02: ENDOCRINE SYSTEM (LAB)

Endocrine system 

Consists of ductless glands that secrete hormones (chemical messengers) into the interstitial fluid

Hypothalamus

Pineal gland

Pituitary gland

Thyroid

Parathyroid

Thymus

Adrenal gland

Pancreas

Ovaries

Testes

Parts of endocrine system 

HORMONES

chemical messengers that travel through the bloodstream to reach their target organs or cells.

ENDOCRINE SYSTEM

• They are network of glands and organs that produce chemical (hormones) that will regulate body processes including metabolism, growth, reproduction, stress responses, fluid balance, and blood compose

hypothalamus, pituitary gland and pineal gland

parts of endocrine system that is located in the brain

thyroid and parathyroid gland

endocrine system located in the neck:

thymus

located in the sternum:

pancreas, adrenal gland, ovaries and testes

other endocrine gland

pituitary gland

Connected to the base of the brain, just inferior to the hypothalamus

stalk

a thin structure that connects two parts together.

infundibulum

the stalk that connects the hypothalamus to the pituitary gland.

pituitary gland

Rest on Sella turcica (sphenoid bone)

anterior and posterior pituitary

pituitary gland 2 lobes consisting of:

posterior pituitary

known as neurohypophysis; stores and releases hormones

anterior pituitary

known as adenohypophysis; makes hormones

Pituitary fossa

where the pituitary gland sits

HYPOTHALAMOHYPOPHYSEAL PORTAL SYSTEM

Specialized set of blood vessels that connects the hypothalamus with the anterior pituitary gland

Neuroendocrine cell nuclei

synthesize and release hormones that stimulate or inhibit hormone secretion

HYPOTHALAMOHYPOPHYSEAL PORTAL SYSTEM

Allows the brain to directly communicate to the anterior pituitary via blood vessels bypassing the general systemic circulation

Superior hypophyseal artery

supply blood to the upper stalk area, branching into the primary capillary plexus where the hypothalamus dumps regulatory hormones

Long portal vessels

travels down the infundibulum and carry regulatory hormones to the anterior pituitary

neuroendocrine cell nuclei

(nerve cells that make and release hormones.)

Superior hypophyseal artery

supplies oxygenated blood to the upper stalk

HYPOTHALAMOHYPOPHYSEAL TRACT

Contains axons from hypothalamus to posterior pituitary gland

Paraventricular and Supraoptic nucleus

clusters of neurons located within the hypothalamus respectively

parathyroid gland

4 glands (small pea-sized yellow cluster) embedded in the posterior part of each lobe of the thyroid gland

inferior thyroid artery

blood vessels supplying the lower portion of the glands

oxyphil and chief cells

2 cells of parathyroid gland

adrenal gland

Also known as the suprarenal glands; superior pole of kidneys

medulla and cortex

adrenal gland consists of 2 parts:

medulla

inner core of the adrenal gland

cortex

outer layer surrounding the medulla

abdominal aorta

main large artery supplying oxygenated blood

superior, middle, inferior suprarenal artery

supply blood directly to the adrenal gland

medulla

from neural crest cells (ectoderm)

cortex

mesoderm

ectoderm

skin + nervous system

mesoderm

muscles + bones + blood + heart + kidneys

zona glomerulosa, zona fasciculata, zona reticularis

3 zones of adrenal gland (GFR)

ZONA GLOMERULOSA

mineralocorticoids (aldosterone); regulates fluid balance and sodium and potassium level

ZONA FASCICULATA

glucocorticoids (cortisol, corticosterone); regulates glucose metabolism and responses to stress

ZONA RETICULARIS

adrenal androgens (DHEA, testosterone)

Adrenal medulla (catecholamines)

epinephrine, norepinephrine; mediates the acute sympathetic fight-or-flight response

ISTHMUS

narrow band that connects thyroid lobes, 20g; high vascular (dark red)

FOLLICLES

functional unit of the gland

FOLLICULAR CELLS

thyroid hormone

PARAFOLLICULAR CELLS

calcitonin

PANCREAS GLANDS

Runs along the duodenum (head) towards spleen (tail)

Exocrine

Acini (clusters of cells)

Function:

• Produce pancreatic juice (digestive enzymes)

• Send it through ducts to the duodenum (small intestine)

Acini → Pancreatic juice → Duodenum (digests food)

Endocrine

Islets of Langerhans

Function:

• Produce hormones such as:

  • Insulin

  • Glucagon

• Controls blood sugar levels

Islets of Langerhans → Hormones → Bloodstream (controls blood sugar)

common bile duct

carry bile from liver and gallbladder to the duodenum

main pancreatic (duct of wirsung)

major papilla

accessory pancreatic duct (duct of Santorini)

minor papilla

Sphincter of Oddi

• A circular muscle surrounding the opening of the Ampulla of Vater.

• It controls what comes out of the Ampulla of Vater.

• Acts like a gatekeeper/valve.

Ampulla of Vater

• It acts like a meeting point for: Bile + Pancreatic juice before they enter the small intestine to help digest food.

• Bile duct + Pancreatic duct → Ampulla of Vater

ENDOCRINE CONDITIONS AND DISORDERS

diabetes, thyroid disorder, hypogonadism, pcos, osteoporosis

diabetes

metabolic condition involving insulation dysfunction and blood sugar regulation

thyroid disorder

conditions affect the thyroid glands leading to hormonal underproduction or overproduction

hypogonadism

condition characterized by the diminished functional activity of the gonads

PCOS (polycystic ovary syndrome)

hormonal disorder common amongst women of reproductive age

OSTEOPOROSIS

bone disease heavily influenced by hormonal changes and inbalances