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Human Biology, 13th Edition - Sylvia S. Mader > Ch 15 - Endocrine System > Flashcards

Ch 15 - Endocrine System Flashcards

1
Q

How are the endocrine and nervous system similar? How are they different?

A

Both systems use chemical signals when they respond to changes that might alter homeostasis

Different because the nervous system is composed of neurons. In the endocrine system, sensory receptors detect changes in the internal and external environment.

The CNS then integrates the information and responds by stimulating muscles and glands. Communication depends on nerve signals.

Different because nervous system response is rapid. Endocrine system response is slow because hormones travel through blood. Endocrine system effects are longer lasting.

Both make use of negative feedback mechanisms

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2
Q

What do glands do in the endocrine system?

A

Secrete hormones via the bloodstream to target cells throughout the body

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3
Q

What are exocrine vs endocrine glands?

A

Exocrine = gland secretes products into ducts that are carried to the lumens of other organs or outside the body

Endocrine = secrete products into bloodstream

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4
Q

What are target cells?

A

Cells that can respond to a specific hormone because they have receptor protein for that hormone. The receptor protein and hormone bind together like a key in a lock

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5
Q

What is androgen insensitivity?

A

An individual has X and Y sex chromosomes. The testes remain in the abdominal cavity and produce testosterone. However, the body’s cells lack receptors that are able to combine with testosterone. So the person appears as a female

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6
Q

Does the hypothalamus secrete hormones?

A

Yes, the neurosecretory cells in the hypothalamus secrete hormones that travel in the capillary network that runs between the hypothalamus and pituitary gland. Some secretions stimulate the pituitary, and others inhibit pituitary secretions.

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7
Q

What are prostaglandins?

A

Local hormones that aren’t carried throughout the body, but rather affect neighboring cells.

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8
Q

What are pheromones?

A

Chemical signals that influence the behavior of other individuals. This is how women who live together will end up on the same cycle (via armpit secretions of a woman who is menstruating).

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9
Q

What are peptide hormones? Provide example and process.

A

Hormones that are peptides, glycoproteins, and modified amino acids. Most endocrine glands secrete peptide hormones.

Example: Epinephrine is released by the adrenals, which causes blood glucose to rise in emergency situations. Glucose provides energy for ATP productions. The binding of the hormone to the receptor activates an enzyme, which activates another enzyme and so forth. An enzyme cascade occurs and glycogen is broken down into glucose.

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10
Q

What are steroid hormones? Which three parts of the body produce steroid hormones? What’s one gland that produces hormones that act similar to steroid hormones?

A

Hormones derived from cholesterol that have the same complex of four carbon rings.

Only the adrenal cortex, the ovaries and the testes produce steroid hormones. Thyroid hormones are amines and act similarly to steroid hormones.

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11
Q

Why are peptide hormones called the first messenger and cAMP is the second messenger?

A

Because the hormone never actually enters the cell, it just signals what needs to happen. The secondary messenger actually sets everything in motion. The secondary messenger

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12
Q

How does the way in which steroid hormones bind to a cell differ from that of peptide hormones? What’s the full process?

A

Steroid hormones are able to enter the cell because they’re lipids, so they don’t need to “bind” to the membrane; they just enter it. Once inside, they DO bind to a receptor, normally in the nucleus (sometimes in the cytoplasm).

Inside the nucleus, the hormone-receptor complex then binds with DNA and activates certain genes. Then messenger RNA (mRNA) moves to ribosomes in the cytoplasm, and protein synthesis follows.

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13
Q

Do peptide or steroid hormones act more slowly? Which hormones actions last longer?

A

Steroid. Because it takes more time to synthesize new proteins than to activate enzymes that are already present in cells. Steroid hormones actions last longer.

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14
Q

Name all of the endocrine glands.

A 
Hypothalamus
Pituitary gland (posterior & anterior)
Thyroid
Parathyroids
Adrenal gland (cortex & medulla)
Pancreas
Gonads (testes & ovaries)
Thymus
Pineal gland
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15
Q

What are the hormones released by each gland, and what are the major functions of these hormones?

A

Pg. 336

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16
Q

What are the hormones released by the hypothalamus:

A
  • Hypothalamic-releasing hormones = regulates anterior pituitary stimulating hormones
  • Example 1: Thyroid-releasing hormone, or TRH, which stimulates anterior pituitary to release TSH [see next flashcard])
  • Example 2: Corticotropin-releasing hormone (CRH) stimulates adrenal cortex
  • Hypothalamic-inhibiting hormones = regulates anterior pituitary inhibiting hormones (i.e. thyroid-inhibiting hormone, or TIH)

As babies suck a mother’s nipple, nerve signals reach the hypothalamus, which creates more oxytocin. Then the pituitary gland releases it

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17
Q

What are the hormones released by the posterior pituitary gland?

A
  • ADH (antidiuretic) = stimulates water reabsorption by kidneys
  • Oxytocin = stimulates uterine muscle contractions, release of milk by mammary glands

Both of these hormones are initially passed through axons from the hypothalamus to the posterior pituitary, where they’re stored in axon endings. Neurons in the hypothalamus are sensitive to water-salt balance of the blood, so if blood is too concentrated, ADH is released from the posterior pituitary so that more water is reabsorbed by the kidneys.

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18
Q

What are the hormones released by the anterior pituitary gland?

A

These hormones pass from the hypothalamus to the pituitary gland by way of the portal system, or capillaries, between these two glands.

These hormones are hypothalamic-releasing or hypothalamic-inhibiting.

Those that act on other glands:

  • TSH (thyroid stim. hormone) = stimulates thyroid
  • ACTH (adrenocorticotropic) = stimulates adrenal cortex
  • FSH + LH (gonadotropic) = stimulate the gonads to produce eggs and sperm, or gametes; sex hormones production

Those that don’t act on or affect other glands (stimulate a structure, or non-gland, directly):

  • Prolactin (PRL) = milk production in mammary glands (mammary glands are not part of endocrine system because they aren’t endocrine, and thus don’t produce hormones)
  • GH (growth hormone) = cell division, protein synthesis and bone growth (acts directly on soft tissues & bones); promotes fat metabolism instead of glucose metabolism
  • MSH (melanocyte-stimulating) = unknown function in humans & concentration very low; causes skin-color changes in many fishes, amphibians, and reptiles
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19
Q

What are the hormones released by the thyroid?

A
  • T4 (thyroxine) + T3 (triiodothyronine) = increases metabolic rate; regulates growth and development
  • Calcitonin = lowers blood calcium level by depositing calcium in the bones

T3 and T4 do not have a target organ. Instead, they stimulate all cells of the body to metabolize at a faster rate. More glucose is broken down and more energy is used

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20
Q

What are the hormones released by the parathyroids?

A
  • PTH (parathyroid) = raises blood calcium level (opposite of calcitonin) by promoting the activity of osteoclasts and releasing calcium from bones. Also activates vitamin D (a hormone called calcitriol) in the kidneys, which promotes calcium reabsorption by the kidneys
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21
Q

What are the hormones released by the adrenal cortex? Type of hormone?

A

Steroid hormones:

  • Cortisol (glucocorticoids) = raises blood glucose level; stimulates breakdown of protein; regulates carb, protein and fat metabolism (to create energy)
  • Aldosterone (mineralocorticoids) = reabsorption of sodium and excretion of potassium (secretions controlled by renin secretions from kidneys)
  • Sex hormones = stimulates reproductive organs and bring about sex characteristics
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22
Q

What are the hormones released by the adrenal medulla?

A
  • Epinephrine & norepinephrine = released in emergency situations to raise blood glucose levels
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23
Q

What are the hormones released by the pancreas?

A
  • Insulin = lowers blood glucose level

- Glucagon = raises blood glucose level (opposite effect of insulin)

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24
Q

What are the hormones released by the gonads (testes & ovaries)? What type of hormone are these?

A

Steroid hormones

Testes:
- Androgens (i.e. testosterone) = stimulate male characteristics

Ovaries:
- Estrogens and progesterone = stimulate female sex characteristics

Feedback from the testes and ovaries controls the hypothalamic secretion of gonadotropin-releasing hormone (GnRH) and the secretions of LH and FSH by the anterior pituitary gland.

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25
Q

What are the hormones released by the thymus?

A

Thymosins = stimulates the production and maturation of T lymphocytes

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26
Q

What are the hormones released by the pineal gland?

A

Melatonin = Controls circadian and circannual rhythms; possibly involved in maturation or sexual organs

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27
Q

How would someone get diabetes insipidus?

A

When someone is unable to produce ADH. They produce copious amounts of urine and are dehydrated.

28
Q

What type of feedback mechanism is NOT used to maintain homeostasis?

A

Positive feedback, because a stimulus causes an effect that’s ever-increasing

29
Q

What is pituitary dwarfism?

A

If too little GH is produced during childhood, they end up having a very small stature (but normal proportions)

30
Q

How would one become a “giant”? What health problems do they usually have?

A

If too much GH is secreted, a person can become a giant. Giants usually have poor health because GH has a secondary effect on blood sugar that promotes a form of diabetes called diabetes mellitus.

31
Q

What is acromegaly?

A

When GH is overproduced in adults. Since long bone growth isn’t possible in adults anymore, only the feet, hands and face (the chin, nose and eyebrow ridges) can respond, so these parts become overly large.

32
Q

Where are the thyroid and parathyroid glands located?

A

Thyroid is in neck, attached to trachea. Parathyroid glands are embedded in the posterior surface of the thyroid gland.

33
Q

What is the thyroid gland composed of? Why is this important? What do we need to keep the thyroid healthy?

A

It’s composed of follicles, or small spheres made of thyroid cells filled with T3 and T4.

T3 contains three iodine atoms.
T4 contains four iodine atoms.

The thyroid actively requires iodine to produce T3 and T4.

34
Q

What happens to the thyroid when we don’t have enough iodine in our diets? What is the name for this?

A

The thyroid is constantly being stimulated by TSH from the anterior pituitary gland, as it receives signals that T3 and T4 still haven’t been released from the thyroid (due to the lack of iodine). Thus the thyroid enlarges, resulting in simple goiter

35
Q

What is congenital hypothyroidism?

A

When the thyroid fails to develop properly since childhood, it doesn’t produce enough thyroid hormones. This causes the child to be a short and stalky individual who has hypothyroidism.

36
Q

What is myxedema?

A

Lethargy, weight gain, loss of hair, slower pulse rate, lowered body temperature and thickness and puffiness of the skin. This is caused by hypothyroidism in adults

37
Q

What is exophthalmic goiter?

A

An overactive thyroid that secretes too much thyroid hormones (hyperthyroidism). In this situation, the eyes protrude because of edema in eye socket tissues. People with this condition usually become hyperactive, nervous, irritable and suffer from insomnia. Removal of a portion of the thyroid can help.

38
Q

What is hypoparathyroidism?

A

Low PTH production. Causes a dramatic drop in blood calcium, followed by excessive nerve excitability. Leads to tetany where body shakes from continuous muscle contraction.

39
Q

What is hyperparathyroidism?

A

High PTH production. Results in osteoporosis because osteoclasts are constantly removing calcium from the bones into the blood. Could form calcium kidney stones.

40
Q

Which of the adrenal glands is under nervous control? What does this mean?

A

The adrenal medulla. The hypothalamus initiates nerve signals that travel by way of the brain stem, spinal cord, and preganglionic sympathetic nerve fibers to the adrenal medulla. This stimulates hormone release from the medulla (nor/epinephrine) – fight or flight response to stress.

41
Q

Stress of all types (physical and emotional) prompts the hypothalamus to stimulate which gland?

A

The adrenals

42
Q

Which hormones (from where) stimulate the adrenal cortex?

A

Corticotropin-releasing hormone (CRH) from hypothalamus and ACTH from the anterior pituitary gland.

43
Q

Does the adrenal cortex or medulla produce a longer response to stress?

A

Adrenal cortex hormones = long-term stress response

44
Q

What’s the role of cortisol/glucocorticoids? What role has to do with why people get sick easier when they’re really stressed?

A
  1. Promote the breakdown of muscle proteins to amino acids, which are then taken up by the liver in the blood stream and are converted into glucose
  2. Promotes the metabolism of fatty acids rather than carbs
  3. Also counteracts inflammatory response that leads to pain and swelling; suppresses immune cells, making the person more susceptible to injury and infection
45
Q

Which hormone is controlled by renin secretions from the kidneys?

A

Aldosterone, which is secreted by the adrenal cortex. Called the renin-angiotensin-aldosterone system raises blood pressure by promoting reabsorption of sodium and excretion of potassium. Reabsorption of sodium causes water to be reabsorbed, and blood pressure increases.

46
Q

Which organ releases ANH (atrial natriuretic hormone) but is not considered an endocrine gland? Why? What is ANH?

A

ANH inhibits the secretion of aldosterone from the adrenal cortex so as to excrete sodium, and thus water, thereby decreasing blood pressure.

It’s not included in the endocrine system because it’s main function is to circulate/pump blood, not to release hormones.

47
Q

What are the three layers of the adrenal cortex?

A
  1. Zona glomerulosa
  2. Zona fasciculata
  3. Zona reticularis
48
Q

What are the sex steroids produced by the adrenal cortex, specifically by the zona fasciculata and zona reticularis?

A
  • androgens = male sex hormones
  • estrogen = female sex hormones
  • DHEA = the primary androgen hormone, which is a precursor for testosterone
  • estradiol = a form of estrogen
49
Q

What is Addison disease?

A

When blood level of glucocorticoids (cortisol) is LOW due to hyposecretion. The presence of excessive but ineffective ACTH (which normally stimulates cortex to produce cortisol) causes a bronzing of the skin because ACTH, like MSH, can lead to a build up of melanin. Without cortisol, glucose can’t be replenished when a stressful situation arises. Mild infections can lead to death. Loss of sodium and water, low blood pressure and severe dehydration.

50
Q

What is Cushing syndrome?

A

HIGH levels of cortisol. Most commonly caused by administering glucocorticoids to treat other conditions like chronic inflammation. Fat gets deposited in midsection and muscle protein is metabolized.

Could also be caused by tumors that affect the pituitary gland, which results in excess ACTH production. OR can affect the adrenal cortex itself.

51
Q

What are the different cell types in the pancreas? Which one stimulates insulin secretions?

A
  • A cells = secrete glucagon, which breaks down glycogen into glucose when our blood sugar levels are low (usually between meals). Promotes use of fat and protein instead of glucose as energy sources
  • B cells = secrete insulin when blood glucose level is high
  • D cells = releases somatostatin, a hormone that’s released at the same time as insulin to regulate the digestive processes
52
Q

What are the different types of tissues of the pancreas?

A
  • Exocrine tissue = produces and secretes DIGESTIVE JUICES that go by way of ducts to the small intestine (the duodenum)
  • Endocrine tissue = “pancreatic islets” or islets of Langerhans that produce hormones (insulin and glucagon)
53
Q

_____ causes glucose to be stored as _____ in:

1.
2.
3.

A

Insulin causes glucose to be stored as glycogen in:

  1. the liver
  2. muscles (forms protein)
  3. adipose tissue (forms fat)
54
Q

What is diabetes mellitus, and what are the symptoms?

A

Also known as just “diabetes.” Type 1 and type 2.
Mellitus = honey or sweetness, b/c people pee out glucose
Symptoms = Fatigue, hunger, weight loss, vision problems.

55
Q

What is type 1 diabetes?

A

When the pancreas doesn’t produce enough insulin. Body turns to metabolism of fat, which leads to buildup of ketones in the blood, called ketoacidosis, which increases acidity of blood. Daily insulin injections

56
Q

What is type 2 diabetes?

A

When insulin binds to a receptor, but the number of glucose carriers does not increase as a result like it should. Therefore the cell is said to be insulin resistant. Oftentimes due to being overweight/obese, as adipose tissue produces a substance that impairs insulin receptor function

57
Q

In a non-diabetic person, how long does it take for blood glucose levels to return to normal after eating glucose?

A

2 hours

58
Q

What is gestational diabetes?

A

Diabetes during pregnancy

59
Q

What are the gonads?

A

The testes and ovaries

60
Q

What are anabolic steroids?

A

Testosterone or related chemicals that athletes take to increase their performance

61
Q

What is the thymus and what hormone does it secrete?

A

Right next to/on top of the heart. Lymphocytes that originate in the bone marrow pass through the thymus and then are transformed into T-lymphocytes.

The lobules of they thymus are lined by epithelial cells that secrete hormones called thymosins. Thymosins stimulate the production and maturation of T-lymphocytes.

62
Q

How are circadian rhythms controlled?

A

By a biological clock in the hypothalamus. The pineal gland produces melatonin

63
Q

What hormones do the kidneys produce?

A
  • renin

- EPO (erythropoietin) = stimulates red blood cell formation in the red bone marrow

64
Q

What is leptin and where is it produced?

A

Leptin is produced by adipose tissue to signal satiety or fullness. Ghrelin is the opposite, and produces the sensation of hunger.

65
Q

What are prostaglandins and where are they produced?

A

They’re potent chemical signals produced within cells from a fatty acid called arachidonate. They act locally (not distributed throughout the blood).

In uterus cause muscles to contract (pain and discomfort of menstruation).

Aspirin reduces body temperature and controls pain because of its effect on prostaglandins.

Some reduce gastric secretions like reflux.

Others lower blood pressure, treatment for hypertension.

66
Q

What is the neuroendocrine system?

A

What we oftentimes call the nervous + endocrine system because they work so closely together. The hypothalamus bridges these activities

Human Biology, 13th Edition - Sylvia S. Mader (16 decks)

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