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MCAT > Biology Ch 5. The Endocrine System > Flashcards

Biology Ch 5. The Endocrine System Flashcards

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1
Q

Endocrine signaling

A

The secretion of hormones directly into the bloodstream, the hormones travel to distant target tissues were they bind to receptors and induce a change in gene expression or cell function

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2
Q

Peptide hormones

A

Composed of amino acids and are derived from larger precursor proteins that are cleaved during posttranslational modification, are polar and cannot pass through the plasma membrane, bind to extracellular receptors to trigger transmission of a second messenger, exert effects that have rapid onset but are short lived, water-soluble so travel freely in bloodstream without special carrier

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3
Q

Second messenger

A

Transmitted when peptide hormones bind to extracellular receptors, common examples include cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3), and calcium

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4
Q

Signaling cascade

A

The connection between the hormone at the surface and the effect brought about by second messengers within the cell, each step can induce amplification of the signal

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5
Q

Amplification

A

Increase in signal intensity

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6
Q

Steroid hormones

A

Derived from cholesterol, or minimally polar and can pass through the plasma membrane, buying two and promote a conformational change in cytosolic or intranuclear receptors, the hormone receptor complex binds to DNA altering the transcription of a particular gene, exert affects that have slow onset butter long lived, or lipid soluble so they cannot dissolve in the blood stream and must be carried by specific proteins

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7
Q

Amino acid – derivative hormones

A

Modified amino acids, chemistry share some features with peptide hormones and some features with steroid hormones, different amino acid derivatives hormones share different features with these other hormone classes, examples include epinephrine, norepinephrine, triiodothyronine, and thyroxine

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8
Q

Hormone types

A

Chain hormones, steroid hormones, amino acid derivative hormones

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9
Q

Hormone classifications by target tissues

A

Direct hormones, tropic hormones

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10
Q

Direct hormones

A

Have major effects on non-endocrine tissues

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11
Q

Tropic hormones

A

Have major effects on other endocrine tissues

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12
Q

Hypothalamus endocrine system

A

Bridge between the nervous and endocrine systems, releases many hormones and is mediated by a number of factors, stimulates the anterior pituitary gland through paracrine release of hormones into the hypophyseal portal system which connects the two organs, interacts with the posterior pituitary via the axons of nerves projected by the hypothalamus

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13
Q

Hypothalamus mediation factors

A

Projections from other parts of the brain, chemo or baroreceptors in the blood vessels, and negative feedback from other hormones

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14
Q

Negative feedback

A

The final hormone (or product) of a pathway inhibits hormones (or enzymes) earlier in the pathway, maintaining homeostasis

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15
Q

Gonadotropin-releasing hormone

A

GnRH - promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

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16
Q

Growth hormone releasing hormone

A

GHRH - promotes the release of growth hormone

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17
Q

Thyroid-releasing hormone

A

TRH – promotes the release of thyroid stimulating hormone (TSH)

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18
Q

Corticotropin – releasing factor

A

CRF - promotes the release of adrenocorticotropic hormone (ACTH)

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19
Q

Prolactin inhibiting factor

A

PIF or dopamine - inhibits the release of prolactin

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20
Q

Hormones from the hypothalamus

A 
To the anterior pituitary
Gonadotropin releasing hormone (GnRH)
Growth hormone releasing hormone (GHRH)
Thyroid releasing hormone (TRH)
Corticotropin releasing factor (CRF)
Prolactin inhibiting factor (PIF or dopamine)

To the posterior pituitary
Antidiuretic hormone (ADH or vasopressin)
Oxytocin

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21
Q

Anterior pituitary

A

Releases hormones in response to stimulation from the hypothalamus

Tropic hormones
FSH, LH, ACTH, and TSH

Direct hormones
Prolactin, endorphins, and growth hormone

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22
Q

Follicle-stimulating hormone

A

FSH - promotes the development of ovarian follicles in females and spermatogenesis in males, peptide hormone

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23
Q

Luteinizing hormone

A

LH - promotes ovulation in females and testosterone production in males, peptide hormone

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24
Q

Adrenocorticotropic hormone

A

ACTH - promotes the synthesis and release of glucocorticoids from the adrenal cortex, peptide hormone

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25
Thyroid stimulating hormone
TSH - promotes the synthesis and release of triiodothyronine and thyroxine from the thyroid, peptide hormone
26
Prolactin
Promotes milk production, peptide hormone
27
Endorphins
Decrease perception of pain and can produce euphoria, peptide hormone
28
Growth hormone
GH - promotes growth of bone and muscle and shunts glucose to these tissues, raises blood glucose concentrations, peptide hormone
29
Posterior pituitary
Releases two hormones produced in the hypothalamus
30
Antidiuretic hormone
ADH or vasopressin - secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, increasing blood volume and decreasing was osmolarity, peptide hormone
31
Oxytocin
Secreted during childbirth and promotes uterine contractions, also promotes milk ejection in may be involved in bonding behavior, unusual in that it has a positive feedback loop, peptide hormone
32
Thyroid
Located at the base of the neck in front of the trachea, it produces three key hormones: triiodothyronine, thyroxine, calcitonin
33
Triiodothyronine
T3 - produced by follicular cells and contain iodine, increase basal metabolic rate and alter the utilization of glucose and fatty acids, are required for proper neurological and physical development in children, amino-acid derivative hormone
34
Thyroxine
T4 - produced by follicular cells and contain iodine, increase basal metabolic rate and alter the utilization of glucose and fatty acids, are required for proper neurological and physical development in children, amino acid derivative hormone
35
Follicular cells
In thyroid, produce triiodothyronine and thyroxine
36
Calcitonin
Produced by parafollicular cells, decrease plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut, and promoting calcium storage in the bone, peptide hormone
37
Parathyroid glands
Release parathyroid hormone, four small structures on the surface of thyroid
38
Parathyroid hormone
PTH - increases blood calcium concentration, decreases excretion of calcium by the kidneys and increases bone reabsorption directly to increase blood calcium concentration, activates vitamin D which is necessary for calcium and phosphate absorption in the gut, peptide hormone
39
PTH and vitamin D
PTH promotes reabsorption of phosphate from bone in reduces reabsorption from phosphate in the kidney, but vitamin D promotes absorption of phosphate from the gut, these two affects on phosphate concentration somewhat cancel each other out
40
Adrenal cortex
Produces three classes of steroid hormones
41
Glucocorticoids
Increase blood glucose concentration, reduce proteins synthesis, inhibit the immune system, and participate in the stress response, release is stimulated by ACTH age, examples include cortisol and cortisone, steroid hormones
42
Mineralocorticoids
Promotes sodium reabsorption in the distal convoluted tubule and collecting duct, thus increasing water absorption, one example is aldosterone, steroid hormones
43
Aldosterone
Promotes sodium reabsorption in the distal convoluted tubule and collecting duct, thus increasing water reabsorption, also increases potassium and hydrogen ion excretion, activity regulated by the renin-angiotensin-aldosterone system, not ACTH, steroid hormone
44
Cortical sex hormones
Include androgens and estrogens in both males and females
45
Adrenal medulla
Derived from the nervous system and secretes catecholamines into the bloodstream
46
Catecholamines
Include epinephrine and norepinephrine, involved in the fight or flight response, promote glycogenolysis, increase the basal metabolic rate, increase heart rate, dilate the bronchi, and alter blood flow, amino acid derivate hormones
47
Pancreas
Produces hormones that regulate glucose homeostasis such as glucagon, insulin, and somatostatin
48
Glucagon
Produced by alpha cells and raises blood glucose levels by stimulating proteins and fat degradation, glucogenolysis, and gluconeogenesis, peptide hormone
49
Insulin
Produced by beta cells and lowers blood glucose levels by stimulating glucose uptake by cells and promoting anabolic processes like glycogen, fat, and protein synthesis, peptide hormone
50
Somatostatin
Produced by Delta cells and inhibits insulin and glucagon secretion, peptide hormone, stimulated by high blood glucose and amino acid concentration
51
Gonads - testes/ovaries
Produce hormones that are involved in the development and maintenance of the reproductive system and secondary sex characteristics
52
Testes hormones
Secrete testosterone, steroid hormones
53
Ovaries hormones
Secrete estrogen (development and maintenance of reproductive system and secondary sex char) and progesterone (endometrium maintenance), steroid hormones
54
Pineal gland
Releases melatonin
55
Melatonin
Helps to regulate the circadian rhythm, peptide hormone
56
Stomach and intestine hormones
Secretin, gastrin, and cholecystokinin, peptide hormones
57
Kidneys hormones
Secrete erythropoietin
58
Erythropoietin
Stimulates bone marrow to produce erythrocytes in response to low oxygen levels in the blood, peptide hormone
59
Atria of the heart hormones
Secrete atrial natriuretic peptide (ANP)
60
Atrial natriuretic peptide
ANP - promotes excretion of salt and water in the kidneys in response to stretching of the atria (high blood volume), peptide hormone
61
Thymus hormones
Secretes thymosin
62
Thymosin
Important for proper T-cell development and differentiation, peptide hormone
63
Glands
Organs that secrete hormones
64
Dimerization
Common conformational change, the pairing of two receptor-hormone complexes
65
Hypophyseal portal system
A blood vessel that directly connects the hypothalamus and the anterior pituitary
66
Axes
Three organ systems
67
Gigantism
Excess of GH during childhood before epiphyseal (growth) plates close
68
Dwarfism
Lack of GH during childhood before epiphyseal (growth) plates close
69
Acromegaly
Excess of GH in adulthood after epiphyseal (growth) plates close, long bones are sealed so primarily the feet, hands, and head grows
70
Hypothyroidism
Thyroid hormones secreted in insufficient amounts, lethargy, decreased body temp, slowed respiratory and heart rate, cold intolerance, and weight gain symptoms
71
Hyperthyroidism
Excess of thyroid hormones, could result in tumor or thyroid overstimulation
72
Adrenal glands
On top of kidney, broken into adrenal cortex and adrenal medulla
73
Renin-angiotensis-aldosterone system
Decreased blood pressure causes the juxtaglomerular cells of the kidney to secrete renin which cleaves an inactive plasma proteins, angiotensinogen, to its active form angiotensin I, which is converted to angiotensin II with angiotensin-converting enzyme in the lungs, angiotensin II stimulates the adrenal cortex to secrete aldosterone
74
Exocrine tissues
Secrete substances directly into ducts such as digestive enzymes
75
Islet of Langerhans
Small clusters of hormone producing cells throughout the pancreas, contains alpha, beta, and delta cells
76
Hypoglycemia
Low blood glucose concentration, can be caused by an excess in insulin
77
Diabetes mellitus
The result of underproduction, insufficient secretion, or insensitivity to insulin, clinically characterized by hyperglycemia
78
Hyperglycemia
Excess glucose in the blood
79
Polyuria
Increased frequency of urination, common in diabetics
80
Polydipsia
Increased thirst, common in diabetics
81
Type I diabetes
Insulin-dependent, caused by autoimmune destruction of the beta cells in the pancreas, resulting in lower or absent insulin production, requires injections of insulin to prevent hyperglycemia and permit uptake of glucose into cells
82
Type II diabetes
Non-insulin-dependent, the result of receptor level resistance to the effects of insulin, partially inherited and partially due to environmental factors such as diet, certain pharmaceutical agents can be taken orally to help the body more effectively use up the insulin it produces

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