HBS Q2 Quest Unit 2.1 Nervous System, HBS 2.1.0-2.1.7 NS divisions, brain, dissection, neurons, action potentials, synapse, reflex/reactions

Axon

A threadlike extension of a neuron that carries nerve impulses away from the cell body.

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Myelin sheath

a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next

Axon terminals

Branches at the end of the axon that contain tiny pouches, or sacs, called synaptic vesicles.

Cell body/soma

the part of a neuron that coordinates information-processing tasks and keeps the cell alive with the nucleus inside

Glial cells

cells in the nervous system that support, nourish, and protect neurons

pseudounipolar neurons

have only one fused axon that extends from cell body and divides into two processes: one process carries sensory information from sensory receptors to cell body; other process carries sensory information from cell body to spinal cord; sensory neurons that carry information related to pain, touch, and pressure

Unipolar neurons

One process

Cell bodies are in ganglia

Sensory

Bipolar neurons

A neuron that has only two projections (one axon/one dendrite) from the cell body

Multipolar neurons

neuron with one axon and many dendrites; most common type of neuron

Nicotine

a stimulating agonist psychoactive drug in tobacco

Morphine

An agonist: a narcotic drug derived from opium, used to treat severe pain

Caffeine

an antagonist found in coffee, tea, and several other plant-based substances

Cocaine

A reuptake inhibitor drug derived from the coca tree.

GABA

The major inhibitory neurotransmitter in the brain

Glutamate

The major excitatory neurotransmitter in the brain

Serotonin

Affects mood/well-being, hunger, sleep. Undersupply linked to depression.

Acetylcholine (ACh)

A neurotransmitter that enables learning and memory and also triggers muscle contraction

Agonist

A chemical that mimics the action of a neurotransmitter.

Antagonist

a chemical substance that blocks or reduces the effects of a neurotransmitter

Inverse agonist

a substance that binds to a receptor and causes it to do the opposite of what the naturally occurring transmitter does

Reuptake inhibitor

substance that interferes with the transport of released neurotransmitter molecules back into the presynaptic terminal

Potassium channel

Lets (for free) K+ ions out of nerve cell axon into extracellular fluid. Uses passive transport.

Sodium channel

A protein channel in the nerve cell membrane that controls the free flow of Na+ ions into the cell. Uses passive transport.

sodium-potassium pump

a protein in the cell membrane of an axon that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell to reset the ion concentration gradients

Depolarization

The process during an action potential when sodium ions are allowed to flow down their concentration gradient into the cell causing the interior become less negative/more positive.

Repolarization

The process during an action potential when potassium ions are allowed to flow down their concentration gradient into the cell while sodium exits the cell causing the interior to become less positive/more negative.

Hyperpolarization

The movement of the membrane potential inside a neuron below resting potential where the sodium-potassium pump resets the ion concentrations to resting potential before the neuron can begin another action potential.

-70mV

resting membrane potential

Threshold potential

The minimum membrane potential -55mV that must be reached in order for an action potential to be generated.

Resting potential

The difference in electric charge between the inside and outside of a neuron's cell membrane -70mV when a neuron is not yet firing an action potential.

Action potential

the brief change in electrical potential (from negative to positive) associated with the passage of an impulse down the axon membrane of a nerve cell. AKA impulse

Frequency of an action potential

The amplitude (height) of an action potential is always the same so it is the frequency of an AP that conveys stimulus strength

-stronger stimulus = more frequent APs

ex: do you want to tap or kick a soccer ball

Hydrophobic

Having an aversion to water; tending to coalesce and form droplets in water. ex: oil, fat

Hydrophilic

Loves water, mixes well with water ex: dirt, soda

Phospholipid heads are

hydrophilic & polar

Phospholipid fatty acid tails are

hydrophobic & nonpolar

Synapse

the thin gap between the axon tip of the sending "pre-synaptic" neuron and the dendrite or cell body of the receiving "post-synaptic" neuron

Neurotransmitter

chemical used by a neuron to transmit a signal across a synapse to the next neuron

Calcium channels

a type of ion channel located on the axon terminals of a neuron. Are activated when the action potential reaches the end of the axon, then they cause vesicles full of neurotransmitters to fuse with the axon terminal and release their contents into the synapse.

homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

active transport

Energy-requiring process that moves material across a cell membrane against its concentration gradient

passive transport

Requires no energy, flow of molecules from a high to low concentration, Moves down their concentration gradient ex: diffusion

phospholipid

A molecule that is the main building block of of cell membranes; having a polar, hydrophilic head and 2 nonpolar, hydrophobic tails.

concentration gradient

A difference in the concentration of a substance across a distance or membrane ex: having more sodium outside a neuron at rest than inside the neuron means if a channel opens the sodium will flow INTO the cell, DOWN its concentration gradient

salty banana

When a neuron is at rest there is more sodium outside and more potassium inside the neuron

Reflex

a simple, automatic response to a sensory stimulus, only goes up to the spinal cord and back hence FAST

Reaction

a calculated response to something that required brain integration & processing, which takes more time the more complex the task is

Patellar tendon

the tendon that encompasses the patella and extends distally across the front of the knee, used in the patellar reflex test to lengthen the quad muscles

Stimulus

A change in an organism's surroundings that causes the organism to respond

Effector

An organ (a gland or muscle) that becomes active in response to nerve impulses.

Sensory/Afferent neuron

transmits action potentials from receptors to CNS to report a sensation

Motor/Efferent neuron

transmits action potentials from CNS to effectors (muscles, glands)

White matter

Whitish nervous tissue of the CNS consisting of neuron axons and their myelin sheaths.

Gray matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei), glial cells, blood vessels, and lacks myelinated axons.

Mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

Range

the difference between the highest and lowest scores in a distribution

Spinal nerve

a peripheral nerve attached to the spinal cord that connects the PNS and CNS

Interneuron

A nerve cell that relays messages (or stop them) between afferent and efferent nerve cells, especially in the brain and spinal cord. Usually have no myelin sheath (and often found in gray matter)

Outlier

A value much greater or much less than the others in a data set (>1.5 times the mean)

Reaction speed over lifespan

Fastest (lowest time) during ages 21-30

Reflex speed over lifespan

Stays about the same, maybe gets slightly slower as we age

What was the purpose of the neuropharmacology cricket lab in 2.1.5?

Show how different drugs affected the nervous system - excitatory or inhibitory to action potentials. Ex: nicotine increased action potential firing while glutamate reduced it

& to see if crickets are a good model organism for studying human physiology

Frontal Lobe

Responsible for problem-solving, reasoning, personality, and motor skills (movement).

Parietal Lobe

Contains the area where bodily sensations occur, such as touch and pain.

Temporal Lobe

Contains areas important to hearing and understanding speech/language.

Occipital Lobe

Contains areas important to vision.

Medulla Oblongata

Part of brain stem that controls vital autonomic processes like regulation of breathing, heart rate and blood pressure.

Cerebellum

Control of finely coordinated movements. Coordination center, voluntary movement and balance.

Cerebellum image

Cerebrum image

Frontal Lobe image

Medulla Oblongata image

Occipital Lobe image

Parietal Lobe image

Brain Stem image

temporal Lobe image

Spinal Cord

Sends signals between brain and rest of body, part of the CNS

Brain Stem

Oldest part of the brain, responsible for survival functions (e.g. breathing, heart beat, etc.); includes medulla and pons; aka "the lizard brain"

Pons

Responsible for coordination and movement (relays messages between cerebrum and cerebellum); involved in sleep, dreams, and attention.

Thalamus

Relays information from the senses and transmits the information to the cerebral cortex.

Limbic System

Collectively: the Hippocampus, Amygdala, Pituitary Gland, Hypothalamus; involved in emotion

Hippocampus

Helps to form memories ("hippo never forgets")

Amygdala

Fight or flight, emotional center, anger or fear, happy or sad

Hypothalamus

Controls body temperature (the body's thermostat), circadian rhythms, and thirst and hunger, and smell.

Pituitary gland

The "master" endocrine gland, responsible for growth.

Corpus Callosum

Thick band that connects left and right hemispheres of the brain.

Cerebrum

Information processing, outer layer of brain.

Lobes of the cerebrum

Occipital, Temporal, Parietal, Frontal

motor cortex

area at the rear of the frontal lobes that controls voluntary movements

sensory cortex

area at the front of the parietal lobes that registers and processes senses, body touch, and movement

Broca's area

controls language expression - an area in the frontal lobe, that directs the muscle movements involved in speech.

Role of the nervous system

-coordinates all body systems

-detects and responds to stimuli

-brain and spinal cord act as switching centers

-nerves carry messages to and from centers

CNS

central nervous system

PNS

peripheral nervous system

how do central and peripheral nervous system work together?

The nerves of the PNS extend from the central nervous system to the outermost areas of the body. The peripheral system allows the brain and spinal cord to receive and send information to other areas of the body, which allows us to react to stimuli in our environment.

How did Henry Molasion's surgery pave the way for further exploration?

While the surgery was successful, it led to H.M. suffering from anterograde amnesia, in which he could no longer form or keep new memories. His case was important as scientists figured out the function of the hippocampus and studied memory and cognitive abilities of the portions of the brain responsible for memory.

Why is the story of Phineas Gage considered so extraordinary? What does his story teach us about the brain?

He survived a pole through his head and his changed personality was linked with his head injury

Afferent Nervous System

consists of all ingoing sensory pathways from PNS to CNS, carrying information from receptors to brain or spinal cord for processing

Efferent Nervous System

consists of all outgoing motor pathways from CNS to organs/glands/etc. to initiate a response