Endocrine System Chapter 18

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Questions and Answers

What are the main functions of oxytocin during and after delivery?

Causes relaxation of the cervix and enhances blood flow to the uterus

Stimulates milk production and reduces uterine contractions

Inhibits uterine contractions during labor and promotes fetal growth

Enhances uterine muscle contraction and facilitates milk ejection (correct)

Which cells in the pancreatic islets are primarily responsible for insulin production?

Beta cells (correct)

F cells

Alpha cells

Delta cells

What percentage of cells in the pancreatic islets produce somatostatin?

5% (correct)

20%

70%

What triggers the release of oxytocin during childbirth?

The stretching of the cervix by the baby's head Signup and view all the answers

What role does ADH play within the context provided?

It promotes water reabsorption in the kidneys Signup and view all the answers

What is the primary function of prolactin in the body?

Initiate milk production from mammary glands Signup and view all the answers

Which hormone is primarily involved in the regulation of calcium blood levels?

Parathyroid hormone (PTH) Signup and view all the answers

What role do corticotrophs play in the endocrine system?

They release adrenocorticotropic hormone (ACTH) Signup and view all the answers

What is the main action of mineralocorticoids like aldosterone?

Increase sodium reabsorption and promote potassium excretion Signup and view all the answers

What is the function of calcitonin in the body?

Stimulate bone formation and reduce calcium reabsorption Signup and view all the answers

How does the hypothalamus regulate lactotrophs?

Through the secretion of prolactin-inhibiting hormone (PIH) or prolactin-releasing hormone (PRH) Signup and view all the answers

Which hormones are produced by the adrenal medulla and mimic the sympathetic nervous system?

Epinephrine and norepinephrine Signup and view all the answers

What is the distinction between the anterior pituitary and posterior pituitary glands?

Anterior pituitary synthesizes hormones, posterior does not Signup and view all the answers

Which of the following functions is NOT regulated by hormones?

Establishing cellular immune memory Signup and view all the answers

Identify the gland that is NOT classified as an endocrine gland.

Sweat Signup and view all the answers

In the context of hormone action, what type of hormone acts on neighboring cells?

Paracrines Signup and view all the answers

Which statement accurately describes the action of water-soluble hormones?

They act as first messengers in signaling pathways. Signup and view all the answers

What type of feedback mechanism is most commonly associated with hormone regulation?

Negative feedback Signup and view all the answers

Which anterior pituitary hormone is responsible for stimulating growth and metabolism?

Human growth hormone (hGH) Signup and view all the answers

What is the primary role of G-protein in the action of water-soluble hormones?

To activate cAMP synthesis within the cytosol Signup and view all the answers

Which hormone secretion control mechanism involves increasing hormone release in response to a change produced by that hormone?

Positive feedback Signup and view all the answers

Which hormone is secreted by thyrotroph cells in the anterior pituitary?

Thyroid-stimulating hormone (TSH) Signup and view all the answers

Which of these glands is NOT associated with hormone secretion as one of its primary functions?

Skin Signup and view all the answers

Study Notes

General Functions of Hormones

Regulate extracellular fluid, metabolism, cardiac and smooth muscle contraction, and glandular secretion.
Influence growth, development, and reproductive processes.
Play roles in some immune functions.

Endocrine Glands Defined

Exocrine glands: Secrete products into ducts (e.g., sweat, oil, mucous, and digestive glands).
Endocrine glands: Secrete hormones directly into the bloodstream (e.g., pituitary, thyroid, adrenal).
Other hormone-secreting organs include the hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, and placenta.

Circulating & Local Hormones

Circulating hormones: Act on distant targets via the bloodstream.
Local hormones:
- Paracrines: Affect neighboring cells.
- Autocrines: Act on the same cell that secretes them.

Action of Hormones

Lipid-soluble hormones:
- Diffuse through cell membranes.
- Bind to intracellular receptors, activating specific genes and protein synthesis that alter cellular activity.
Water-soluble hormones:
- Cannot diffuse through cell membranes and bind to membrane receptor proteins.
- Activate G-proteins that convert ATP to cyclic AMP (cAMP) in the cytosol.

Control of Hormone Secretion

Regulated by nervous system signals, blood chemical changes, or other hormones.
Negative feedback control: Returns hormone levels to set point (most common).
Positive feedback control: Amplifies hormone release (e.g., oxytocin during childbirth).

Types of Anterior Pituitary Cells

Somatotrophs: Secrete human growth hormone (hGH) promoting growth and metabolism through insulin-like growth factors.
Thyrotrophs: Secrete thyroid-stimulating hormone (TSH), regulating thyroid secretion.
Gonadotrophs: Secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH), influencing sex hormone production and oocyte maturation.
Lactotrophs: Produce prolactin, initiating milk production in mammals.
Corticotrophs: Secrete adrenocorticotropic hormone (ACTH), stimulating adrenal glucocorticoid secretion.

Actions of Thyroid Hormones

T3 & T4 Hormones: Regulate metabolic rate, protein synthesis, fat breakdown, and glucose utilization for ATP.
Calcitonin: Lowers blood calcium levels by promoting bone formation and reducing bone resorption.

Parathyroid Hormone

Increases blood calcium levels by stimulating osteoclast activity and enhancing calcium reabsorption in the kidneys.
Promotes calcitriol formation which boosts calcium and magnesium absorption in the intestines.

Prolactin (PRL)

Regulated by hypothalamic hormones (PIH or PRH) acting on lactotroph cells.
Suckling enhances prolactin release, promoting milk production.

Adrenocorticotropic Hormone (ACTH)

Stimulated by hypothalamic releasing hormones.
Promotes secretion of mineralocorticoids from the adrenal cortex, primarily aldosterone.

Mineralocorticoids

Mainly aldosterone, regulates sodium reabsorption and potassium excretion in kidneys.
Balances electrolyte and fluid levels in the body.

Adrenal Medulla

Contains chromaffin cells innervated by the sympathetic nervous system.
Produces epinephrine and norepinephrine, triggering fight-or-flight responses.

Posterior Pituitary Gland (Neurohypophysis)

Stores and releases hormones (ADH and oxytocin) produced by hypothalamic neurons.
Does not synthesize its own hormones.

Oxytocin

Targets uterus and mammary glands.
Increases uterine contractions during childbirth and facilitates milk ejection in response to suckling.

Anatomy of the Pancreas

Predominantly consists of acinar cells producing digestive enzymes.
Endocrine cells (1% of the pancreas) in the islets of Langerhans generate hormones.

Cell Types in the Pancreatic Islets

Alpha cells: Produce glucagon (20%).
Beta cells: Produce insulin (70%).
Delta cells: Produce somatostatin (5%).
F cells: Produce pancreatic polypeptide.

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Description

Explore the key functions of hormones in the human body with this quiz on Chapter 18 of the Endocrine System. Understand how hormones regulate various physiological processes including metabolism, growth, reproduction, and more. Test your knowledge on the complexities of the endocrine system!