*Anatomy - Endocrine System Flashcards
what is a gland responsible for?
Manufacturing, storing and releasing at least 1 specific hormone
What happens do a hormone that is released by an endocrine gland?
It is secreted into the bloodstream to act at a distant target site(s) (cells displaying the correct receptor for the hormone are its target site)
What triggers a physiological response in the target cells?
Hormone binding to receptor
What type of processes do hormones control? (duration or speed)
Processes that require duration of action rather than speed of action (nervous system)
Why must the blood level of a hormone be controlled within the normal range?
To achieve homeostasis
What is homeostasis?
Maintenance of the bodies’ physiological parameters relatively constant despite opposing external influences (conditions are necessary for normal cellular function)
What type of feedback mechanism almost always controls hormone levels?
Negative feedback
What are the 2 types of endocrine gland tumours?
Functioning = too much hormone secreted Non-functioning = tumour destroys gland and too little hormone secreted
Apart from a tumour, how else may hormone negative feedback go wrong? (2)
Target cells sensitivity to hormone may change
Inappropriate magnitude of cellular activity
2 main endocrine glands in the head?
Hypothalamus Pituitary gland (hypophysis)
5 main endocrine glands in the head?
4 parathyroid glands
Thyroid gland
3 main endocrine glands in the abdomen?
2 adrenal (suprarenal) glands and the pancreas
2 main endocrine glands in the female pelvis?
2 ovaries
2 main endocrine glands in the male pelvis?
2 testes
What forms the central core of the cerebrum with connections to the right and left cerebral hemispheres and the midbrain?
The diencephalon
What are the 2 parts of the diencephalon?
Thalamus
Hypothalamus
What are the 3 parts of the brainstem?
Midbrain
Pons
Medulla (Oblongata)
Where is the pituitary gland located in relation to the skull?
Midline structure in the pituitary fossa of the sphenoid bone
What anatomically and functionally connects the hypothalamus to the pituitary gland?
The infundibulum
What is the pituitary anatomically and functionally divided into?
The anterior pituitary and posterior pituitary
Where do the axons of the hypothalamic neurones pass?
Down the infundibulum into the posterior pituitary
What 2 hormones does the hypothalamic neurones manufacture?
Oxytocin
Vasopressin (ADH)
(also releasing hormones or release-inhibitory hormones)
What are oxytocin and vasopressin transported to the posterior pituitary within?
The axoplasm (cytoplasm of the axons) by axoplasmic transport
In terms of the anterior pituitary, what does the hormones released from from the hypothalamic neurones either do?
Stimulate or prevent the anterior pituitary releasing hormones into the bloodstream
What hormones does the anterior pituitary release?(6)
GH (growth hormone) Prolactin (milk production) TSH (thyroid stimulating hormone) ACTH (adrenocoricotrophic hormone) LH (lutenising hormone - gonads) FSH (follicle stimulating hormone -ovaries)
How does the releasing hormones or release-inhibiting hormones pass into the anterior pituitary gland?
Hormones are released into the hypophyseal portal system
These drain blood from the hypothalamus to anterior pituitary capillary beds (blood contains the release/ inhabiting hormones)
What drains venous blood from the anterior and posterior pituitary glands?
The hypophyseal veins which eventually drains the blood to the SVC
What is a portal system?
When a capillary bed lies between 2 sets of veins
Name 2 portal systems?
Hepatic portal system
Hypophyseal portal system
What is the “master gland” of the body?
Why is it called this?
The pituitary gland
It controls the output of hormones from many other endocrine glands
What are the anatomical parts of the thyroid gland?
right lobe
left lobe
Isthmus
what is the name given to an enlarged thyroid gland?
A goitre (will move superiorly and then inferiorly with the larynx during swallowing)
What are the 2 thyroid hormones?
What does the thyroid gland use to manufacture these?
Triiodothyronine (T3)
Thyroxine (T4)
What do thyroid hormones regulate and stimulate?
Regulate metabolism and stimulate growth
What thyroid hormone can we not live without?
Triiodothyronine (T3)
What is a dietary cause of a goitre?
Dietary lack of iodine
Where are the 4 parathyroid glands located in relation to the thyroid gland?
On the posterior surfaces of the thyroid gland’s lobes
What are the names of the 4 parathyroid glands?
Right superior and inferior
Left superior and inferior
What hormone does the parathyroid glands manufacture and secrete
Parathyroid hormone (PTH)
What does PTH control?
The amount of calcium in blood and bone (cannot live without PTH)
What arteries supply the thyroid and parathyroid glands?
Right and left interior thyroid arteries (branch from the subclavian arteries)
Right and left superior thyroid arteries (branches of right and left common carotid arteries)
Other brand from the the right common carotid artery midline
What drains blood from the thyroid and parathyroid glands?
Right and left superior, middle and inferior thyroid veins (branches from the internal jugular veins and the left brachiocephalic vein
What lies posterior to the pancreas?
The aorta and IVC
What lies to the patients left - the aorta or IVC?
IVC (aorta on right)
Is the pancreas under control from the pituitary gland?
No
What are the 2 anatomically and functionally distinct parts of the pancreas?
The endocrine pancreas Islets of Langerhans)
The exocrine pancreas
What is the role of the endocrine pancreas?
It manufactures at least 6 hormones which are secreted into the blood (e.g. insulin is secreted into the venous blood in response to islet cells detecting increased blood glucose)
What is the purpose of the exocrine pancreas?
Manufactures digestive enzymes and secretes them (plus electrolytes) via a duct system into the duodenum
What are the 2 anatomically and functionally discrete endocrine parts?
Adrenal cortex
Adrenal medulla
What 3 hormones are released from the adrenal cortex?
Glucocorticoids (release is under control of pituitary ACTH)
Mineralocorticoids
Androgens
What 2 hormones are released by the adrenal medulla?
Adrenaline
Noradrenaline
(Fight or flight response)
What 2 hormones secreted by the adrenal cortex can we not live without?
Glucocorticoids (minerals)
Mineralocorticoids (blood pressure control)
What are the 2 paired branches of the abdominal aorta?
Adrenal arteries
Renal arteries
Gonadal arteries
What are the names of the 3 arteries that supply each adrenal gland?
Right/ left superior suprarenal artery
Middle suprarenal artery
Inferior suprarenal artery
What is the superior suprarenal artery formed from?
Continuation of adrenal artery which branches bilaterally from the aorta
What is the middle suprarenal artery formed from?
It branches directly from the aorta
What is the inferior suprarenal artery formed from?
Bach of renal artery
What is the menus drainage of the right adrenal gland?
Right suprarenal vein which drains directly into the the IVC
Where does the left suprarenal vein drain into?
The left renal vein
What dos the testes secrete?
In response to what?
Testosterone
LH from the anterior pituitary
What does the ovaries secrete (2)?
In response to what? (2)
Oestrogen
Progesterone
FSH and LH from the anterior pituitary
What provides arterial drainage of the gonads?
The gonadal arteries (paired branches of the abdominal aorta)
where does the gonads venous blood drain into?
Right gonad = directly into the IVC
Left gonad = left renal vein
What is the roles of testosterone and oestrogen? (3)
Development of secondary sexual characteristics, promote the closure of epiphyseal growth plates and stimulate sperm and ovum development
What is the role of progesterone?
To prepare the uterus for pregnancy
