Nuts and bolts of the endocrine system

Question 1

Nervous system

Answer 1

Neural impulse transmission

Mediator molecules - neurotransmitters

Very fast

Act locally from pre to post synapse

Question 2

Endocrine system

Answer 2

Via the release of hormones

Mediator molecules - hormones

Much slower

Act anywhere in the body via the circulatory system

Question 3

Properties of endocrine cells

Answer 3

Ductless

Hormone is released to interstitial space - blood stream or lymphatic system

Highly vascularised

Question 4

Chemical classification of hormones

Answer 4

Steroid

Protein/ peptide

Amine

Question 5

NO

Answer 5

Neurotransmitter and a hormone

Question 6

Source of steroids

Answer 6

Ovaries, testis, adrenal cortex

Derived from embryonic mesodermal tissue

Question 7

Source of protein/ peptide

Answer 7

Adenohypophysis (pituitary) - ectodermal tissue of the oral cavity

Thyroid; parathyroid; pancreas - cells of endodermal origin of the GI tract

Question 8

Source of amine

Answer 8

Thyroid; adrenal medulla

Cells of ectodermal origin

Question 9

Discrete glands

Answer 9

Hypophysis

Thyroid

Parathyroid

Adrenal

Question 10

Larger glands

Answer 10

Have both endocrine and exocrine function

Kidneys

Ovaries/ testis

Placenta

Question 11

Diffuse neuroendocrine system

Answer 11

Scattered nerve cells with endocrine function

Question 12

Hypophysis

Answer 12

Pituitary gland

Suspended from hypothalamus by infundibulum

Located in the sella turcica (sphenoid bone)

Question 13

Hypophysis function

Answer 13

Master endocrine gland

Produces several hormones that influence activity of other endocrine glands

Question 14

Hypophysis gross anatomy

Answer 14

No larger in size than a pea

Two divisions

• adenohypophysis: glandular part; outpouching of actoderm of oral cavity
• neurohypophysis: neural part; downgrowth from diencephalon of brain

Question 15

Hypophysis blood supply

Answer 15

2 blood vessels branch off internal carotid

Superior hypophyseal supplies:

• median eminence
• upper part of stalk

Inferior hypophyseal supplies:

• neurohypophysis
• lower part of stalk

Question 16

Hypophysis veins

Answer 16

Capillary plexus in median eminence and stalk ending drained by portal veins

Pass to anterior lobe of pituitary

Form secondary capillary plexus

Provides route for neurosecretory substances released from hypothalamus to also reach the anterior lobe

Question 17

Hypophysis control

Answer 17

Signals from hypothalamus are responsible for hormone release from both lobes

Question 18

Thyroid gland

Answer 18

Bilobed gland in the neck

2 lateral lobes connected by an isthmus that courses anterior to the trachea

From just below oblique line of thyroid cartilage to 5/6 tracheal ring; immediately anterior to the trachea

Question 19

Thyroid gland derived from

Answer 19

Endoderm

Develops as a growth from floor of pharynx, near base of tongue

Question 20

Essential role of thyroid

Answer 20

Regulating tissue metabolism, growth and development

Question 21

T3

Answer 21

Triiodothyronine

Question 22

T4

Answer 22

Thyroxine

Question 23

Thyroid gland blood course

- arteries

Answer 23

Superior thyroid (from external carotid)

Inferior thyroid (from subclavian)

Question 24

Thyroid gland blood course

- veins

Answer 24

From an extensive plexus into the

• internal jugular vein
• brachiocephalic vein

Question 25

Care in surgery

Answer 25

Cricothyrotomy Recurrent nerve (from vagus)

Question 26

Parathyroid glands

Answer 26

To the side of thyroid gland 4 parathyroid glands: 2 superior and 2 inferior; embedded in capsule of thyroid; posterior aspect Very small, about the size of a grain of rice

Question 27

Parathyroid gland origins

Answer 27

Mostly cells originating from 3rd/ 4th pharyngeal pouches; migrate caudally with the thymus Inferior parathyroids travel further than superior

Question 28

Role of parathyroid glands

Answer 28

Secrete parathyroid hormone Regulates calcium and phosphate levels within homeostasis

Question 29

Parathyroid glands arteries

Answer 29

Primarily inferior thyroid Also some superior

Question 30

Parathyroid glands veins

Answer 30

Superior, middle and inferior thyroid

Question 31

Parathyroid glands nerves

Answer 31

From middle and inferior cervical ganglions

Question 32

Adrenal glands location

Answer 32

Superior pole of kidneys (T12) Retroperitoneal

Question 33

Adrenal gland shapes

Answer 33

Pyramidal (R) Semilunar (L)

Question 34

Origin of adrenal glands

Answer 34

Cortex derived from mesoderm (mesothelium) Medulla derived from neural crest cells

Question 35

Adrenal glands - cortex

Answer 35

Cells subadjacent to capsule - secrete mineralocorticoids - aldosterone - maintain electrolyte balance Deeper part of cortex - secrete glucocorticoids - hydrocortisone - affect metabolism and electrolyte balance Cortex also produces adrenal androgens e.g. testosterone

Question 36

Adrenal glands - medulla

Answer 36

Secretory cells (chromaffin) develop from same embryonic tissue as sympathetic ganglia Modified sympathetic ganglion (ANS) Secretes adrenaline and smaller amounts of noradrenaline Fight or flight response

Question 37

Adrenal glands blood supply

Answer 37

Supplied by - superior (from inferior phrenic) - middle (from aorta) - inferior suprarenal arteries (from renal) Arteries branch before entering capsule and the rami supply the cortex and medulla of gland

Question 38

Adrenal gland blood course

Answer 38

Medullary arteries pass throug cortex to supply the medulla Hormones produces by cortical cells influence activity of medulla

Question 39

Venous drainage of adrenal glands

Answer 39

Adrenal veins drain into - IVC (R) - renal vein (L)

Question 40

Adrenal gland activity

Answer 40

Under control of - hypothalamus - sympathetic division of ANS Adrenocorticotrophic hormone - stimulates secretion of corticosteroids