Endocrine System Chapter 18 Flashcards

Questions and Answers

What is the function of the endocrine and nervous systems?

They work together to monitor and adjust physiological activities in the body at any given moment.

What does the endocrine system consist of?

Pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands.

What is the definitive function of the endocrine system?

Produces hormones.

What produces steroid-cholesterol-based molecules?

Adrenal cortex and sex organs. Signup and view all the answers

What is an amino acid derivative?

Similar to amino acids, effective by second messengers. Signup and view all the answers

What is an example of an amino acid derivative?

Thyroid hormone. Signup and view all the answers

What are peptides?

Groups of amino acids. Signup and view all the answers

What exerts nervous control on the adrenal medulla?

ANS. Signup and view all the answers

What is the role of the hypothalamus in the endocrine system?

Has direct control over endocrine cells and produces ADH and oxytocin. Signup and view all the answers

What causes diabetes insipidus?

Decrease in ADH. Signup and view all the answers

What is negative feedback?

Most common type of feedback; has stabilizing effects, maintains homeostasis. Signup and view all the answers

What is positive feedback?

Uncommon; has destabilizing effects. Signup and view all the answers

What is an example of positive feedback?

Release of oxytocin in response to uterine contractions. Signup and view all the answers

What is another name for posterior pituitary?

Neurohypophysis. Signup and view all the answers

What do the supraoptic nucleus of the posterior pituitary contain?

Axons for producing ADH. Signup and view all the answers

What is ADH?

Antidiuretic hormone or vasopressin. Signup and view all the answers

What are the functions of ADH?

Concentrates urine, conserves water. Signup and view all the answers

What triggers the release of ADH?

Rise in electrolyte concentration or drop in blood pressure. Signup and view all the answers

What does the paraventricular nucleus of the posterior pituitary produce?

Oxytocin. Signup and view all the answers

What are the functions of oxytocin?

Induces uterine contractions in childbirth, ejects milk from breasts, induces contraction of prostate gland in males. Signup and view all the answers

What is another name for anterior pituitary?

Adenohypophysis. Signup and view all the answers

What are the parts of the anterior pituitary?

Pars distalis, pars intermedia, pars tuberalis. Signup and view all the answers

What is the hypophyseal portal system?

Blood flows from one capillary bed into another before returning to the heart. Signup and view all the answers

What are the hormones of the anterior pituitary?

Melanocyte stimulating hormone (MSH), adrenocorticotropic hormone (ACTH), growth hormone (GH), somatostatin, thyroid stimulating hormone (TSH), prolactin (PRL), follicle stimulating hormone (FSH), leutinizing hormone (LH), interstitial cell stimulating hormone (ICSH). Signup and view all the answers

Where is MSH released from?

Pars intermedia. Signup and view all the answers

What does ACTH do?

Stimulates adrenal cortex to produce glucocorticoids. Signup and view all the answers

What do GH and somatostatin target?

Muscle and bone. Signup and view all the answers

What are the functions of GH?

Mobilizes fat, glucose. Signup and view all the answers

What does TSH target?

Thyroid. Signup and view all the answers

What does PRL target?

Mammary tissue. Signup and view all the answers

What does FSH target and promote?

Targets follicles of ovary and cells of testes; promotes ovum and sperm production. Signup and view all the answers

What is the function of LH?

Stimulation of corpus luteum for progesterone production. Signup and view all the answers

What is the function of ICSH?

Stimulates interstitial cells of testes for testosterone production. Signup and view all the answers

What is the thyroid?

Butterfly-shaped gland in the throat below the larynx; sequesters iodine to be incorporated into its hormones. Signup and view all the answers

What do the two lobes of the thyroid contain?

Thyroglobulin-colloidal form that can be iodized to become active thyroxine (TX, T4) and triiodothyronine (T3). Signup and view all the answers

What do TX, T4, and T3 do?

Accelerate metabolic rate, energy usage. Signup and view all the answers

What do C cells of the thyroid produce?

Calcitonin. Signup and view all the answers

What does calcitonin do?

Decreases blood calcium levels in body fluids. Signup and view all the answers

Where does the thyroid store its hormones?

Extracellularly. Signup and view all the answers

What are the parathyroid glands?

Four tiny glands embedded in the back of the thyroid. Signup and view all the answers

What do the principal (chief) cells of the parathyroid gland produce?

Parathormone (PTH). Signup and view all the answers

What does PTH do?

Increases calcium levels; antagonistic to thyroid calcitonin activity; moderates blood calcium level. Signup and view all the answers

What does decreased PTH result in?

Muscle spasm. Signup and view all the answers

What are the characteristics of the thymus?

Sits on the mediastinum above the heart and is most active in infancy and childhood. Signup and view all the answers

What does thymosin do?

Enhances lymphocyte production and competence. Signup and view all the answers

What does the adrenal cortex produce?

Steroids. Signup and view all the answers

What are the functions of zona glomerulosa?

Produces mineralcorticoids; targets kidneys; affects mineral balance of body. Signup and view all the answers

What does zona fasciculata produce?

Glucocorticoids such as cortisone and cortisol. Signup and view all the answers

What are the characteristics of zona fasciculata?

Resist stress, anti-inflammatory; makes up over 3/4 of adrenal cortex. Signup and view all the answers

What would damage to zona fasciculata result in?

Increase in urine volume and water retention. Signup and view all the answers

What does zona reticularis produce?

Gonadocorticoids. Signup and view all the answers

What is an important role of TX, T4, T3?

Physical, intellectual and sexual maturation. Signup and view all the answers

What is unique about GH?

It's the only hormone to target all cells to some degree. Signup and view all the answers

What is a gonadocorticoid?

Source of testosterone. Signup and view all the answers

Study Notes

Endocrine System Overview

The endocrine system and nervous system collaborate to regulate physiological activities continuously.
Key components include the pituitary gland, thyroid gland, parathyroid glands, thymus, and adrenal glands.

Hormones and Functions

The primary function is hormone production, which impacts various bodily functions.
Steroid hormones produced by the adrenal cortex and sex organs are cholesterol-based.
Amino acid derivatives, like thyroid hormones, act through second messengers.
Peptides, composed of groups of amino acids, also play significant roles in hormone function.

Hypothalamus Role

Acts as the "manager" of the endocrine system, controlling endocrine cells.
Signals the anterior pituitary to release or inhibit hormones through releasing hormones (RH) and inhibiting hormones (IH).
Produces antidiuretic hormone (ADH) and oxytocin.

Feedback Mechanisms

Negative feedback is common, stabilizes physiological processes, and maintains homeostasis.
Positive feedback is rare but used in processes like oxytocin release during childbirth.

Pituitary Gland

Anterior pituitary is also known as adenohypophysis; posterior pituitary is called neurohypophysis.
Anterior pituitary releases several hormones through the hypophyseal portal system to minimize dilution.
Major anterior pituitary hormones include:
- Melanocyte-Stimulating Hormone (MSH)
- Adrenocorticotropic Hormone (ACTH)
- Growth Hormone (GH)
- Prolactin (PRL)
- Thyroid Stimulating Hormone (TSH)
- Follicle-Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)

Thyroid Gland

A butterfly-shaped gland below the larynx, responsible for iodine incorporation into hormones.
Produces thyroxine (T4) and triiodothyronine (T3) which accelerate metabolism and energy usage.
C cells in the thyroid produce calcitonin, reducing blood calcium levels.

Parathyroid Glands

Four tiny glands located on the back of the thyroid.
Principal cells produce parathormone (PTH) which increases blood calcium levels, opposing calcitonin's effects.
Decreased PTH can cause muscle spasms.

Thymus

Located in the mediastinum, most active during infancy and childhood.
Produces thymosin which promotes lymphocyte development.

Adrenal Glands

Adrenal Cortex
- Divided into three zones:
  - Zona Glomerulosa produces mineralcorticoids like aldosterone, affecting mineral balance and fluid retention.
  - Zona Fasciculata produces glucocorticoids such as cortisone and cortisol, essential for stress resistance and anti-inflammatory responses.
  - Zona Reticularis produces gonadocorticoids, contributing to testosterone production.

Hormonal Effects

Thyroid hormones (T4 and T3) are crucial for physical, intellectual, and sexual maturation.
GH uniquely targets all cells, promoting growth and mobilizing fats and glucose.
Functions of ADH include urine concentration and water conservation, triggered by electrolyte rise or blood pressure drop.
Oxytocin induces uterine contractions and milk ejection, influencing reproduction and lactation.

Summary of Key Hormones

FSH targets ovarian follicles and testicular cells, promoting gametogenesis.
LH stimulates the corpus luteum for progesterone production.
ICSH (Interstitial Cell Stimulating Hormone) stimulates testes interstitial cells for testosterone production.

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Test your knowledge on the endocrine system with these flashcards focused on Chapter 18. Learn about the functions, components, and overall significance of the endocrine system in the body. Perfect for students looking to reinforce their understanding of this critical biological system.