GHM L2 Flashcards
Describe the position of the hypothalamus
Located below the thalamus, between the midbrain + optic chiasm
What is the thickness of hypothalamus?
3-4mm thick
Size of almond
What are the inputs of hypothalamus?
- Somatosensory
- Taste
- Smell
- Limbic system
- Retina
What factors does the hyothalamus sensor?
Hormones
BP
Temp
What are the functions of hypothalamus?
Regulation of body temp
Regulation of autonomic nervous system
Regulation of emotional responses
Regulartion of hunger
Regulation of growth
Give 2 nuclei of hypothalamus and state their functions
- PVN: Paraventricular nucleus. Responsible for
-Stress reponse
-Food intake
-Thyroid regulation
-Osmoregulation
SON: Supraoptic nucleus. Responsible for
-Blood pressure
-Osmoregulation
-Lactation
-Parturition
Give 2 hormones produced by the hypothalamus
- Liberins - releasing hormones
- Statins - inhibiting hormones
How are releasing + inhibiting hormones transported from hypothalamus to anterior pituitary gland?
They are transported directly only to anterioir pituitary gland via hypothalamic hypophyseal portal vein
What is the role of releasing hormones produced by hypothalamus?
Control of other hormones by stimulating release.
“turn on”
What is the role of inhibiting hormones produced by hypothalamus?
Control of other hormones by inhibiting release
“turn off”
Where is the pituitary gland located?
Located in hypophyseal fossa in sphenoid bone
Pea sized
Describe the structure of the pituitary gland
Pituitary - hypophysis
Anterior pituitary gland - ADENOHYPOHISIS
Posterioir pituitary gland NEUROHYPHISIS
Describe the structure of the anterioir pituitary gland?
The adenohyphysis
- Pars tuberalis
- Pars intermedia
- Pars distalis
Describe the structure of the posterioir pituitary gland?
- Pars nervosa
- Infundibular stalk
Sate the function of pars tuberalis
Reception for endocrine signals
State the function of pars intermedia
Sheath between the anterioir + posterior pituiatry gland. Small in humans
State the function of pars distalis
Hormone production
State the function of pars nervosa
Storage of OT (oxytocin) and ADH
State the function of infundibular stalk
Connecting bridge between hypothalmus and hypophysis (pituitary gland)
What are the 5 types of hormone secreting cells in the anterioir pituitary gland (adenohypohysis) and what hormones do they secrete?
- Somatotropes - growth hormone - bone + muscle tissue
- Lactotropes - Prolactin - breasts
- Gonadotropes - FSH, LH - ovaries, testes
- Corticotropes - adrenocorticotropin - adrenal cortex
- Thyrotropes - thyroid stimulating hormone - to the thyroids
Which two hormones are secreted by cells in the posterior pituitary gland?
Oxytocin - breasts
ADH - kidneys
Thyroid disorders
Change in conc of thyroid hormones (T3 and T4). This affects metabolism, which affects activity levels.
Usually caused by tumours
Can lead to:
Hypothyrodism - Hashimoto’s thyrodism
Hyperthyrodism - Grave’s dosease
GOITRE
Give 3 examples of adrenocorticotropins
CORALDA -COR-ALD-A
Adrenocotrical hormones:
- Cortisol
- Aldosterone
- Androgens
State the function of cortisol
-Carbohydrate metabolism
-Stress response
State the function of aldosterone
Salt regulation
Water homeostasis - osmoregulation
State the function of androgen
Male seconday sex characteristics
Virilization in females
Describe the corticotropin releasing hormone pathway
Corticotropin releasing hormone is produced in the paraventricular nucleus in the hypothalamus.
It is relased into the anterior postiuitary gland.
Here, it stimulates corticotropes to release adrenocorticotropins
Adrenocotricotropins are secreted in adrenal cortex where they stimulate production of
-cortisol
-aldosterone
-androgen
-glucocorticoids
-mineralcorticoids
Describe the physiological actions of cortisol
Cortisol is released in a diurnal rythm.
This is good for seasonal breeding of animals
Cortisol - glucose metabolism. It increases synthesis of enzymes involved in gluconeogenesis in liver - anabolic
It increases break down of fat + muscle tissue to release energy - catabolic
Net effect - higher levels of glucose (hyperglycemia)
Peak of cortisol releaese: 6-8 am
Lowest - midnight
Fluctuates after a meal
Describe “Cushing’s Disease” and state the causes
- Too high cortisol levels
- Adrenal tumour, pituitary tumour, lung tumour
LAP
LUNG ADRENAL PITUITARY
LAP IS A CUSHION
How does aldosterone regulate salt levels in the human body?
Aldosterone is a primary mineralcorticoid
It controls the conc of Na+ + K+ in the epithelial cells, it also controls movement of Na
+ + K+ out of TARGET epithelial cells
It stimulates active transport of Na+ into epithelial cells of distal convuluted tubules
Aldosterone increases the number of Na+ channels in the apical membrane
Aldosterone also increases the number of Na/K ATPase molecules
State 2 aldosterone disorders
- Addision’s disease
- Hyperaldosteronism
State a cause of Addision’s disease
- Inadequate amount of mineralcorticoid - aldosterone
State symtoms/effects of Addision’s disease
- Low BP
- Hyperpigmentation of skin
State a cause of hyperaldosteronism disease
Too much aldosterone
State symtoms/effects of hyperaldosteronism
- High BP
- Hypopigmentation of skin
Where is growth hormone produced?
Somatotropes in anterioir pituitary gland
Explain the functions of growth hormone
- Direct function
Diabetigenic
Opposes insulin action
Lypolytic in fat
Gluconeogenic in muscle
Indirect Function
Stimulates release of IGF-1 FROM LIVER, this leads to growth of bone tissue, lipolysis, protein synthesis in muscle
Describe what happens when we have too much growth hormone
ACROMEGALY
overgrowth of bony areas
CAUSED BY anterior pituitary tumor
Describe what happens when we have too little growth hormone
Dwarfism in infants
Describe the control of the posterior pituitary gland
Neurones which control posterior pituitary found in the
- PVN
- SON
These neurones send neural projectoons down infundibular stalk
Cause POSTERIOIR PITUITARY (PARS NERVOSA) TO Secrete ADH, oxytocin directly into blood stream
Describe the effect of high ADH
- Collecting ducts more permeable to water. therefore, HYPEROSMOTIC urine
What factors determine ADH release
Blood vol
detected by osmoreceptors in hypothalamus - they detect osmolarity of blood
State the name of the carrier protein which transports ADH to posterior pituitary
NEUROPHYSIN II
Where are ADH receptors found?
- Kidney
- Pituitary
- Brain
- Blood vessels
-Platelets
-Gonads
-Tumours
What are the 3 type of ADH receptors?
V1a, V1B V2
-G protein coupled receptors
Where is oxytocin synthesised?
PVN, SON (hypothalamus)
State the name of the carrier protein which transports oxytocin to posterior pituitary
Neurophysin I
Functions of oxytocin
-Lactation
-Partuition
-Maternal behaviour
