Endocrinology 1
Hypothalamus: Homeostasis
HR
BP
Temp
Electrolyte balance
Appetite and body weight
Sleep cycle
GI secretions
Regulates the anterior pituitary gland via release of hormones
Produces Dopamine-inhibits prolactin release
Synthesises hormones that are released by the posterior pituitary: oxytocin and ADH
Pituitary gland:
Negative feedback loops
Synthesises and releases hormones
Anterior: ACTH,LH,FHS,TSH,GH,Prolactin
Posterior: ADH and Oxytocin
Embryological development of the pituitary gland:
Rathke’s pouch- protrusion of the ectoderm from roof of mouth= anterior
Neuroectoderm- diencephalon=posterior
HPA Axis:
Circadian cycle, is a natural, internal process that regulates
the sleep–wake cycle and repeats roughly every 24 hours.
= diurnal secretion- night and day
Response to stress
ACTH- regulates the adrenal cortex and Renin/aldosterone
Cortisol secretion:
Increases blood glucose (gluconeogenesis)
Suppresses the immune system
Alters fat, protein and carb metabolism
Decreases bone formation
Mineralcorticoid effects increase Na= increase BP decrease K
Cortisol levels are highest in the morning
Lowest at night
Therefore, when testing- if levels are lower in the morning indication of a problem
, Cushing disease Buffalo hump
Excess of cortisol due to increased ACTH Central obesty and thin limbs
secretion from pituitary
Complications:
Cushing syndrome: Cortisol excess Type 2 diabetes
Hypertension
Causes: Osteoporosis
Pituitary ACTH excess
Ectopic ACTH secretion- cancer Investivations:
Adrenal cortisol excess 24hr urine cortisol
Exogenous steroids Midnight cortisol-elevated due to diurnal
variation
ACTH
Symptoms:
Lethargy Treatment:
Depression Medical- inhibitors of steroidogenesis
Muscle weakness (multistep process for biosynthesis
Irregular periods of steroid hormones from
Erectile dysfunction cholesterol)
Surgical
Clinical features: Radiotherapy
Facial plethora
Acne Pseudo-cushing’s syndrome- clinical and
Hirsuitism biochemical features secondary to other
Thinning scalp hair conditions
Thin skin-bruise easily Eg alcohol,obesity
HPG axis:
Role:
Development, reproduction and aging
GnRH=pulsatile
Low activity in childhood- activated in adolescence
Low frequency for FSH release
High frequency for LH release
Males have frequent pulses
Females: Frequency varies.-large surge before ovulation
GnRH- not needed for pregnancy
LH and FSH- regulate menstrual cycle, spermatogenesis and testosterone production
Sex hormones- needed for bone metabolism
Axis affected by environment factors
Hypothalamus: Homeostasis
HR
BP
Temp
Electrolyte balance
Appetite and body weight
Sleep cycle
GI secretions
Regulates the anterior pituitary gland via release of hormones
Produces Dopamine-inhibits prolactin release
Synthesises hormones that are released by the posterior pituitary: oxytocin and ADH
Pituitary gland:
Negative feedback loops
Synthesises and releases hormones
Anterior: ACTH,LH,FHS,TSH,GH,Prolactin
Posterior: ADH and Oxytocin
Embryological development of the pituitary gland:
Rathke’s pouch- protrusion of the ectoderm from roof of mouth= anterior
Neuroectoderm- diencephalon=posterior
HPA Axis:
Circadian cycle, is a natural, internal process that regulates
the sleep–wake cycle and repeats roughly every 24 hours.
= diurnal secretion- night and day
Response to stress
ACTH- regulates the adrenal cortex and Renin/aldosterone
Cortisol secretion:
Increases blood glucose (gluconeogenesis)
Suppresses the immune system
Alters fat, protein and carb metabolism
Decreases bone formation
Mineralcorticoid effects increase Na= increase BP decrease K
Cortisol levels are highest in the morning
Lowest at night
Therefore, when testing- if levels are lower in the morning indication of a problem
, Cushing disease Buffalo hump
Excess of cortisol due to increased ACTH Central obesty and thin limbs
secretion from pituitary
Complications:
Cushing syndrome: Cortisol excess Type 2 diabetes
Hypertension
Causes: Osteoporosis
Pituitary ACTH excess
Ectopic ACTH secretion- cancer Investivations:
Adrenal cortisol excess 24hr urine cortisol
Exogenous steroids Midnight cortisol-elevated due to diurnal
variation
ACTH
Symptoms:
Lethargy Treatment:
Depression Medical- inhibitors of steroidogenesis
Muscle weakness (multistep process for biosynthesis
Irregular periods of steroid hormones from
Erectile dysfunction cholesterol)
Surgical
Clinical features: Radiotherapy
Facial plethora
Acne Pseudo-cushing’s syndrome- clinical and
Hirsuitism biochemical features secondary to other
Thinning scalp hair conditions
Thin skin-bruise easily Eg alcohol,obesity
HPG axis:
Role:
Development, reproduction and aging
GnRH=pulsatile
Low activity in childhood- activated in adolescence
Low frequency for FSH release
High frequency for LH release
Males have frequent pulses
Females: Frequency varies.-large surge before ovulation
GnRH- not needed for pregnancy
LH and FSH- regulate menstrual cycle, spermatogenesis and testosterone production
Sex hormones- needed for bone metabolism
Axis affected by environment factors
