Ch 16 - Endocrine System

Question 1

Long-distance chemical messengers that cause a change in metabolic activity of a cell

Answer 1

Hormone

Effects are usually long-lasting!!

Question 2

Hormones control:

Answer 2

1) Reproduction
2) Growth and development
3) Immune system activation
4) Maintenance of various blood components (glucose, electrolytes, water, etc.)
5) Etc, etc, etc.

Question 3

Glands Involved in Endocrine System

Answer 3

Endocrine glands, obviously
But also sonetimes autocrine and paracrine glands

autocrine - affects same cell
paracrine - affects different cell in same tissue

Question 4

Classification of hormones

Answer 4

1) Amino acid-based hormones - molecular size varies (amino acid derivatives, peptides, proteins) - water soluble, circulate w/o carrier
2) Steroid hormones - synthesized from cholesterol (gonadal hormones and adrenocortical hormones are only steroid hormones in body) - non water soluble, circulates WITH carrier

Question 5

Hormone Actions

Answer 5

1) Altering plasma membrane permeability or membrane potential
2) Stimulates synthesis of enzymes/proteins inside cell
3) Activates/deactivates enzymes
4) Induces secretory activity
5) Stimulates mitosis

can only affect target cells with receptors that can bind it

Question 6

Mechanisms of Hormone Action

Answer 6

1) Second messenger-systems: use receptors found on surface of plasma membrane (glucagon, TSH)
2) Intracellular systems: hormone enters cell first, then binds to intracellular receptors (steroid hormones, T3, T4)

Receptor-hormone complex binds specific regions of DNA - DNA transcription occurs

Question 7

Hormone stimulus mechanisms

Answer 7

1) Humoral stimuli: changing blood levels of ions & nutrients (Ca2+ levels + parathyroid gland)
2) Neural stimuli: nerve fibers stimulate hormone release (infrequent, NE&epinephrine release)
3) Hormonal stimuli: hormone released in response to other hormones (hypothalamic hormones stimulate/inhibit anterior pituitary gland)

controlled by negative feedback mechanisms

Question 8

Factors of activiation of cell by hormone

Answer 8

1) Blood levels of hormone
2) Number of receptors for specific hormone on/in cell
3) Affinity of receptor to the hormone

Question 9

How amount of hormone in blood/cell can change the NUMBER OF RECEPTORS in/on target cell

Answer 9

Up-regulation: increase receptor number in response to low hormone levels (increase sens.)
Down-regulation: decrease in response to high (decrease sens.)

Question 10

Hormone Interactions at Target Cells

Answer 10

1) Permissiveness: one hormone cannot have full effect without binding of a second type of hormone
2) Synergism: 2+ hormones with similar effects bind target cell - amplification occurs
3) Antagonism: one hormone opposes the effect of another hormone

Question 11

Duration of hormone effects on target cell

Answer 11

Not always immediate - can be seen after hours or days of exposure to hormone
Duration of effect varies as well

Question 12

Major Endocrine Organs

Answer 12

1) Pituitary Gland (hypophysis) - (connected to hypothalamus - master endocrine organ)
2) Thyroid Gland - produces, secretes, stores hormones (thyroid hormone - major metabolic hormone)
3) Parathyroid Gland - parathyroid hormone (Ca2+ homeostasis)
4) Adrenal Glands - stress response, electrolyte balance
5) Pineal Gland - melatonin
6) Pancreas - glucagon and insulin
7) Gonads & Placenta - estrogens/progesterone; testosterone; placenta temporary

Question 13

Regions of Pituitary Gland

Answer 13

1) Anterior pituitary: manufactures and releases several different hormones
2) Posterior pituitary: composed mostly of neural tissue and nerve fibers - stores and releases neurohormones produced by hypothalamus

Question 14

Hormone relase of pituitary control

Answer 14

Controlled by Hypothalamus:
1) Action potentials from hypothalamus cause hormone relase
2) Hypothalamic hormones released into hypophyseal portal system - stimulate or inhibit

Question 15

Posterior pituitary & hypothalamic hormones

Answer 15

1) Oxytocin - stimulant for uterine contraction, milk ejection, “cuddle hormone”
2) ADH (antidiuretic hormone) - prevents water being added to urine (maintains water content of blood)

Question 16

Function of Oxytocin

Answer 16

Stimulates uterine contraction, milk ejection, “cuddle hormone”

Works as a neurotransmitter in the brain - promotes nurturing, couple bomding, trust, affectionate behavior

Positive Feedback!!

Question 17

Control of release of ADH

Answer 17

Osmoreceptors in hypothalamus monitor solute concentration and release the antidiuretic hormone when solute concentration is too high

Question 18

Six Anterior Pituitary Hormones

Answer 18

1) Growth Hormone (GH) (category 2 tropic hormone)
2) Thyroid-Stimulating Hormone (TSH) (Tropin)
3) Adrenocorticotropic Hormone (ACTH) (Tropin)
4) Follicle-stimulating hormone (FSH) (Tropin)
5) Luteinizing hormone (LH) (Tropin)
6) Prolactin (PRL) (category 2 tropic hormone)

Tropins are hormones that affect the activity of another endocrine gland

Question 19

Effects of GH

Answer 19

metabolic: decreases glucose uptake, mobilizes fat stores - releases fatty acids to blood, increases aimo acid uptake

growth: liver, bone, skeletal muscle, etc. produce insulin-like growth factor (IGFs) in presence of GH - stimulate growth (increase nutrient uptake, formation of collagen and deposition of bone matrix

Technically not a tropin

Anterior pituitary hormone

Question 20

Release and Function of TSH

Answer 20

Thyroid-htimulating hormone stimulated by Thyrotropin-releasing hormone (TRH)
function: stimulates developmet and secretory activity of thyroid gland

Tropin

Anterior pituitary hormone

Question 21

Release and Function of ACTH

Answer 21

Adrenocorticotropic hormone stimulated by Corticotropin-releasing hormone (CRH)
function: stimulates developmet and secretory activity of thyroid gland

Tropin

Anterior pituitary hormone

Question 22

Release and Function of FSH

Answer 22

follicle-stimulating hormone stimulated by Gonadotropin-releasing hormone (GnRH)
function: stimulates production of gametes

Tropin

Anterior pituitary hormone

Question 23

Release and Function of LH

Answer 23

Lutenizing hormone hormone stimulated by Gonadotropin-releasing hormone (GnRH)
function: stimulates production of gonadal hormones

Tropin

Anterior pituitary hormone

Question 24

Release and Function of PRL

Answer 24

Prolactin levels rise and fall with blood estrogens (rising estrogen = more PRL) - controlled by dopamine
function: stimulates milk production in breast tissue & contributes to reproductive system function

PRL increases toward end of pregnancy

Tropin

Anterior pituitary hormone

Question 25

Release and Function of TH

Answer 25

Thyroid hormone produced depending on the presencce of iodine **Affects virtually every body cell** 1) Increases metabolic rate and body heat production 2) Regulates tissue growth/development 3) Maintains blood pressure ## Footnote Thyroid gland retains ~3 months normal supply of hormone

Question 26

Release and Function of PTH

Answer 26

Decreasing blood Ca2+ levels stimulate Parathyroid hormone release by: 1) Stimulating osteoclasts to increase bone degredation 2) Enhancing Ca2+ reabsorption by kidneys 3) Activating vitamin D - increases absorption of Ca2+ from digestive system

Question 27

Functional areas of the Adrenal glands

Answer 27

1) **Adrenal Cortex** - outermost region, produces 3 corticosteroids (mineralcorticoids, glucocorticoids, gonadocorticoids) 2) **Adrenal Medulla** - innermost region of adrenal gland, synthesize NE and Epinephrine (80% epinephrine)

Question 28

Corticosteroid that regulates electrolyte concentration in ECF (esp. Na+ and K+)

Answer 28

**Mineralcorticoids** *importance:* - Na+ influences water movement - can affect blood volume and blood pressure - K+ determines resting membrane potential - imbalance affects responsiveness of neurons ## Footnote Adrenal Cortex Hormone

Question 29

Corticosteroid that influences energy metabolism of cells, provides resistance to stressors

Answer 29

**Glucocorticoids** *specific types:* cortisol, cortisone, corticosterone Release stimulated by ACTH - neg. feedback Stress affects cortisol release - CNS overrides negative feedback mechanism & more cortisol released

Question 30

Effects of glucocorticoids

Answer 30

1) Mobilizes body stores to create more glucose 2) Provokes sympathetic nervous system 3) Excessive release causes: - Depressed cartilage & bone formation - Inhibits inflammation - Depresses immune system - Disrupts normal cardiovascular, neural, gastrointestinal functions

Question 31

Gonadocorticoid release and function

Answer 31

Small amounts of androgens released by adrenal cortex - much less than produced by gonads *effects:* - Contribute to axillary and pubic hair development - in females: contributes to libido & produce estrogens post-menopause ## Footnote Some converted to testosterone, others to estrogen

Question 32

Function of Adrenal Medulla

Answer 32

Synthesizes EPI and NE (80-20) Release initiated by sympathetic nervous system Hormones not essential for flight-or-fight response ## Footnote EPI has a greater influence on metabolic activity & is a dilator of airways in lungs, whereas NE has a greater influence on blood vessel diameter

Question 33

Function of Pineal Gland

Answer 33

Secretes melatonin Regulating night-day cycles Release controlled indirectly by intensity & duration of light

Question 34

Pancreatic Hormones, and where they are produced

Answer 34

Produced in **pancreatic islets:** 1) **Glucagon:** (alpha cells) stimulates liver to break down glycogen, convert non-carbohydrate molecules to glucose, release glucose from liver cells - HYPERglycemic effect 2) **Insulin:** (beta cells) increases glucose uptake by body cells, inhibits glycogen breakdown, inhibits conversion of non-carbohydrate molecules to glucose ## Footnote Release of insulin controlled by: - Elevated blood glucose - Rising blood levels of amino acids & fats - Acetylcholine release from parasympathetic nervous system - Any hyperglycemic hormone

Question 35

Types of Diabetes Mellitus

Answer 35

**Type 1) Autoimmune condition** - insulin is not produced by the pancreas at all **Type 2) "Insulin resistance"** - insulin produced & released, cells do not respond

Question 36

Causes/Treatment of DM1

Answer 36

Caused by destruction of beta cells by immune system *Treatment:* insulin shots before meals or cont. fusion pumps If left untreated - development of vascular & neural problems

Question 37

Causes/Treatment of DM2

Answer 37

Caused by a combination of genetics & lifestyle *Treatment:* can be managed with diet and exercise Similar complications to type 1 diabetes if not managed/treated