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bio 116: exam 2 > endocrine system I & II > Flashcards

endocrine system I & II Flashcards

1
Q

what are hormones?

A

they come from the greek word “to excite,” they are chemical signaling molecules responsible for regulation, basically the messengers of the endocrine system!

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2
Q

what is endocrine signaling?

A

a form of intercellular communication where the hormone is secreted into the body fluids (typ. diffuses into bloodstream) and travels/binds to target cells. all cells are exposed to the message, but only those with the correct receptor respond

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3
Q

what are receptors?

A

they are large proteins or glycoproteins on/in target cells. they recognize and bind to SPECIFIC hormones. they are continually synthesized and degraded.

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4
Q

what happens when there is a high level of a hormone present for a long period?

A

the receptors of that hormone become down regulated, meaning they cells become less sensitive to the hormone because they reduce the number of receptors available to bind with it

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5
Q

what happens when there is low levels of a hormone present for a long period?

A

the receptors become up-regulated, meaning the cells increase the number of receptors to become more sensitive to the hormone

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6
Q

how are types of intercellular communication classified?

A

by the type of secreting cell and the route take by signal to target

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7
Q

what are paracrine and autocrine signaling?

A

they are both types of intercellular communication that involve the production and secretion of signaling molecules. they are both rapid forms of signaling because the molecules act locally.

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8
Q

what is the difference between paracrine and autocrine signaling?

A

in paracrine signaling, cells release local regulators that diffuse through the extracellular fluid to nearby target cells, while autocrine signaling occurs when a cell targets itself by releasing signaling molecules that act on receptors within the same cell

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9
Q

what is synaptic signaling?

A

a type of intercellular communication where neurons,(basic unit of nervous system, form synapses with the target cells. the neuron releases chemical messengers called neurotransmitters, which diffuse across the synapse and binds to receptors on target cells

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10
Q

what is neuroendocrine signaling?

A

a type of intercellular communication where neurosecretory cells (specialized neurons) secrete neurohormones, which diffuse from the nerve cell endings into the bloodstream

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11
Q

what is signaling by pheromones?

A

pheromones are chemical signals released into an external environment that target other individuals of the same specials, they can do things like define territory, warn predators, and attract mates.

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12
Q

what are some types of local regulators for autocrine and paracrine signaling?

A

modified fatty acids, gases, and polypeptides

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13
Q

what is a modified fatty acid local regulators?

A

contains long hydrocarbon chains
example: prostaglandin – regulate many processes

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14
Q

what is an example of a gas local regulator and how does it work?

A

nitric acid! when blood oxygen levels increase the blood vessel lining releases nitric acid. it diffuses to surrounding muscle, activates enzymes, relaxes cells, leading to vasodilation (increased blood flow to tissue)

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15
Q

what are polypeptide local regulators?

A

cytokines and growth factors

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16
Q

what are the three major chemical classes of hormones?

A

polypeptides: tend to be 100s of amino acids
steroids: lipids w/ four rings, all derived from cholesterol
amines: synthesized from single amino acids

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17
Q

what are water soluble hormones?

A

can dissolve in blood but cant cross the cell membrane (hydrophilic). involves signal transduction. they have effects in the cytoplasm of target cells and are much faster compared to lipid soluble hormones

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18
Q

what is the pathway for water soluble hormones?

A

secreted via exocytosis, travels freely in bloodstream, binds receptor on target, often G-couples receptor, the hormone does not enter the cell, instead the g protein is activated leading to a series of events that ultimately affect protein activity, resulting in a response (signal transduction)

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19
Q

what are lipid soluble hormones?

A

they are hydrophobic and cant dissolve in blood but can cross the cell membrane, they affect gene expression of target cells and are slower compared to water soluble hormones but have a longer lasting affect

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20
Q

what is the pathway for lipid soluble hormones?

A

the hormone diffuses across cell membrane, binds to transport protein in blood, enters target cells, and either binds to receptor in cytoplasm or directly binds to receptor inside the nucleus, affecting gene expression resulting in a response

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21
Q

what is signal transduction?

A

signal goes from outside target cell to inside, involving several signaling molecules

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22
Q

do hormones only have one effect?

A

many hormones have more than one type of effect, regardless of their solubility, target cells may differ in receptor and response molecule leading to varied effects

23
Q

what is an example or a hormone with multiple effects?

A

epinephrine causes a rapid response in the body during emergencies. it triggers the breakdown of glycogen in the liver, increases the blood flow in the skeletal muscle, and decreases the blood flow in smooth muscle. these effects can occur due to diff receptors or diff intracellular proteins responding to the epinephrine

24
Q

what are endocrine glands?

A

they are ductless and release hormones directly into the surrounding fluid. they can be isolated cells, part of organs, or secret structures. these glands function alongside the nervous system to regulate metabolism and maintain homeostasis.

25
Q

what are exocrine glands?

A

secretion from these glands involves ducts. they release materials such as sweat, mucus, and digestive enzymes, into target areas throughout these ducts.

26
Q

what is the simple endocrine pathway?

A

the endocrine cells respond directly to stimulus by secreting a hormone, the hormone travels via bloodstream, interacts with target cells, elicits a physiological response

27
Q

what is a simple neuroendocrine pathway?

A

when the stimulus is received by a sensory neuron, this stimulates neurosecretory cells to secrete neurohormones, travel via bloodstream and interacts with target schools leading to a physiological response
ex: milk release during nursing

28
Q

what is the hypothalamus?

A

a key regulatory structure found in the brain. it is part of the neuroendocrine system, linking the nervous and endocrine systems together. it is connected to the pituitary gland by portal vessels.

29
Q

what does the hypothalamus do?

A

releases releasing hormones (RH) or inhibiting hormones (IH). these hormones travel thru the pituitary portal vessels and reach the anterior pituitary (AP). there they stimulate or inhibit the release of specific hormones from the anterior pituitary.

30
Q

what is the pituitary gland?

A

the hypothalamus signals the pituitary gland, which has two main parts: the posterior pituitary and the anterior pituitary

31
Q

what is the posterior pituitary and what does it do?

A

stores and secretes antidiuretic hormone (ADH) and oxytocin which are both produced by the neurosecretory cells in the hypothalamus. the axons of these cells extend into the posterior pituitary, where the hormones are stored in vesicles until they are needed

32
Q

what is the anterior pituitary and what does it do?

A

an endocrine gland that releases hormones directly into the bloodstream. each hormone from AP is controlled by at least one releasing hormone from the hypothalamus, and some are regulated by inhibiting hormones. there are three types of hormones produced by the AP: trophic, growth, and prolactin

33
Q

what is antidiuretic hormone (ADH)?

A

hormone that plays a key role in regulating amnt of water reabsorbed by the kidneys

34
Q

what is oxytocin?

A

hormone that pays a role in social bonding, sexual reproduction, and childbirth. (ex: stimulates uterine contractions during labor and helps to stimulate release of milk after childbirth)

35
Q

what is a trophic hormone?

A

hormone that regulates the function of another endocrine gland

36
Q

what is the hormone cascade pathway?

A

term for sets of hormones from hypothalamus, AP, target endocrine gland, and response tissue

37
Q

what do thyroid hormones do?

A

they stimulate cellular metabolism in virtually all cells, help maintain normal BP, heart rate, muscle tone, and regulate digestive and reproductive functions

38
Q

what are the steps of thyroid regulation?

A
  1. hypothalamus
  2. __ tropin-releasing hormone (tropic)
  3. stimulates AP
  4. __-stimulating hormone (tropic- can also be called ___tropin)
  5. ___gland
  6. ____hormone (nontropic)
  7. response
39
Q

what is the thyroid gland?

A

located on the ventral surface of the trachea in the neck and consists of two lobes. it secretes two hormones, both called thyroid hormone, they are derived from the amino acid tyrosine and iodine.
- triiodothyronine (T3) contains 3 iodine atoms
- thyroxine (T4) contains four iodine atoms

40
Q

what is the thyroid hormone (TH)?

A

acts on cells throughout the body and is regulated through a negative feedback loop. When thyroid hormone levels are low, the hypothalamus secretes thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH). This, in turn, stimulates the thyroid gland to produce more thyroid hormone. When thyroid hormone levels are normal, TSH and TRH secretion is suppressed through negative feedback, helping to maintain thyroid hormone levels within a normal range.

41
Q

what is hypothyroidism?

A

low amounts of thyroid hormones. this can cause weight gain and lethargy, slower metabolism, and an intolerance to cold

42
Q

what is goiter?

A

an enlarged thyroid gland that can be caused by iodine deficiency, unable to make T3/T4 (causes iodine levels to drop). the AP secretes a lot of TSH which causes the thyroid gland to grow abnormally

43
Q

what is hyperthyroidism?

A

too much thyroid hormones. causes high body temp, profuse sweating, weight loss, irritability, high blood pressure

44
Q

what is graves disease?

A

the most common thyroid disorder, it is an autoimmune disorder where antibodies bind to TSH receptors and there is a hypersecretion of thyroid hormone

45
Q

what is the parathyroid?

A

consists of 4 glands located in connective tissue surrounding the thyroid. secretes parathyroid hormone (PTH) and controls blood Ca2+ levels

46
Q

what happens when there is low blood Ca2+?

A

PTH is released, bone releases Ca2+, kidneys reabsorb Ca2+, the liver produces vitamin D which leads to the absorption of Ca2+ from intestines and causes a rise in blood Ca2+ levels

47
Q

what happens where this is high blood Ca2+?

A

the thyroid secretes calcitonin, this inhibits Ca2+ removal in the bone and increases Ca2+ excretion in kidneys. calcitonin is antagonistic to PTH.

48
Q

what are the adrenal glands?

A

they are small glands on top of each kidney that consist of two parts, the central: adrenal medulla
the outer: adrenal cortex
functions as distinct glands, both regulate metabolism and respond to stress

49
Q

what is the adrenal medulla?

A

a neuroendocrine gland responsible for alarm reaction (flight or flight) to short term stress, it continuously secretes epinephrine, norepinephrine in small amounts

49
Q

how does the adrenal medulla work when we are stressed?

A

the hypothalamus activates the adrenal medulla via nerve impulse, the adrenal medulla then releases epinephrine and norepinephrine: more blood to the brain, muscles, and heart, glycogen breaks down glucose, and an increase in O2 delivery (higher heart rate, stroke volume, and breathing rate

49
Q

what is the adrenal cortex?

A

responds to chronic stress, responds to an endocrine signal rather than nervous, when stressed the hypothalamus secretes corticotropin releasing factor (CRF) and the AP releases ACTH (adrencordicotropic hormone)

50
Q

what does the ACTH from AP do

A

it stimulates the adrenal cortex to produce corticosteroids, there are two main types and both steroid hormones are synthesized from cholesterol

51
Q

what is glucocorticoids?

A

a corticosteroid produced by the adrenal cortex, it promotes glucose formation from non-carb sources (like protiens), acts on skeletal muscle by causing the breakdown of muscle proteins, glucose is then released into the blood and the blood glucose levels go up under the stess, ensures edequate food for stressed ceclls, high lexels can suppress immune components

52
Q

what is mineralocorticoids?

A

a corticosteroid produced by the adrenal cortex, regulates mineral metabolism, maintains salt and water balance, aldosterone is a princelple minerocoritoid, also regulates H2O/Na+ balance in the blood

bio 116: exam 2 (6 decks)

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