Endocrine system overview

Question 1

Chemical messenger-what is a autocrine chemical messenger?

Answer 1

Secreted by cells in a local area; influences the activity of the same cell from which it was secreted.

Question 2

Chemical messenger-what is a Paracrine chemical messenger?

Answer 2

Produced by a wide variety of tissues and secreted into

extracellular fluid; has a localized effect on other tissues

Question 3

Chemical messenger-what is a Neurotransmitter chemical messenger?

Answer 3

Produced by neurons; secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells

Question 4

Chemical messenger-what is a Endocrine chemical messenger?

Answer 4

Secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function

Question 5

what is the endocrine system?

Answer 5

 One of two systems responsible for the maintenance of homeostasis
through the secretion of chemical messengers

 Comprised of endocrine glands and specialised cells which secrete hormones (chemical messengers) into the blood

 Specific sites called target tissues or effectors

Question 6

Regulatory functions of the endocrine system?

Answer 6

 Metabolism
 Ion regulation
 Water balance
 Tissue maturation
 Immune system regulation
 Heart rate and blood pressure
 Control of reproductive functions
 Control of food intake and metabolism
 Control of blood glucose and other nutrients

Question 7

what are the endocrine glands in the brain?

Answer 7

Hypothalamus
Pituitary
Pineal gland

Question 8

what are the endocrine glands in the neck?

Answer 8

Thyroid

Parathyroids (posterior part of thyroid)

Question 9

what is the endocrine glands in the chest?

Answer 9

Thymus

Question 10

what are the endocrine glands in the abdomen?

Answer 10

Adrenals

Pancreas (islets)

Question 11

what are the endocrine glands in the reproduction area?

Answer 11

Ovaries (female)

Testes (male)

Question 12

what are the similarities of the nervous and endocrine system?

Answer 12

1. Both systems associated with the brain
   • Hypothalamus
   • Epithalamus

                                                  2. May use same chemical messenger as neurotransmitter and hormone. • Epinephrine                               
   
                                                  3. Two systems are cooperative • Nervous system secretes neuroendocrine peptides, or neurohormones, into circulatory system • Some parts of endocrine system innervated directly by nervous system

Question 13

what are the differences between the endocrine and nervous system?

Answer 13

◦ Mode of transport
 Axon
 Blood

◦ Speed of response
 Nervous – instant/milliseconds
 Endocrine – delayed/seconds

◦ Duration of response
 Nervous – milliseconds/seconds
 Endocrine – minutes/days

Amplitude vs. frequency

Question 14

what are the 3 general characteristics of hormones?

Answer 14

1. Stability 2. Communication 3. Distribution

Question 15

general characteristics of hormones-stability?

Answer 15

• Half-life: The length of time it takes for half a dose of
substance to be eliminated from circulatory system

– Long half-life: regulate activities that remain at a constant rate through time. Usually lipid soluble and travel in plasma attached to proteins

– Short half-life: water-soluble hormones as proteins, epinephrine, norepinephrine. Have a rapid onset and short duration

Question 16

general characteristics of hormones-communication?

Answer 16

• Interaction with target cell

Question 17

general characteristics of hormones-distributed?

Answer 17

• Hormones dissolve in blood plasma and are transported in
unbound or are reversibly bound to plasma proteins.

• Hormones are distributed quickly because they circulate in the blood.

Question 18

how are hormones classified?

Answer 18

 Hormones can be categorized as two basic types:
◦ Lipid-Soluble
◦ Water-Soluble

 Based on chemical behaviour

 Determines ability to pass through the plasma
membrane, therefore determining potential sites of action for each hormone.

 Within each category, hormones can be further
subdivided into:
◦ Steroid hormones
◦ Non-steroid hormones

Question 19

Lipid-soluble hormones:

Answer 19

 Non-polar and include:
◦ Steroid hormones
◦ Thyroid hormones
◦ Fatty acid derivative hormones

 Travel in blood bound to binding proteins
◦ Small
◦ Low solubility
◦ Slower degradation → longer half life

Question 20

water-soluble hormones: Polar molecules and include:

Answer 20

◦ Protein hormones
◦ Peptide hormones
◦ Most amino acid derivative hormones

Question 21

water-soluble hormones: Can dissolve in?

Answer 21

In the blood → many circulate as free

hormones

Question 22

water-soluble hormones: why can’t many readily diffuse through plasma membranes?

Answer 22

 Many are quite large so can’t readily diffuse through
plasma membranes → slower diffusion
◦ Capillaries of organs regulated by protein hormones are
generally very porous

Question 23

water-soluble hormones: how do some small hormones able to avoid being filtered out of the blood?

Answer 23

 Some are quite small so attach to larger protein to

avoid being filtered out of the blood

Question 24

hormone receptors: transported in blood so…

Answer 24

 Transported in blood so come into contact with

virtually all body tissues

Question 25

hormone receptors: lock and key binding ensures…

Answer 25

 Lock and key binding ensures they can only activate in a specific location

Question 26

hormone receptors: either alters the cell’s…

Answer 26

 Either alters the cell’s existing proteins or turning on genes that will build a new protein

Question 27

what are the 3 patterns of hormone secretion?

Answer 27

• Chronic hormone secretion.
• Acute hormone secretion.
• Episodic (Cyclic) hormone secretion.

Question 28

what is Chronic hormone secretion?

Answer 28

Maintenance of relatively constant concentration of hormone. Thyroid hormone.(stable and long lasting)

Question 29

what is Acute hormone secretion?

Answer 29

Epinephrine in response to stress. (reacts to the immediate stimuli)

Question 30

what is Episodic hormone secretion?

Answer 30

Female reproductive hormones. (continuous cycle, always occurs with the same amount)