Topic 18: Endocrine System

Question 1

what is the basis of the endocrine system?

Answer 1

-contains ductless glands + endocrine tissues within other organs
-secretes chemical signals (hormones) into the blood

Question 2

how are hormones transported within the endocrine system?

Answer 2

-transported to target cells by circulation
-bind to receptors on/within target cells
-initiate a change in the cell (response)

Question 3

what is a target cell?

Answer 3

-a cell with a receptor that is for a specific hormone

Question 4

what are the hormone classes?

Answer 4

-steroids
-hormones derived from amino acids
-peptide + protein hormones

Question 5

what are steroids?

Answer 5

-synthesized from cholesterol
-ex: testosterone, estrogen, vitamin d

Question 6

what are of hormones derived from amino acids?

Answer 6

-derived from tyrosine
-thyroxine/T4
-epinephrine + norepinephrine

Question 7

what is thyroxine/T4?

Answer 7

-a thyroid hormone
-controls cellular metabolism, growth, and development

Question 8

what is epinephrine + norepinephrine

Answer 8

-adrenaline and noradrenaline
-secreted by the adrenal medulla
-part of the fight or flight stress response
-part of sexual climax (orgasm)

Question 9

what are peptide + protein hormones?

Answer 9

-chains of amino acids
-held together by peptide bonds
-ex: oxytocin, antidiuretic hormone (ADH), growth hormone (GH), insulin

Question 10

what are endocrine glands?

Answer 10

-do not contain ducts
-pure endocrine glands
-glands with no other function (only function is to produce and secrete hormones)

Question 11

what are examples of pure endocrine glands?

Answer 11

-pituitary gland
-thyroid gland
-parathyroid glands
-adrenal glands

Question 12

what is the pituitary gland?

Answer 12

-suspended from the hypothalamus
-in the sella turcica of the sphenoid bone
-has 2 lobes

Question 13

what are the 2 lobes of the pituitary gland?

Answer 13

-anterior pituitary
-posterior pituitary

Question 14

what are the characteristics of the anterior pituitary lobe?

Answer 14

-glandular epithelial tissue
-hormone secretion is regulated by hormones released by the hypothalamus

Question 15

what hormones are released by the anterior pituitary lobe?

Answer 15

-growth hormone (GH)
-thyroid stimulating hormone (TSH)
-adrenocorticotropic hormone (ACTH)
-gonadotropins (reproductive hormones)
-prolactin (PRL)

Question 16

what is the function of growth hormone?

Answer 16

-affects growth and metabolism

Question 17

what is the function of thyroid stimulating hormone (TSH)?

Answer 17

-stimulates secretions of the thyroid gland

Question 18

what is the function of adrenocorticotropic hormone (ACTH)?

Answer 18

-stimulates the secretion of steroid hormones from the adrenal gland

Question 19

what is the function of prolactin (PRL)?

Answer 19

-stimulates milk production by the mammary glands

Question 20

what are the characteristics of the posterior pituitary lobe?

Answer 20

-nervous tissue
-extension of the hypothalamus
-stores and secretes hormones produced in the hypothalamus

Question 21

what hormones are secreted by the posterior pituitary lobe?

Answer 21

-oxytocin
-antidiuretic hormone (ADH/vasopressin)

Question 22

what is the function of oxytocin?

Answer 22

-stimulates uterine contractions and milk ejection during suckling

Question 23

what is the function of antidiuretic hormone (ADH)?

Answer 23

-enhances water reabsorption by collecting duct cells of nephrons in the kidney

Question 24

what are the characteristics of the thyroid gland?

Answer 24

-butterfly shaped
-on the anterior surface of the superior part of the trachea
-inferior to the larynx

Question 25

what is the histology of the thyroid?

Answer 25

-follicles -parafollicular cells

Question 26

what cells create the walls of follicles in the thyroid gland? what do these cells secrete?

Answer 26

-epithelial cells (follicle cells) -secrete the hormone thyroxine (T4) -thyroxine is converted to its active form (T3) in target cells

Question 27

what are parafollicular cells?

Answer 27

-between the follicles -secrete calcitonin

Question 28

what is the function of calcitonin?

Answer 28

-increases Ca2+ uptake into bone (bone formation) -lowers blood Ca2+

Question 29

what are the parathyroid glands?

Answer 29

-secrete parathyroid hormone (PTH) -4 glands typically (embedded in the posterior thyroid)

Question 30

what is the function of parathyroid hormone (PTH)?

Answer 30

-acts on bone and kidneys to increases blood calcium levels

Question 31

what are the adrenal glands?

Answer 31

-on the superior surface of each kidney (2 total) -2 parts

Question 32

what are the 2 parts of the adrenal glands?

Answer 32

-adrenal cortex (outer) -adrenal medulla (inner)

Question 33

what is the adrenal cortex?

Answer 33

-epithelial tissue forming glands -only secretes steroids -has 3 layers which each secrete a different hormone

Question 34

what are the 3 layers of the adrenal cortex? superficial to deep.

Answer 34

-zona glomerulosa -zona fasciculata -zona reticularis

Question 35

what hormone does the zona glomerulosa secrete? what is its function?

Answer 35

-mainly aldosterone -acts on nephrons to regulate salt balance

Question 36

what hormone does the zona fasciculata secrete? what is its function?

Answer 36

-secretes mainly cortisol -regulates many body processes during long-term stress

Question 37

what hormone does the zona reticularis secrete?

Answer 37

-secretes androgens (sex hormones) -converted into testosterone or estrogens in other tissues

Question 38

what is the adrenal medulla? what hormones does it secrete?

Answer 38

-modified nervous tissue -secretes 2 main hormones -epinephrine (80%) -norepinephrine (20%) -regulate the fight or flight response

Question 39

what are endocrine tissues?

Answer 39

-hormone secreting cells or tissues located in organs that have other functions -not strictly glands that secrete hormones

Question 40

what are examples of endocrine tissues?

Answer 40

-pancreatic islets of langerhans -hypothalamus -gonads -other

Question 41

what are the pancreatic islets?

Answer 41

-alpha cells and beta cells in the pancreas

Question 42

what do the alpha cells of the pancreatic islets secrete? what is its function?

Answer 42

-secrete glucagon -increases blood glucose concentration

Question 43

what do the beta cells of the pancreatic islets secrete? what is its function?

Answer 43

-secrete insulin -decreases blood glucose concentration

Question 44

what does the hypothalamus do?

Answer 44

-produces and secretes hormones that stimulate or inhibit the secretion of hormones from the anterior pituitary -produces hormones that are stored and secreted by the posterior pituitary

Question 45

what does gonadotropin releasing hormone (GnRH) stimulate the release of?

Answer 45

-FSH (follicle stimulating hormone) -LH (luteinizing hormone)

Question 46

which cells secrete testosterone in the testes?

Answer 46

-interstitial endocrine (leydig) cells

Question 47

which cells in the ovaries secrete estrogen + progesterone?

Answer 47

-granulosa cells of secondary and vesicular follicles secrete estrogen -corpus luteum secretes estrogen + progesterone

Question 48

what other organs have endocrine tissues? what hormones do they secrete?

Answer 48

-duodenum = secretin + cholecystokinin (CCK) -kidney = renin + erythropoietin (EPO) -skin = vitamin D -heart = atrial natriuretic peptide (ANP)

Question 49

what are 2 examples of gonadotropins?

Answer 49

-luteinizing hormone (LH) -follicle stimulating hormone (FSH)

Question 50

what is the function of luteinizing hormone (LH)?

Answer 50

-stimulates ovulation and formation of corpus luteum in the ovary -stimulates testosterone production by interstitial endocrine (leydig) cells in the testes

Question 51

what is the function of follicle stimulating hormone (FSH)?

Answer 51

-stimulates sustentocytes and follicle cells

Question 52

what hormones does the hypothalamus produce/secrete?

Answer 52

-growth hormone releasing hormone (GHRH) -growth hormone inhibiting hormone (GHIH) (somatostatin) -gonadotropin releasing hormone (GnRH)