Endocrine - Introduction

Question 1

what are the 4 things that the Endocrine system controls?

Answer 1

1. Development and growth
2. energy regulation (storage & mobilization)
3. internal homeostasis
4. Reproduction (sex, pregnancy, lactation)

Question 2

endocrine

Answer 2

borne via bloodstream

Question 3

paracrine

Answer 3

acting in local environment

Question 4

autocrine

Answer 4

acting on secreting cell

Question 5

endocrinology is

Answer 5

the study of the homeostatic chemical adjustments and other activities that hormones accomplish

Question 6

what are amino hormones ?

Answer 6

derived from tyrosine

Question 7

what are peptide and protein hormones?

Answer 7

encoded in genes

Question 8

what are steroid hormones?

Answer 8

derived from cholesterol

Question 9

what kind of hormones are epinephrine and norepinephrine?

Answer 9

amino hormones

Question 10

what kind of hormones are thyroxine (T4) and trioidothyronine (T3)?

Answer 10

amino hormones

Question 11

how are protein hormones produced?

Answer 11

they are transcribed from genes and translated in the rough ER. They may undergo one or more post-translational modification and are stored in secretory vesicles where they are released upon stimulation by exocytosis

Question 12

are protein hormones hydrophilic or hydrophobic?

Answer 12

hydrophilic, which means they cannot freely cross membranes

Question 13

what are some examples of steroid hormones?

Answer 13

• glucocorticoids
• mineralocorticoids
• androgens
• estrogens
• progestins

Question 14

can steroid molecules cross membranes?

Answer 14

yes because they are lipophilic

Question 15

what do steroids bind to when traveling through the blood?

Answer 15

steroid-binding globulins (SBGs)

Question 16

What are the 3 axes for which the endocrine system acts?

Answer 16

1. HPT - hypothalamic-pituitary-thyroid axis
2. HPA - hypothalamic - pituitary - adrenal axis
3. HPG - hypothalamic - pituitary - gonadal axis

Question 17

When do the endocrine axes use positive feedback control instead of negative ?

Answer 17

1. mid-cycle surge of gonadotropins (LH & FSH) stimulated by high level of estrogen
2. oxytocin during parturition and suckling

Question 18

what is the physiological and clinical significance of pulsatile and hormone secretion?

Answer 18

1. maintains target organ sensitivity

2. prevents down-regulation of receptors

Question 19

what are 3 types of second messenger systems?

Answer 19

1. cAMP or cGMP
2. phospholipids diacylglycerol and inositol triphosphate (DAG and IP3)
3. Calcium

Question 20

what converts ATP to cAMP?

Answer 20

adenylate cyclase

Question 21

what does phospholipase C convert PIP2 into?

Answer 21

DAG and IP3

Question 22

how do cells down-regulate receptors?

Answer 22

• after hormone binding, receptors are internalized (coated pits)

Question 23

which hormones act via intracellular receptors?

Answer 23

1. steroid

2. thyroid hormones

Question 24

hyposecretion

Answer 24

too little hormone secreted

Question 25

hypersecretion

Answer 25

too much hormone is secreted

Question 26

what is secondary hyposecretion?

Answer 26

gland is normal but too little hormone is secreted due to deficiency of its tropic hormone

Question 27

what is primary hyposecretion?

Answer 27

too little hormone is secreted due to abnormality within gland

Question 28

primary hypersecretion

Answer 28

too much hormone is secreted due to abnormality within gland (ex. hormone secreting tumours)

Question 29

secondary hypersecretion

Answer 29

Excessive stimulation from outside the gland causes over secretion