Anatomy and Physiology: Endocrine System

Questions and Answers

What is the primary long-term function of the endocrine system?

Regulating blood pressure

Facilitating metabolism (correct)

Maintaining pH levels

Controlling respiration

Which type of hormone is characterized as lipid-soluble and can cross cell membranes?

Modified Amino Acids

Eicosanoids

Polypeptides

Steroids (correct)

In which type of hormonal communication do hormones act on neighboring cells?

Endocrine

Autocrine

Paracrine (correct)

Neuroendocrine

What is the role of water-soluble hormones in target cells?

Utilize second messenger systems Signup and view all the answers

What connects the hypothalamus to the pituitary gland?

Pituitary stalk Signup and view all the answers

Which gland releases hormones in response to hypothalamic stimuli?

Anterior pituitary Signup and view all the answers

Which type of hormone acts on the cell that secretes it?

Autocrine hormones Signup and view all the answers

What is a characteristic of circulating hormones?

They are released directly into the bloodstream Signup and view all the answers

What hormone is primarily regulated by the anterior pituitary gland through TSH?

Thyroxine (T4) Signup and view all the answers

Which of the following glands is located behind the thyroid gland and is involved in calcium homeostasis?

Parathyroid Glands Signup and view all the answers

Which statement accurately describes the location of the thyroid gland?

Located anterior to the trachea. Signup and view all the answers

What structure is primarily responsible for draining blood from the posterior pituitary?

Cavernous sinus Signup and view all the answers

Which hormone is secreted by the medulla of the adrenal glands?

Norepinephrine Signup and view all the answers

Which of the following is NOT a function of thyroid hormones?

Stimulate red blood cell production Signup and view all the answers

What regulates the secretion of parathyroid hormones?

Calcium levels Signup and view all the answers

Which of the following correctly describes the structure of the adrenal glands?

Comprised of medulla and cortex Signup and view all the answers

What is the primary role of aldosterone in the body?

Regulates sodium and potassium homeostasis Signup and view all the answers

Which of the following correctly describes the blood supply to the adrenal glands?

The middle adrenal artery arises from the abdominal aorta Signup and view all the answers

What is the function of cortisol released during stress?

Stimulates the breakdown of triglycerides Signup and view all the answers

Which component activates the renin-angiotensin-aldosterone pathway?

Dehydration and sodium deficiency Signup and view all the answers

Which percentage correctly represents the composition of catecholamines released by the adrenal medulla?

80% adrenaline and 20% norepinephrine Signup and view all the answers

What stimulates the secretion of renin from the kidneys?

Decreased blood volume Signup and view all the answers

Which of the following is NOT a primary effect of adrenaline during the fight-or-flight response?

Increased peripheral vasodilation Signup and view all the answers

What is a primary physiological effect of glucocorticoids like cortisol?

Enhance protein breakdown in muscles Signup and view all the answers

Study Notes

Endocrine System Overview

Maintains homeostasis through hormones as chemical messengers
Short-term functions: control of blood pressure, pH regulation, and respiration
Long-term functions: growth, reproduction, and metabolism

Function of Hormones

Hormones responsive to stimuli restore equilibrium
Target specific tissues with corresponding receptors
Water-soluble hormones target cell surface receptors; lipid-soluble hormones bind to intracellular receptors

Communication Mechanisms

Endocrine: hormones travel via circulatory system over long distances
Paracrine: hormones act on nearby cells in extracellular fluid
Autocrine: hormones act on the secreting cell itself
Neuroendocrine: hormones secreted from nerve cells

Types of Hormones

Polypeptides: water-soluble, cannot pass cell membranes
Steroids: lipid-soluble, can cross cell membranes
Modified Amino Acids: small and water-soluble, can pass through membranes
Eicosanoids: local hormones like prostaglandins

Hormone Classification

Circulating Hormones: travel in bloodstream (e.g., insulin)
Local Hormones: act near secretion site
- Paracrine: affect neighboring cells
- Autocrine: affect secreting cell itself (e.g., interleukin-1)

Mechanisms of Hormone Action

Lipid-soluble hormones trigger direct responses in target cells
Water-soluble hormones use second messenger systems for signal amplification

Hypothalamic-Pituitary Axis

Central regulatory component of the endocrine system
Hypothalamus integrates neural and hormonal signals; communicates with the pituitary gland

Hypothalamus Details

Located at the base of the forebrain
Connects to the pituitary gland via pituitary stalk
Receives signals from blood and neurons for hormone secretion

Pituitary Gland

Anterior Pituitary: located in the sella turcica, releases hormones in response to hypothalamic signals
Posterior Pituitary: releases ADH and oxytocin, located posterior to anterior pituitary

Thyroid Gland

Anterior to the trachea, butterfly-shaped, connected by isthmus
Produces calcitonin, T3, and T4 for metabolic regulation; stores thyroglobin and iodine
Regulated by TSH from anterior pituitary

Actions of Thyroid Hormones

Increase basal metabolic rate and body temperature
Stimulate glucose and fatty acid utilization, promote lipolysis
Support nervous tissue and bone development

Parathyroid Glands

Located behind the thyroid gland; regulates calcium and phosphate levels
Contains chief cells regulated by calcium levels

Adrenal Glands

Paired glands above each kidney; consists of medulla and cortex
Medulla secretes catecholamines (epinephrine and norepinephrine)
Cortex produces glucocorticoids (cortisol), mineralocorticoids (aldosterone), and androgens

Blood Supply to Adrenal Glands

Superior adrenal artery from inferior phrenic artery
Middle adrenal artery from abdominal aorta
Inferior adrenal artery from renal arteries
Drained by right adrenal vein into inferior vena cava and left into left renal vein

Renin-Angiotensin-Aldosterone Pathway

Triggered by dehydration, hemorrhage, or sodium deficiency leading to decreased blood volume and pressure
Kidneys secrete renin, converting angiotensin to angiotensin I, then to angiotensin II by ACE inhibitors
Angiotensin II stimulates adrenal cortex to secrete aldosterone

Aldosterone Function

Regulates sodium and potassium homeostasis, influencing blood pressure
Part of renin-angiotensin-aldosterone system, activated by low blood volume and pressure

Glucocorticoids

Main glucocorticoid is cortisol, released during stress
Effects include protein breakdown, gluconeogenesis, lipolysis, and anti-inflammatory responses

Catecholamines

Epinephrine (80%) and norepinephrine (20%) involved in fight-or-flight response
Increase heart rate, blood flow to muscles, airway dilation, and energy production

Pancreas Overview

Retroperitoneal gland that contains endocrine (Islets of Langerhans) and exocrine components

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Description

Explore the crucial role of the endocrine system in maintaining homeostasis through hormone regulation. This quiz covers both short and long-term functions of hormones, including effects on blood pressure, growth, and metabolism. Test your understanding of how hormones interact with target tissues to restore equilibrium.