Anatomy II - Endocrine Physiology

Question 1

What is the function of the Endocrine System?

Answer 1

Secreting and producing hormones (chemical messengers)

Question 2

Endocrine vs Nervous System

Answer 2

Nervous system:
- Effects are immediate
- Releases neurotransmitters to target cells
- Operates through series of NEURONS

Endocrine System:
- Hormones effect is longer-lasting and can take place within seconds, hours, or days.
- Releases Hormones into bloodstream

Question 3

Describe the route hormones take to get to the target cell.

Answer 3

1. Hormones are secreted into interstitial fluid, then diffuse into blood capillaries.
2. Blood transports hormones to the heart via the veins.
3. After leaving the heart, blood transports hormones to rest of the body via the arteries.
4. In the capillary beds, the hormones diffuse out of the blood, into the interstitial fluid, and then bind onto the target cell receptors.

Question 4

Endocrine signaling vs Paracrine signaling vs Autocrine signaling

Answer 4

Endocrine: Hormones are released into the bloodstream and travel LONG DISTANCES to target distant organs or tissues.

Paracrine: Hormones or signaling molecules act on nearby cells in the local area (SHORT DISTANCE).

Autocrine: The cell secretes a hormone or signaling molecule that acts on ITSELF (the SAME cell that produced it).

Question 5

What are antagonists?

Answer 5

Two hormones that work against each other, opposing or counteracting one another’s effects.

Ex: Calcitonin lowers blood calcium levels, while parathyroid hormone raises them

Question 6

What are Synergists?

Answer 6

Two or more hormones that work together to produce a stronger or more effective outcome.

Ex: Epinephrine and norepinephrine: Work together to increase the heart rate

Question 7

Define: Amin-acid Hormones

Answer 7

hormones that are derived from amino acids (the building blocks of proteins). They are hydrophilic (water soluble) and bind to plasma membrane receptors.

Question 8

Define: Steroid Hormones

Answer 8

Hormones derived from cholesterol, and are lipid-soluble & hydrophobic. They bind to receptors in cytosol or nucleus.

Question 9

Three dimensional shapes are _____ specific for the hormone molecule that they bind to.

Answer 9

HIGHLY

Question 9

Where are hormones embedded/reside in?

Answer 9

Embedded in plasma membrane and reside in cytosol or within nucleus of the target cell.

Question 10

Hydrophilic hormones _____ cross plasma membrane while _______ hormones ________ cross through plasma membrane

Answer 10

CANNOT; HYDROPHOBIC; CAN

Question 11

Hormone Action Mechanism: Up-Regulation

Answer 11

Target cell produces more receptors when hormone in blood decreases

Question 12

Hormone Action Mechanism: Down-Regulation

Answer 12

Target cell decreases receptors when hormone in blood is high.

Question 13

Explain the steps of the process of a Hydrophilic Hormone Signaling

Answer 13

1. Hydrophilic hormone binds to receptors on plasma membrane.
2. Receptors activate G-protein
3. G-protein activates enzyme which creates the formation of the secondary messenger. (ex: G-protein activates AC enzyme which forms cAMP.)
4. Secondary messenger initiates series of events within the cell that leads to changes in activity.

Question 14

Explain the steps of the process of a Hydrophobic Hormone Signaling.

Answer 14

1. Hydrophobic Hormone crosses plasma membrane & interacts with receptors on cytosol or nucleus of target cell.
2. Hormone then forms complex with receptor (interacts with DNA)
3. Complexes changes rate of protein synthesis of one or more proteins

Question 15

Hormones continue to circulate in the blood stream UNTIL _______ or ______.

Answer 15

Taken up by target cell or broken down & deactivated.

Question 15

How are hormones inactivated rapidly?

Answer 15

Reactions catalyzed by enzymes

Question 16

What does the amount of a hormone within the bloodstream at a given moment depend on?

Answer 16

1. How fast & how much of the hormone the endocrine gland produced
   AND
2. How fast secreted hormone is removed from the blood

Question 17

How are hormones inactivated slowly?

Answer 17

Eliminated in urine from the KIDNEYS and/or broken down by enzymes within the LIVER.

Question 18

What does the rate at which hormones are eliminated depend on?

Answer 18

It depends on structure and degree of binding to proteins.

Question 19

Define: Half-Life

Answer 19

Amount of time it take plasma concentration of hormone to reduce by half.

Question 20

Who has the longer and shorter half lives between Hydrophobic and Hydrophilic hormones?

Answer 20

Hydrophobic hormones have longest half life (a week or more) because of protein-binding
while,
Hydrophilic hormones have shorter half lives (few minutes to seconds)

Question 21

Describe a negative feedback pathway in a simple endocrine pathway.

Answer 21

Stimulus: Physiological Level changes from normal range
Receptor: Endocrine cell receptors detect the change
Control Center: Endocrine Cell increases or decreases stimulation of the particular hormone.
Effector/Response: Hormone triggers response that brings conditions back to normal range.

Question 22

Why are hydrophilic hormones not able to cross through the plasma membrane unlike hydrophobic ones?

Answer 22

The phospholipid bilayer does not allow for hydrophilic hormones to pass through so they have to bind to receptors on the plasma membrane.

Question 23

Humeral vs Hormonal vs Neural Stimulation

Answer 23

Humeral is anything BUT a hormone & neuron that releases a hormone because of something that is not a hormone.

Hormonal is when Hormones cause other hormones to be released.

Neural Stimulation is when an electrical impulse is sent via the nerves in order to cause the release of a hormone.