Endocrine I

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Questions and Answers

Which of the following best describes an endocrine gland?

A gland that has no significant role in metabolism

A gland that connects with the nervous system directly

A gland that secretes substances outside the body

A cluster of cells that produces hormones within the body (correct)

Neuroendocrine hormones are synthesized by muscular tissue.

False

What is the primary function of hormones within the endocrine system?

Regulate bodily functions and maintain homeostasis.

Hormones are subjected to tight regulation by feedback from target __________.

organs Signup and view all the answers

Match the following types of hormones with their characteristics:

Steroid hormones = Lipid-soluble, derived from cholesterol Peptide hormones = Chains of amino acids, water-soluble Neuroendocrine hormones = Synthesized by nervous tissue, secreted into the blood Autocrine signals = Act on the same cell that secretes them Signup and view all the answers

What is the primary role of negative feedback in hormone regulation?

To maintain hormone levels within a specific range Signup and view all the answers

Peptide hormones are formed directly from cholesterol.

False Signup and view all the answers

Name one major hormone produced by the pituitary gland.

Luteinizing hormone (LH) Signup and view all the answers

The ________ is the gland responsible for synthesizing estrogen.

ovary Signup and view all the answers

Which of the following hormones is primarily involved in the regulation of blood pressure?

Aldosterone Signup and view all the answers

Which modification involves the attachment of carbohydrate chains to proteins?

Glycosylation Signup and view all the answers

Arachidonic acid is a derivative of amino acids.

False Signup and view all the answers

What hormone is secreted by the pineal gland during dark phases?

melatonin Signup and view all the answers

The pancreas secretes _________ to lower blood glucose levels.

insulin Signup and view all the answers

Which of the following hormones promotes the production of red blood cells in the bone marrow?

Erythropoietin Signup and view all the answers

Match the gland with its primary hormone:

Pancreas = Insulin Adipose Tissue = Leptin Pineal Gland = Melatonin Kidneys = Erythropoietin Signup and view all the answers

Eicosanoids primarily exert endocrine effects throughout the body.

False Signup and view all the answers

Name a hormone released by the gastrointestinal tract that stimulates the pancreas.

secretin Signup and view all the answers

Dopamine, norepinephrine, and epinephrine are all derived from ________.

tyrosine Signup and view all the answers

What effect does cholecystokinin have?

Stimulates the gall bladder Signup and view all the answers

Study Notes

Endocrine System

Endocrine glands produce and release hormones within the body
Hormones act at a distance from the release site
Paracrine hormones act on nearby cells
Autocrine hormones act on the same cell that secreted them
Neuroendocrine hormones are synthesized by nervous tissue and carried in the blood

Hormones

Regulatory chemicals synthesized by endocrine glands and secreted into the bloodstream
Act on target cells to alter metabolism
Involved in maintaining homeostasis
Subject to tight regulation by feedback mechanisms

Negative Feedback Control

Regulates hormone release by acting as a loop
Example: Estrogen secretion from the ovary leads to LH release from the pituitary gland
LH causes ovulation and removal of follicle, leading to decrease in estrogen and reduction in LH
Example: LH released from the pituitary gland stimulates the ovary to produce estrogen

Hormone Classification

Steroid hormones are synthesized from cholesterol by multiple enzymes
Steroid hormones are lipid-soluble and can diffuse through cell membranes
Peptide, protein, and glycoprotein hormones are chains of amino acids
The sequence of amino acids determines the hormone's structure and function
Synthesized via transcription and translation
Modified after translation by adding carbohydrates (glycosylation) or phosphate groups (phosphorylation)
Packaged in the endoplasmic reticulum and Golgi apparatus
Released by exocytosis
Amino acid-derivative hormones are derived from tyrosine or tryptophan
Examples include thyroid hormones (T3 and T4) and catecholamines (dopamine, norepinephrine, epinephrine)
Fatty acid-derivative hormones (eicosanoids) are produced from cell membrane phospholipids, particularly arachidonic acid
Eicosanoids have mainly autocrine and paracrine effects

Major Endocrine Glands

Pineal Gland: located on the roof of the third ventricle, secretes melatonin which is influenced by the hypothalamus and plays a role in sleep patterns and season recognition
Gastric Tract: stomach wall releases gastrin to stimulate acid secretion; small intestine secretes secretin to stimulate the pancreas, cholecystokinin to stimulate the pancreas and gallbladder, and gastric inhibitory peptide to inhibit stomach activity.
Kidneys: secrete renin which increases aldosterone secretion by the adrenal cortex; produce erythropoietin to increase production of red blood cells in bone marrow.
Adipose Tissue: releases leptin and other adipokins to communicate energy storage status to the hypothalamus, regulating appetite.

Table: Endocrine Gland, Hormone, and Effects

Pancreas: Insulin promotes glucose uptake by many organs; glucagon stimulates glycogen formation in the liver
Liver: Somatomedins (IGFs) stimulate growth in multiple organ systems