BI108 Quiz #5

Hormone

A molecule that acts as a long-distance signal between cells in the same multicellular individual. (Type of Ligand)

Ligand

Any molecule that binds to a receptor and triggers a response. Includes both long-distance and short-distance cell-to-cell signals as well as intracellular signals.

Signal Transduction

A change in the form of a signal, for example from a hormone that binds to a receptor on the surface of a cell to a second messenger or phosphorylation cascade inside the cell. Converting one signal to another type of signal.

Kinase

An enzyme that catalyzes the addition of a phosphate group from ATP to a recipient molecule.

Phosphorylation Cascade

A chain reaction that amplifies the signal from a chemical messenger. It occurs when each kinase in a signaling network phosphorylates multiple target proteins, which each then go on to phosphorylate multiple target proteins, and so on.

Second Messenger

An ion or small molecule that is released in response to a chemical messenger binding to a cell-surface receptor and acts as an intracellular signal

Signal Amplification

One activated molecule may activate multiple molecules of the next step often through a phosphorylation cascade. Signals (the primary messenger) can release second messengers that can also amplify the signal.

Chemical Communication Sequence of Events

1) The signaling molecule is released in response to a stimulus from cells where the signal is synthesized and stored.

2) The messenger travels from source cells to target cells

3) The signal binds to a receptor protein in a target cell. This binding event is extremely specific.

4) When a signal binds to a receptor, the protein changes shape in a way that acts as a trigger. This change initiates events that lead to the recipient cell changing its activity.

Amines

Messengers are derived from the amino acids tryptophan or tyrosine.

Peptides

Small proteins that include messengers like insulin, oxytocin, and growth hormones.

Steroids

Lipids that have a characteristic of 4 ring structures and have messenger synthesized from cholesterol. include estrogen, cortisol, and testosterone.

Lipid Solubility

If a signaling molecule is small enough and hydrophobic enough, it is lipid soluble and can cross the other membrane to enter the interior of target cells. If it is too large and hydrophillic it cannot do this.

Mobile Loop

Closes off an active site inside the structure but swings back and reveals active site when phosphorylated.

Intracellular Signals

Wide array of short distance chemical messengers that affect nearby cells. Activated by chemical messengers that can lead to an array of outcomes.

Cross Talk

Cells can integrate information from an array of different chemical messengers because their signaling networks interacts.

Homeostasis

The process by which biological systems maintain stability, while adjusting to changing external conditions. Internal environment is always challenged by external environment and metabolic activities. Physiological systems aim to maintain optimal physical and chemical environment for all metabolic processes.

Control Systems

Sense when conditions deviate from "normal" and initiate physiological mechanisms to correct the error.

Feedback Information

Information that is compared to the set point or reference point.

Error Signal

Any difference between the set point and feedback information.

Effector

Tissues or organs that can after the internal environment.

Negative Feedback

Is information that returns system to set point (returns system to homeostatic balance)

Positive Feedback

Amplifies a response and increases deviation from a set point (pushes system away from homeostatic balance)

Cell Signaling

Cells can send/receive, process, and respond to information from the intracellular and extracellular environments. Responsible for maintaining homeostasis

Reception

Part of cell signaling pathway where information is transmitted by a signal and received by a receptor.

Transduction

Part of cell signaling where theres a conversion of signal to a cellular response

Cellular Response

Part of cell signaling where theres changes in cell behavior in response to the signal. Result of signaling pathway can be short term or long term. Ex: changes in gene expression, change in rate of cellular respiration, cell growth/divison

Juxtacrine

Cell Signaling requiring physical contact

Autocrine

Signal affects cell that produced the signal.

Paracrine

Signal affects nearby cells

Endocrine

Signal travels to distant cells - ex: hormones

Conformational Change

Occurs when receptors bind to specific ligands

Intracellular Receptor

Receptor within the cell and bind to a signaling molecule that can pass through the lipid bilayer.

Membrane Receptor

Receptors embedded in the cell membrane; bind to signaling molecules outside of the cell. ( Hydrophillic signaling molecules or ligands are NOT able to pass through the lipid bilayer. )

Phosphatases

Remove phosphates to inactivate molecules within the pathway because signaling molecules don't stay bound to receptors forever.

Mitogens

Ligands that stimulate mitosis.

Diffusion

Movement of ions or molecules from regions of high concentration to regions of low concentration. Can be passive or spontaneous which decreases level of organization and increases entropy.

Gradients

Exist when the concentration of an ion or molecule differs from one to another, or the amount of electrical charge differs from one area to another.

Electrical Potential Gradient

A difference in charge carried by ions in one area versus another, almost always across a cell membrane or organelle membrane. Substances move down their electric potential gradients passively and spontaneously, toward unlike charges and away from like charges.

Membrane Voltage

In cells, an electrical potential created by a separation of charge across a membrane. Also called a transmembrane potential or a membrane potential.

Electric Current

In cells, a flow of charge in the form of ions.

Concentration Gradient

A difference in the concentration of an ion or molecule in one area versus another, often across a cell membrane or organelle membrane. Substances move down their concentration gradients passively and spontaneously, via diffusion.

Electrochemical Gradient

The overall gradient across a cell membrane or organelle membrane, produced by differences in concentration of substances combined with differences in the distribution of charge.

Overall Membrane Voltage

Function of the concentration of all the ions on either side of the membrane. Allow you to predict which way ions will flow if a channel changes configurations from a closed to an open position or if a carrier is activated. Negative value means the inside of the cell is negative compared to outside of the cell.

Co-Transport

Occurs when specialized carrier proteins in cell membranes use a steep concentration and electrical gradient for an ion like H+ to move a different substance against a concentration and electric gradient that is not as steep.

Neuron

A nervous system cell that receives, processes, and transmits action potentials. Has membranes studded with ion channels. Each ____ cell receives electrical signals from on set of ___ cells and then transmits electrical signals to a different set of ____ cells often packaged into bundles called nerves.

Action Potential

A rapid and transient set of changes in membrane voltage that occurs the same way every time. Formed by excited neurons that generate and transmit electrical signals.

Dendrite

Long, thin projections that communicate with other neurons in a network, receive information in the form of action potentials and transmit the information to the cell body.

Cell Body

The part of a neuron that contains most of the cell's volume and processes information from dendrites to other points in the network.

Axon

A projection from the cell body of a neuron that transmits information to other neuron it is networked with.

Resting Potential

The membrane potential of an excitable cell (neuron or muscle cell) in the normal or unexcited state. Cells that can transmit action potentials have a normal membrane voltage

Ion Channels

Regulate the flow of ions across the nerve cell membrane. Proteins that span the membranes of most cells, including nervous system cells.

Nervous System Tissue

Formed from neurons and glia also responding to information and processing

Central Nervous System (CNS)

Consists of the brain and spinal cord

Peripheral Nervous System (PNS)

All other parts of the nervous system. Comprises neurons that radiate throughout the body and carry information to and from the central nervous system.

Reductionism

Practice of analyzing complex phenomena by breaking them down into their compound parts and studying those simpler aspects, independently of the whole.

Nervous System

One of the major functions is to maintain homeostasis of the internal environment of the organism. Made of neurons and glia.

Autonomic Nervous System (ANS)

Consists of Parasympathetic and Sympathetic Divisions and they work in opposition to each other to finely control autonomic effectors.

Parasympathetic Nervous System

"rest and digest"

Sympathetic Nervous System

"fight or fight"

Sensors

Provide information about external environment and internal status.

Effectors

Cells or tissues that carry out the orders from the control system.

Glia

Do not transmit electrical signals. Many different kinds with different roles/generally the "support system" for all neurons.

Sensory/Afferent Neurons

Carry signals from sensor to the CNS

Interneurons

Only in the CNS, integrate and coordinate signals between CNS and PNS.

Efferent Neurons

Convey signals from CNS to effectors

Axon Terminals

Carry information as action potentials away from the presynaptic cell to the post synaptic cell

Synapse

The junction where two neurons or a neuron and a muscle cell communicate across a space called the synaptic cleft.

Active Transport in Ion Channels

Energy Required: Sodium-Potassium (Na+-K+) Pump

Passive Transport in Ion Channels

No outside energy required (diffusion): K+ leak channel, Voltage gated Na+ Channel, Voltage gated K+ channel,

Na+/K+ pump

Uses energy from ATP to move Na+ and K+ against their concentration or electrical potential gradients --> maintains the electrochemical gradient in the membrane. Creates a gradient and K+ flows down the gradient

K+ leak channel

Help establish and maintain the resting membrane potential. Allows K+ to move down its concentration gradient out of the cell as the channels are always open. Moves even more positive charges out of the cell.

Peak of Action Potential

All Na+ voltage gated channels open-maximum membrane potential

Falling (RePolarization of Action Potential)

Na+ voltage gated channels close (temporarily can't open) K+ voltage gated channels open. K+ leaves cell down concentration and chemical gradient. Positive charges leaves cell, repolarizing the membrane potential

Refractory Period (Hyperpolarization)

Membrane Potential goes under resting potential. Open K+ channels continue to allow K+ to exit causing hyperpolarization. Then, all K+ channels close. Voltage gated Na+ and K+ channels are closed and can't be open again for a period of time. Restored to resting membrane potential after 2ms

Myelination

Occurs when the Schwann Cells wrap their cell membranes multiple times around a section of axon. Moves fast because wrapping makes it "air tight" so charge spread moves down fast. Signal "jumps" from node to node, where voltage gated channels are clustered, as rapid charge spread.

Neuromuscular Junctions

Chemical synapses between motor neurons and skeletal muscle cells

Hyperpolarized

If a membrane voltage becomes more negative than the resting potential

Depolarized

If it becomes less negative than the resting potential-more positive

Voltage Gated Channel

Ion channel that opens or closes depending on membrane potential. If the membrane becomes sufficiently depolarized, both types of channels open and ions begin to flow.

Voltage Gated Na+ Channel

Open quickly, allowing sodium ions to rush from the outer membrane to inner membrane. Membrane potential swings positive but after opening for about a millisecond, the Na+ channels close for a millisecond. As a result, movement of sodium ions stop.

Voltage Gated K+ channels

Don't start to open until depolarization is well underway. This creates a strong electrochemical gradient favoring potassium movement from inner membrane to outer. Potassium rushes out repolarizing the membrane, and enough potassium leaves to hyperpolarize the membrane.

Schwann Cell

A type of glia that wraps its membrane around the axons of many types of neurons and speeds signal propagation.

Myelin Sheath

A structure made up of Schwann cells that insulates axons and functions in faster action potential propagation.

Presynaptic Neuron

A neuron whose axon terminus communicates with a postsynaptic neuron via neurotransmitters.

Synaptic Vesicles

Small membrane-bound spheres that hold neurotransmitters and deliver them to the synaptic cleft.

Neurotransmitters

Signaling molecules that are released from a pre-synaptic neuron, diffuse across the synaptic cleft, and bind to ligand-gated channels in the post-synaptic neuron, causing them to open

Ligand Gated Channels

Channels that open and close in response to a binding event

Heart

A muscular organ that pumps circulatory fluid (blood or hemolymph)

Atrium

A structure in the heart that receives blood from the body

Ventricle

A structure in the heart that pumps blood out to the body

Artery

A vessel that carries blood away from the heart

Capillary

An extremely small vessel where oxygen and other nutrients diffuse from the blood to tissues and where carbon dioxide and other wastes diffuse from tissues to the blood. The smallest-diameter blood vessel in the body.

Vein

A vessel that carries blood toward the heart

Hemolymph

Circulatory fluid that doesn't carry of O2 and CO2

Vertebrates

Animals that have a bony vertebral column protecting the spinal cord.

Right Ventricle

Blood flows in from the right atrium. Pumps the low O2 blood (deoxygensted) through an artery that branches to the left and right lungs.

Left Atrium

High O2 blood flows through veins from each lung to the ___

Left Ventricle

Blood flows in from the left atrium. It pumps the high O2 blood (oxygenated) through an artery that branches to the head and the rest of the body. Its the thickets muscle tissue because it has to pump blood all the way to the head, toes, and back.

Pulmonary Circuit

Arteries, capillaries, and veins that serve the lungs

Systemic Circuit

Arteries, capillaries, and veins that serve the rest of the body- everything but lungs.