Endocrine System Flashcards by Unknown Unknown

: How do endocrine glands deliver hormones?

They secrete hormones into the bloodstream, which carries them to target tissues or cells.

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What is another name for the pituitary gland?

Hypophysis.

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Where is the pituitary gland located?

base of brain

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What are the two lobes of the pituitary gland?

Anterior lobe and posterior lobe.

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What is another name for the anterior pituitary lobe?

Adenohypophysis.

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What is the anterior lobe made of and what does it do?

Glandular tissue (Pars distalis); secretes most of the pituitary hormones.

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What is another name for the posterior pituitary lobe?

*Neurohypophysis.

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What is the posterior lobe made of and what does it do?

Nervous tissue (Pars nervosa); stores and releases hormones made by the hypothalamus.

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Growth hormone (where, taget and action)

*-anterior pituitary (adenophypophysis)
-bone, muscles, other tissues
-stimulates cell growth and divison

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Adrenocorticotrophic hormone (ACTH)

-anterior pituitary (adenophypophysis)
-adrenal cortex
-stimulates release of thyroid hormones

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Thyroid stimulating hormone

-anterior pituitary (adendophypophysis)
-thyroid gland
-stimulates release of thriod hormones

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Follicle stimulating hormone (FSH)

anterior (adeno)
gonads
stimulating developement of ova and sperm

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Luteinizing hormone (LH)

anterior (adeno)
gonads
stimulates secretion of sex hormones

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Prolactin

anterior (adneo)
mammary glands
stimmulates milk production

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Melanocyte stimulating hormones

anterior (adneo)
melanocytes
stimulates melanin production

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antidiuretic hormone (adh) (where, taget and action)

posterioir (neurohypophysis)
renal tubules
stimulates water reabsorption

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ocytocine (OXT)

posterioir (neuro)
uterus and mammary glands
stimulates uterine contractions during labor and delivery and release of milk

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What does FSH (Follicle-Stimulating Hormone) do?

*Acts on gonads to stimulate the production of gametes (sperm in males, eggs in females).

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What does LH (Luteinizing Hormone) do?

*Acts on gonads to regulate the production of sex hormones (testosterone, estrogen, progesterone).

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What are the main parts of the pituitary gland?

Pars tuberalis, pars distalis (anterior lobe), pars intermedia, and pars nervosa (posterior lobe).

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*Which part of the pituitary shows dense histology with many stained nuclei?

Pars distalis (anterior lobe), due to its many hormone-secreting cells.

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*What is the pars nervosa made of and how does it appear in histology?

Made of neurons (posterior lobe); appears lighter and less dense under the microscope.

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Where is the thyroid gland located?

Anterior neck, just below the larynx, partially wrapping around the trachea.
butterfly -shaped

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What are thyroid follicles?

Spherical structures that store colloid, a protein material containing hormones.

What do follicular cells of the thyroid secrete?

Thyroxine (T₄) and triiodothyronine (T₃).

Where are parafollicular cells found and what do they secrete?

Found between follicles; secrete calcitonin, which helps lower blood calcium.

Thyroxine (T4) & Triiodothyronine (T3) (where, secreted by, taget and action)

-thyroid gland -follicle cells -essentially every cell of body -T3 & T4 work tg to regulate oxygen utilization and rate of metabolism of the cells

Calcitonin (where, secreted by, taget and action)

-Thyroid gland -parafollicular cells -bone and kidneys - reduces blood calcium levels by causing calcium to be deposited into bone and excreted by the kidneys

Parathyroid Glands (secrete, target, function)

-Parathyroid hormone (PTH) -bone and kidneys -raises blood calcium level by causing calciu mto be removed from bone and reabsorbed by the kidney

What hormone do the parathyroid glands secrete & function?

Parathyroid hormone (PTH). -Raises blood calcium levels by causing calcium to be removed from bone and reabsorbed by the kidneys.

What are the two cell types in the parathyroid gland?

Chief cells and oxyphil cells.

What do chief cells do?

Secrete parathyroid hormone (PTH) to regulate blood calcium levels.

What is the function of oxyphil cells in the parathyroid gland?

Function is not well understood.

What are the two main regions of the adrenal glands?

Cortex and medulla.

What hormones are secreted by the adrenal cortex?

Mineralocorticoids (aldosterone), glucocorticoids (cortisol), and androgens.

What is the target and function of aldosterone (a mineralocorticoid)?

Target: Kidneys. Action: Increases renal reabsorption of sodium.

What is the target and function of cortisol (a glucocorticoid)?

Target: Most cells. Action: Affects rate of glucose metabolism.

What is the role of adrenal androgens?

Precursor to male and female sex hormones; has little effect in adults due to small amount.

What hormones are secreted by the adrenal medulla?

Epinephrine and norepinephrine.

What is the target and function of epinephrine/norepinephrine?

Target: Most cells. Function: Increases cardiac activity, blood pressure, and blood glucose levels (fight-or-flight response).

*What are the three layers of the adrenal cortex, from outermost to innermost?

Zona glomerulosa Zona fasciculata Zona reticularis

*What hormone is secreted by the zona glomerulosa and what is its function?

Aldosterone (a mineralocorticoid); regulates sodium reabsorption in kidneys.

*What hormone is secreted by the zona fasciculata and what is its function?

Cortisol (a glucocorticoid); regulates glucose metabolism and stress response.

*What hormone is secreted by the zona reticularis and what is its function?

Androgens; act as precursors to sex hormones.

*What is located in the center of the adrenal gland and what does it secrete?

Adrenal medulla; secretes epinephrine and norepinephrine.

*Be able to identify the adrenal zones in histology

What are pancreatic acini and what is their function?

*They are exocrine cells surrounding the pancreatic islets; secrete digestive enzymes and buffers.

What are pancreatic islets (Islets of Langerhans)?

*Clusters of endocrine cells that appear lighter under the microscope, surrounded by darker acinar cells.

What hormone is secreted by beta cells in pancreatic islets, and what is its action?

Insulin; lowers blood glucose by stimulating glucose uptake by cells.

What hormone is secreted by alpha cells in pancreatic islets, and what is its action?

Glucagon; raises blood glucose by stimulating the liver to break down glycogen.

How do pancreatic islets appear in histology slides?

*As pale-staining clusters (endocrine) surrounded by dark-staining acinar cells (exocrine).

Thymus (no histology but rmb the function!)

Thymosin; promotes the development and maturation of T lymphocytes (T cells).

What hormone is secreted by pinealocytes in the pineal gland and what does it regulate? (no histology but rmb the function!)

Melatonin; regulates circadian rhythms (sleep-wake cycles).

What is the function of testosterone?

Supports sperm production and development of male secondary sex characteristics.

What ovarian cells secrete estrogens?

Follicular cells.

What structure in the ovary secretes progesterone?

Corpus luteum.

What are the functions of estrogen and progesterone?

Estrogen: Regulates menstrual cycle, supports development of female sex characteristics. Progesterone: Prepares uterus for implantation and maintains pregnancy.

negative feedback

The presence of a hormone causes its secretion to stop.