+) Male secondary sexual characteristics
FSH
Follicle Cells
Ovulation (Day 14)
1) LH Surge: rate-limiting step
2) Granulosa/Theca cells convert to mainly Progesterone secretion
3) Progesterone results in expulsion of ovum
4) Cells then Leuteinize (LH) & become Corpus Luteum following ovulation
5) Corpus Luteum secretes large amounts of progesterone & estrogen
Growth
At 9-12y.o, these hormones increase in level
Days 1-4: 6-12 primordial follicles --> primary follicles
rapid proliferation of granulosa cells
Secondary Follicle : Development of 2nd layer of cells, Theca cells.
Theca interna: secrete androgens-Testosterone & Progesterone
FSH stimulates Testosterone to move into granulosa cells & is converted to Estrogen by aromatase
Theca externa: highly vascular capsule
Vesicular cell growth: 2 stimuli
(1) Estrogen secreted by theca cells & up-regulates FSH receptors & increases receptor sensitivity
(2) FSH & Oestrogen combine to promote LH receptors on original granulosa cells
Tertiary cells form through FSH & LH
Rapid growth occurs once both hormones synergise
Atresia --> 1 Mature follicle
From Primordial to Antral stage (mostly FSH alone)
Leydig Cells
6) Becomes Corpus Albicans 12 days post-ovulation
7) Sudden cessation of secretion of androgens & inhibin removes (-) feedback so cycle can begin again
Lutein cells also secrete Inhibin (-)
Sertolli Cells
Spermatogenesis: Spermatids --> Sperm
8