Chapter 17 - Endocrine System (General Functions and Components)

Question 1

Where does the endocrine system glands secrete secretions into?

Answer 1

The bloodstream because it lacks ducts

Question 2

What other system does the endocrine system act with to coordinate and integrate activity of body cells?

Answer 2

Nervous system

Question 3

Influences metabolic activities via _______ transported in blood

Answer 3

Hormones

Question 4

The endocrine system controls and integrates…

Answer 4

1.) Reproduction
2.) Growth and development (regulates embryonic cell division and differentiation)
3.) Maintenance of electrolyte, water and nutrient balance of blood (regulates metabolism and amount of specific substances dissolved within blood)
4.) Regulation of cellular metabolism and energy balance
5.) Mobilization of body defenses

Question 5

Endocrine glands contain _______ tissue that makes and releases hormones within a _________ tissue hormone

Answer 5

Epithelial tissue, connective tissue

Question 6

What are the endocrine organs with solely endocrine function?
(HINT: Patty Takes Pies And Pancakes)

Answer 6

1.) Pituitary
2.) Thyroid
3.) Parathyroid
4.) Adrenal
5.) Pineal

Question 7

What is a neuroendocrine organ and which organ of the body is a neuroendocrine organ?

Answer 7

Neuroendocrine: An organ that combines elements of both nervous and endocrine system and has the ability to produce/release hormones in response to neural signals
- Hypothalamus

Question 8

Which organs have exocrine and endocrine functions?

Answer 8

1.) Pancreas
2.) Gonads
3.) Placenta

Question 9

What are 2 differences between exocrine and endocrine system?

Answer 9

1.) Hormones –> Exocrine glands secrete nonhormonal substances (ex: sweat, saliva) while endocrine glands produce hormones
2.) Ducts –> Exocrine glands have ducts to carry secretion to the membrane surface while endocrine glands lack ducts

Question 10

What are the steps of the general endocrine system?

Answer 10

1.) Hormones are released from endocrine gland cells into the interstitial fluid and enter blood within capillaries
2.) Hormone molecules are transported within blood by cardiovascular system
3.) Hormones randomly leave the blood from the capillaries and enter interstitial fluid (allow access to many body cells)
4.) Hormone binds to target cell receptor

Question 11

Define and describe the two main classes of hormones
1.) Amino acid-based hormones
2.) Steroids

Answer 11

1.) Amino acid-based hormones
- Water soluble
- Include amino acid derivatives, peptides, and proteins
2.) Steroids
- Synthesized from cholesterol
- Lipid soluble
- Gonadal (ex: estrogen) and adrenocortical (ex: cortisol) hormones

Question 12

Describe circulating hormones

Answer 12

• Transported within the blood
• Synthesized within endocrine cells from either cholesterol or amino acids
  -Include steroids, biogenic amines, and proteins

Question 13

Describe steroids

Answer 13

• Lipid soluble
• From cholesterol
• Includes hormones produced within gonads and adrenal cortex
• Circulating hormones

Question 14

Describe biogenic amines (monoamine)

Answer 14

• Water soluble (except thyroid hormone, which is lipid soluble
• Derived from amino acid that is modified (modification includes removal of carboxyl functional group)
• Include catecholamines, thyroid hormone, and melatonin
• Circulating hormones

Question 15

Describe proteins

Answer 15

• Water soluble
• Consists of amino acid chains
• Most hormones are proteins
• Includes small peptides, large peptides, and glycoproteins
• Circulating hormones

Question 16

Describe local hormones. What type of stimulation do they have?

Answer 16

• Short-lived molecules that influence cells within the local tissue from which they were produced
• Include autocrine and paracrine stimulation

Question 17

What is the primary type of local hormone and describe it

Answer 17

• Eicosanoids are the primary type of local hormones
• Come from 20-carbon fatty acid (arachidonic acid) from phospholipid molecule of a cells plasma membrane
• Includes prostaglandins, thromboxanes, and leukotrienes
• Prostaglandins are the most diverse category

Question 18

Define hormones, autocrines, and paracrines

Answer 18

Hormones: Long-distance chemical signals that travel in blood or nymph
THE FOLLOWING ARE LOCAL MESSENGERS AND NOT PART OF ENDOCRINE SYSTEM
Autocrines: Chemicals that exert effects on same cell that secrete them
Paracrines: Locally acting chemicals that affect cells other than those that secrete them

Question 19

What are the two hormone soluble types and what are their general mechanisms?

Answer 19

1.) Water soluble hormones (include all amino-based hormones except thyroid hormone)
- Acts on plasma membrane receptors
- Act via G protein second messengers!
- Cannot enter cell
2.) Lipid- soluble hormones (include steroid and thyroid hormones)
- Act on intracellular receptors that directly activate gemes
- Can enter the cell
- Don’t dissolve in blood and use carrier protein (0.1-10% of hormones transported in blood are unbound)

Question 20

What is the general mechanism of water-soluble hormones?

Answer 20

1.) Hormone binds to receptor on membrane
2.) G protein binds to receptor
3.) GDP on G-protein keeps it inactive until it is replaced by GTP
4.) The activated G-protein with GTP attaches to adenylate cyclase enzyme to turn it on
5.) Activated adenylate cyclase takes ATP and converts it to C.A.M.P
6.) C.A.M.P turns on inactive protein kinase
7.) The now active protein kinase will trigger responses in the cell (ex: turn on other enzymes, command cell to secrete something)

Question 21

What is the water-soluble mechanism for PIP2 calcium signaling?

Answer 21

1.) water soluble hormone attaches to receptor
2.) The G-protein attaches to receptor and GDP is changed to GTP and that structure will now bing to phospholipase C
3.) Phospholipase C breaks down PIP2 (phospholipid) into IP3 and DAG
4.) IP3 binds to channel on endoplasmic reticulum
5.) Ca2+ is released out of ER (Ca2+ is the 2nd messenger)
6.) Ca2+ binds to protein kinase C and DAG to activate protein kinase C and Ca2+ can also open different ion channels while protein kinase C can activate/deactivate some proteins in the cell

Question 22

Describe the process of intracellular receptors and direct gene activation. What hormones does it include?

Answer 22

• Includes steroid hormones and thyroid hormone
  1.) Unbound hormone diffuses through membrane and binds with intracellular receptor, either within the cytosol or the nucleus, for form a hormone-receptor complex (HRC)
  2.) The HRC binds with a specific DNA sequence called a hormone-response element (HRE)
  3.) Binding of the HRC to HRE stimulates mRNA synthesis (transcription)
  4.) mRNA exits the nucleus and is translated by a ribosome in the cytosol –> a new protein is synthesized

Question 23

What is up-regulation?

Answer 23

Target cells form more receptors in response to low hormone levels

Question 24

What is down-regulation?

Answer 24

Target cells lose receptors in response to high hormone levels

Question 25

What are the 3 types of endocrine stimulation (ways to give a command to gland to secrete hormone)?

Answer 25

1.) Hormonal stimulation - A gland cell releases its hormone when some other hormone binds to it (Thyroid-stimulating hormone and thyroid hormone)
2.) Humoral stimulation - A gland cell releases its hormone when there is a certain change in levels of nutrient or ion in the blood (increased blood glucose and insulin)
3.) Neural stimulation - A gland cell releases its hormone when a neuron stimulates (ex: adrenal gland)

Question 26

What are the 3 types of interactions between hormones at target cells?

Answer 26

1.) Permissiveness - One hormone cannot exert its effects without another hormone being present (ex: oxytocin’s milk ejection effect requires prolactin’s milk-generating effect)
2.) Synergism - More than one hormone produces same effects on target cell –> amplification (ex: estrogen and progesterone effects on a target cell)
3.) Antagonism - One or more hormones oppose(s) action of another hormone (ex: glucagon increases blood glucose while insulin lowers it)