Endocrine - Done

What is the endocrine system?

The system of glands that release hormones into the bloodstream to regulate body functions

How do endocrine glands differ from exocrine glands?

• Endocrine - release hormones into blood

• Exocrine - secrete through ducts to surfaces

What are hormones?

Chemical messengers transported in blood that alter activities of target cells

What determines a cell’s response to a hormone?

The presence of specific receptors for that hormone

What are the major endocrine organs? (H, P, T, P, AG, P, PG, G)

Hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, pineal gland, gonads

What are the three classes of hormones? (AA, P, L)

Amino acid derivatives, peptide hormones, lipid derivatives

What are amino acid derivative hormones?

Synthesised from tyrosine/tryptophan

What are peptide hormones?

Chains of amino acids

What are lipid derivative hormones?

Derived from cholesterol

What is a target cell?

A cell with receptors capable of binding and responding to a specific hormone

What is hormone receptor specificity?

Only cells with the matching receptor respond to the hormone

What is the mechanism of action for peptide hormones?

Bind to membrane receptors and activate second messenger systems

What is the mechanism of action for steroid hormones?

• Enter

• Bind

• Activate

Enter cells, bind intracellular receptors, activate gene transcription

What is a second messenger?

A molecule such as cAMP that mediates intracellular signalling after hormone binding

What is amplification in hormone signalling?

1 hormone binding event triggers production of many intracellular signals

What regulates hormone secretion?

Negative feedback

What is humoral stimulus?

Release of hormone in response to changes in blood chemistry

What is neural stimulus?

Hormone release triggered by nervous system input

What is hormonal stimulus?

Hormone release triggered by another hormone

What is the role of the hypothalamus?

Endocrine organ, controls pituitary gland and integrates neural/endocrine systems

What hormones does the hypothalamus release to control the pituitary?

Releasing and inhibiting

What are the two lobes of the pituitary gland?

Anterior pituitary and posterior pituitary

How does the hypothalamus control the anterior pituitary?

Releasing/inhibiting hormones via hypophyseal portal system

How does the hypothalamus control the posterior pituitary?

By direct neural connection and release of stored hormones

What hormones are stored in the posterior pituitary? (A, O)

ADH and oxytocin

What is the function of ADH?

Reduces water loss at kidneys and increases water retention

What is the function of oxytocin?

Stimulates uterine contractions and milk ejection

What are tropic hormones?

Hormones that regulate other endocrine glands

What anterior pituitary hormones are tropic? (T, A, F, L)

TSH, ACTH, FSH, LH

What is the function of TSH?

Stimulates thyroid hormone release

What is the function of ACTH?

Stimulates adrenal cortex secretion of cortisol

What is the function of GH?

Stimulates growth protein synthesis and metabolic regulation

What is the function of PRL?

Stimulates milk production in mammary glands

What are FSH and LH responsible for?

Regulation of reproduction and gamete production

What is negative feedback control in endocrine regulation?

Hormone effects reduce further hormone release to maintain homeostasis

What hormones does the thyroid gland produce? (TT, C)

Triiodothyronine thyroxine and calcitonin

What is the function of thyroid hormones? (MR, OC, HR/G)

Increase metabolic rate, oxygen consumption, heart rate/growth

What element is essential for thyroid hormone synthesis?

Iodine

What is the function of calcitonin?

Reduces blood calcium levels by inhibiting osteoclasts

What hormone does the parathyroid gland produce?

Parathyroid hormone

What is the function of PTH?

Increases blood calcium by stimulating osteoclasts enhancing absorption and increasing kidney retention

Which two hormones regulate calcium homeostasis?

Calcitonin and parathyroid hormone

What are the two parts of the adrenal gland?

Adrenal cortex and adrenal medulla

What hormones are produced by the adrenal medulla?

Epinephrine and norepinephrine

What is the effect of adrenal medulla hormones?

Increase heart rate blood pressure glucose release and sympathetic responses

What are the zones of the adrenal cortex? (G, F, R)

glomerulosa, fasciculata, reticularis

What does the zona glomerulosa secrete?

Aldosterone

What is the function of aldosterone?

Increases sodium retention and potassium excretion in kidneys

What does the zona fasciculata secrete?

Cortisol

What is the role of cortisol?

Regulates metabolism suppresses inflammation and increases glucose availability

What does the zona reticularis secrete?

Androgens

What hormone does the pineal gland produce?

Melatonin

What is the function of melatonin?

Regulates circadian rhythms and seasonal cycles

What endocrine and exocrine functions does the pancreas have?

Releases digestive enzymes and regulates blood glucose through hormones

What does insulin do?

Lowers blood glucose by promoting uptake and storage of glucose

What does glucagon do?

Raises blood glucose by promoting glycogen breakdown and glucose release

Which cells produce insulin?

Beta cells of the pancreatic islets

Which cells produce glucagon?

Alpha cells of the pancreatic islets

What is diabetes mellitus?

Condition marked by high blood glucose due to impaired insulin production or function

What is type 1 diabetes?

Autoimmune destruction of beta cells leading to insulin deficiency

What is type 2 diabetes?

Insulin resistance and impaired insulin secretion

What complications arise from diabetes?

Cardiovascular damage kidney failure vision loss neuropathy

What are the endocrine effects of the heart?

Releases ANP and BNP to lower blood pressure

What hormones do the kidneys produce? (ER, C)

Erythropoietin renin and calcitriol

What is the function of erythropoietin?

Stimulates red blood cell production

What is the role of renin?

Initiates the renin angiotensin aldosterone system to increase blood pressure

What is the role of calcitriol?

Enhances calcium and phosphate absorption in the intestines

What hormone does adipose tissue produce?

Leptin

What is the function of leptin?

Regulates appetite and energy balance