Week 10 - Endocrine System

What are the endocrine glands?

• pituitary

• thyroid

• parathyroid

• adrenal

• pineal

What are hormones?

chemical messengers secreted into the interstitial space (where they diffuse into the bloodstream)

Where are hormones secreted from?

endocrine glands

What are endocrine glands?

ductless secretory tissues

List some of the organs that have endocrine tissue.

• hypothalamus

• skin

• thymus

• heart

• liver

• stomach

• pancreas

• kidneys

• small intestines

• ovaries

• testes

• adipose tissue

• skeletal muscle

• placenta

What is TAPPP?

Thyroid

Adrenal

Pituitary

Parathyroid

Pineal

What are lipid-soluble hormones???

What are water-soluble hormones?

What are amine hormones?

What are steroid hormones?

What are thyroid hormones?

What are peptide/protein hormones?

What is up-regulation of a hormone receptor?

What is down-regulation of a hormone receptor?

What is permissive effect?

How are hormones regulated?

through negative feedback loops, along with three main types of stimuli: humoral, hormonal, and neural controls

How do negative feedback loops regulate hormones?

rising hormone levels signal the brain (or glands) to stop releasing more hormones, bringing levels back down to normal

e.g., thermostat turning off the heat when an ideal temp is reached

How do positive feedback loops regulate hormones?

hormone release is amplified/ramped up (instead of stopped) when trace amounts of a hormone are released

e.g., oxytocin during childbirth (“OK, it’s time to go, let’s release the floodgates”)

True or false: hormone secretion is “bolus” dosing rather than continuous release

true

True or false: hormone secretion is regulated by positive feedback mechanisms

false

What are some examples that are hormonal positive feedback processes?

• oxytocin in childbirth

• coagulation cascade

Where is the hypothalamus located?

ventral brain above the pituitary gland and below the third ventricle

Which hormones are released by the hypothalamus?

• TRH

• GnRH

• GHRH

• GHIH

• CRH

• PRH

• PIH

• somatostatin

• dopamine

• oxytocin

• ADH

What is PIH?

prolactin-inhibiting hormone

What is ADH?

antidiuretic hormone

What is another term for ADH?

vasopressin

Where is ADH produced?

hypothalamus

Where is ADH stored?

posterior pituitary

Where is oxytocin produced?

hypothalamus

Where is oxytocin stored?

pituitary gland

What are the major functions of the hypothalamus?

coordination of endocrine function of

• pituitary gland

• thyroid gland

• adrenal glands

• kidneys

• musculoskeletal system

• reproductive organs

What is the major functions of the anterior pituitary gland?

regulation of cellular processes such as growth, metabolism, reproduction, and response to stress/trauma

What are the effects of LH?

stimulates the production of sex hormones by gonads

What are the effects of FSH?

stimulates the production of sperm and eggs

What are the effects of TSH?

stimulates the release of thyroid hormone (TH)

What are the effects of TH?

What are the effects of PRL?

promotes milk production within the mammary glands

What is the effect of GH?

What are the effects of ACTH?

What hormones are released by the posterior pituitary gland?

• oxytocin

• ADH

How are the hormones released by the pituitary gland regulated?

hypothalamus via the hypophyseal portal circulation

What is the hypophyseal portal circulation?

a network of blood vessels that directly connects the hypothalamus to the anterior pituitary gland using two linked capillary bed which lets tiny amounts of brain hormones travel straight to the pituitary gland without getting lost or diluted in the rest of the body

What is SIADH?

What is diabetes insipidus?

What is hypothyroidism?

What is gigantism?

What is adrenal insufficiency?

Where is the thyroid gland located?

neck, just below the larynx (anterior, interior)

Which hormones are released by the thyroid gland?

How is the thyroid gland regulated?

What are the major functions of the thyroid gland?

What is T3?

triiodothyronine

What is T4?

thyroxine

How are T3 and T4 transported within the bloodstream?

bound to thyroxine-binding globulin (TBG)

What is thyroxine-binding globulin?

a primary transport protein produced by the liver that binds and carries thyroid hormones (specifically thyroxine (T4) and triiodothyronine (T3)) through the bloodstream

What is the difference between free vs. bound hormones?

unbound = free

unbound = biologically active

Where is the parathyroid gland located?

4 small glands embedded in the posterior thyroid gland

Which hormones are released by the parathyroid gland?

parathyroid hormone (PTH)

What is the role of PTH?

calcium, magnesium, and phosphate regulation (in conjunction with calcitonin)

What are chromaffin cells?

specialized neuroendocrine cells located mainly in the adrenal medulla that act as a bridge between the nervous system and endocrine systems via release of epinephrine and norepinephrine (drives the body's fight-or-flight stress response)

Where is the adrenal medulla located?

What is the major function of the adrenal medulla?

How is the adrenal medulla regulated?

What are the effects of glucocorticoids?

• protein breakdown

• gluconeogenesis

• lipolysis

• resistance to stress

• immune suppression

  • harder to heal wounds

• anti-inflammatory

True or false: one of the risks of glucocorticoids is type 2 diabetes due to the excess glucose

true

What is the location of the adrenal cortex?

What are the hormones released by adrenal cortex?

What are the major functions of the adrenal cortex?

How is the adrenal cortex regulated?

• HPA axis

• RAAS

What is the HPA axis?

hypothalamic-pituitary-adrenal axis

What is the role of the HPA axis?

How is the HPA axis regulated?

What is zona fasciculata?

What is zona reticularis?

the innermost layer of the adrenal cortex, bordering the adrenal medulla

What is the function of the zona reticularis?

• release ACTH

• production of weak androgen precursor hormones

What is a pheochromocytoma?

rare tumor (usually benign) that forms in the adrenal glands and produces excess adrenaline, causing high blood pressure, fast heartbeats, heavy sweating, and other sympathetic nervous system responses

What are the “5 P’s” of pheochromocytoma?

Pressure

Pain

Palpitations

Perspiration

Pallor

Where is the pineal gland located?

mid-line of the brain (outside the blood-brain barrier) and attached to the roof of the third ventricle by a short stalk

What are the functions of the pineal gland?

• regulation of the body’s internal clock (circadian rhythm) by production of melatonin = translation of signals about lightness/darkness into daily sleep-wake patterns

• controls the hormone levels that affect sexual development and puberty

True or false: the pancreas is composed of endocrine tissue, but is classified as a digestive organ

true

What can cause pineal gland calcification (other than age)?

Where is the pancreas located?

What are the three distinct parts of the pancreas?

1. head

2. body

3. tail

What are pancreatic islet cells (islets of Langerhans)?

Which hormones are released by the pancreas?

• glucagon

• insulin

• somatostatin

• pancreatic polypeptide

What are the major functions of the pancreas?

• blood glucose regulation

• regulation of glandular secretions

How is the pancreas regulated?

• negative feedback loops

• hormonal regulation

• neuronal regulation

  • remember fight or flight response (sympathetic nervous system)

Which type of pancreatic cell releases glucagon?

alpha

Which type of pancreatic cell releases insulin?

beta

Which type of pancreatic cell releases somatostatin?

delta (D cells)

Which type of pancreatic cell releases pancreatic polypeptide?

F or PP cells

What is the thymus?

What is the endocrine tissue of the heart?

What is the endocrine tissue of the liver?

What is the endocrine tissue of the thymus?

What is the endocrine tissue of the skin?

What is the endocrine tissue of the GI tract?

What is the endocrine tissue of the kidneys?

What is the endocrine function of adipose tissue?

secretion of adipokines