Lecture 15 2/13/24

Question 1

Which three mechanisms are required for homeostasis?

Answer 1

-receptor
-control center
-effector

Question 2

What is the role of the receptor?

Answer 2

sensing component responsible for monitoring and responding to changes in internal/external environment

Question 3

What is the role of the control center?

Answer 3

receive and process information from the receptor

Question 4

What is the role of the effector?

Answer 4

responds to command of the control center to either oppose or enhance the stimulus

Question 5

Which main systems are involved in coordinating the functions of body organs?

Answer 5

-nervous system
-endocrine system

Question 6

What are the characteristics of the nervous system?

Answer 6

-ultra-fast, localized responses
-operates using electrical signals
-response based on frequency of impulses and number of nerve fibers

Question 7

What are the general functions of the endocrine system?

Answer 7

-regulation of:
–extracellular fluid
–metabolism/energy balance
–biological clock
–mineral balance
–stress
–immune functions
-growth and development
-reproduction

Question 8

Where does the endocrine system secrete hormones?

Answer 8

into the blood

Question 9

What are hormones?

Answer 9

chemical messengers that affect the function of specifically receptive organs/tissues when transported to them via bodily fluids

Question 10

What are the characteristics of hormones?

Answer 10

-produced in small amounts
-stimulatory or inhibitory
-control physiologic processes
-bathe all body cells
-responses to hormones are dose and time dependent

Question 11

Why is endocrine disease systemic?

Answer 11

due to the hormones bathing all cells in the body

Question 12

What is the main characteristic of the pituitary-dependent system of the hypothalamus?

Answer 12

hormone secretion stops when hypothalamus/pituitary are damaged/separated

Question 13

What is the main characteristic of the pituitary-independent system of the hypothalamus?

Answer 13

hormone secretion does not stop with pituitary damage

Question 14

What is the main characteristic of the transient endocrine system?

Answer 14

short duration

Question 15

What are some examples of pituitary-independent regulation?

Answer 15

-regulation of glycemia
-regulation of calcium
-regulation of Na+ and K+
-regulation of digestive enzymes

Question 16

What is the function of the transient endocrine system?

Answer 16

present only in the female to provide support for pregnancy, delivery, and onset of lactation

Question 17

What is intracrine signaling?

Answer 17

hormone acts inside cell which produced it

Question 18

What is autocrine signaling?

Answer 18

secreted hormone acts by binding to receptor on same cell from which it was released

Question 19

What is paracrine signaling?

Answer 19

secreted hormone acts on target cells in the vicinity of the cell from which it was released

Question 20

What is endocrine signaling?

Answer 20

secreted hormone acts by being distributed in the circulation to distant target cells

Question 21

What is neuroendocrine signaling?

Answer 21

secreted hormone acts by being distributed in circulation to distant target cells or neurons

Question 22

What are Leydig cells?

Answer 22

cells that produce testosterone

Question 23

What is a neuroendocrine reflex?

Answer 23

a physical stimulus that causes a nervous signal, triggering the release of hormones from the brain into the blood

Question 24

How do neurohormones differ from neurotransmitters?

Answer 24

-neurohormones are hormones synthesized in neurosecretory cells/neurons
-neurotransmitters are chemicals released by nerve endings into synaptic clefts without release into blood

Question 25

What are examples of neurohormones?

Answer 25

-hypothalamic-releasing hormones -hypothalamic-inhibiting hormones -oxytocin -ADH

Question 26

What are the three chemical classifications of hormones?

Answer 26

-amino acid/fatty acid-derived -steroid -peptide/polypeptide

Question 27

What are the characteristics of steroids/T3/T4?

Answer 27

-similar among species -stable at room temp. -plasma half-life of minutes to days -synthesized and released -hydrophobic/lipophilic -oral administration

Question 28

What are the characteristics of protein hormones?

Answer 28

-species differences -labile -plasma half-life of minutes -synthesized and stored -hydrophilic -no oral administration

Question 29

How do peptides and steroids differ in terms of presence in the plasma?

Answer 29

-peptides like to stay in the plasma -steroids are easier to get out of the plasma

Question 30

What leads to the majority of hormones being secreted in "pulses"?

Answer 30

-feedback mechanisms -limited lifespan/half-life

Question 31

What is a circadian rhythm?

Answer 31

one cycle per 24 hours

Question 32

What is an infradian rhythm?

Answer 32

cycle that exceeds circadian rhythm; longer than 24 hrs but less than 1 yr

Question 33

What is an ultradian rhythm?

Answer 33

many cycles within 24 hr period

Question 34

Which type of rhythm do most hormones follow?

Answer 34

ultradian rhythm

Question 35

Which factors impact hormone secretion?

Answer 35

-age -sex -disease -surgery -trauma -anxiety -drugs -temp. -photoperiod

Question 36

What is a dose-dependent response?

Answer 36

hormones are only produced in response to a stimulus when the stimulus is at necessary concentration

Question 37

What is a time-dependent response?

Answer 37

hormones are produced based on when a stimulus is received, and will decrease in concentration as time goes on