Endocrinology: Hormones and Target Cells Flashcards
• the study of hormones, the endocrine system, and their physiological role in the body
Endocrinology
Endocrine Gland
• secretes its products into the _____ and _____
interstitial fluid and the blood
• a chemical messenger released from living cells that travels through the blood to target cells and induces a biological effect or response
Hormone
• cells with receptors to specific hormones
Target Cells
• only cells with specific_____ will react with a specific hormone
receptor
Hormone Receptors
• In or on the surface of the cell membrane: _________
• In the cell cytoplasm:________
• In the cell nucleus:_______
peptide and catecholamine hormones
steroid hormones
thyroid hormones
• may consist of a single cell or a group of cells that secrete substances into ducts (tubes), onto a surface, or into the blood in the absence of ducts
Glands
Glands
two major types
• endocrine glands
• exocrine glands
Exocrine Glands
• glands with_____
ducts
• products pass out of the cell and away from the gland by means of ducts into a luminal area
Exocrine glands
Exocrine Glands
example:
•______, as an exocrine gland, secretes amylase, lipase, and trypsinogen
pancreas
Examples of exocrine glands
Sweat
Salivary
Pancreatic
• products are released from the cell, passed directly into the circulation, and are carried by the blood to body tissues and eventually target cells
Endocrine Glands
Manners of Secretion
• Autocrine
• Paracrine
• Juxtacrine
• Intracrine
• Ectocrine
• Endocrine
• Example: insulin-like growth factor-| (IGF-I)
Autocrine
• interaction between secreted chemical messenger with a receptor on the same type of cell that synthesized it
Autocrine
• Example: somatostatin secretion inhibits insulin secretion
Paracrine
• interaction of a secreted chemical messenger with receptors on adjacent cells on the same tissue
Paracrine
• Example: cell adhesion proteins (laminin)
Juxtacrine
• expressed on surface of effector cell and interacts with target cell via direct cell-cell contact
Juxtacrine
• secretes own hormone that acts inside the same cell, regulating intracellular events
Intracrine
• one organism releases a substance (pheromone) that causes a response in another organism
Ectocrine
• a chemical messenger produced by a ductless gland or tissue and carried in the blood to a target organ where it effects a change in cellular activity
Endocrine
Principal Functions of the Endocrine System (3)
• maintenance of the internal environment in the body (homeostasis)
• integration and regulation of growth and development
• control, maintenance, and instigation of sexual reproduction
Types of Hormones
• Peptide
• Steroids
• Amines
Peptide Hormones
• May contain_______ amino acids
(TRH: ___; GH: ___)
3 to 200
3; 200
Peptide hormones
• Secretion:_______
exocytosis
• Water soluble; no need for transport proteins
Peptide hormone
Peptide hormone
• Synthesized in_____; stored in_____
ribosomes
vesicles
• fast acting, short half-life
Peptide hormone
Steroid Hormones
• Derived from_______ which are rapidly mobilized
• found in____
• through_______
cholesterol
Plasma
De novo synthesis
• Hydrophobic/lipophilic; require specific transport proteins as carriers
Steroid hormones
Steroid hormones
• Secretion:
diffusion across cell membrane
• slow-acting; longer half-life
Steroid hormones
• derivatives of single amino acid residues, either from tyrosine or tryptophan
Amine Hormones
• can behave either like peptides or steroids
Amine hormone
•________ (behave like peptides; cell surface receptors)
• ________ (behave like steroids; nuclear receptors)
Catecholamines
Thyroid hormones
Amine Hormones
• behave like protein hormones because they circulate unbound to protein, have a short half-life, and have a similar mechanism of action
catecholamines
Amine Hormones
• have a long half-life, circulate bound to a carrier protein, and have a mechanism of action similar to steroids
thyroid hormones
Key Concepts to Remember
• All hormones interact with ______by first binding to_____ located either on the plasma membrane or as a cytosolic protein
• The receptor for hormones must be linked to a component that is able to respond to the binding of hormone with its receptor
target cells; specific receptors
Control of Hormone Release
Substrate control
Nervous control
Tropic hormones
Control of Hormone Release
• Substrate control
• Example:
glucose and insulin
• Nervous control
• Example:
adrenal medulla hormones
• Tropic hormones
• Example:
release of hormones by anterior pituitary to stimulate other glands (e.g., ACTH to adrenal cortex)
: Direct response to substance levels in the blood (e.g., glucose controlling insulin).
: Hormone release driven by signals from the nervous system (e.g., adrenaline release in response to stress).
: Hormones that signal other glands to release their hormones (e.g., ACTH from the pituitary stimulating the adrenal cortex).
• Substrate Control
• Nervous Control
• Tropic Hormones
Feedback Mechanisms
• the final hormone produced regulates its own secretion by inhibiting the secretion of one or more of the precursor hormones
Negative Feedback (Homeostatic)
Feedback Mechanisms
• the final hormone produced actually enhances or induces the initial hormone and causes its own production to be increased
Positive Feedback (Non-Homeostatic)
Positive feedback
• example:
estrogen and luteinizing hormone
Disorders of the Endocrine System
The levels of disorders
Primary disorder
Secondary disorder
Tertiary disorder
• Explanation: In a ____ disorder, the gland responsible for producing the hormone is malfunctioning, either overproducing (hyper-) or underproducing (hypo-) the hormone.
Primary Disorder:
• Example: when the thyroid gland fails to produce enough thyroid hormones (T3 and T4), leading to symptoms like fatigue, weight gain, and cold intolerance.
Primary Disorder:
• Definition: The problem originates in the gland that produces the hormone itself.
Primary Disorder:
• Explanation: In _____ disorders, the issue lies in the pituitary gland or any other gland that controls the primary gland.
The primary gland doesn’t receive the correct signals to produce hormones.
Secondary Disorder:
• Example: ______ when the pituitary gland fails to produce enough thyroid-stimulating hormone (TSH), which signals the thyroid to produce its hormones. The thyroid itself might be healthy, but it isn’t stimulated properly.
Secondary Disorder:
• Definition: The problem is with the gland that stimulates the primary gland to release hormones.
Secondary Disorder:
• Explanation: _____ disorders are at the top of the chain and affect the hypothalamus, which regulates the pituitary gland. This leads to downstream effects on the primary gland.
Tertiary Disorder:
• Example: when the hypothalamus doesn’t release enough thyrotropin-releasing hormone (TRH), which signals the pituitary gland to produce TSH. This leads to low TSH and, in turn, low thyroid hormone production.
Tertiary Disorder:
• Definition: The problem originates even higher up in the regulatory chain, usually in the hypothalamus.
Tertiary Disorder:
