Endocrine System: Hormones and Glands

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Questions and Answers

What are the chemical messengers of the endocrine system called?

Neurotransmitters

Glands

Hormones (correct)

Enzymes

What is the primary difference between exocrine and endocrine glands?

Location in the body

Method of secretion release (correct)

Function in the body

Type of secretion produced

Which type of hormone is derived from cholesterol?

Amine Hormones

Peptide/Protein Hormones

Steroid Hormones (correct)

Eicosanoids

What is the role of receptors in the endocrine system?

To bind to specific hormones and initiate a response Signup and view all the answers

What is the second messenger system involved in?

Signal amplification and cellular response Signup and view all the answers

How do steroid hormones affect cellular function?

By passing through the cell membrane and binding to intracellular receptors Signup and view all the answers

What is the process by which a segment of DNA is copied into RNA?

Gene transcription Signup and view all the answers

What is the term for a cell that has specific receptors for a hormone?

Target cell Signup and view all the answers

What type of stimuli triggers hormone release in response to changes in blood levels of ions and nutrients?

Humoral Stimuli Signup and view all the answers

Which hormone regulates the secretion of thyroid hormones?

Thyroid-Stimulating Hormone (TSH) Signup and view all the answers

What is the primary function of the posterior pituitary gland?

To store and release hormones produced by the hypothalamus Signup and view all the answers

What is the term for the network of blood vessels that connects the hypothalamus with the anterior pituitary?

Hypophyseal Portal System Signup and view all the answers

Which hormone is responsible for stimulating the growth and metabolic functions of tissues?

Growth Hormone (GH) Signup and view all the answers

What is the term for hormones that prevent the anterior pituitary from secreting hormones?

Inhibiting Hormones Signup and view all the answers

What is the primary function of the anterior pituitary gland?

To produce and secrete hormones that regulate various bodily functions Signup and view all the answers

What is the term for the type of stimuli that involves nerve fibers stimulating hormone release?

Neural Stimuli Signup and view all the answers

Study Notes

Chemical Messengers of the Endocrine System

Hormones are the chemical messengers of the endocrine system.

Exocrine vs Endocrine Glands

Exocrine glands release secretions through ducts to the outside of the body or onto a surface within the body.
Endocrine glands release hormones directly into the bloodstream without the use of ducts.

Types of Hormones

Steroid hormones are derived from cholesterol (e.g., cortisol, testosterone).
Peptide/protein hormones are composed of amino acids (e.g., insulin, growth hormone).
Amine hormones are derived from single amino acids (e.g., epinephrine, thyroid hormones).
Eicosanoids are derived from fatty acids (e.g., prostaglandins).

Hormone Action

A target cell is a cell that has specific receptors for a hormone, allowing the hormone to exert its effects on that cell.
Receptors are proteins located on the surface or inside of a target cell that bind to specific hormones, enabling the cell to respond to the hormone's signal.
The second messenger system amplifies the signal and initiates a cascade of cellular processes, leading to the hormone's effects.

Steroid Hormones

Steroid hormones pass through the cell membrane and bind to intracellular receptors.
The hormone-receptor complex then enters the nucleus and binds to DNA, altering gene transcription and ultimately protein synthesis, affecting cellular function.

Gene Transcription

Gene transcription is the process by which a segment of DNA is copied into RNA by the enzyme RNA polymerase, leading to protein synthesis.

Stimuli for Hormone Release

Humoral stimuli: changes in blood levels of ions and nutrients trigger hormone release (e.g., calcium levels regulate parathyroid hormone).
Hormonal stimuli: hormones from one gland stimulate or inhibit the release of hormones from another gland (e.g., hypothalamic hormones regulate pituitary hormones).
Neural stimuli: nerve fibers stimulate hormone release (e.g., sympathetic nervous system stimulates adrenal medulla to release epinephrine).

Hypothalamus Control of the Pituitary Gland

The hypothalamus releases releasing and inhibiting hormones into the hypophyseal portal system, which directly influences the anterior pituitary to release or inhibit its hormones.
The hypothalamus produces hormones (oxytocin and ADH) that are transported down nerve fibers to the posterior pituitary, from where they are released into the bloodstream.

Releasing and Inhibiting Hormones

Releasing hormones stimulate the anterior pituitary to secrete hormones (e.g., TRH, CRH).
Inhibiting hormones prevent the anterior pituitary from secreting hormones (e.g., somatostatin, dopamine).

Hypophyseal Portal System

A network of blood vessels that directly connects the hypothalamus with the anterior pituitary, allowing hypothalamic hormones to quickly reach the anterior pituitary.

Anterior Pituitary Gland

The anterior pituitary gland (adenohypophysis) is true glandular tissue.

Posterior Pituitary Gland

Stores and releases oxytocin and antidiuretic hormone (ADH) that are produced by the hypothalamus.

Six Hormones of the Anterior Pituitary

Growth Hormone (GH): targets liver, muscle, bone, and other tissues; stimulates growth and metabolic functions.
Thyroid-Stimulating Hormone (TSH): targets thyroid gland; stimulates the secretion of thyroid hormones.
Adrenocorticotropic Hormone (ACTH): targets adrenal cortex; stimulates the release of cortisol.
Follicle-Stimulating Hormone (FSH): targets ovaries and testes; stimulates gamete production.
Luteinizing Hormone (LH): targets ovaries and testes; stimulates the formation of corpus luteum and testosterone production.
Prolactin (PRL): targets breast tissue; stimulates milk production.

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Description

Learn about the chemical messengers of the endocrine system, the differences between exocrine and endocrine glands, and the different chemical groups of hormones.