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Human Physiology 1 > Lectures 5 & 6 JUST Terms > Flashcards

Lectures 5 & 6 JUST Terms Flashcards

1
Q

Adenylyl Cyclase

A

membrane-bound enzyme that converts ATP to cyclic AMP

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2
Q

Afferent Pathway

A

the pathway that connects a receptor to an integrating center

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3
Q

Agonists

A

molecules that combine with a receptor & mimic a response

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4
Q

Amplifier Enzyme

A

a membrane enzyme that creates 2 or more 2nd messengers during signal transduction

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5
Q

Antagonists

A

1 substance opposes the action of another

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6
Q

Arachidonic Acid

A

20-carbon fatty acid precursor of eicosanoid signal molecule

dual function:

  1. are themselves 2nd messengers within a cell
  2. diffuse out of the cell & act as a ligand for GPCR cell membrane & adjacent cells
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7
Q

Autocrine Signal

A

signaling to self

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8
Q

Calmodulin

A

intracellular 2nd messenger that binds Ca2+

- a calcium-binding protein which then activates other proteins

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9
Q

Cascade

A

response in which a series of inactive molecules convert to active forms until a product is formed

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10
Q

Cellular Response

A

the end of the line for a signal brought to the target cell by a signaling molecule ?

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11
Q

Chemical Signals

A

are molecules secreted by cells into the ECF

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12
Q

Connexins

A

each connexon is made of 6 connexin monomers/subunits

2 connexons (12 connexins) form a functional gap junction b/t 2 adjacent cells

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13
Q

Contact-Dependent Signals

A 
a molecule (ligand) in the extracellular matrix of one cell binds to a receptor in the membrane of the adjacent cell
- immune system, development
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14
Q

Cyclic AMP (cAMP)

A
  • a second messenger molecule synthesized by adenylyl cyclase
  • cAMP is a small molecule that diffuses throughout the cell, & activates the PK-A protein kinase
  • some GPCR pathways activate adenylyl cyclase, some inhibit it (allowing the concentration of cAMP in a cell to decrease)
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15
Q

Cytosolic Receptors (nuclear receptors)

A

the binding sites for steroid hormones, thyroid hormones, vitamin D, and retinoic acids. ?

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16
Q

Dephosphorylation

A

removal of a phosphate group

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17
Q

Desensitization

A

reversible form of receptor down-regulation achieved using modulators

  • receptors can be desensitized - meaning they need higher dose to achieve the same effect
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18
Q

Diacylglycerol (DAG)

A

a lipid product of the cleavage of phospholipid in the cell membrane by the enzyme PL-C
- this lipid remains associated with the cell membrane, & can achieve the PK-C enzyme

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19
Q

Drug Tolerance

A

down-regulation & desensitization are 1 explanation for the development of drug tolerance, a condition in which the response to a given dose decreases despite continuous exposure to the drug

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20
Q

Effectors

A

the cell or tissue that carries out the homeostatic response

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21
Q

Efferent Pathway

A

outgoing signal that goes from the integrating center to an effector

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22
Q

Eicosanoids

A

are a subset of oxylipins
- polyunsaturated fatty acid, having a length of 20 carbon atoms
Arachidonic Acid is an ex

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23
Q

Electrical Signals

A

are changes in the cell’s membrane potential

- when the ligand binds, the channel opens. allows ions to enter & leave cells

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24
Q

Feedback Loop

A

modulate the response loop

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25
Q

Feedforward Control

A

allows the body to ANTICIPATE change, generate a response before variable changes (may be argued this is not a loop)

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26
Q

First Messenger

A

chemical signal molecules released by cells

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27
Q

G Protein

A

membrane proteins that couple membrane receptors to ion channels or membrane enzymes
- called g-proteins b/c they bind GDP & GTP

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28
Q

G Protein-Coupled Adenylyl Cyclase-cAMP system

A

the first signal transduction system discovered

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29
Q

G Protein-Coupled Receptors (GPCR)

A

hundreds of known GPCR
- many have unknown functions (orphan receptors)

also called

  • metabotropic receptors
  • 7 transmembrane domain receptor (7TR)
  • serpentine receptor

activation of GPCR leads to generation/release of second messengers

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30
Q

Gap Junctions

A
  1. Channels that connect adjacent cells
    - 2 adjacent cells express channel proteins called connexins
  2. Water filled pore: allows small molecules & ions to diffuse from one cell to the next
  3. Common in heart, smooth muscle, & some neurons
  4. Cells are connected by cytoplasmic bridges
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31
Q

Guanylyl Cyclase

A

enzyme that controls formation of cyclic GMP

- which leads to relaxation of smooth muscle

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32
Q

Histamine

A

paracrine secreted by mast cells & basophiles; acts as a vasodilator & bronchoconstrictor ?

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33
Q

Hormones

A

chemical secreted by a cell or group of cells into the blood for transport to a distant target where it acts in very low concentrations to affect growth, development, homeostasis, or metabolism

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34
Q

Inositol Triphosphate (IP3)

A
  • a second messenger molecule produced by the hydrolysis of phospholipids in the cell membrane by PL-C
  • IP3 is small & water soluble, & diffuses easily throughout the cell, but not across cell membranes
  • IP3 binds to the IP3 receptor channel located in the endoplasmic reticulum of the cell
  • this causes the IP3 receptor channel to gate open, & release sequestered Ca2+ into the cytoplasm, thus causing a large increase in free intracellular Ca2+
  • when the IP3 receptor channel gates closed, Ca2+ ATPase transporters pump the cytoplasmic Ca2+ back into the endoplasmic reticulum stores
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35
Q

Integrating Center

A

the control center that evaluates incoming signal & decides on an appropriate response

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36
Q

Integrin Recptors

A
  • binds extracellular matrix proteins (collagen for ex)
  • binding ligand stimulates changes in cytoskeleton
  • which then causes: cell movement, growth, wound healing
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37
Q

Ligand

A

the molecule that binds to a protein

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38
Q

Ligand-Gated

A

aka receptor channel (ion channel)

  • the ligand is often a neurotransmitter
  • when the ligand binds, the channel opens
  • allows ions to enter & leave cells = electrical signal (synaptic transmission)
  • allow Ca2+ into cells (calcium is an important intracellular signal)
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39
Q

Lipophilic Signal Molecules

A

enter cells by simple diffusion through the phospholipid bilayer of the cell membrane

40
Q

Lipophobic Signal Molecules

A

are unable to enter cells by simple diffusion through the cell membrane
- instead, these signal molecules remain in the extracellular fluid & bind to receptor proteins on the cell membrane

41
Q

Local Communication

A

includes

(1) GAP JUNCTIONS, which allow direct cytoplasmic transfer of electrical & chemical signals b/t adjacent cells
(2) CONTACT-DEPENDENT SIGNALS, which occur when surface molecules on another cell’s membrane; &
(3) chemicals that diffuse through the ECF to act on cells close by

42
Q

Long-Distance Communication

A

(4) uses a combination of chemical & electrical signals carried by nerve cells & chemical signals transported in the blood

43
Q

Negative Feedback

A

are homeostatic - stabilize variable

44
Q

Neurocrine

A

any molecule secreted by a nerve cell

45
Q

Neurohormone

A

an electrical signal travels distance along a nerve cell

  • causes release of a chemical
  • the chemical is released into the blood, & acts at DISTANT targets
46
Q

Neurotransmitter

A

an electrical signal travels distance along a nerve cell

  • causes release of a chemical
  • the chemical travels ACROSS A SMALL GAP ONTO A TARGET
47
Q

Output Signal

A

part of control system ?

48
Q

Oxytocin

A

posterior pituitary hormone that causes uterine & breast smooth muscle constraction

49
Q

Paracrine Signal

A

signaling to cells in the immediate vicinity

50
Q

Phospholipase A2 (PLA2)

A

enzyme that converts a membrane phospholipid into 2 different 2nd messenger molecules, DAG & IP3

51
Q

Phospholipase C (PL-C)

A

an amplifier enzyme that primarily converts membrane phospholipids (primarily Phosphatidylinositol 4,5-biphosphate) into the messengers:

(1) Diacylglycerol &
(2) Inositol tri-phosphate

52
Q

Physiological Control System

A

can operate over short or long distances

  • local = cells & tissue level
  • long distance = endocrine or nervous control (“reflex control”)
53
Q

Positive Feedback Loop

A

reinforce a stimulus

- are NOT homeostatic? (some people think this)

54
Q

Protein Kinase A (PK-A)

A
  • cAMP activates protein kinase A (PKA)
  • PKA diffuses within cell to phosphorylate many other proteins
  • many types of proteins can be phosphorylated, giving rise to complex/co-ordinated cellular responses
55
Q

Protein Kinases

A

enzymes that transfer a phosphate group from ATP to a protein

56
Q

Protein Phosphates

A

a phosphatase enzyme that removes a phosphate group from the phosphorylated amino acid residue of its substrate protein ?

57
Q

Receptor

A

a cellular protein that binds to a ligand

58
Q

Receptor-Channel

A

(ion channel)

  • the ligand is often a neurotransmitter
  • when the ligand binds, the channel opens
  • allows ions to enter & leave cells = electrical signal (synaptic transmission)
  • allow Ca2+ into cells (calcium is an important intracellular signal)
59
Q

Receptor-Enzymes

A

membrane proteins that bind ligands on the extracellular side & activate enzymes on the intracellular side

60
Q

Response Loop

A

control pathway that begins with the stimulus & ends with the response

61
Q

Second Messenger System

A

intracellular molecules that translate the signal from a 1st messenger into an intracellular response

62
Q

Second Messengers

A

is a signaling molecule synthesized or released by a cell in response to an extracellular signalling molecule (hormone, for ex)
- sometimes they are synthesized, sometimes they are released from a storage compartment

63
Q

Sensitivity

A

the ability of an organism or organ to respond to external stimuli. ?

64
Q

Setpoint

A

the physiological value around which the normal range fluctuates ?

65
Q

Signal Amplification

A

a small amount of ligand creates a large effect

- aka the generation of a large # of intracellular molecules

66
Q

Signal Transduction

A

is the process by which an extracellular signal molecule activates a membrane receptor that in turn alters intracellular molecules to create a response
- converts one form of signal to another

67
Q

Specificity

A

the ability of an enzyme or receptor to bind to a particular molecule or a group of closely related molecules

68
Q

Syncytium

A

when the channel is open, the connected cells function like a single cell that contains multiple nuclei (syncytium) ?

69
Q

Target Cells (Targets)

A

A target cell responds to a hormone because it bears receptors for the hormone. In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone. ?

70
Q

Transducer

A

is a device that converts a signal from one form into a different form

71
Q

Tyrosine Kinase

A

transfers a phosphate group from ATP to a tyrosine residue (an amino acid) of a protein, enhancing or inhibiting its activity. (phosphorylates tyrosine residues)

72
Q

Amplification Signal

A

a small amount of ligand creates a large effect

- aka the generation of a large # of intracellular molecules ?

73
Q

Catalytic Receptor

A

2 types:

  1. receptor-enzyme: ligand binding to a receptor-enzyme activates an intracellular enzyme
  2. integrin receptor: ligand binding to integrin receptors alters enzymes of the cytoskeleton
74
Q

Central Receptor

A

sensory receptors located in or closely linked to the brain

75
Q

Cycloxygenase (COX)

A

enzyme that converts arachidonic acid to prostanoids

76
Q

Cytokinases

A

physical process of cell division ??

77
Q

Endogenous

A

an endogenous ligand is something natural in your body: for ex a hormone or neurotransmitter

non-endogenous may be a drug or toxin

78
Q

Epinephrine (Adrenaline)

A

activates alpha & beta2 receptors

79
Q

Half-Life

A

the amount of time required to reduce the concentration of hormone by one-half

80
Q

Hydrogen Sulfide

A

a soluble gas recognized as second messengers

  • the newest gaseous signal molecule to be described
  • also acts in the cardiovascular system to relax blood vessels
81
Q

Leukotrienes

A

are molecules produced by the action of the enzyme lipoxygenase on arachidonic acid

  • are secreted by certain types of white blood cells
  • they play a significant role in asthma, a lung condition in which the smooth muscle of the airways constrict, making it difficult to breathe, & in the severe allergic reaction known as anaphylaxis
  • for this reason, pharmaceutical companies have developed drugs to block leukotriene synthesis or action
82
Q

Input Signal

A

when activated by a change, the sensor sends an input (afferent) signal to the integrating center for the reflex

83
Q

Janus Kinase (JAK)

A

is a family of intracellular, non-receptor tyrosine kinases that transduce cytokine-mediated signals via the JAK-STAT pathway. ?

84
Q

Neuromodulator

A

chemicals that alter the response of a neuron more slowly than neurotransmitters

85
Q

Orphan Receptors

A

one that has no known ligand (AKA unknown function)

86
Q

Peripheral Receptors

A

sensory receptors that are not located in or close to the brain

87
Q

Prostaglandins

A

part of the arachidonic acid cascade

  • prostanoids are molecules produced when the enzyme cyclooxygenase (COX) acts on arachidonic acid
  • prostanoids include prostaglandins & thromboxanes
  • these eicosanoids act on many tissues of the body, including smooth muscle in various organs, platelets, kidney, & bone
  • in addition, prostaglandins are involved in sleep, inflammation, pain & fever
88
Q

Protein-Coupled Receptor

A

g-protein-coupled receptors (GPCRs) are a large & complex family of membrane-spanning proteins that cross the phospholipid bilayer 7 times

89
Q

Reflex

A

any long-distance pathway that receives input about a change, integrates the information, & uses the nervous system, endocrine system, or both to react appropriately

90
Q

Pathways

A

network of interconnected chemical reactions formed by the enzymatic reactions of metabolism

91
Q

Sensor

A

or sensory receptor continuously monitors its environment for a particular variable

92
Q

Stimulus

A

the disturbance or change that sets a reflex in motion

93
Q

Systemic Response

A

describes what those specific cellular & tissue events mean to the organism as a whole
- ex: when the blood vessels constrict, the systemic response is an increase in blood pressure

94
Q

Threshold

A

(1) the minimum depolarization that will initiate an action potential in the trigger zone
(2) the minimum stimulus required to set a reflex response in motion

95
Q

Thromboxanes

A

part of the arachidonic acid cascade

  • prostanoids are molecules produced when the enzyme cyclooxygenase (COX) acts on arachidonic acid
  • prostanoids include prostaglandins & thromboxanes
  • these eicosanoids act on many tissues of the body, including smooth muscle in various organs, platelets, kidney, & bone
96
Q

Tonic Control

A

ongoing control that is adjusted up & down

97
Q

Transduce

A

Transduction is the process by which a virus transfers genetic material from one bacterium to another ?

Human Physiology 1 (32 decks)

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