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Anatomy & Physiology > Chapter #16: Endocrine System > Flashcards

Chapter #16: Endocrine System Flashcards

1
Q

The Endocrine System

A

-Secretes various hormones
-Hormones: long-distance chemical messengers that cause a change in metabolic activity of a cell
-Effects are usually long-lasting

-Endocrine glands secrete hormones directly to blood
-Glands highly vascularized

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2
Q

How are hormones long-distance?

A

they do not effect the cells that are in the same tissue that it’s in, travels all over the body through the blood

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3
Q

Hormones control

A

-Reproduction
-Growth and development
-Immune system activation
-Maintenance of various blood components (glucose, electrolytes, water, etc.)

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4
Q

Autocrines and paracrines

A

-sometimes considered part of the endocrine system
-Both are short-distance chemical messengers
-Autocrine: a chemical message that affects the same cell that produces the message

-Paracrine: a chemical message that is produced by one cell but affects a different cell
-Both cells are in the same tissue

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5
Q

Chemical structure of hormones determines

A

determines longevity, transport in blood, & receptivity by cell

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6
Q

Two major classification of hormones

A

1) Amino acid-based hormones
2) Steroid hormones

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7
Q

Amino acid-based hormones

A

-Molecular size varies: amino acid derivatives, peptides, proteins

-Water-soluble: circulate without carrier

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8
Q

What is a carrier protein?

A

a specific type of protein that transports a substance from point A to point B

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9
Q

Steroid hormones

A

-Synthesized from cholesterol

-Gonadal hormones and adrenocortical hormones are only steroid hormones in body

-Lipid-soluble: circulate with carrier

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10
Q

How do hormones act?

A

-Hormones can only affect target cells with appropriate receptors
-Different cell types can have different receptors that can bind the same hormone

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11
Q

How does the fact that different cell types can have different receptors that bind to the same hormone affect the response of target cells?

A

if you change the receptor shape, you may alter the effect the hormone has on the cell

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12
Q

Major changes produced by hormone binding

A

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

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13
Q

Two mechanisms of hormone action

A

1) Second messenger-systems
2) Intracellular systems

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14
Q

Second-messenger systems

A

-use receptors found on surface of plasma membrane

-Receptors are usually coupled to regulatory G-proteins
-G-protein activates intracellular second messenger: causes response in cell

-This system is extremely efficient!!

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15
Q

What class of hormone uses the second-messenger systems?

A

amino-acid hormones

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16
Q

What is the effector enzyme in the second-messenger-systems? What is the second messenger?

A

-the effector enzyme is adenylate cyclase
-the second messenger is cAMP

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17
Q

Intracellular systems

A

-Hormone enters cell, then binds to intracellular receptors

-Receptor-hormone complex binds specific regions of DNA: DNA transcription occurs
-Effect: certain proteins produced in larger numbers

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18
Q

What hormones use intracellular systems?

A

steroid hormones (must be lipid soluble)

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19
Q

Hormone Release

A

-Stimulating hormone release
-Hormone synthesis & release is controlled by negative feedback mechanisms
-if not for the negative feedback mechanism, a target cell would be doing too much or too little, so you shut of that second release before it happens

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20
Q

Stimulus mechanisms

A

1) Humoral stimuli: changing blood levels of critical ions & nutrients
-Ex: monitoring Ca2+ levels by parathyroid gland

2) Neural stimuli: nerve fibers stimulate hormone release
-Infrequent
-Ex: norepinephrine & epinephrine release by sympathetic nervous system

3) Hormonal stimuli: hormone released in response to other hormones
-Ex: hypothalamic hormones stimulate or inhibit anterior pituitary gland

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21
Q

Hormone concentration in blood depends on

A

1) How fast it is being released by endocrine organ

2) How fast it is broken down
-Most hormones removed by kidneys and/or liver
-Water-soluble hormones have shortest half-life

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22
Q

Cellular Response to Hormones

A

-Target cells only respond to a hormone if it has a specific receptor protein for that hormone
-One hormone may only be able to interact with a few cell types, while another hormone may be able to interact with every cell type

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23
Q

Activation of cell depends on

A

1) Blood levels of hormone (more concentration in blood = greater likelihood of binding)
2) Number of receptors for specific hormone on/in cell (more receptors = greater likelihood of binding)
3) Affinity of receptor to the hormone (easier it binds, the easier it can have an effect)

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24
Q

Up-regulation

A

-increase receptor number in response to low hormone levels
-increase the likelihood it can bind to it

25
Q

Down-regulation

A

-decrease receptor number in response to high hormone levels
-decrease the likelihood it can bind to it

26
Q

2+ hormones binding on the same target cell at the same time may result in

A

1) Permissiveness: one hormone cannot have full effect without binding of a second specific hormone
-Lack of the second hormone may delay or completely inhibit effects of first

2) Synergism: 2+ hormones with similar effects bind target cellamplification occurs

3) Antagonism: one hormone opposes the effect of another
-Hormones can compete for the same receptor
-Hormones act through different metabolic pathways
-Hormones can down-regulate receptor of another hormone

27
Q

Duration of hormone effects on target cell

A

-Hormone effect is not always immediate: effects seen after hours or days

-Some hormones must be activated before binding can occur

-Duration of effect varies
-Effects can disappear as levels drop or can persist for hours after levels drop
-Importance: variation of effects = strict control of hormone release

28
Q

The Pituitary Gland (Hypophysis)

A

-Connected to hypothalamus

-Two regions of the gland:
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

29
Q

Release of hormones from the pituitary controlled by hypothalamus in 1 of 2 ways

A

1) Action potentials from hypothalamus cause hormone release
-controlled by Posterior pituitary

2) Hypothalamic hormones released into hypophyseal portal system: stimulate or inhibit hormone release
-controlled by anterior pituitary

30
Q

Posterior Pituitary & Hypothalamic Hormones

A

1) Oxytocin
2) Antiduretic Hormone (ADH)

31
Q

Oxytocin

A

-Functions: stimulant for uterine contraction, milk ejection, “cuddle hormone”
-Neurotransmitter in brain: promotes nurturing, couple bonding, trust, affectionate behavior

-Stretching of cervix during childbirth sends afferent impulses to hypothalamus: stimulates posterior pituitary to release oxytocin
    -positive feedback mechanism

-Stimulates milk-producing glands to contract during breastfeeding
-Oxytocin is released when blood solute concentration is low
32
Q

Antidiuretic Hormone (ADH)

A

-Function: inhibits formation of urine by increasing return of water to blood supply by kidneys
-Importance: ADH will influence how much water leaves the body through urine

-Osmoreceptors in hypothalamus monitor solute concentration
-high blood solute concentration because ADH causes more water ti come in when solute concentration is high to balance it

33
Q

Anterior Pituitary Hormones

A

-Four of six hormones are tropins: affect activity of another endocrine gland

34
Q

1) Growth Hormone (GH) (Anterior Pituitary Hormone)

A

-Metabolic effects
1) Decreases glucose uptake by cells
2) Mobilizes fat stores: releases fatty acids to blood
3) Increases amino acid uptake by cells

-Growth effects
-Liver, bone, skeletal muscle, etc. produce insulin-like growth factor (IGFs) in presence of GH
-IGFs stimulate growth:
1) Increase nutrient uptake by tissue
2) Formation of collagen and deposition of bone matrix

-Release of GH controlled by growth hormone-releasing hormone (GHRH) or growth hormone-inhibiting hormone (GHIH)

35
Q

2) Thyroid-Stimulating Hormone (TSH)
(anterior pituitary hormone)

A

-Function: Stimulates development and secretory activity of thyroid gland
-Thyrotropin-releasing hormone (TRH) stimulates TSH release

36
Q

3) Adrenocorticotropic Hormone (ACTH)

A

-Function: stimulates adrenal cortex to release hormones
-Corticotropin-releasing hormone (CRH) stimulates ACTH release

37
Q

4 & 5) Gonadotropins (anterior pituitary hormone)

A

-Two hormones: 4) Follicle-stimulating hormone (FSH) and 5) Luteinizing hormone (LH)

-Function: regulate function of gonads
-FSH: stimulates production of gametes
-LH: stimulates production of gonadal hormones (estrogen, progesterone, and testosterone)

-Gonadotropin-releasing hormone (GnRH) stimulates release of FSH and LH
-Rising gonadal hormone blood levels inhibit release of GnRH

-Gonadotropins only released after puberty (not released throughout entire lifetime)

38
Q

6) Prolactin (PRL) (anterior pituitary hormone)

A

-Function: stimulates milk production in breast tissue
-In males, also produce and release, but do not know what it does

-PRL release increases toward end of pregnancy

-Levels of PRL rise and fall in tandem with blood estrogens
-Rising estrogen stimulates PRL release

-Release controlled by dopamine: inhibitory hormone

39
Q

The Thyroid Gland

A

-Produces, secretes, and stores hormones
Retains ~3 months normal supply of hormone

-Function: produces Thyroid Hormone (TH): major metabolic hormone

-Production of TH depends on presence of iodine

-Affects virtually every body cell:
1) Increases metabolic rate and body heat production
2) Regulates tissue growth/development
3) Maintains blood pressure

40
Q

The Parathyroid Gland

A

-Secretes parathyroid hormone (PTH)
-Function: contributes to calcium homeostasis in body

-Falling blood Ca2+ levels stimulate PTH release by:
1) Stimulating osteoclasts to increase bone degradation

2) Enhancing Ca2+ reabsorption by kidneys

3) Activating vitamin Dincreases absorption of Ca2+ from digestive system

41
Q

The Adrenal Glands

A

-Function: stress response, electrolyte balance

-Two areas of the gland, each functions as individual unit:
1) Adrenal Cortex
2) Adrenal Medulla

42
Q

Adrenal Cortex (part of adrenal gland)

A

-outermost region
-Produces corticosteroids
-Three subdivisions:
A) Zona glomerulosa: produce mineralcorticoids

B) Zona fasciculata: produce glucocorticoids

C) Zona reticularis: produce gonadocorticoids

43
Q

Mineralcorticoids (part of adrenal cortex)

A

-regulate electrolyte concentration in ECF: especially Na+ and K+

-Importance:
-Na+ influences water movement: can affect blood volume and blood pressure

-K+ determines resting membrane potential: imbalance affects responsiveness of neurons
44
Q

Glucocorticoids (part of adrenal cortex)

A

-influence energy metabolism of cells, provide resistance to stressors
-Specific types: cortisol, cortisone, corticosterone

-Cortisol release stimulated by ACTH
     -Negative feedbackrising cortisol prevents ACTH release

    -Release usually secretory bursts: increases when we first wake up & during eating

    -Stress affects cortisol release: CNS overrides negative feedback mechanism & more cortisol released
45
Q

Effects of glucocorticoids

A

-Mobilizes body stores to create more glucose

-Provokes sympathetic nervous system: vasoconstriction

46
Q

Excessive release of glucocorticoids causes

A

-Depressed cartilage & bone formation

-Inhibits inflammation

-Depresses immune system

-Disrupts normal cardiovascular, neural, gastrointestinal functions

47
Q

Gonadocortioids (part of adrenal cortex)

A

-small amounts of androgens released by adrenal cortex

-Some converted to testosterone, others converted to estrogen

-Amount produced by adrenal cortex is very small compared to what is produced by gonads

-Effects:
-Contribute to axillary and pubic hair development

 -Females: contributes to sex drive, produce estrogens post-menopause
48
Q

Adrenal Medulla (part of adrenal gland)

A

-innermost region of adrenal gland
-Synthesize epinephrine & norepinephrine
-Unequal amounts stored & released
-80% epinephrine: greater influence on metabolic activity & is a dilator of airways in lungs
-20% norepinephrine: greater influence on blood vessel diameter

-Release is initiated by sympathetic nervous system
-Release is short-lived

-Hormones from adrenal medulla are not essential
-sympathetic division produces enough on its own

49
Q

The Pineal Gland

A

-Function: secretes melatonin

-Effect: regulates night-day cycles, sleeping schedule

-Release controlled indirectly by visual pathways: intensity & duration of sunlight

50
Q

The Pancreas

A

-Hormones produced in pancreatic islets

-Function: controls blood sugar levels

-Produces & secretes 2 hormones

51
Q

The Pancreas produces & secretes 2 hormones

A

1) Glucagon
2) Insulin

52
Q

Glucagon

A

-produced by alpha cells
-Hyperglycemic effect

 -Effects: Stimulates liver to break down glycogen, convert non-carbohydrate molecules to glucose, release glucose from liver cells

 -Release controlled by dropping blood glucose levels
53
Q

Insulin

A

-produced by beta cells
-Hypoglycemic effect

-Effects: Increases glucose uptake by body cells, inhibits glycogen breakdown, inhibits conversion of non-carbohydrate molecules to glucose

-Release controlled by:
1) Elevated blood glucose
2) Rising blood levels of amino acids & fats
3) Acetylcholine release from parasympathetic
4) Any hyperglycemic hormone

54
Q

What does “hyperglycemic” mean?

A

raises blood sugar levels

55
Q

What does “hypoglycemic” mean?

A

lowers blood sugar levels

56
Q

Diabetes mellitus

A

-inadequate (or absent) release of insulin by pancreas

-Effect: consistently high blood sugar levels
-Normal range (fasting): 99 mg glucose/dl blood (or lower)
-Diabetes (fasting): 126+ mg glucose/dl blood

57
Q

Two types of diabetes mellitus

A

-Type 1: autoimmune condition: insulin is not produced by the pancreas
-Several genes contribute to condition
-Treatment: insulin shots before meals or continuous fusion pumps
-If left untreateddevelopment of vascular & neural problems

-Type 2: insulin resistance: insulin released, but cells do not respond
-Correlated more with lifestyle
-Some genetic component, but almost all are overweight and underactive
-Similar complications to type 1 diabetes if not managed/treated
-Can be managed with diet and exercise

58
Q

Gonads

A

-Females: ovaries produce estrogens & progesterone
-Estrogen function: maturation of reproductive organs, appearance of secondary sex characteristics
-Progesterone function: breast development, cyclic changes in uterine mucosa

-Males: testes produce testosterone
-Function: maturation and maintenance of reproductive organs, appearance of secondary sex characteristics, sex drive, normal sperm production

59
Q

Placenta

A

-temporary endocrine organ
-Produces estrogens, progesterone, human chorionic gonadotropin (hCG)
-Function: maintains pregnancy

Anatomy & Physiology (15 decks)

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