Lecture 8: Endocrine System Flashcards Preview

APBI 311 > Lecture 8: Endocrine System > Flashcards

Flashcards in Lecture 8: Endocrine System Deck (66):
1

Endocrinology

Concerned with chemical integration of the body

2

Integration with...

The nervous system, and it is very important for normal function that they work together

3

Hormone

-Greek for stimulate
-a chemical substance produced in one part of body (endocrine gland) that diffuses or is transported to another area where it influences activity and integrates component parts of the organism
-regulates rate of existing reactions that have enzymes or initiates metabolic reactions

4

How could an excess of hormones be as detrimental as a deficiency?

They influence reaction rate through interaction with enzymes, which can reduce the response of enzymes if overused

5

Local/Para Hormones

-Prostaglandins: reproduction
-Erythropoietins
-Histamines
-Gastro-intestinal hormones
-Kidney hormones: Renin, for Na/K balance

6

Erythropoietin

produced by anoxic kidney and stimulates bone marrow production of RBC

7

Histamine

produced by injured tissues and action locally on the surrounding tissue

8

Gastro-Intestinal Hormones

Gastrin, secretin, Pancreozymin, Cholecystokinin

9

Kidney Hormone:

Renin, for Na/K balance

10

History: how did Aristotle show possibility of internal control of functions of the body?

-through observing the effects of castrating birds

11

Endocrine organs

hypothalamus, pituitary, pineal, thyroid, parathyroid, pancreas (islets of langerhans, adrenal, ovary, testis, placenta, and many tissues (prostaglandins)

12

TRH, thyrotropin-releasing hormone activates,
originates from the hypothalamus

TSH, thyroid stimulating hormone, which stimulates the thyroid and parathyroid; originates from the anterior pituitary

13

PRH, prolactin releasing hormone
hypothalamus

PRL, prolactin, which stims the mammary glands
from anterior pituitary

14

PIH, prolactin release-inhibiting hormone; from the hypothalamus

inhibits PRL, prolactin

15

CRH, corticotropin-releasing hormone;
from the hypotalamus

ACTH, adrenocorticotropic hormone stims the adrenal glands;
from the anterior pituitary

16

GnRH, gonadotropin releasing hormone
from the hypothalamus

stimulates 1. LH, Luteinizing hormone for the testis, or 2. FSH, follicle-stimulating hormone for the ovaries;
from the anterior pituitary

17

GHRH, growth hormone releasing hormone;
from hypothalamus

stimulates GH, growth hormone, which stims growth of bone, muscle, and adipose tissue

18

SS, somatostatin;
from hypothalamus

inhibits GH, growth hormone

19

adrenal gland

sits atop the kidney and consists of the Cortex and Medulla

20

Adrenal cortex

produces glucocorticoids (cortisol, cortisone, and corticosterone), and aldosterone

21

Adrenal Medulla

produces epinephrine and norepinephrine

22

Glucocorticoids

-cortisol, cortisone, and corticosterone
-aid in gluconegenesis, decrease of peripheral glucose utilizatoin, anti-flammatory effect, anti-allergic effect, and euphoric effect

23

Aldosterone

-electrolyte and water metabolism

24

Epinephrine

glycogenolysis to raise blood glucose

25

Norepinephrine

Cardiovascular function; Mainly Pressor Effect

26

Ovaries produce

Progesterone, Estrogesn (estradiol, estrone, and others), and Relaxin

27

Progesterone

w/ estrogen it develops uterus for implantation and pregnancy maintenance

28

Estrogens

-estradiols, estrone, and others
-development, maintenance, and cyclic changes of female tubular genital tract
-glandular duct development of mammae and uterus
-secondary sex characteristics and behavior
-accessory sex organs
-calcium and fat metabolism in birds

29

Relaxin

-dissolution of symphysis pubis and relaxes pelvic tissues

30

Testis

produce testosterone

31

Testosterone

development of accessory sex organs and secondary sex characteristics
-behaviour
-spermatogenesis
-anabolism

32

Pancreas/Islets of Langerhans

Alpha cells that secrete glucagon and Beta cells that secrete insulin

33

Glucagon

Increases blood glucose level by favoring liver glycogenolysis

34

Insulin

Decreases blood glucose level by storage or utilization
-also aids fat and protein metabolism

35

Placenta

hCG-chorionic gonadotropin (primates)
PMSG-Pregnant Mare Gonadotropin
Estrogens
Progesterone
Relaxin

36

hCG-Chorionic Gonadotropin

Mainly LH-like, although some FSH-like properties

37

PMSG-Pregnant Mare Gonadotropin

Mainly FSH-like, but also some LH-like properties

38

Interrelation of Endocrine and Nervous system

hormones of hypothalamus, pituitary, and other endocrine glands interact with nervous system
-nervous system serves as an afferent branch bringing impulse to the hypothalamus, and then the endocrine system (pituitary) releases hormonal substances, which act peripherally to complete the reflex
-endocrine=wireless; nervous=wire system
-both important for maintenance of homeostasis

39

examples of interrelation of endocrine and nervous system

-physical stim of vagina/cervix during copulation causes impulse to travel to spinal cord
-impulse reaches hypothalamus and here GnRH is released
-GnRH is carried by hypophyseal portal vessels to the anterior pituitary
-anterior pituitary releases luteinizing hormone (LH) and LH is carried in the circulatory system
-LH will act on the mature follicles and cause ovulation
-another example is let-down of milk

40

genetic make up of individual affects...
phenotypic characteristics are manifestations of..

-growth and development and reproduction
-biochemical coding in DNA of the gene

41

relationship of genetics and endocrinology

-amount and kind of hormone produced are coded in the DNA
-thus errors could result in malfunction of the endocrine organ or a hereditary disease
-any malfunctions could result in over or underproduction or production of an abnormal hormone
-selection for growth, number of eggs laid/egg size, milk production, etc are all possible

42

Chemical classes of hormones

-polypeptide hormones
-steroid hormones
-catecholamines and iodothyronines

43

Polypeptide hormones

produced in hypothalamus, pituitary, parathyroid, and islets of langerhans
-building blocks are amino acids
-production depends on substrate, energy supply, biological stimulation

44

Polypeptide hormone administration

parenternal: outside digestive system
-oral administration thus leads to destruction of their structure by digestive enzymes

45

Steroid hormones

-produced by gonads, adrenal cortex, and placenta
-building blocks: acetate-cholesterol
-alterations can determine which steroid is released
-steroid structures are similar but have very different physiological/pharmacological effects

46

Catecholamines and Iodothyronines

-tyrosine derivatives, of which represent 5% of mammalian hormones
-catecholamines=epinephrine/nor-epinephrine
-iodothyronines=thyroxin, tri iodothyronine

47

Catecholamines

=epinephrine/nor-epinephrine
-share similar mechanism of action with polypeptide hormones

48

Iodothyronines

=thyroxin, tri iodothyronines
-more closely resemble the characteristics of steroid hormones

49

prostaglandins are made of ...

fatty acids

50

Hormone Transport

1.Polypeptide hormones are produced and stored in a gland until needed, then they are released into capillaries
2. steroid hormones are not stored, but released when produced; they also do not circulate freely in the blood, but are bound to carrier proteins
3. thyroxin and tri-iodothyronine are stored in thyroid follicles until needed

51

steroid and thyroxin hormone carrier proteins

TBG: thyroxin binding globulin
CBG: corticosteroid binding globulin; binds to corticosteroids and progesterone
SHBG: Sex-hormone binding globulin, binds to estradiol and testosterone

52

Significance of binding

-restricts diffusion through tissues/cells
-prolongs their action: binding protects against degradation/elimination
-bound form cannot enter the cell

53

steroid and thyroids are smaller or larger than peptide hormones?

smaller, and can diffuse freely into most cells, membrane does not act as a barrier
-polypeptide hormones are much larger, and therefore must exert action on surface of the target cell since they cannot pass through the plasma membrane

54

Target cells and receptor sites

though all cells are exposed to hormones produced by endocrine glands, only a few respond (target cells) because they have highly specific receptor sites
-receptor sites are on the surface of the cell for peptide hormones, in the nucleus chromatin for thyroid hormones, and in the cytoplasm and nucleus for steroid hormones

55

events of hormone-binding: polypeptide hormone LH

1. specific receptor site in target organ binds a hormone, LH (first messenger), to the membrane of cell
2. the binding stimulates an enzyme, Adenyl Cyclase in membrane to convert ATP to cyclic 3, 5 adenosine monophosphate (cyclic AMP), the second messenger

56

polypeptide hormone LH binding part two: cAMP second messenger

3. cAMP conveys message of hormone to intracellular sites initiating a chain of reactions that result in physiological effects
4. ACTH, LH, FSH, TSH, and HCG produce their effects by cAMP second messenger
5. depending on its structure, cAMP will either modifiy the enzyme, affect membrane permeability, or stimulate hormone release
6. cAMP is common amongst all peptide hormone action

57

Steroid/Thyroid hormone action

-stimulate targets by intracellular action on the control and synthesis of specific proteins
1. only target cells have specific receptor protein to bind the steroid in question
2. once bound, the hormone can move from the cytoplasm into the nucleus where there is an acceptor site on the chormosome
3. next the gene responds by forming a specific messenger RNA, which leaves the nucleus and directs synthesis of a particular protein necessary for the function of the particular steroid

58

Steroid/thyroid special points

- although most hormones have target organ that responds to a greater extent than any other tissue, other tissues may have some receptors
ie. estradiol exerts most profound action on uterus, vagina, and mammary glands, but also affects other tissues that have receptors to estrogen like skin, hair, and bone

59

can target organs function in absence of a hormone?

yes: at minimal levels they can continue to function

60

some physiological events require more than one hormone, name those for lactation and parturition

lactation: estrogen, progesteron, oxytocin, prolactin, somatotrophin, thyroxin, and cortisone
parturition: oxytocin, estrogen, relaxin, corticosteroids, prostaglandin

61

regulation of hormone secretions

endocrine glands are important regulators of many processes in the body, therefore careful regulation of their output is critical and depends on many mechanisms

62

types of control of hormone secretions

humoral and nervous

63

humoral regulation

-concentration of a blood constituent
ie. change in level of blood glucose; low blood glucose=insulin needed to facilitate glucose movement through the cell membrane (metabolized or stored), lowering blood glucose
-concentration of another hormone

64

if blood glucose drops below normal levels...

glucagon, the blood glucose rising hormone is released, stimulating the release of glucose from the liver

65

Anterior pituitary's role in regulation of hormone secretion

-inhibited directly or indirectly via hypothalamic releasing factors by hormones produced by endocrine organs
-therefore balance is maintained between stimulating effects of the anterior pituitary and the resultant inhibitory effects on anterior pituitary output; aka positive and negative feedback

66

Regulation of hormone output by concentration of another hormone

ie. anterior pituitary, which secretes hormones that regulate other gland, which is called a feedback mechanism