Endocrine System - Lecture Notes Review

A comprehensive set of practice flashcards covering key endocrine system concepts, glands, hormones, mechanisms of action, regulation, and common disorders.

What are the main topics listed under Endocrine Topics?

How the system works; hormone effects on cells; regulation of hormone secretion; glands and hormones

How does information transfer differ between the nervous and endocrine systems?

Nervous uses electrical signals for rapid, targeted responses; endocrine uses chemical hormones with concentration dependent strength and responses that last seconds to days and travel via blood

Name at least five core functions controlled by the endocrine system

Reproduction, growth and development, chemical and fluid balance, cellular metabolism, and mobilization of body defenses

What is endocrinology?

The study of the endocrine system

What is the difference between endocrine and exocrine glands

Endocrine glands have no ducts and release hormones into interstitial space then blood; exocrine glands have ducts and release onto surfaces

What is a hormone

Chemical messengers that travel in extracellular fluids to reach target cells

What are paracrines and autocrines

Paracrines act locally within the tissue; autocrines affect the same cells that secrete them

List the major endocrine glands

Pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, gonads

What are the two major lobes of the pituitary gland and their tissue types

Anterior lobe is glandular tissue; posterior lobe is neural tissue

What is the hypophyseal portal system

A capillary connection between the hypothalamus and the anterior pituitary that transports releasing or inhibitory hormones to control anterior pituitary release

Name the hormones released by the anterior pituitary

Growth hormone GH, thyroid stimulating hormone TSH, adrenocorticotropic hormone ACTH, follicle stimulating hormone FSH, luteinizing hormone LH, prolactin PRL

What are the direct and indirect actions of growth hormone

Direct actions are anti insulin and raise blood glucose; mobilize fats. Indirect actions involve insulin like growth factors IGFs that promote growth of bone and skeletal muscle

What are the major signs of growth hormone imbalance

Hypersecretion before or during puberty causes gigantism in children and acromegaly in adults; hyposecretion causes dwarfism in children

What are the thyroid hormones and where are they produced

Thyroid hormones T3 and T4 produced by follicular cells; Calcitonin produced by parafollicular C cells

What are the effects of thyroid hormones on the body

Increase basal metabolic rate and heat production; regulate carbohydrate, lipid, and protein metabolism; essential for nervous system development; affect cardiovascular, muscular, GI, reproductive, and integumentary systems

Differences between hypothyroidism and hyperthyroidism

Hypothyroidism causes low metabolism with cold intolerance and weight gain; can be congenital or autoimmune; hyperthyroidism causes high metabolism with weight loss and heat intolerance often with exophthalmos

Calcitonin function

Inhibits osteoclast activity and promotes calcium deposition in bones

Parathyroid hormone effects

Increases blood calcium by stimulating osteoclasts, increasing kidney calcium reabsorption, and increasing intestinal calcium absorption via vitamin D

Adrenal cortex zones and their hormones

Zona glomerulosa makes mineralocorticoids including aldosterone; zona fasciculata makes glucocorticoids like cortisol; zona reticularis makes gonadocorticoids (androgens)

Adrenal medulla hormones

Catecholamines epinephrine and norepinephrine released in response to stress

What regulates aldosterone release

Renin angiotensin aldosterone system, plasma potassium, ACTH has minor influence; ANP inhibits aldosterone

Hormones produced by tissues outside the major glands and their roles

Thymus paracrines for T cell maturation; Heart ANP lowers blood volume; GI tract hormones secretin, CCK, gastrin, ghrelin; Placenta hormones; Skin cholecalciferol; Kidneys EPO and calcitriol; Adipose leptin, resistin, adiponectin; Bone osteocalcin

What is ANP and what does it do

Atrial natriuretic peptide released with atrial stretch; inhibits aldosterone and lowers blood volume and pressure

What is the difference between diabetes mellitus and diabetes insipidus

Diabetes mellitus involves high blood glucose with sugar in urine; polyuria, polydipsia, polyphagia; diabetes insipidus is polyuria without sugar due to ADH issues

Gonad hormones produced by ovaries and testes

Ovaries produce estrogens and progesterone; testes produce androgens including testosterone

Pineal gland function

Produces melatonin, may regulate circadian rhythms, may inhibit early maturation, acts as antioxidant

Thymus function

Produces paracrines such as thymulin thymopoietins thymosins important for T lymphocyte maturation

ANP effect on the kidney and blood pressure

Inhibits aldosterone leading to reduced sodium reabsorption and lower blood volume and pressure

Second messenger mechanism for water soluble hormones

Hormone binds receptor, activates G protein, stimulates adenylate cyclase to make cyclic AMP, which activates kinases and triggers cellular responses

Intracellular receptor mechanism for lipid soluble hormones

Lipid soluble hormones diffuse through the membrane, bind intracellular receptors, hormone receptor complex acts as transcription factor to regulate gene expression

Receptor regulation of target cells

Target cells have receptors; receptor affinity and hormone blood level affect response; up regulation when hormone is low, down regulation with high hormone levels

Posterior pituitary hormones and their origin

Oxytocin and ADH are stored in the posterior pituitary but produced in hypothalamic neurons

Hypothalamus to pituitary connection

Hypothalamus releases releasing and inhibiting hormones to anterior pituitary via portal system; posterior pituitary stores hypothalamic hormones

My note on growth hormone regulation

GHRH stimulates GH release; GHIH somatostatin inhibits GH; hypothalamus integrates signals and negative feedback from GH/IGFs

Calcitriol and renin functions

Calcitriol is active vitamin D produced in kidney to promote calcium absorption; Renin initiates the renin-angiotensin system increasing blood pressure and aldosterone release

Osteocalcin function

Bone derived peptide with role in insulin production and sensitivity

ADH release stimuli and inhibitors

Released with high blood solute, low blood volume; inhibited by adequate hydration and alcohol

Adrenal hormone imbalance diseases

Hypersecretion leads to Cushing disease and adrenogenital syndrome; hyposecretion leads to Addison disease

Type I vs Type II diabetes mellitus

Type I is autoimmune no insulin production; Type II insulin resistance (receptors do not respond)