ANAPHY: U8.1 Endocrine System (Functional Organization of the Endocrine System)

Hormones

Chemical messengers secreted in small amounts by the endocrine glands into the interstitial fluid.

Target Tissues/Effectors

The specific sites hormones circulate through the bloodstream to

Endo ("within") and krino ("to secrete")

Greek root words of endocrine

Endocrinology

Study of the endocrine system

Hypothalamus, Pituitary Gland, Pineal gland, Thyroid Gland, Thymus, Parathyroid Glands, Adrenal Glands, Ovaries (female), Pancreas (Islets), Testes (male)

10 Major Endocrine Glands and Tissues

SHARNG

Acronym for 6 Similarities Between Endocrine & Nervous System

1. Use Structures in the brain

2. Hypothalamus is a critical area of the brain

3. ADH and oxytocin produced by hypothalamic neurons

4. Regulate critical body processes

5. Some Neurons secrete hormones

6. Both neurotransmitters and hormones can affect their targets through receptors linked to G proteins

6 Similarities Between Endocrine & Nervous System

DMS

Acronym for 3 Differences Between Endocrine & Nervous System

Duration of Response, Mode of Transport, Speed of Response

3 Differences Between Endocrine & Nervous System

Duration of Response

Difference between endocrine and nervous system since nervous system activated targets quickly and only for as long as action potentials are sent to the target; endocrine system tends to have longer lasting effects and hormones remain in the bloodstream from days to weeks, activating target tissue for as long as they remain in the bloodstream

quickly; action potentials

Nervous system activates targets ___ compared to the endocrine system but only for as long as ___ ___ are sent to the target

Mode of Transport

Difference between endocrine and nervous system since the endocrine system releases hormones, while the nervous system releases neurotransmitters

milliseconds

Neurotransmitters are transported in ____ (time)

seconds

Hormones are transported in ____ (time)

Speed of Response

Difference between endocrine and nervous system since the nervous system responds faster with neurotransmitters being transported in milliseconds but hormones in seconds

Chemical messengers

Allow cells to communicate with each other to regulate body activities

specific collection of cells; gland

Most chemical messengers are produced by a ___ ___ __ ___ or by a ___.

Autocrine, Paracrine, Neurotransmitter, Endocrine

4 Classes of Chemical Messengers

Autocrine

Class of chemical messenger in which chemical messengers are secreted by cells in a local area; influencing the activity of the same cell from which it was secreted

Eicosanoids (prostaglandins, thromboxanes, prostacyclins, leukotrienes)

Examples of Autocrine chemical messengers

Paracrine

Class of chemical messengers in which chemical messengers are produced by a wide variety of tissues and secreted into extracellular fluid, having a localized effect on nearby tissues

Somatostatin, histamine, eicosanoids

Examples of Paracrine chemical messengers

Neurotransmitter

Class of chemical messengers in which chemical messengers are produced by neurons, being secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells

Acetylcholine, epinephrine

Examples of Neurotransmitter chemical messengers

Endocrine

Class of chemical messengers in which chemical messengers are secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function

Thyroid hormones, growth hormone, insulin, epinephrine, estrogen, progesterone, testosterone

Examples of Endocrine chemical messengers

CDS

Acronym for 3 General Characteristics of Hormones

Communication, Distribution, Stability

3 General Characteristics of Hormones

Communication

General characteristic of hormone in which hormones must be able to interact with their target tissue in a specific manner in order to activate a coordinated set of events

Distribution

General characteristic of hormone in which hormones are transported by the blood to many locations and therefore have the potential to activate any cell in the body, including those far away from where they were produced

hydrolytic enzymes; aqueous solution

The blood contains many ___ ___, which break down substances, and is an ___ ___

Quickly digested by hydrolytic enzymes in the blood & easily filtered from blood in kidneys

2 challenges of small, water-soluble hormones

Lipid-soluble Hormones

Type of hormones that have low solubility in blood plasma

Binding Proteins

Blood proteins that are bound to by hormones that require a chaperone

Bound Hormones

Name for hormones that attach to a binding protein

Becomes more water-soluble

Effect of lipid-soluble hormones binding to protein

Transthyretin

Specific binding protein of thyroid hormones

Testosterone-binding globulin

Specific binding protein of testosterone

Progesterone-binding globulin

Specific binding protein of progesterone

Stability

General characteristic of hormone in which hormones concentrations are consistent in the blood stream but some are more than others

Larger, more complex hormones are more stable than smaller, simpler hormones

Stability of hormones

Half-life

A hormone’s life span can be expressed as its ___, which is the amount of time it takes for 50% of the circulating hormone to be removed from the circulation and excreted

Lipid-soluble & water-soluble hormones

2 Chemical Categories of Hormones

Amino acid derivatives, peptides, or proteins, including glycoproteins

Most hormones are categorized into these 3 categories

Steroid hormones from cholesterol, and thyroid hormones from tyrosine

2 exceptions of categorization of hormones

Nonpolar

Polar or nonpolar? Lipid soluble hormones

Steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids

Examples of Lipid soluble hormones

Small size; low solubility

Size and solubility of lipid-soluble hormones

Binding proteins

Due to the size and solubility of lipid-soluble hormones, they travel in the bloodstream bound to ___ ___

Conjugation

Process used to terminate a lipid-soluble hormone response and remove the hormones from circulation

Polar

Polar or nonpolar? Water soluble hormones

Protein hormones, peptide hormones, and most amino acid derivative hormones

Examples of Water soluble hormones

Free hormones

Since water-soluble hormones can dissolve in the plasma of the blood, many circulate as ___ ___, meaning that most of them dissolve directly into the plasma and are delivered to their target tissue without binding to a binding protein

False

True or false: water-soluble hormones need to bind to a binding protein when delivered to target tissue

ACE

Acronym for 3 Patterns of Hormone Secretion

Acute, Chronic, Episodic

3 Patterns of Hormone Secretion

Acute Hormone Secretion

Pattern of hormone secretion when the hormone's concentration changes suddenly and irregularly, and its circulating levels differ with each stimulus

Chronic Hormone Secretion

Pattern of hormone secretion in which there is relatively constant blood levels of hormone over long periods of time.

Thyroid hormones

Example of a hormone that undergoes chronic hormone secretion

Episodic hormone secretion

Pattern of hormone secretion when hormones are secreted at fairly predictable intervals and concentrations.

Reproductive Steroid Hormones

Example of a hormone that undergoes episodic hormone secretion that fluctuate over a month in cyclic fashion during the human reproductive years

Control by Humoral Stimuli, Control by Neural Stimuli, Control by Hormonal Stimuli

3 Types of Control of Hormone Secretion

Humoral Stimuli

Type of control of hormone secretion in which metabolites and other molecules in the bloodstream that can directly stimulate the release of some hormones

Neural Stimuli

Type of control of hormone secretion in which following action potentials, neurons release a neurotransmitter into a synapse with hormone-producing cells and the neurotransmitter stimulates the cells to secrete their hormone.

Releasing Hormones

Name for some neuropeptides stimulate hormone secretion from other endocrine cells, usually hormones from the hypothalamus

Hormonal Stimuli

Type of control of hormone secretion in which hormones stimulate the secretion of other hormones

Tropic Hormones

Name of hormones that usually regulate using hormonal stimuli; hormones from the anterior pituitary gland

Inhibition of Hormone Release by Humoral Stimuli, Inhibition of Hormone Release by Neural Stimuli, Inhibition of Hormone Release by Hormonal Stimuli

3 Types of Inhibition of Hormone Release

Inhibiting Hormones

Name for the hormones from the hypothalamus that prevent the secretion of tropic hormones from the pituitary gland

Negative Feedback Mechanism

Mechanism most hormones are regulated by; hormone's secretion is inhibited by the hormone itself once blood levels have reached a certain point and there is adequate hormone to activate the target cell

Positive Feedback Mechanism

Mechanism in which the release of the hormone promotes the further synthesis and secretion of that hormone

Tropic Hormone

Example of a hormone the undergoes a positive feedback mechanism

Receptors

Target cell proteins that hormones bind to to exert their actions

Receptor Site

The specific portion of each receptor molecule where a hormone binds

Agonist

A drug that binds to a hormone receptor and activates it

Antagonist

A drug that binds to a hormone receptor and inhibits its action

Nuclear Receptors

Type of receptors lipid soluble hormones bind to

Membrane-Bound Receptors

Type of receptors water-soluble hormones bind to