endocrinology anatomy Flashcards
describe the location and surroundings of the hypothalamus
- Thalamus makes up the wall of the third ventricle
- Below thalamus is the hypothalamus
o Also makes up part of inferior wall of 3rd ventricle - Anterior commissure is an anterior border to the hypothalamus
- Hypothalamic sulus marks superior limit of hypothalamus
- Inferiorly the optic nerve/ optic chiasm
- Mamillary body is sometimes thought of as part of the hypothalamus
what nerves surround the base of the hypothalamus and what is the raised platform which the pituitary stalk sits on called
Olfactory nerve, optic tract, crus cerebri all together formt his diamond shaped area
- Within this is the base of the hyppothalamus
- Tuber cinerum is a raised platform upon this is the infundibulum aka the pituitary stalk
describe the cells within the hypothalamic nucleus and how they secrete hormones
The cells within these nuclei are able to make systemically active hormones
- These hormones can travel down the axon of the magnocellular neurons
- Axons pass down pituitary stalk
- End of this stalk/ the axons is in the the pituitary gland
- Then these hormones are secreted into the circulation from here
what are some of the important hypothalamic nuclei
- Paraventricular Nucleus
- Supraoptic nucleus
- Suprachiasmatic nucleus
- Dorsomedial nucleus
- Ventromedial nucleus
- Posteroior nucleus
- Mammillary body
where does the hypothalamus receive info from
Limbic system
- Emotion, memory, instinctive and learned behaviours
Circulating blood
- Physical, chemical and hormonal state
Reticular formation
- State of arousal
- Can go via the thalamus to the hypothalamus or directly
Autonomic NS
- Chemical constituents in fluid filled cavities
- Pressure in smooth muscle walls
where does the hypothalamus disperse info to
Limbic system - Via the thalamus - Motor behaviour Brainstem - Wakefulness and asleep ANS - Internal organ control Pitutary Gland - Secretes hormones
the pituitary gland - what is it, what are the 2 parts and their locations/ surroudings
Aka hypophys cerebri (meaning something hanging off the bottom of the brain)
- Functional output from hypothalamus
- Connected to hypothalamus via infundibulum (pituitary stalk)
- Posterior = neurpophysis = neuronal
o Expansion of distal infundibulum
- Anterior = adenohypophysis = epithelial
o Upgrowth from roof of primitive oral cavity
explain what the pituitary fossa is - where it is and what the hole in the middle is called
Depression in the middle of the skull
Hypophysial fossa – or pituitary fossa
- Extension of dura that goes over top of this fossa
- creates a shelf with a hole in the middle for the infundibulum to travel through
- This is known as the seller diaphragm
- Seperates cavity from rest of cranial cavity
what hormones are made in the anterior pituitary and what do they do
Adrenocorticotrophic hormone (ACTH) - Adrenal gland production of sex hormones and corticosteroids Luteinising Hormones (LH) - Same as below Follicle stimulating hormones (FSH) - Stimulates ovarian follicale and production of oestrogen and progesterone Thyroid stimulation (TSH) - Thyroxine production from thyroid Growth Hormone (GH) - Growth in epiphyseal cartilage Prolactin (PL) - Lactogenesis
hormones made in the hypothalamus and what hormones do they promote/ inhibit
ACTH - CRH promotes LH and FSH - LRHR promotes TSH - TRH promotes GH - GHRH promotes - GHIH inhibits PL - PRH promtoes - PIH inhibits
cells in the anterior pituitary and what they make
Somatotrophs - GH Mammotrophs - PL Corticotrophs - Corticotrophin Thyrotrophs - TSH Gonadotrophs - FSH and LH
does the posterior pituitary make hormones?
Posterior pituitary isn’t making the hormones it’s just where the hormones are released into the systemic circulation
what hormones are released from the posterior pituitary and what hypothalamic nuclei make these
Oxytocin
- Milk production and uterine contraction
- Paraventricular nucleus (PVN) make this hormone
Vasopression (anti-diuretic hromone, ADH)
- Increase water uptake in the kidneys
- Supraoptic nucleus (SON) make this hormone
blood supply to the pituitary
Superior hypophyseal artery is one of the earliest branches of the internal carotid artery
- Comes off at the base of the infidibulum to create the pituitary portal system
- Also important as general blood supply
Inferior hypophyseal artery is another branch of the I. carotid artery
veins draining the pituitary
Veins
- Drain sinusoids
- Carry hormones away from pituitary gland into systemic circulation
what 2 hormones does the thyroid produce
- Iodine containing hormones
o T3 (tirhydorthyronine) and T4 (thyroxine)
o T3 more metabolically active, T4 secreted more by throid then activate in systemic circulation
o Regulate basal metabolic rate
o Secretion regulated by TSH from anterior pituitary gland - Calcitonin
o Controls blood calcium levels
o Not under control of pituitary – negative feedback loop with blood calcium
whats special about the thyroid glands storage capacity
Stores hormones in inactive form in extracellular compartment
- Other organs can’t do this – instead store in intracellular compartments
what is the location of the thyroid in relation to muscles
- Deep to sternocleidomastoid muscle
- Deep to sternothyroid muscle
blood supply of the thyroid
From 2 sources
- Branch of subclavian artery called the thyrocervical trunk, brach from this called inferior thyroid artery and
- Branch of the external carotid called the superior thyroid artery
recurrent laryngeal nerve what does it supply and whats its relevance to the thyroid
- Supllies larynx
- It’s very close to the thyroid and is commonly damaged during thyroid surgery
venous drainage of the thyroid
- Supeior thyroid vein
- Middle thyroid vein
- Inferior thyroid vein
histology of the thyroid
- Unique as it has extracellular spaces to store thyroid hormones
- Follicles surrounded by cuboidal epithelial cells
- Have extracellula rspace amongst this
- Whole throid gland is seperated by the septa
o Connective tissue that’s came in from the fibrous capsule
o These carry the blood vessels
