Ch. 11 Endocrine Glands Flashcards

1
Q

Homeostatic effectors are controlled by which gland: endocrine or exocrine?

A

Endocrine glands

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2
Q

Endocrine Glands

A

Secrete hormones into blood

Hormones are carried to Target Cells which have receptors for those hormones

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3
Q

Many organs secrete hormones. List 4.

A
  1. Heart
  2. Liver
  3. Kidneys
  4. Adipose tissue

Hormone signaling involves a lot of different organs

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4
Q

Neurohormones

A

Secreted by specialized cells of the hypothalamus

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5
Q

Hormones help regulate many different things. List 3.

A
  1. Body metabolism
  2. Growth
  3. Reproduction
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6
Q

Chemical Classification of Hormones: Amines

A

Derived from tyrosine and tryptophan

ex: hormones from adrenal medulla, thyroid, and pineal glands

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7
Q

Chemical Classification of Hormones: Polypeptides and Proteins

A

ex: antidiuretic hormone, insulin, and growth hormone

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8
Q

Chemical Classification of Hormones: Glycoproteins

A

Long polypeptides bound to a carbohydrate

ex: follicle-stimulating and luteinizing hormones

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9
Q

Chemical Classification of Hormones: Steroids

A

Lipids derived from cholesterol (not very water-soluble)

ex: testosterone, estradiol, progesterone, cortisol

Secreted by adrenal cortex and gonads

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10
Q

Synergistic Effects

A

Occur when 2 or more hormones work together to produce a particular effect

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11
Q

Synergistic Effects: Additive

A

Epinephrine and norepinephrine each affect the heart in the same way

Even if you take epinephrine away, norepinephrine is still affecting the organ in the same way

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12
Q

Synergistic Effects: Complementary

A

Each hormone contributes a different piece of an overall outcome
–ex: producing milk requires estrogen, prolactin, and oxytocin

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13
Q

Permissive Effects

A

Subset of complementary effect

Occur when one hormone makes the target cell more responsive to a second hormone

Exposure to estrogen makes the uterus more responsive to progesterone
–estrogen sets stage for effects of progesterone

Increased secretion of PTH makes intestines more responsive to Vitamin D3 in calcium absorption

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14
Q

How do permissive effects work?

A

First hormone –> sensitizes organ to effects of 2nd hormone –> get desired effects from 2nd hormone (2nd hormone is actually inducing effect)

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15
Q

Antagonistic Effects

A

Occur when hormones work in opposite directions

Insulin and glucagon both affect adipose tissue

  • -insulin stimulates fat storage
  • -glucagon stimulates fat breakdown

Have to be working on same organ to be antagonistic effects

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16
Q

Hormone Action

A

Hormones bind to receptors on or in target cells

  • -binding is highly specific
  • -hormones bind to receptors w/ a High Affinity
  • -hormones bind to receptors w/ a low capacity; saturating the receptors w/ hormone molecules

Hormones are released at really low doses

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17
Q

Hormone Action: Lipophilic hormone receptors

A

In cytoplasm or nucleus

Hydrophobic, receptors found inside cell

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18
Q

Hormone Action: Water-soluble hormone receptors

A

On outer surface of plasma membrane

Facing eternal environment

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19
Q

Nuclear Receptors

A

Lipophilic steroid hormones and thyroid hormone

  • -travel to target cells attached to Carrier Proteins
  • -at the target cell, dissociate from the carrier protein and diffuse across the plasma membrane
  • -receptors are found w/in the nucleus and are called Nuclear Hormone Receptors because they activate genetic transcription

These hormone receptors serve as Transcription Factors
–making mRNA

They are activated by the binding of the hormone

The effect of these hormones is therefore to produce new proteins, usually enzymes that change metabolism inside the cell

Going to affect gene expression

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20
Q

Hormones: 2nd Messengers

A

Hormones that cannot cross the plasma membrane
–water-soluble

Activate an intracellular mediator called a 2nd Messenger

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21
Q

List the 3 major 2nd messenger mechanisms

A
  1. Adenylate cyclase (activates a protein kinase)
  2. Phospholipase C (controls intracellular Ca2+)
  3. Tyrosine kinases
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22
Q

Pituitary gland is attached to the hypothalamus by the ____.

A

Infundibulum

23
Q

The pituitary gland is divide into what lobes?

A

Anterior lobe (adenohypophysis)

Posterior lobe (neurohypophysis)

24
Q

Anterior Pituitary

A

Glandular epithelium w/ 2 parts - pars distalis and pars tuberalis

25
Posterior Pituitary
Nervous tissue aka pars nervosa
26
Anterior Pituitary Hormones
Trophic hormones stimulate hormone secretion in other glands: - -growth hormone (GH) - -thyroid-stimulating hormone (TSH) - -adrenocorticotropic hormone (ACTH) - -follicle-stimuatling hormone (FSH) - -luteinizing hormone (LH) - in the male, it is interstitial cell stimulating hormone (ICSH) - -prolactin (PRL)
27
Feedback Control of the Anterior Pituitary
Final product regulate secretion of pituitary hormones - negative feedback inhibition Relationship between the hypothalamus, anterior pituitary, and target tissue is called an Axis Inhibition can occur at the pituitary gland level, inhibiting response to hypothalamic hormones Inhibition can occur at the hypothalamus level, inhibiting secretion of releasing hormones
28
Posterior Pituitary Hormones
Stores and releases 2 hormones made in hypothalamus - -Antidiuretic Hormone (ADH): promotes retention of water in kidneys (also called arginine vasopressin - AVP) - -Oxytocin: stimulates contractions in childbirth and milk let-down in lactation
29
Adrenal Glands
Found atop the kidneys Consist of an outer adrenal cortex and an inner adrenal medulla that function as 2 separate glands --one organ, 2 real parts
30
Adrenal Glands: Adrenal Medulla
Adrenal Medulla is neural tissue and secretes epinephrine and norepinephrine in response to sympathetic neural stimulation
31
Adrenal Glands: Adrenal Cortex
Adrenal Cortex is glandular epithelium and secretes steroid hormones in response to ACTH (comes from anterior pituitary gland) 3 layers: - -zona glomerulosa - -zona fasciculata - -zona reticularis
32
Adrenal Cortex
Secretes hormones made from cholesterol; called corticosteroids or corticoids 3 categories: - -Mineralocorticoids - -Glucocorticoids - -Adrenal androgens
33
Mineralocorticoids
From zona glomerulosa Regulate Na+ and K+ balance ex: Aldosterone
34
Glucocorticoids
From zona fasciculata Regulate glucose metabolism ex: Cortisol
35
Adrenal Androgens
From zona reticularis Weak sex hormones that supplement those made in the gonads
36
Cortisol (Hydrocortisone)
Stimulates protein degradation --allows us to get energy from protein Stimulates gluconeogenesis (making glucose) and inhibits glucose utilization to raise blood glucose levels Stimulates lipolysis
37
When do cortisol levels spike?
Early in the day | When stressed
38
Thyroid Gland
Located just below the larynx Has 2 lobes on either side of the trachea, connected by the isthmus
39
Thyroid Gland Structure
Consists of hollow spaces called Thyroid Follicles lined w/ simple cuboidal epithelium composed of Follicular Cells that produce Thyroglobulin Interior of the follicles is filled w/ a fluid called Colloid Outside of the follicles are Parafollicular Cells that secrete Calcitonin
40
Production of Thyroid Hormone
Thyroglobulin is made by follicular cells Thyroid follicles actively accumulate Iodide (I-) and secrete it into the colloid. - -iodine is attached to tyrosines w/ the thyroglobulin molecule - -1 iodine produces monoiodotyrosine (MIT) - -2 iodines produce diiodotyrosine (DIT) Enzyme w/in the colloid attach MIT and DIT together: - -DIT + DIT = T4 (thyroxine) - -DIT + MIT = T3 (triiodothyronine) These are still bound to thyroglobulin - -dissociate from thyroglobulin when the thyroid gland is stipulated by TSH - -secreted into the blood
41
What is T4?
Thyroxine DIT + DIT = T4
42
What is T3?
Triiodothyronine DIT + MIT =T3
43
T3/T4: Which one is the active form? Which one can be converted to the other by iodinases?
T3 is active form T4 (longer half-life) can be converted by T3 by iodinases in cells
44
Thyroid Hormone
1. Stimulates protein synthesis 2. Promotes maturation of nervous system 3. Increases rates of cellular respiration 4. Elevates basal metabolic rate
45
What are 2 diseases associated w/ thyroid problems?
Hyperthyroidism and Hypothyroidism
46
Parathyroid Gland
Generally 4 glands embedded in the back of thyroid gland Secrete Parathyroid Hormone (PTH) Hormone promotes a rise in blood calcium by acting on bones, kidneys, and intestines --PTH tells kidneys to retain calcium, tells bones to break down a little to get more calcium, and tells intestines to absorb more calcium
47
Pancreas
Both an endocrine and exocrine gland Endocrine cells are located in pancreatic islets (islets of Langerhans)
48
Pancreas: Alpha Cells
Glucagon
49
Pancreas: Beta Cells
Insulin destruction of Beta cells = type 1 diabetes
50
Insulin
Primary hormone regulating plasma glucose concentration Secreted by beta cells when blood glucose levels rise after a sugary or CHO meal Its purpose is to lower blood glucose levels to the "normal' range
51
Insulin: Mechanisms of Work
Binds to receptors on target cells - -vesicles w/ GLUT4 carrier proteins bind to membrane - -glucose diffuses through GLUT4 channels by facilitated diffusion - -occurs in adipose tissue, skeletal muscle, and the liver Indirectly stimulates the enzyme glycogen synthase in liver and skeletal muscles to promote sugar storage Stimulates adipose tissue to store fat
52
How soon does the body to store blood glucose after eating?
W/in minutes in ingesting a meal
53
Glucagon
Antagonistic to insulin Secreted by alpha cells when blood glucose levels are low Purpose is to raise blood glucose levels to a "normal" level Stimulates liver to hydrolyze glucagon into glucose (glycogenolysis) and release it into the blood Stimulates gluconeogenesis, conversion of nonCHOs into glucose Stimulates lipolysis in adipose tissue so fat is released as used as a fuel source instead of glucose