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Anatomy & Physiology > Week 9 - Endocrine System > Flashcards

Week 9 - Endocrine System Flashcards

1
Q

What is the Endocrine System?

A
  • second controlling system of the body
  • – nervous system is the fast-control system
  • uses chemical messengers (hormones) that are released into the blood
  • endocrinology is the scientific study of hormones and endocrine organs
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2
Q

What major processes do hormones control?

A
  • reproduction
  • growth and development
  • mobilization of body defenses
  • maintenance of much of homeostasis
  • regulation of metabolism
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3
Q

What cells produce hormones?

A

specialized cells

  • cells secrete hormones into extracellular fluids
  • blood transfers hormones to target sites
  • these hormones regulate the activity of other cells
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4
Q

What is the Chemistry Classification of Hormones?

A
  • amino acids-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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5
Q

What is the Hormone action?

A
  • hormones affect only certain tissues or organs (target cells or target organs)
  • target cells must have specific protein receptors
  • hormone binding alters cellular activity
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6
Q

What is the stimuli for control of hormone release?

A
  • hormone levels in the blood are maintained by NEGATIVE ( - ) feed feedback
  • a stimulus or low hormone levels in the blood trigger the release of more hormone
  • hormone release stops once an appropriate level in the blood is reached
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7
Q

What are the 3 major categories that the stimuli that activate endocrine glands fall into?

A
  1. hormonal
  2. humoral
  3. neural
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8
Q

What is Hormonal stimuli?

A
  • most common category of stimulus

- endocrine organs are activated by other hormones

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9
Q

example of hormonal stimuli

A

hormones of the hypothalamus stimulate the anterior pituitary to secrete its hormones

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10
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)
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11
Q

example of humoral stimuli

A
  • 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
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12
Q

what is neural stimuli?

A
  • nerve fibers stimulate hormone release

- most are under the control of the sympathetic nervous system

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13
Q

example of neural stimuli

A

sympathetic stimulation of the adrenal medulla to release epinephrine and norepinephrine

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14
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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15
Q

Overview of the major endocrine organs

A
  • some glands have purely endocrine functions
  • – anterior pituitary, thyroid, adrenals, parathyroids
  • endocrine glands are DUCTLESS glands
  • hormones are released directly into blood or lymph
  • other glands are mixed glands, with both endocrine and exocrine functions (pancreas, gonads)
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16
Q

What is the pituitary gland?

A
  • pea-sized gland that hands by a stalk from the hypothalamus in the brain
  • protected by the sella turcica of the sphenoid bone
  • has two functional lobes
  • often called the “master endocrine gland”
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17
Q

What are the pituitary gland’s 2 functional lobes?

A
  1. glandular tissue

2. nervous tissue

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18
Q

What is the hypothalamus?

A
  • produces releasing hormones and inhibiting hormones

- – these hormones released into portal circulation, which connects hypothalamus to anterior pituitary

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19
Q

What are the two hormones that the hypothalamus makes?

A
  1. oxytocin hormone
  2. antidiuretic hormone (ADH)
    - carried to posterior pituitary via neurosecretory cells for storage
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20
Q

What is the posterior pituitary?

A
  • does not make the hormones it releases

- stores hormones made by the hypothalamus

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21
Q

What is oxytocin?

A
  • stimulates contractions of the uterus during labor, sexual relations, and breastfeeding
  • causes milk ejection (let-down reflex) in a breastfeeding woman
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22
Q

What is antidiuretic hormone (ADH)?

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
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23
Q

What are the 6 anterior pituitary hormones?

A

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. adrenocorticptropic hormone
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24
Q

describe the anterior pituitary hormones

A
  • are proteins (or peptides)
  • act through second-messenger systems
  • are regulated by hormonal stimuli
  • are regulated mostly by negative feedback
25
Q

What are growth hormones (GH)?

A
  • general metabolic hormone
  • major affects 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
26
Q

Function of Prolactin (PRL)

A
  • stimulates and maintains milk production following childbirth
  • function in males is unknown
27
Q

What are Gonadotropic hormones?

A

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
28
Q

Function of Thyrotropic hormone (TH)

A
  • aka thyroid-stimulating hormone (TSH)

- influences growth and activity of thyroid gland

29
Q

Function of Adrenocorticotropic hormone (ACTH)

A
  • regulates endocrine activity of the adrenal cortex
30
Q

What is the pineal gland?

A
  • hangs from the rood 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
31
Q

What is the Thyroid gland?

A
  • found at the base of the throat
  • inferior to the Adam’s apple
  • consist of two lobes and a connecting isthmus
  • follicles are hollow structures that store colloidal material
32
Q

What are the two hormones that the thyroid gland produces?

A
  1. thyroid hormone

2. calcitonin

33
Q

What is the thyroid hormone?

A
  • major metabolic hormone
  • controls rate of oxidation of glucose to supply body heat and chemical energy
  • needed for tissue growth and development
34
Q

What are the two active iodine-containing hormones that the thyroid hormone is composed of?

A
  1. Thyroxine (T4)
    secreted by thyroid follicles
  2. Triiodothyronine (T3)
    conversion of T4 at target tissues
35
Q

What is calcitonin?

A
  • decreases blood calcium levels by causing calcium deposition on bone
  • antagonistic to parathyroid hormone
  • produced by pararfollicular cells found between the follicles
36
Q

What are parathyroid glands?

A
  • tiny masses on the posterior of the thyroid
  • secrete parathyroid hormone (PTH)
  • – most important regulator of calcium ion (Ca^2+) homeostasis of the blood
  • – stimulates osteoclasts to remove calcium from bone
  • – hypercalcemic hormone (increases blood calcium levels)
  • – stimulate the kidneys and intestine to absorb more calcium
37
Q

describe the thymus

A
  • located in the upper thorax
  • posterior to the sternum
  • largest in infants and children
  • decreases in size throughout adulthood
  • produces a hormone called “thymosin”
38
Q

What is thymosin hormone?

A
  • matures some types of white blood cells

- important in developing the immune system

39
Q

where are the adrenal glands?

A

sit on top of the kidneys

40
Q

What are the two regions of the adrenal gland?

A
  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. adrenal medulla (inner neural tissue region)
41
Q

What is the mineralocorticoids hormone of the adrenal cortex?

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
42
Q

what is the release of aldosterone 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

Aldosterone production is inhibited by atrial natriuretic peptide (ANP), a hormone produced by the heart when the blood pressure is too high

43
Q

What is the glucocorticoids?

A

(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
44
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
45
Q

what is the adrenal medulla?

A
  • produces two similar hormones (catecholamines)
  • 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
46
Q

what are the two similar hormones that the adrenal medulla produces?

A
  1. epinephrine (adrenaline)

2. norepinephrine (noradrenaline)

47
Q

describe the pancreas?

A
  • located in the abdomen, close to stomach

- mixed gland, with both endocrine and exocrine function

48
Q

what hormones does the pancreatic islets (islets of Langerhans) produce?

A
  • insulin — produced by beta cells
  • glucagon — produced by alpha cells
    these hormones are antagonists that maintain blood sugar homeostasis
49
Q

describe insulin

A
  • released when blood glucose levels are high
  • increases the rate of glucose uptake and metabolism by body cells
  • effects are hypoglycemic
50
Q

describe glucagon

A
  • released when blood glucose levels are low

- stimulates the liver to release glucose to blood, thus increasing blood glucose levels

51
Q

what are gonads?

A
  • produce sex cells

- produce sex hormones

52
Q

describe ovaries

A
  • female gonads located in the pelvic cavity

- produce eggs

53
Q

what are the two groups of steroid hormones produced by the ovaries?

A
  1. estrogens

2. progesterone

54
Q

describe testes

A
  • male gonads suspended outside the pelvic cavity
  • produce sperm
  • produce androgens (ie, testosterone)
55
Q

describe estrogens

A
  • stimulate the development of secondary female characteristics
  • mature the female reproductive organs

with progestrerone, estrogens also:

  • promote breast development
  • regulate menstrual cycle
56
Q

describe progesteron

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
57
Q

describe testes

A
  • 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
58
Q

what are the other hormone-producing tissues and organs?

A

(organs that are generally nonendocrine in function also secrete hormones)

  • stomach
  • small intestine
  • kidneys
  • heart
59
Q

what are the developmental aspects of the endocrine system?

A
  • without a disease, the efficiency of the endocrine system is high until old age
  • decreasing function of female ovaries at menopause leads to symptoms (osteoporosis, increased change of heart disease, and possible mood changes)
  • efficiency of all endocrine glands gradually decreases with aging, which leads to generalized increase in incidence of:
  • – diabetes mellitus
  • – immune system depression
  • – lower metabolic rate
  • – cancer rates in some areas

Anatomy & Physiology (9 decks)

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