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1

what are the 4 things that the Endocrine system controls?

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

2

endocrine

borne via bloodstream

3

paracrine

acting in local environment

4

autocrine

acting on secreting cell

5

endocrinology is

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

6

what are amino hormones ?

derived from tyrosine

7

what are peptide and protein hormones?

encoded in genes

8

what are steroid hormones?

derived from cholesterol

9

what kind of hormones are epinephrine and norepinephrine?

amino hormones

10

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

amino hormones

11

how are protein hormones produced?

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

12

are protein hormones hydrophilic or hydrophobic?

hydrophilic, which means they cannot freely cross membranes

13

what are some examples of steroid hormones?

- glucocorticoids
- mineralocorticoids
- androgens
- estrogens
- progestins

14

can steroid molecules cross membranes?

yes because they are lipophilic

15

what do steroids bind to when traveling through the blood?

steroid-binding globulins (SBGs)

16

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

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

17

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

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

18

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

1. maintains target organ sensitivity
2. prevents down-regulation of receptors

19

what are 3 types of second messenger systems?

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

20

what converts ATP to cAMP?

adenylate cyclase

21

what does phospholipase C convert PIP2 into?

DAG and IP3

22

how do cells down-regulate receptors?

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

23

which hormones act via intracellular receptors?

1. steroid
2. thyroid hormones

24

hyposecretion

too little hormone secreted

25

hypersecretion

too much hormone is secreted

26

what is secondary hyposecretion?

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

27

what is primary hyposecretion?

too little hormone is secreted due to abnormality within gland

28

primary hypersecretion

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

29

secondary hypersecretion

Excessive stimulation from outside the gland causes over secretion