Exam 3: The Endocrine System

Question 1

What does the endocrine system do?

Answer 1

• Regulates and controls many metabolic processes
• Helps maintain body homeostasis
  
  • e.g., maintaining blood glucose levels during erratic food intake
• Serves as one of the two major control systems of the body
  
  • with the nervous system

Question 2

What is the endocrine system composed of?

Answer 2

Endocrine glands located throughout the body

Question 3

What do endocrine glands do?

Answer 3

• synthesize and secrete hormones
• released into the blood and transported through the body
• Very active in small amouts

Question 4

What is a Hormone?

Answer 4

Mediator molecule released from one part of the body but regulates the activity of cells in other parts of the body

Question 5

What is the difference between exocrine and endocrine?

Answer 5

Exocine secretes OUT of the body, endocrine secretes IN the body.

Question 6

What happens when the Target cell binds it’s hormone?

Answer 6

Initiates or inhibits selective activities.

Question 7

What are target cells?

Answer 7

Cells with a specific receptor for a hormone

Question 8

What are the features of the endocrine system that are different than the nervous system?

Answer 8

–Hormones transported within blood to target cells

–Causes metabolic changes in target cells

–Target any cells with receptors

–Exhibit longer reaction times

–More widespread effects throughout the body

–Longer-lasting effects (minutes to days and weeks)

Question 9

What are the features of the endocrine system that are in common with the nervous system?

Answer 9

–Release chemical substances, ligands

–Bind to cellular receptor on particular target cells

–Initiates cellular change in target cells

Question 10

What are the general functions of the Endocrine System?

Answer 10

1. ) Maintaining homeostasis of blood composition and volume
2. )Controlling reprodictive activites
3. ) Regulating development, growth, and metabolism
4. ) Controlling digestive processes

Question 11

–Maintaining homeostasis of blood composition and volume

Answer 11

• regulate amount of substances dissolved in blood
• e.g., glucose, cations, anions
• regulate blood volume, cellular concentration, and platelet number

Question 12

–Controlling reproductive activities

Answer 12

• affect development and function
• affect expression of sexual behaviors

Question 13

–Regulating development, growth, and metabolism

Answer 13

• regulatory roles in embryonic cell division and differentiation
• involved in catabolism and anabolism of proteins, carbohydrates, and lipids

Question 14

–Controlling digestive processes

Answer 14

• influence secretory processes
• influence movement through digestive tract

Question 15

What is an endocrine organ?

Answer 15

single organ that is entirely endocrine in function

Question 16

What are some of the endocrine organs?

Answer 16

• pituitary gland
• pineal gland
• thyroid gland
• parathyroid glands
• adrenal glands

Question 17

Endocrine Cells Within Other Organs

Answer 17

–Housed in tissue clusters in specific organs

–Secrete one or more hormones

• organ with additional primary function

Question 18

What are some of the endocrine cells within other organs?

Answer 18

• hypothalamus, skin, thymus
• heart, liver, stomach
• pancreas, small intestine
• kidneys, gonads

Question 19

Hormones affect only specific target cells that have the necessay for the hormone to bind

Answer 19

Receptor

Question 20

Receptors constantly synthesized and degraded in order to modulate effect of hormone

Answer 20

Down-regulation

Up-regulation

Question 21

What are the hormone types?

Answer 21

Circulating

Local Hormones

Question 22

Circulating Hormones

Answer 22

circulate in blood throughout body – affect target tissues

Question 23

Local Hormones

Answer 23

–act locally

• Paracrine
• Autocrine

Question 24

Paracine

Answer 24

Act on neighboring cells

Question 25

Autocrine

Answer 25

Act on the same cell that secreted them

Question 26

What are the chemical classes of hormones?

Answer 26

Lipid-soluble Water-soluble

Question 27

Lipid- Soluble

Answer 27

•Do not readily dissolve in blood and therefore must be attached to a carrier protein while being transported in the blood –Steroids –Thyroid hormones T3 and T4 –Nitric oxide (NO)

Question 28

Water-Soluble

Answer 28

•Readily dissolve in blood and therefore circulate in “free” form without a carrier protein –Amine –Peptide/ protein –Eicosanoids

Question 29

Answer 29

Circulating Hormones

Question 30

Answer 30

Local Hormones

Question 31

Answer 31

Lipid Soluble Hormone

Question 32

How does the lipid soluble hormone get into the cell?

Answer 32

1. The unbound lipid-soluble hormone diffuses through the plasma membrane and binds with an intracellular receptor, (either within the cytosol or the nucleus) to form a hormone-receptor complex. 2. The hormone-receptor complex then binds with a specific DNA sequence called a hormone-response element. 3. This binding stimulates mRNA synthesis. 4. mRNA exits the nucleus and is translated by a ribosome in the cytosol. A new protein is synthesized.

Question 33

Endocrine Reflexes

Answer 33

* Regulated secretion of hormone controlled through reflex * Usually negative feedback system * There are a few examples of positive feedback systems * Preprogrammed response to certain stimuli

Question 34

Endocrine Reflexes are initiated by which types of stimulation?

Answer 34

hormonal, humoral, or nervous

Question 35

Hormonal Stimulation

Answer 35

* e.g., thyroid stimulating hormone released from anterior pituitary * stimulates thyroid gland to secrete thyroid hormone

Question 36

Humeral Stimulation

Answer 36

* respond to changing level of nutrients or ions * act on target cells to offset further loss or eliminate excess

Question 37

Nervous Stimulation

Answer 37

e.g., release of epinephrine and norepinephrine by adrenal medulla in response to sympathetic nervous stimulation

Question 38

Types of receptors on target cells

Answer 38

* Membrane Bound Receptors * Intracellular Receptors

Question 39

Membrane Bound Receptors

Answer 39

– In plasma membrane of target cell – Water soluble hormones are the ligand – Binding activates intracellular signaling cascades

Question 40

Intracellular Receptors

Answer 40

\_Inside of the cell somewhere (cytosol or nucleus) – Lipid soluble hormones are the ligand – Binding alters gene expression – increase in mRNA synthesis (transcription)

Question 41

What are the three different results of water soluble hormones binding to membrane-bound receptors?

Answer 41

1. Alteration of membrane permeability 2. Activation of G proteins 3. Receptors linked to intracellular enzymes through intracellular mediators

Question 42

Answer 42

Alternation of Membrane Permeability

Question 43

Activation of G-Proteins

Answer 43

– Binding of some water-soluble hormones causes activation of G- proteins – Initiate series of biochemical events, signal transduction pathway * initiated by the hormone, the first messenger – Docking results in formation of second molecule * termed second messenger * modifies some cellular activity

Question 44

GTP=

Answer 44

ON

Question 45

GDP=

Answer 45

OFF