The Endocrine The Endocrine SystemSystem

Chapter 9Chapter 9

Intro to the Endocrine Intro to the Endocrine SystemSystem

• Nervous vsNervous vs Endocrine SystemsEndocrine Systems

– Endrocrine’s role in the body Endrocrine’s role in the body is to communicate and is to communicate and coordinate organs and tissuescoordinate organs and tissues

Nervous vs. Nervous vs. EndocrineEndocrine

Uses: Electrical chargeUses: Electrical charge Uses: Uses: hormones that hormones that travel in the bloodtravel in the blood

Controls: muscles & Controls: muscles & Controls: tissues Controls: tissues some glandssome glands (regulatory & (regulatory &

homeostasis)homeostasis)

Feedback: quick! Feedback: seconds Feedback: quick! Feedback: seconds

monthsmonths

The Makeup of Endocrine The Makeup of Endocrine GlandsGlands

The “Ductless” glandsThe “Ductless” glands

**Make hormones that are picked **Make hormones that are picked up and up and

carried in the bloodcarried in the blood

**made from cuboidal cells**made from cuboidal cells

Endocrine glandsEndocrine glands

(Use picture to label glands)(Use picture to label glands)

Hormones: The Chemical Hormones: The Chemical Messenger of the BodyMessenger of the Body

Hormones & their Target cellsHormones & their Target cells

**hormones travel in blood and lymph**hormones travel in blood and lymph

**hormones **hormones bindbind to to target cellstarget cells that that have receptors for that specific have receptors for that specific hormonehormone

**How well a hormone finds and **How well a hormone finds and binds with its receptor depends on binds with its receptor depends on three factorsthree factors

1.1. Level of hormones in the bloodLevel of hormones in the blood

**level too low = cells don’t make **level too low = cells don’t make needed changesneeded changes

**level too high = cells work too **level too high = cells work too hard and cause too much hard and cause too much changechange

2.2. Number of receptors in/on the Number of receptors in/on the target cellstarget cells

**more receptors improves **more receptors improves chances of hormone binding to itchances of hormone binding to it

3. 3. Strength of the bond between Strength of the bond between receptor and hormonereceptor and hormone

**shape of hormone must “fit” **shape of hormone must “fit” the shape of the receptor in the shape of the receptor in order to initiate the “message” order to initiate the “message” of the hormoneof the hormone

--if a poor “fit” occurs, the --if a poor “fit” occurs, the action on the cell may not occuraction on the cell may not occur

Hormones TypesHormones Types

• Type of hormone determines how Type of hormone determines how the message can be delivered to the the message can be delivered to the cellcell

1.1. Amino Acid Based hormonesAmino Acid Based hormones

**proteins = too large to diffuse right **proteins = too large to diffuse right through cell membranethrough cell membrane

2.2. Steroid Hormones Steroid Hormones

** made of cholesterol = move easily ** made of cholesterol = move easily through cell membranethrough cell membrane

Four Actions that Four Actions that Hormones Can Cause on Hormones Can Cause on

Target CellTarget Cell1.1. Change the permeability of the cell Change the permeability of the cell

membranemembrane

2.2. Increase or decrease the synthesis of Increase or decrease the synthesis of protein for repair/healing or the protein for repair/healing or the making of regulatory molecules making of regulatory molecules (hormones)(hormones)

3.3. Increase or decrease enzyme activityIncrease or decrease enzyme activity

4.4. Increase or decrease secretory activityIncrease or decrease secretory activity

Control of Hormone Control of Hormone ReleaseRelease

Three mechanisms for hormone releaseThree mechanisms for hormone release1.1. Hormonal Stimulation (hormones Hormonal Stimulation (hormones

stimulate the release of other stimulate the release of other hormones)hormones)

2.2. Humoral Stimulation: hormones are Humoral Stimulation: hormones are releases/inhibited in response to a releases/inhibited in response to a specific level of hormone, electrolyte, specific level of hormone, electrolyte, water and/or sugar level in the bloodwater and/or sugar level in the blood

3.3. Neural Stimulation: The release of a Neural Stimulation: The release of a hormone when a motor neuron hormone when a motor neuron stimulates the gland. (fastest but least stimulates the gland. (fastest but least used)used)