Section 1
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Animals long distance signalling
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Section 1
(50 cards)
Animals long distance signalling
endocrine signaling and nervous system
Paracrine Signalling
secretion of signal from cell to target cell
Cell Junctions
direct connection of cytoplasm between different cells; these signals pass freely between cells
Cell-to-Signalling importantce
devolpment, grwth, and homostasis
Universal mechanisms of cell communication suggests an ____________ similarity among different species
evolutionary
Kinase
an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule
Autocrine
term for hormones that act on same cells that secrete them
Response
a reaction to the relayed signal
How do most intracellular receptors function?
doing the entire transduction on their own; testosterone behaving as a transcription factor by controls which genes, DNA, are transcribed into mRNA
Stage Three - Response
a specific cell response is triggered; like enzymes, movement of cell, etc.
G-Protein steps
GDP is bound so it's inactive When ligand binds to G-protein coupled receptor in the membrane the receptor is activated and changes its shape so the receptor can bind to the inactive G-protein and exchange GTP for GDP Active G-protein removes from receptor and diffuses along the membrane to bind an enzyme and the altered activity triggers the next step in cell response
Juxtacrine
signals act through direct stimulation of the adjacent cells
How does Cholera toxin work?
Modifying a G-protein involved in regulating salt and water secretion; forces g-protein into active state and forces it to make cAMP
Why are ligand-gated ion receptors important to the nervous system?
Source of needed calcium and salt ions
Long distance communication
specialized cells secrete signal, hormones, into body fluids, circulatory system, reach virtually all cells in different locations in body
What do membrane receptors have that act as a gate?
They change shape so things can move through
How does a G-protein work?
Is either on or off, when GDP is attached it's inactive
Paracrine
Referring to a secreted molecule that acts on a neighboring cell.
Cholera
a disease caused by bacteria in food and water
What does the binding of epinephrine cause?
leads to an increase in cAMP concentration; enzyme converts ATP to cAMP in response to epinephrine, this can act on protein kinase and does the cellular activity of breaking down glycogen into glucose
Hydrophobic signal molecules
nonpolar molecules that can go across the cell membrane; testosterone
Stage One - Reception
detection of a signaling molecule from outside of cell by a target cell; ligand binds to receptor
How does calcium act as a second messenger?
different between cytoplasm and extracellular fluid and inside organelles like ER or mitochondria; ATP pumps more calcium from cytoplasm against gradient when the calcium levels rise
What are the steps of signal tranduction?
Reception, transduction, and response
What would need to occur in a cell to deactivate the protein kinase enzymes?
Inhibitor, death of cell, or deactivation of protein
G protein-coupled receptors (GPCRs)
cell surface transmembrane receptors that work with the help of a G protein
Signals can be...
local or over a long distance
Reception
ligand binds to receptor
Why can amplifying ligands be helpful?
Can have multiple responses from a single ligand
Second Messengers
other important component of transduction pathway; most components are enzymes or proteins; nonpolar, small, water soluble molecules
Why is calcium concentration important?
muscle contractions, secretion of substances, cell division, hormonal changes
cyclic AMP (cAMP)
second messenger that carries signal initiated by epinephrine from the cell membrane
What kind of travel do synaspes use?
Paracrine
Local
these signals are produced by cells that only affect the activity of nearby cells
What does epinephrine do?
involved in fight or flight response; brings about the breakdown of glycogen storage into glucose, and this function along with G-protein-coupled receptors and receptors tyrosine kinases
Transduction
transforms the signal so it can be relayed
How does a ligand fit into the receptor?
perfectly
1st messenger
receptor; only GPCR and RTK have 2nd messangers
What do G-proteins bind to?
GTP
Cell-to-Cell Recognition
direct contact between two cells with ligands and receptors present
GPCRs
large family of proteins that are structurally similar and have binding sites for signaling and G-proteins
Synaptic Signalling
in animal nervous system between two cells
Ligand
A molecule that binds specifically to another molecule, usually a larger one.
How do cells communicate?
chemical messengers like hormones, cell-to-cell contact like cell junctions, synaptic signalling like neurotransmitters diffusing across a synapse to a single cell
Endocrine
the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
protein phosphatases
Enzymes that can rapidly remove phosphate groups from proteins.
What does Cholera produce?
Cholera toxin which is made in the small intensive of infected
Stage Two - Transduction
The binding of signaling molecule receptor protein in some way starting up the whole process of transduction; the signal is converted to a form that can bring up specific cellular response; like a relay race
When is the gate of ligand-gated ion receptors open?
When accepting ions like Na+ and Ca +2 through the channel
Plant long distance signalling
plant growth regulator
Section 2
(50 cards)
Repolarization
Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.
How does potassium change the ion gradient?
Apoptosis process
cell rounds up and the nucleus fragments plasma membrane blisters cell dissolves into fragments
Central Nervous System (CNS)
brain and spinal cord; where integration takes place
How does a hormone qualify as a long-distance signaling example?
Hormone Signalling, specialized endocrine cells secrete hormones into body fluids, often the blood; hormones may reach virtually all body cells
Chemical Signals
short-distance communication
Presynaptic Neuron
synthesizes and packages the neurotransmitter in synaptic vesicles located in the synaptic terminal
When do cells need to die?
to control cells that are infected; protect neighboring cells in the development of organisms. like in hands and feet; immune cells controlling infection in body
Electrical Signals
long-distance communcation
Signal Transduction Pathway
The process by which a signal on a cell's surface is converted into a specific cellular response.
Synaptic Terminal
of one axon passes information across the synapse in the form of chemical messengers called neurotransmitters
Apoptosis
process of programmed cell death
Do neurotransmitters affect ion channels?
yes
Gangila
higher order processing of nervous signals may involve clusters of neurons
Four Stages of Nervous System Processing
sensory input, integration, motor output
Synaptic Cleft
The narrow gap that separates the presynaptic neuron from the postsynaptic cell.
First Messengers
the extracellular signaling molecule that binds to the membrane receptor
Neurons
a nerve cell; the basic building block of the nervous system
Hyperpolarization
The movement of the membrane potential of a cell away from rest potential in a more negative direction.
Nerves
bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs
Peripheral Nervous System (PNS)
Carries information into and out of the CNS
How do neurotransmitters work?
Neurotransmitters are released at nerve terminals, diffuse across the synapse, and bind to receptors on the surface of the target cell (often another neuron, but also possibly a muscle or gland cell). These receptors act as on- and-off switches for the next cell.
Acetylcholine
A neurotransmitter that enables learning and memory and also triggers muscle contraction; PNS - activates skeltal muscles; CNS - inhibits heart tissue
Axons
longer and transmit signals
Refractory Period
a period of inactivity after a neuron has fired
Synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
Association
interneurons; located in spinal cord or grain integrate or evaluate impulses for appropriate responses
Depolarization
The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.
Glial Cells
astrocytes and oligodendrocytes; nourish neurons, insulate axons, and regulate the extracellular fluid around the neuron
local signaling
cell junction and cell-to-cell recognition
Excitatory Postsynaptic Potentials (EPSPs)
depolarizations that bring the membrane potential toward thereshold
Synaptic Terminals
ends of axons, releases neurotransmitters across a synapse
sodium-potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
Yeast Mating Process
Release mating factor, receive complementary factor, response is to grow toward opposite type, nuclei fuse and genetics are recombined
After release, the neurotransmitter
May diffuse out of the synaptic cleft May be taken up by surrounding cells May be degraded by enzymes
Brain
structured groups of neurons
Sensory
afferent; recieves stimulus, detect external stimuli and internal counditions and transmit information
Motor
efferent; stimulate effectors which are target cells, muscles, sweat glands, stomach, etc.
What do signals do once they get into the nucleus?
Make mRNA and then proteins
How does sodium change the ion gradient?
C. elegans
worm used in genetic studies
Quorum Sensing
Signalling system used by bacteria to determine the population density of their species in a local area
Dendrites
receives signals
Inhibitatory postsynaptic potential (IPSP)
hyperpolarizations that move the membrane potential farther from the threshold
Cell Body
contains nucleus and organelles, numerous extensions
What can neurotransmitters do?
More than 100 neurotransmitters Same neurotransmitters can have different results in different types of cells A single neurotransmitter may have more than a dozen different receptors
Ced-9
inhibitor of Ced-4 and Ced-3
Yeast
type of fungi; mating is believed to be the first form of cell signalling
Glial
nourish and support the neurons
What do Ced-4 and Ced-3 do when active?
Kill off the cell
Section 3
(50 cards)
Pathogen
A disease causing agent
Step Six of Cell Signal
Return to resting potential (resting)
Agonists
mimic drugs that resemble a neurotransmitter
Parasympathetic Nervous System
the division of the autonomic nervous system that calms the body, conserving its energy
Excitable Cells
Muscle and neuron cells
Sympathetic Nervous System (SNS)
The component of the autonomic nervous system that responds to stressful situations by initiating the fight-or-flight response.
Gray Matter
Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.
Antagonist
block action of neurotransmitters
Immune Response to a Pathogen
Spikes on immune response the second time of contact, means people can't the disease again
Step Two of Cell Signal
depolarization (hits threshold)
cell-mediated immune response
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells.
The operation of the sodium-potassium "pump" to return the neuron to a normal state moves
sodium ions out of the cell and potassium ions into the cell
Cocaine is known to block dopamine transporters, which leads to excess dopamine being trapped in the synapse where it repeatedly stimulates target cells. This action is considered to be
antagonistic
What steps goes with which polarization?
Polarization - 6 Depolarization - 1,2,3,4 Hyperpolarization - 5
Resting Potential
The difference in electric charge between the inside and outside of a neuron's cell membrane
How can cells change their potential?
opening and closing ion channels
Step Five of Cell Signal
undershoot of resting phase (hyperpolarization)
Synaptic Vesticles
a small, spherical structure that contains molecules of neurotransmitter
Automatic Nervous System (ANS)
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
Step Three of Cell Signal
rising phase of action potential
Innate Immunity
Immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens.
Step Four of Cell Signal
Falling phase of action potential (depolarization)
White Matter
Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.
Step One of Cell Signal
Resting potential
How do depolarization reactions respond?
all or nothing; once threshold is reached, always creates the same voltage spike regardless of intensity of the stimulus but strength can increase the speed
Principal Ion Inside of Cell
K+; negative charge
What's the threshold potential for sodium?
-55 mV
Saltatory Conduction
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
Ranvier Nodes
gaps between the plates in myelin sheath, serve as points along which the action potential, increases speed
What is the point of the refactory period?
to be sure the signal can only go one way
Blood Stream
the blood circulating through the body of a person or animal.
Principal Ion Outside of Cell
Na+; positive charge
Adaptive Immunity
the ability to recognize and remember specific antigens and mount an attack on them
Myelin Sheath
covers axons in vertebrates, acts as insulators, has gaps as they are like plates
T-cell Helper
Cells responsible for identifying an antigen
Schwann cells (PNS)
Form myelin sheath in the peripheral nervous system
Phagocytosis
Cell eating
Cell Polarization Chart
Threshold Potential
the potential at which the voltage-gated channels open
Effector T
fight intracellular infected cells (viruses, cancer cells)
Memory Th
cells that reactivate their immune response when re-introduced
What's the threshold potential for potassium?
+35 mV
Somatic Nervous System (SNS)
the part of the peripheral nervous system that controls voluntary movement of skeletal muscles
Antigen-presenting cells (APCs)
cells such as B cells, macrophages, and dendritic cells that can present exogenous antigens to naive or memory T cells, activating them
Gated Ion Channels
open and close in response to stimuli; only in nerve cells
Antibody
A protein that acts against a specific antigen
Humoral Response
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.
Phagocytes
A type of white blood cell that ingests invading microbes
Antigen
substance that triggers an immune response
Anaphylaxis
a severe response to an allergen in which the symptoms develop quickly, and without help, the patient can die within a few minutes.
Section 4
(50 cards)
Cytotoxic T cells
recognize MHC Class I markers and release chemicals to kill infected cells
Acquired Immunity
develops with exposure to various antigens and works to protect the body against those specific antigens in the future
Helper T Cells
bind to APCs and release cytokines, alarm system, to make more helper t-cells
Mucus Membranes
epitheial tissue that protects the interior surfaces of the body by trapping pathogens that initally enter into areas that are open to the exterior
T-Cell Structure
circle with spikes
Antibodies
recognize pathogens and will latch to them
How antibodies destory pathogens
blocking antigen site, by clumping proteins together, or activating complement proteins that lyse the pathogen
Constant Region
this place is identical in all antibodies
Specific Defenses
3rd line of defense; cells and tissues that recognize and attack specific foreign substances in the body
Immune
safe from harm; protected
Cilia
sweep pathogens to exterior opening of respritory tract
Primary response memory cells
clonal selection, specific effector cells are produced
Monoclonal Antibodies
a collection of identical antibodies that interact with a single antigen site
Second line of defense, internal defenses
Phagocytes, natural killer cells, complement system / antimicrobial proteins, interferons, inflammatory response (histamine, vasodilation, phagocytes, complement)
Histamine
released in inflammatory response and causes increased blood flow to damaged area, allowing specific immune cells to destroy the pathogen
Self and Nonself Recognition
ability to mount attacks against invaders while not attacking the body's own tissues. This ability is lost in autoimmune diseases
Specify
one antibody for every antigen (clonal selection)
Four Types of Inflammatory response
heat, redness, swelling, pus
Diversity
can recognize lots of different antigens
Immune System
A system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response
Natural killer cells
circulate through the body and detect the abnormal cells
Interferon
proteins inhibit the production of viruses, increases body temperature
pH
pH of stomach and vagina destroy pathogens that are able to enter
Neutrophils
engulf and destroy pathogens
Examples of Immune system barrier
Skin, mucus membranes, cilia, body fluids, pH
B-Cell Structure
circle with spikes, has a branching at end
Skin
provides physical and chemical protection, the skin blocks pathogens from entering the body, the skin releases sweat oils and waxes that contain chemicals that are toxic to pathogens
Non-specific Defenses
attack any antigen not recognized as 'self'; 1st and 2nd line of defense
Antimicrobial proteins
function by attacking pathogens or impeding their ability to reproduce
What happens when the white blood cells get an antigen?
exposure to an antigen from a pathogen activities B and T cells with specific antigen receptors against that pathogen
Lysozyme
an enzyme released in sweat and tears
Barriers
1st line of defense
Cytokines
released that enhance the immune response
Memory Cells
modified B cell - acquired immunity that remember specific anitgens
Dendritic cells (DCs)
stimulate development of adaptive immunity
Agglutination
clumping proteins together
Lymphocytes
The two types of white blood cells that are part of the body's immune system: B lymphocytes form in the bone marrow and release antibodies that fight bacterial infections; T lymphocytes form in the thymus and other lymphatic tissue and attack cancer cells, viruses, and foreign substances.
Eosinophils
discharge destructive enzymes
T cells
mature in the thymus, cell mediated immunity
Self-Tolerance
there are no antigen receptor for self (exception = autoimmune disease)
Complement proteins
result in the lysis of invading pathogens and helps trigger inflammation
Macrophages
found throughout the body, "big eaters"
B cells
mature in bone marrow, produce antibodies
Immunity
active vs passive; booster shots vs mom providing fetus
secondary response memory cells
faster, because now memory cells
Antigens
substances that elicit a response form B or T
Fever
incredibly important 2nd line of defense as it suppresses bacterial growth and stimulates the immune system
Variable Region
place where the antibody binds to antigen
Neutralization
blocking antigen site
Major Histocompatibility Complex (MHC)
genes encode molecules on the cell surface
Section 5
(48 cards)