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MCAT kaplan study prep > Biology Chapter 4: The Endocrine System > Flashcards

Biology Chapter 4: The Endocrine System Flashcards

1
Q

What are the different kinds of hormones? (3)

A

Peptide hormones, steroids, amino acid derivatives

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2
Q

Define Peptide hormones

A

peptide hormones are those that are derived from amino acids,
can be small or large,
charged (can not pass through plasma membrane)
they are called first messengers,
they are water soluble and can travel through the blood stream with ease

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3
Q

First hormone messengers

A

bind to a receptor that activates another signaling cascade known as the secondary messenger possibly amplifying the signal

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4
Q

Common secondary messengers

A

cAMP and IP3 and calcium

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5
Q

what happens when the hormone activates a g-protien coupled receptor?

A

the signal will either activate or inhibit an enzyme called adenylate cyclase, which raises or lowers the amount of cAMP present

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6
Q

cAMP does what in the cell

A

cAMP has the ability to intracellularly activate enzymes such as protien kinase A, which then phosphorylates transcription factors such as cAMP

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7
Q

what is the rate of peptide hormones?

A

they are generally rapid, but they are short lived because they act through secondary messengers
effects do not last without continuous stimulation

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8
Q

Steroid hormones Define

A
  • derived from cholesterol
  • produced by the gonads and adrenal cortex
  • non polar (easily transfer through the cell membrane)
  • receptors are intracellular or intranuclear
  • they create steroid/receptor complexes and can then bind to DNA and effect transcription
  • they are slower but they are longer lived effects because they effect the mRNA production
  • they are not water soluble, therefore need carriers in the blood stream
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9
Q

Define amino acid derivative hormones

A

they are less common than the other two kinds of hormones
they include: epinephrine, norepinephrine, thyroxine
derived from one or two amino acids

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10
Q

Catecholamines

A

epinephrine and norepinerphrine

bind to G protein coupled receptors

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11
Q

Where do thyroid hormones bind?

A

they bind intraceulluarly

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12
Q

define direct hormones

A

they are released and then they act directly on the tissue in question
insulin- increase up take of glucose by muscles

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13
Q

define tropic hormones

A

they require and intermediate to act
example:
GnRH (Gonadotrophin- releasing hormone) stimulates the release of the luteinizing hormone (LH) and Follicle stimulating hormone (FSH)
LH then acts on the gonads

they usually originate from the brain or anterior pituitary gland

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14
Q

Define Hypothalamus

A

Bridge between nervous system and the endocrine system

regulates the pituitary gland using Trophic hormones organism wide effects

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15
Q

where is the hypothalamus located?

A

in the forbrain
above the pituitary gland
below the Thalamus

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16
Q

where does the hypothalamus receive its information?

A

from all around the body

blood, retinas ect…

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17
Q

what regulates the release of hormones by the hypothalamus?

A

A Negative feed back loop

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18
Q

Define a negative feedback loop

A

when a product later in a pathway inhibits products earlier in the pathway
prevents wasted energy by restricting production of products that are already present in sufficient quantities

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19
Q

Pituitary gland has how many sides that interact with the hypothalamus?

A

two, anterior and posterior

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20
Q

How does the Anterior Pituitary gland interact with the hypothalamus?

A

Hormones travel down the seal connection blood pathway from the hypothalamus into the anterior pituitary and then bind to receptors that release other hormones

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21
Q

Define the hypophyseal portal system

A

blood vessel that connects the hypothalamus with the anterior pituitary gland

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22
Q

Gonadotrophin - releasing hormone (GnRH) from they hypothalmus activates what hormone in the anterior pituitary gland?

A 
follicle- stimulating hormone (FSH) 
Leutinizing hormone (LH)

they act on the gonads (ovaries and testes)

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23
Q

Growth hormone releasing Hormone (GHRH) from the hypothalamus activates what hormone in the pituitary gland?

A

Growth hormone (GH)

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24
Q

Thyroid releasing hormone (TRH) from the hypothalamus activates what hormones in the anterior pituitary gland ?

A

thyroid stimulating hormone (TSH)

this hormone acts on thyroid

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25
Corticotrophin- releasing factor (CRF) from the hypothalmus releases what hormone from the anterior pituitary gland?
adrenocorticotrophic hormone (ACTH) this hormone acts on the adrenal cortex
26
Define Axes in terms of hormone feedback loops
once the amount of substance that was signaled has reached its maximum, it will then tell the hypothalamus and the pituitary gland that enough of the substance has been created and will signal the organs to stop signaling
27
Interactions between the hypothalamus and the posterior pituitary gland
posterior pituitary does not receive tropic hormones Axons run down the pituitary stalk and into the posterior pituitary and then when signaled, hormones oxytocin and antiduriretic hormones are released
28
Define Oxytocin
hormone that stimulates uterine contractions during labor as well as milk let down during lactation positive feedback loop
29
Antidiuretic hormone (ADH) also know as vasopressin does what?
increases re absorption of water in the collecting ducts of the kidney. this is activated when there is an increase in concentration of solutes within the blood also due to plasma osmolarity
30
How many different products does the anterior pituitary gland release?
7 products | 4 tropic hormones and 3 direct hormones
31
Define Endorphins
decrease the perception of pain
32
Where is the thyroid located?
in front of the trachea, organ near the base of the neck
33
what are the functions of the thyroid?
setting a basal metabolic rate and calcium homeostasis
34
what does the thyroid use to control calcium concentrations?
Calcitonin
35
what does the thyroid use to control the basal metabolic rate?
triiodothyronine (t3) and thyroxine (t4)
36
T3 and T4 purposes? and how?
they function by making energy production more efficient or less efficient as well as altering the utilization of glucose and fatty acids
37
what happens when there is an increased amount of T3 and T4?
cellular respiration will increase therefore speeding up the degregation of the sugars and fatty acids present in the blood controlled by a negative feed back loop
38
define hypothyroidism
deficiency in iodine or inflamation of the thyroid | thyroid hormones do not get secreted at all or very little
39
describe some symptoms associated with hypothyroidism
lethargy, decreased body temp, slowed respiratory rate and heart rate weight gain
40
define hyperthyroidism
over production of iodine, excess thyroid hormone
41
symptoms of hyperthyroidism
higher activity, increased body temp, heat intolerance, weight loss
42
name the three ways that Calcitonin works to decrease calcium in the plasma
increase Ca2+ excretion from the kidneys decrese Ca2+ absorption from the gut and increase Ca2+ storage in the bone
43
what is the parathyroid glands?
four pea sized structures that sit on the posterior surface of the thyroid the hormone produced is parathyroid hormone (PTH)
44
where are the adrenal glands located?
on top of the kidneys | each gland has a cortex and a medulla
45
where are the adrenal glands located?
on top of the kidneys | each gland has a cortex and a medulla
46
Glucocorticoids
Steroid Hormones that regulate glucose levels | they also affect protien metabolism
47
what are the main two kinds of glucocorticoids?
cortisol and cortisone
48
how does cortisol and cortisone work?
they raise glucose in the blood by increasing glucogensis and decreasing protien synthesis
49
mineralocorticoids
used in salts and water homeostasis, profound effect on the Kidneys
50
Aldosterone
increases sodium re-absorption in the distal convoluted tube and collecting duct of the of the nepheron also promotes excretion of potassium and hydrogen ions
51
Cortical Sex Hormones
made by the adrenal glands
52
what are the three main functions of corticosteroids
Salt Sugar Sex
53
Adrenal Medulla
inside of the adrenal cortex responsible for the production of sympathetic hormones epinephrine and norepinerphrine
54
Pancreas
both exocrine and endocrine systems
55
define glucagon
secreted during times of fasting when glucose levels run low stimulates the break down of proteins and of fats and the conversion into glucose via glucogenisis
56
Define Insulin
released when blood glucose levels are high insulin stimulates the muscles and liver cells to take up the glucose present in the blood and to store it for later also stimulates fats and protien synthesis
57
hypoglycemia define
when insulin is too high | and the blood glucose levels are too low
58
Diabetes Mellitus aka hyperglycemia
is the body's insensitivity to insulin
59
Type 1 Diabetes define
autoimmune destruction of the beta cells of the pancreas, these people produce little or no insulin these patients need constant insulin to prevent hyperglycemia and to induce glucose uptake
60
Type 2 Diabetes Define
Receptor level insulin insensitivity partially inherited and partially environmental obesity and high carbohydrate diet these patients require insulin when their bodies can not break down glucose
61
Somatostatin
inhibitor of glucogon and insulin high blood glucose and amino acid present in the blood stimulate the production produced by the hypothalmus
62
Pineal Gland
located deep within the brain where it secretes hormone called Melatonin

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