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SEMI FINALS > ENDOCRINE SYSTEM > Flashcards

ENDOCRINE SYSTEM Flashcards

1
Q

Hormones are classified chemically as:

A

•Amino acid–based, which includes:
▪ Proteins
▪ Peptides
▪ Amines
•Steroids—made from cholesterol
•Prostaglandins—made from highly active lipids that act
as local hormones

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2
Q

Hormones act by two mechanisms

A
  1. Direct geneactivation
    ▪ Used by steroid hormones and thyroid hormone
  2. Second-messengersystem
    ▪ Used by protein and peptide hormones
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3
Q

what is the
activation is

  1. Steroid hormones 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
A

▪Direct gene activation

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4
Q

WHAT TYPE OF ACTIVATION

  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
A

Second Messenger System

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5
Q

The stimuli that activate endocrine glands fall into three major categories

A
  1. Hormonal 2. Humoral 3. Neural
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6
Q

▪ 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

A

Hormonal stimuli

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7
Q

▪ 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 levels

A

Humoral stimuli

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8
Q

▪ 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

A

Neural stimuli

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9
Q

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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10
Q

Some glands have purely endocrine functions

A

▪ Anterior pituitary, thyroid, adrenals, parathyroids

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11
Q

Other glands are mixed glands, with both endocrine and exocrine functions

A

(pancreas, gonads)

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12
Q

▪ Pea-sized gland that hangs by a stalk from the
hypothalamus in the brain
▪ Protected by the sella turcica of the sphenoid bone

▪ Has two functional lobes
▪ Anterior pituitary—glandular tissue ▪ Posterior pituitary—nervous tissue
▪ Often called the “master endocrine gland”

A

Pituitary gland

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13
Q

Hypothalamus also makes two hormones:

A

oxytocin and antidiuretic hormone

▪ Carried to posterior pituitary via neurosecretory cells for storage

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14
Q

▪ Does not make the hormones it releases
▪ Stores hormones made by the hypothalamus
▪Two hormones released ▪ Oxytocin
▪ Antidiuretic hormone (ADH)

A

Posterior pituitary

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15
Q

WHAT HORMONE?
▪ Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding
▪ Causes milk ejection (let-down reflex) in a breastfeeding woman

A

▪ Oxytocin

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16
Q

WHAT HORMONE

▪ 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

A

(Posterior pituitary )
Antidiuretic hormone (ADH)

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17
Q

Six anterior pituitary hormones
▪ Two hormones affect nonendocrine targets
1. Growth hormone
2. Prolactin
▪ Four are tropic hormones
1. Follicle-stimulating hormone
2. Luteinizing hormone
3. Thyrotropic hormone
4. Adrenocorticotropic hormone

A

Six anterior pituitary hormones
▪ Two hormones affect nonendocrine targets
1. Growth hormone
2. Prolactin
▪ Four are tropic hormones
1. Follicle-stimulating hormone
2. Luteinizing hormone
3. Thyrotropic hormone
4. Adrenocorticotropic hormone

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18
Q

All anterior pituitary hormones: ARE?

A

▪ Are proteins (or peptides)
▪ Act through second-messenger systems
▪ Are regulated by hormonal stimuli
▪ Are regulated mostly by negative feedback

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19
Q

WHAT HORMONE

▪ 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

A

Growth hormone (GH)

PITUITARY GLAND & HYPOTHALAMUS

20
Q

WHAT HORMONE?

Stimulates and maintains milk production following
childbirth
▪ Function in males is unknown

A

Prolactin (PRL)

PITUITARY GLAND & HYPOTHALAMUS

21
Q

WHAT HORMONE?

▪ Regulate hormonal activity of the gonads
▪ Follicle-stimulating hormone (FSH)
▪ Stimulates follicle development in ovaries ▪ Stimulates sperm development in testes
▪ Luteinizing hormone (LH)
▪ Triggers ovulation of an egg in females
▪ Stimulates testosterone production in males

A

Gonadotropic hormones

PITUITARY GLAND & HYPOTHALAMUS

22
Q

WHAT HORMONE?

Influences growth and activity of the thyroid gland

A

▪Thyrotropic hormone (TH), also called thyroid- stimulating hormone (TSH)

PITUITARY GLAND & HYPOTHALAMUS

23
Q

▪ Regulates endocrine activity of the adrenal cortex

A

Adrenocorticotropic hormone (ACTH)
PITUITARY GLAND & HYPOTHALAMUS

24
Q

WHAT GLAND

Hangs from the roof of the third ventricle of the brain
▪Secretes 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

A

PINEAL GLAND

25
Q

WHAT GLAND

▪Found at the base of the throat, inferior to the Adam’s apple
▪Consists of two lobes and a connecting isthmus
▪Follicles are hollow structures that store colloidal
material
▪Produces two hormones 1. Thyroidhormone
2. Calcitonin

A

Thyroid Gland

26
Q

WHAT HORMONE

▪ 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

A

Thyroid hormone

Thyroid Gland

27
Q

WHAT HORMONE

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

A

Calcitonin

Thyroid Gland

28
Q

WHAT GLAND

▪Tiny masses on the posterior of the thyroid ▪Secrete parathyroid hormone (PTH)
▪ Most important regulator of calcium ion (Ca2+) 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

A

Parathyroid Glands

29
Q

WHAT GLAND

▪Located in the upper thorax, posterior to the sternum
▪Largest in infants and children
▪Decreases in size throughout adulthood
▪Produces a hormone called thymosin
▪ Matures some types of white blood cells
▪ Important in developing the immune system

A

Thymus

30
Q

WHAT GLAND

▪Sit on top of the kidneys ▪Two regions
1. Adrenal cortex—outer glandular region has three layers that produce corticosteroids
▪ Mineralocorticoids are secreted by outermost layer
▪ Glucocorticoids are secreted by middle layer
▪ Sex hormones are secreted by innermost layer
2. Adrenalmedulla—inner neural tissue region

A

Adrenal Glands

31
Q

WHAT GLAND

▪ Mineralocorticoids (mainly aldosterone)
▪ 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

A

▪Hormones of the adrenal cortex

Adrenal Glands

32
Q

WHAT GLAND

▪Hormones of the adrenal cortex (continued) ▪ Release of aldosterone is stimulated by:
▪ 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
▪ Aldosterone production is inhibited by atrial natriuretic peptide (ANP), a hormone produced by the heart when blood pressure is too high

A

Adrenal Glands

33
Q

WHAT GLAND

▪ Glucocorticoids (including cortisone and cortisol)
▪ 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

A

Hormones of the adrenal cortex (continued)
ADRENAL GLANDS

34
Q

)WHAT GLAND
▪ Sex hormones
▪ 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

A

▪Hormones of the adrenal cortex (continued)
ADRENAL GLANDS

35
Q

WHAT GLAND

▪ Produces two similar hormones (catecholamines)
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

A

▪Adrenal medulla

Adrenal Glands

36
Q

WHAT GLAND

▪ Located in the abdomen, close to stomach
▪ Mixed gland, with both endocrine and exocrine functions
▪The pancreatic islets (islets of Langerhans) produce hormones
▪ Insulin—produced by beta cells
▪ Glucagon—produced by alpha cells
▪ These hormones are antagonists that maintain blood sugar homeostasis

A

▪ Pancreas

Pancreatic Islets

37
Q

WHAT HORMONE
▪ Released when blood glucose levels are high
▪ Increases the rate of glucose uptake and metabolism by body cells
▪ Effects are hypoglycemic

A

▪ Insulin

Pancreatic Islets

38
Q

WHAT HORMONE

▪ Released when blood glucose levels are low
▪ Stimulates the liver to release glucose to blood, thus increasing blood glucose levels

A

Glucagon
Pancreas Islets

39
Q

WHAT GLAND

▪ Produce sex cells
▪ Produce sex hormones

A

▪ Gonads

40
Q

▪ Female gonads located in the pelvic cavity
▪ Produce eggs
▪ Produce two groups of steroid hormones 1. Estrogens
2. Progesterone

A

▪ Ovaries

Gonads

41
Q

▪ Male gonads suspended outside the pelvic cavity
▪ Produce sperm
▪ Produce androgens, such as testosterone

A

Testes

Gonads

42
Q

WHAT HORMONE

▪ Stimulate the development of secondary female
characteristics
▪ Mature the female reproductive organs
▪With progesterone, estrogens also: ▪ Promote breast development
▪ Regulate menstrual cycle

A

Estrogens

43
Q

WHAT HORMONE

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

A

Progesterone
GONADS

44
Q

▪Produce several androgens
▪Testosterone is the most important androgen
▪ Responsible for adult male secondary sex characteristics
▪ Promotes growth and maturation of male reproductive system
▪ Required for sperm cell production

A

Testes
GONADS

45
Q

Other organs that are generally nonendocrine in function also secrete hormones

A

▪ Stomach ▪Small intestine ▪ Kidneys
▪ Heart

46
Q

▪ 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 (hPL) prepares the breasts for lactation
▪ Relaxin relaxes pelvic ligaments and pubic symphysis for childbirth

A

Placenta

47
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

SEMI FINALS (5 decks)

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