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Anatomy and Physiology > Ch.9: The Endocrine System > Flashcards

Ch.9: The Endocrine System Flashcards

1
Q

The endocrine system is the _____ of the body.

A
  • Second controlling system

* Nervous system is the fast-control system

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2
Q

Uses chemical messengers _____ that are released into the blood

A

Hormones

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3
Q

Hormones control which major processes?

A
  • Reproduction
  • Growth and development
  • Mobilization of body defenses
  • Maintenance of much of homeostasis
  • Regulation of metabolism
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4
Q

Hormones are produced by:

A

Specialized cells

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5
Q

Cells secrete hormones into:

A

Extracellular fluids

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6
Q

Blood transfers hormones to:

A
  • Target sites

* These hormones regulate the activity of other cells

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7
Q

Endocrinology is the scientific study of:

A

Hormones and endocrine organs

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8
Q

Hormones are classified chemically as:

A
  • Amino acid-based
  • Steroids
  • Prostaglandins
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9
Q

What are steroids made from?

A

Cholesterol

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10
Q

What are prostaglandins made from?

A

Highly active lipids that act as local hormones

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11
Q

Hormones affect only what certain tissues or organs?

A

Target cells or target organs

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12
Q

Target cells must have specific:

A

Protein receptors

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13
Q

Hormone binding alters:

A

Cellular activity

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14
Q

Concept Link

A

A hormone’s relationship to its target cells resembles that of an enzyme to its substrate. Recall that enzymes interact very specifically with their substrates (Chapter 2, pp. 51‒52). Hormone interactions with target cell receptors are also very specific and fit together like two pieces of a puzzle.

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15
Q

When hormones arouse cells or alter cellular activity, typically, one or more of the following occurs:

A
  • Change plasma membrane permeability or membrane potential by opening or closing ion channels
  • Activate or inactivate enzymes
  • Stimulate or inhibit cell division
  • Promote or inhibit secretion of a product
  • Turn on or turn off transcription of certain genes
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16
Q

Hormones act by what two mechanisms?

A
  1. Direct gene activation
    • Used by steroid hormones and thyroid hormones
  2. Second-messenger system
    • Used by protein and peptide hormones
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17
Q

What is the process of direct gene activation?

A
  1. Steroid diffuse through the plasma membrane of target cells
  2. Once inside the cell, the hormone enters the nucleus
  3. Then, the hormone binds to a specific protein within the nucleus
  4. Hormone-receptor complex binds to specific sites on the cell’s DNA
  5. Certain genes are activated to transcribe messenger RNA
  6. New proteins are synthesized
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18
Q

What is the process of the second-messenger system?

A
  1. Hormone (first messenger) binds to a membrane receptor
  2. Activated receptor sets off a series of reactions that activates an enzyme
  3. Enzyme catalyzes a reaction that produces a second-messenger molecule (such as cyclic AMP, known as cAMP)
  4. Oversees additional intracellular changes to promote a specific response in the target cell
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19
Q

Hormone levels in the blood are maintained mostly by:

A

Negative feedback

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20
Q

A stimulus or low hormone levels in the blood trigger the release of more:

A

Hormone

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21
Q

Hormone release stops once an _____ in the blood is reached.

A

Appropriate level

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22
Q

The stimuli that activate endocrine glands fall into what three major categories?

A

Hormonal
Humoral
Neural

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23
Q

What is hormonal stimuli?

A

• Most common category of stimulus
• Endocrine organs are activated by other hormones
• Example:
*Hormones of the hypothalamus stimulate the anterior pituitary to secrete its hormones

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24
Q

What is humoral stimuli?

A

Changing blood levels of certain ions and nutrients stimulate hormone release
• Humoral indicates various body fluids, such as blood and bile
Examples:
• Parathyroid hormone and calcitonin are produced in response to changing levels of blood calcium levels
• Insulin is produced in response to changing levels of blood glucose

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25
Q

What is neural stimuli?

A

• Nerve fibers stimulate hormone release
• Most are under the control of the sympathetic nervous system
• Examples:
Sympathetic stimulation of the adrenal medulla to release epinephrine and norepinephrine

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26
Q

What are the major endocrine organs?

A
  • Hypothalamus
  • Pituitary gland
  • Pineal gland
  • Thyroid gland
  • Parathyroid glands
  • Thymus
  • Adrenal glands
  • Pancreas
  • Gonads (testes and ovaries)
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27
Q

What are some glands that have purely endocrine functions?

A
  • Anterior pituitary
  • Thyroid
  • Adrenals
  • Parathyroids
  • Other glands are mixed glands, with both endocrine and exocrine functions (pancreas, gonads)
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28
Q

Endocrine glands are _____ glands.

A

Ductless

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29
Q

Hormones are released directly into _____ or _____.

A
  • Blood

* Lymph

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30
Q

What is the pituitary gland?

A
  • Pea-sized gland that hangs by a stalk from the hypothalamus in the brain
  • Protected by the sella turcica of the sphenoid bone
  • Often called the “master endocrine gland”
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31
Q

The pituitary gland has what two functional lobes?

A
  • Anterior pituitary—glandular tissue

* Posterior pituitary—nervous tissue

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32
Q

Hypothalamus produces _____ hormones and _____ hormones

A
  • Releasing
  • Inhibiting
  • These hormones are released into portal circulation, which connects hypothalamus to anterior pituitary
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33
Q

The hypothalamus makes what two hormones?

A
  • Oxytocin and antidiuretic hormone

* Carried to posterior pituitary via neurosecretory cells for storage

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34
Q

What is the function of the posterior pituitary gland?

A
  • Does not make the hormones it releases

* Stores hormones made by the hypothalamus

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35
Q

What are the two hormones released by the posterior pituitary gland?

A
  • Oxytocin

* Antidiuretic hormone (ADH)

36
Q

What is the function of oxytocin when it is released by the posterior pituitary gland?

A
  • Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding
  • Causes milk ejection (let-down reflex) in a breastfeeding woman
37
Q

What is the function of antidiuretic hormone (ADH) when it is released by the posterior pituitary gland?

A
  • Inhibits urine production (diuresis) by promoting water reabsorption by the kidneys
  • Urine volume decreases, blood pressure increases
  • In large amounts, causes constriction of arterioles, leading to increased blood pressure (the reason why ADH is known as vasopressin)
  • Alcohol inhibits ADH secretion
38
Q

What are the six anterior pituitary hormones?

A 
Two hormones affect nonendocrine targets
1. Growth hormone
2. Prolactin
Four are tropic hormones
3. Follicle-stimulating hormone
4. Luteinizing hormone
5. Thyrotropic hormone
6. Adrenocorticotropic hormone
39
Q

What are the properties which relate all anterior pituitary hormones?

A
  • Are proteins (or peptides)
  • Act through second-messenger systems
  • Are regulated by hormonal stimuli
  • Are regulated mostly by negative feedback
40
Q

What is growth hormone and what is its function?

A
  • General metabolic hormone
  • Major effects are directed to growth of skeletal muscles and long bones
  • Plays a role in determining final body size
  • Causes amino acids to be built into proteins
  • Causes fats to be broken down for a source of energy
41
Q

What is the function of prolactin (PRL)?

A
  • Stimulates and maintains milk production following childbirth
  • Function in males is unknown
42
Q

What are the types of gonadotropic hormones and what are their functions?

A
  • Regulate hormonal activity of the gonads
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
43
Q

What is the function of follicle-stimulating hormone (FSH)?

A
  • Stimulates follicle development in ovaries

* Stimulates sperm development in testes

44
Q

What is the function of luteinizing hormone (LH)?

A
  • Triggers ovulation of an egg in females

* Stimulates testosterone production in males

45
Q

What is the function of thyrotropic hormone (TH), also called thyroid-stimulating hormone (TSH)?

A

Influences growth and activity of the thyroid gland

46
Q

What is the function of adrenocorticotropic hormone (ACTH)?

A

Regulates endocrine activity of the adrenal cortex

47
Q

The pineal gland hangs from the roof of the _____ of the brain.

A

Third ventricle

48
Q

The pineal gland secretes:

A
  • Melatonin
  • Believed to trigger the body’s sleep/wake cycle
  • Believed to coordinate the hormones of fertility in humans and to inhibit the reproductive system until maturity occurs
49
Q

The thyroid gland is found at the base of the _____, inferior to the _____.

A
  • Throat

* Adam’s apple

50
Q

The thyroid gland consists of _____ and a connecting _____.

A
  • Two lobes

* Isthmus

51
Q

Follicles found in the thyroid gland are _____ structures that store _____ material.

A
  • Hollow

* Colloidal

52
Q

The thyroid produces what two hormones?

A
  1. Thyroid hormone

2. Calcitonin

53
Q

What is thyroid hormone and what is its function?

A

• Major metabolic hormone
• Controls rate of oxidation of glucose to supply body heat and chemical energy
• Needed for tissue growth and development
• Composed of two active iodine-containing hormones
*Thyroxine (T4)—secreted by thyroid follicles
*Triiodothyronine (T3)—conversion of T4 at target tissues

54
Q

What is the function of calcitonin?

A
  • Decreases blood calcium levels by causing calcium deposition on bone
  • Antagonistic to parathyroid hormone
  • Produced by parafollicular cells found between the follicles
55
Q

What are parathyroid glands?

A

Tiny masses on the posterior of the thyroid

56
Q

Parathyroid glands secrete:

A
  • Parathyroid hormone (PTH)
  • Most important regulator of calcium ion (C a2+) homeostasis of the blood
  • Stimulates osteoclasts to remove calcium from bone
  • Hypercalcemic hormone (increases blood calcium levels)
  • Stimulates the kidneys and intestine to absorb more calcium
57
Q

The thymus is located in the upper _____, posterior to the _____.

A
  • Thorax

* Sternum

58
Q

The thymus is largest in _____ and _____.

A
  • Infants

* Children

59
Q

The thymus _____ in size throughout adulthood.

A

Decreases

60
Q

The thymus produces a hormone called:

A
  • Thymosin
  • Matures some types of white blood cells
  • Important in developing the immune system
61
Q

The adrenal glands sit on top of the _____.

A

Kidneys

62
Q

What are the two regions of the adrenal glands?

A
  1. Adrenal cortex

2. Adrenal medulla

63
Q

What is the adrenal cortex?

A

Outer glandular region of the adrenal glands that consists of three layers that produce corticosteroids
• Mineralocorticoids are secreted by outermost layer
• Glucocorticoids are secreted by middle layer
• Sex hormones are secreted by innermost layer

64
Q

What is the adrenal medulla?

A

Inner neural tissue region of the adrenal glands

65
Q

What are mineralocorticoids (mainly aldosterone)?

A
  • Produced in outer adrenal cortex
  • Regulate mineral (salt) content in blood, particularly sodium and potassium ions
  • Regulate water and electrolyte balance
  • Target organ is the kidney
66
Q

Release of aldosterone is stimulated by:

A
  • Humoral factors (fewer sodium ions or too many potassium ions in the blood)
  • Hormonal stimulation (ACTH)
  • Renin and angiotensin II in response to a drop in blood pressure
67
Q

Aldosterone production is inhibited by _____, a hormone produced by the heart when _____ is too high

A
  • Atrial natriuretic peptide (ANP)

* Blood pressure

68
Q

What are glucocorticoids (including cortisone and cortisol)?

A
  • Produced by middle layer of adrenal cortex
  • Promote normal cell metabolism
  • Help resist long-term stressors by increasing blood glucose levels (hyperglycemic hormone)
  • Anti-inflammatory properties
  • Released in response to increased blood levels of ACTH
69
Q

What are sex hormones?

A
  • Produced in the inner layer of the adrenal cortex
  • Small amounts are made throughout life
  • Most of the hormones produced are androgens (male sex hormones), but some estrogens (female sex hormones) are also formed
70
Q

The adrenal medulla produces what two similar hormones (catecholamines)?

A
  1. Epinephrine (adrenaline)
  2. Norepinephrine (noradrenaline)
    • These hormones prepare the body to deal with short-term stress (“fight or flight”) by:
    *Increasing heart rate, blood pressure, blood glucose levels
    *Dilating small passageways of lungs
71
Q

What is the pancreas?

A
  • Located in the abdomen, close to stomach

* Mixed gland, with both endocrine and exocrine functions

72
Q

The pancreatic islets (islets of Langerhans) produce _____.

A
  • Hormones
  • Insulin
  • Glucagon
  • These hormones are antagonists that maintain blood sugar homeostasis
73
Q

What is insulin produced by and what is its function?

A
  • Beta cells
  • Released when blood glucose levels are high
  • Increases the rate of glucose uptake and metabolism by body cells
  • Effects are hypoglycemic
74
Q

What is glucagon produced by and what is its function?

A
  • Alpha cells
  • Released when blood glucose levels are low
  • Stimulates the liver to release glucose to blood, thus increasing blood glucose levels
75
Q

What do gonads produce?

A
  • Sex cells

* Sex hormones

76
Q

What are ovaries and what are their function?

A 
• Female gonads located in the pelvic cavity
• Produce eggs
• Produce two groups of steroid hormones
1. Estrogens
2. Progesterone
77
Q

What are testes and what are their function?

A
  • Male gonads suspended outside the pelvic cavity
  • Produce sperm
  • Produce androgens, such as testosterone
78
Q

What is the function of estrogens?

A
  • Stimulate the development of secondary female characteristics
  • Mature the female reproductive organs
79
Q

With progesterone, estrogens also:

A
  • Promote breast development

* Regulate menstrual cycle

80
Q

What is the function of progesterone?

A
  • Acts with estrogen to bring about the menstrual cycle
  • Helps in the implantation of an embryo in the uterus
  • Helps prepare breasts for lactation
81
Q

Testes produce several:

A

Androgens

82
Q

Testosterone is the most important androgen

A
  • Responsible for adult male secondary sex characteristics
  • Promotes growth and maturation of male reproductive system
  • Required for sperm cell production
83
Q

Other organs that are generally nonendocrine in function also secrete hormones, such as:

A
  • Stomach
  • Small intestine
  • Kidneys
  • Heart
84
Q

What is the function of the placenta?

A
  • Produces hormones that maintain pregnancy
  • Some hormones play a part in the delivery of the baby
  • Produces human chorionic gonadotropin (hCG) in addition to estrogen, progesterone, and other hormones
  • Human placental lactogen (h P L) prepares the breasts for lactation
  • Relaxin relaxes pelvic ligaments and pubic symphysis for childbirth
85
Q

In the absence of disease, efficiency of the _____ remains high until _____.

A
  • Endocrine system

* Old age

86
Q

Decreasing function of female ovaries at menopause leads to such symptoms as:

A
  • Osteoporosis
  • Increased chance of heart disease
  • Possible mood changes
87
Q

Efficiency of all endocrine glands gradually decreases with aging, which leads to a generalized increase in incidence of:

A
  • Diabetes mellitus
  • Immune system depression
  • Lower metabolic rate
  • Cancer rates in some areas

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