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A & P Unit 4 > Chapter 16 Endocrine System > Flashcards

Chapter 16 Endocrine System Flashcards

1
Q

The body’s second great controlling system which influences metabolic activities of cells by means of hormones is

A

the endocrine system

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2
Q

Endocrine glands are

A

the pituitary, thyroid, parathyroid, adrenal, pineal, and thymus

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3
Q

The pancreas and gonads produce both

A

hormones and exocrine products

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4
Q

What has both neural functions and releases hormones?

A

the hypothalamus

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5
Q

Other tissues and organs that produce hormones are:

A

adipose cells, pockets of cells in the walls of the small intestine, stomach, kidneys, and heart

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6
Q

Major endocrine organs

A
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7
Q

Autocrines

A

chemicals that exert effects on the same cells that secrete them

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8
Q

Paracrines

A

locally acting chemicals that affect cells other than those that secrete them

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9
Q

Autocrines and Paracrines are

A

not considered hormones since hormones are long-distance chemical signals

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10
Q

Hormones

A

chemical substances secreted by cells into the extracellular fluids

  • regulate the metabolic function of other cells
  • have lag times ranging from seconds to hours
  • tend to have prolonged effects
  • are classified as amino acid-based hormones or steroids
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11
Q

Elcosanoids

A

biologically active lipids with local hormone-like activity

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12
Q

Types of hormones

A
  • amino acid-based
    • ​amines, thyroxine, peptide and protein hormones
  • Steroids-gonadal and adrenocortical hormones
  • Elcosanoids-leukotrienes and prostaglandins
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13
Q

Hormones alter target cell activity by one of two mechanisms

A
  • second messengers:
    • regulatory G proteins
    • amino acid-based hormones
  • direct gene activation
    • steroid hormones

The precise response depends on the type of target cell

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14
Q

Hormones produce one or more of the following cellular changes in target cells:

A
  • alter plasma membrane permeability
  • stimulate protein synthesis
  • activate or deactivate enzyme systems
  • induce secretory activity
  • stimulate mitosis
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15
Q

Amino Acid-Based hormone action:

cAMP Second Messenger*

A
  • hormone (first messenger) binds to its receptor, which then binds to a G protein
  • the G protein is then activated as it binds GTP, displacing GDP
  • activated G protein activated the effector enzyme adenylate cyclase
  • adenylate cyclase generates cAMP (second messenger) from ATP
  • cAMP activates protein kinases, which then cause cellular effects
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16
Q

Amino Acid-Based Hormone Action:

PIP-Calcium*

A
  • hormone binds to the receptor and activates the G protein
  • G protein binds and activates phospholipase
  • phospholipase splits and phospholipids PIP2 into diacylglycerol (DAG) and IP3 (both act as second messengers
  • DAG activates protein kinases; IP3 triggers the release of Ca2+ stores
  • Ca2+ (third messenger) alters cellular responses
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17
Q

Steroid hormones

A
  • this interaction prompts DNA transcription to produce mRNA
  • the mRNA is translated into proteins, which bring about a cellular effect
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18
Q

Target Cell Specificity

A
  • hormones circulate to all tissues but only activate cells referred to as target cells
  • target cells must have specific receptors to which the hormone binds
  • these receptors may be intracellular or located on the plasma membrane
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19
Q

Target cell Activation depends on three factors:

A
  • Blood Levels of the hormone
  • Relative number of receptors on the target cell
  • the affinity of those receptors for the hormone-(means how likely they will bind)
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20
Q

Up-regulation is when

A

target cells form more receptors in response to the hormone

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21
Q

Down-regulation is when

A

target cells lose receptors in response to the hormone

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22
Q

Hormones circulate in the blood in what two forms:

A

free or bound

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23
Q

Hormones are removed from the blood by:

A
  • degrading enzymes
  • the kidneys
  • liver enzyme systems
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24
Q

Interaction of Hormones at Target Cells

The three types of hormone interaction:

A
  • permissiveness
  • synergism
  • antagonism
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25
Q

permissiveness is when

A

one hormone cannot exert its effects without another hormone being present

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26
Q

synergism is when

A

more than one hormone produces the same effects on a target cell

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27
Q

antagonism is when

A

one or more hormones opposes the action of another hormone

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28
Q

Blood levels of hormones are

A

controlled by negative feedback systems

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29
Q

Hormones are synthesized and released in response to:

A
  • Humoral stimuli
  • Neural stimuli
  • Hormonal stimuli
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30
Q

Humoral stimuli:

A

secretion of hormones in direct response to changing blood levels of ions and nutrients

Example: concentration of calcium ions in the blood

  • declining blood Ca2+ concentration stimulates the parathyroid gland to secrete PTH (parathyroid hormone)
  • PTH causes Ca2+ concentrations to rise and the stimulus is removed
31
Q

Neural stimuli:

A

nerve fibers stimulate hormone release

32
Q

Hormonal stimuli:

A

release of hormones in response to hormones produced by other endocrine organs

33
Q

Major endocrine organs: Pituitary (Hyopohysis)

What are the 3

A
  1. pituitary gland
  2. neurohypophysis (posterior lobe)
  3. adenohypophysis (anterior lobe)
34
Q

Pituitary gland:

A

a two-lobed organ that secrets nine major hormones

35
Q

Neurohypophysis:

A

posterior lobe (neural tissue) and the infundibulum

  • receives, stores and releases hormones from the hypothalamus
36
Q

Adenohypophysis:

A

anterior lobe made up of glandular tissue

  • synthesizes and secretes a number of hormones
37
Q

Major Endocrine Organs: Pituitary (Hypophysis)

A
38
Q

The six hormones of the adenohypophysis:

A
  • abbreviated as GH, TSH, ACTH, FSH, LH, and PRL
  • regulate the activity of other endocrine glands

In addition, pro-opiomelanocortin (POMC):

  • has been isolated from the pituitary
  • is split into ACTH, opiates, and MSH
39
Q

Activity of the Adenophypophysis

The hypothalamus sends a chemical stimulus to the anterior pituitary

A
  • Releasing hormones to stimulate the synthesis and release of hormones
  • inhibiting hormones shut off the synthesis and release of hormones
40
Q

The tropic hormones that are release are:

A
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
41
Q

Growth Hormone (GH)

  • produced by somatotropic cells of the anterior lobe that:
A
  • stimulate most cells, but target bone and skeletal muscle
  • promote protein synthesis and encourage the use of fats for fuel
42
Q

Metabolic action of growth hormone:

A
  • GH stimulates the liver, skeletal muscle, bone, and cartilage to produce insulin-like growth factors
43
Q

Metabolic Action of Growth Hormone (GH)

A
44
Q

Thyroid-stimulating hormone (Thyrotropin)

A
  • stimulates the normal development and secretory activity of the thyroid
45
Q

Adrenocorticotropic Hormone (Corticotropin)

A
  • stimulates the adrenal cortex to release corticosteroids
  • internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of CRH
46
Q

Gonadotropins-follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

A
  • regulate the function of the ovaries and testes
  • FSH stimulates gamete (egg or sperm) production
47
Q

Prolactin (PRL)

A
  • in females, stimulates milk production by the breasts
48
Q

The posterior pituitary and hypothalamic hormones

posterior pituitary made of:

A

axons of hypothalamic neurons, stores antidiuretic hormone (ADH0 and oxygen

  • ADH and oxytocin are synthesized in the hypothalamus
  • ADH influences water balance
  • Oxytocin stimulates smooth muscle contraction in breasts and uterus
  • both use PIP-calcium second-messenger mechanism
49
Q

Oxytocin:

A
  • Oxytocin is a strong stimulant of uterine contraction
  • regulated by a positive feedback mechanism to oxytocin in the blood
  • this leads to an increase in the intensity of uterine contractions, ending in birth
  • oxytocin triggers milk ejection (“letdown” reflex) in women producing milk
50
Q

Antidiuretic Hormone (ADH)

ADH helps to:

A
  • avoid dehydration or water overload
    • prevents urine formation
  • alcohol inhibits ADH release and causes copious urine output
51
Q

Thyroid Gland is the

A

largest gland, located in the anterior of the neck, consists of two lateral lobes connected by a median tissue mass called the isthmus

52
Q

Thyroid Gland

A
53
Q

Thyroid hormone is a:

A

major metabolic hormone

  • consists of two related iodine-containing compounds
    • ​T4-thyroxine: has two tyrosine molecules plus four bound iodine atoms
    • T3-triiodothyronine: has two tyrosines with three bound iodine atoms
54
Q

Effects of Thyroid Hormone

TH is concerned with:

A
  • glucose oxidation
  • increasing metabolic rate
  • heat production
55
Q

Effects of Thyroid Hormone

TH plays a role in:

A
  • maintaining blood pressure
  • regulating tissue growth
  • developing skeletal and nervous systems
  • maturation and reproductive capabilities
56
Q

Calcitonin

A
  • a peptide hormone produced by the parafollicular, or C, cells
  • lowers blood calcium levels in children
  • antagonist to parathyroid hormone (PTH)
  • calcitonin targets the skeleton
  • regulated by a humoral (calcium ion concentration in the blood) negative feedback mechanism
57
Q

Parathyroid glands are

A
  • tiny glands embedded in the posterior aspect of the thyroid
  • cells are arranged in cords containing oxyphil and chief cells
  • chief (principal) cells secrete PTH
  • PTH (parathormone) regulates calcium balance in the blood
58
Q

Parathyroid Glands

A
59
Q

Effects of Parathyroid Hormone

PTH release increases Ca2+ in blood as it:

A
  • stimulates osteoclasts to digest bone matrix
  • enhances the reabsorption of Ca2+ and the secretion of phosphate by the kidneys
  • increases absorption of Ca2+ by intestinal mucosal

Rising Ca2+ in the blood inhibits PTH release

60
Q

Effects of Parathyroid Hormone

A
61
Q

Adrenal (Suprarenal) Glands

Adrenal glands:

A
  • are paired, pyramid-shaped organs atop the kidneys

Structurally and functionally, they are two glands in one

  • Adrenal medulla-neural tissue that acts as part of the SNS
  • Adrenal cortex-glandular tissue derived from embryonic mesoderm
62
Q

Adrenal Cortex

A
  • synthesizes and releases steroid hormones called corticosteroids
  • different corticosteroids are produced in each of the three layers
    • Zona glomerulosa-mineralocorticoids: regulate electrolytes in extracellular fluids. (most important to aldosterone)
    • Zona fasciculata-glucocorticoids: help the body resist stress. (Chiefly cortisol)
    • Zona reticularis-gonadocorticoids: most are androgens (male sex hormones), and the most important one is testosterone. (androgens contribute to the onset of puberty)
63
Q

Adrenal Cortex

A
64
Q

Adrenal Medulla

A

made up of chromaffin cells that secrete epinephrine and norepinephrine

65
Q

Pancreas

A
  • a triangular gland, which has both exocrine and endocrine cells, located behind the stomach
66
Q

Pancreatic islets (islets of Langerhans)

A

produce hormones (endocrine products)

The islets contain two major cell types:

  • Alpha (a) cells that produce glucagon
  • Beta (B) cells that produce insulin
67
Q

Glucagon

Its major target is the liver, where it promotes:

A
  • Glycogenolysis-the breakdown of glycogen to glucose
  • Gluconeogenesis-synthesis of glucose from the lactic acid and noncarbohydrates
  • release of glucose to the blood from liver cells
68
Q

Insulin

A
  • lowers blood glucose levels
69
Q

Diabetes Mellitus (DM)

  • Results from hyposecretion or hypoactivity of insulin
  • The three cardinal signs of DM are:
A
  • Polyuria-huge urine output
  • Polydipsia-excessive thirst
  • Polyphagia-excessive hunger and food consumption
70
Q

Gonads: Female

  • Paired ovaries in the abdominopelvic cavity produce estrogens and progesterone
  • They are responsible for:
A
  • maturation of the reproductive organs
  • the appearance of secondary sexual characteristics
  • breast development and cyclic changes in the uterine mucosa
71
Q

Gonads: Male

  • Testes located in an extra-abdominal sac (scrotum) produce testosterone
  • Testosterone:
A
  • initiates maturation of male reproductive organs
  • causes the appearance of secondary sexual characteristics and sex drive
  • is necessary for sperm production
  • maintains sex organs in their functional state
72
Q

Pineal Gland is the:

A
  • small gland hanging from the roof of the third ventricle of the brain
  • secretory product us melatonin
  • melatonin is involved with:
  • day/night cycles
73
Q

Thymus

A
  • lobulated gland located deep to the sternum
  • these hormones are essential for the development of the T lymphocytes (T cells) of the immune system
  • the thymus gland, located behind your sternum and between your lungs, is only active until puberty. After puberty, the thymus starts to slowly shrink and become replaced by fat.
74
Q
A

A & P Unit 4 (6 decks)

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