Chapter 2 (Cells/Neurons) Flashcards
What kind of neurons detect the environment and transmit it to the brain?
(afferent neurons/sensory neurons)
What kind of neurons contract muscles; move away from the brain towards the muscles
(efferent neurons/motor neurons)
What kind of neurons connect the sensory and motor cells (intermediaries)
Interneurons
The brain and spinal cord make up the system
CNS
The cranial and spinal nerves and sensory organs make up the ___
PNS
This part of the neuron receives communication from the presynaptic neuron and intakes NT from its terminal button…
dendrites
This part of the neuron contains the cell body with the nucleus and major supporting structures
soma
this part of the neuron carries information from the cell body to the terminal button
axon
Terminal Buttons do what function(s)?
They send information to the next neuron using neurotransmitters; where NT is stored
Neurons can be classified based on 3 things…
- What type of NT they are (serotonin, norepinephrine)
- The effects of the neuron (Excitatory or inhibitory)
- Number of processes (unipolar) (bipolar) (multipolar)
A neuron that has one stalk that splits into two branches is…
Unipolar
A neuron that has one axon and one dendritic tree is…
bipolar
A neuron that has one axon and many dendritic branches
multipolar
What are the 5 steps for Electrochemical Conduction
- Dendrites receive chemical messages (NT) from upstream cells
- NTS/Chem messengers activate receptors in the dendrite
- Receptors open ion channels which may alter cell potential
- AP can result which is propagated down the membrane
- If AP happens, causes release of transmitter from axon terminals
This part of the cell defines the outer boundary and is made up of a double layer of lipid molecules…
Membrane
This part of the cell is a jelly-like substance which contains and suspends important structures
cytoplasm
The nucleus contains these 2 things…
Nucleolus (produces ribosomes) and chromosomes (contain DNA and make mRNA which makes protein with ribosomes)
Microtubules serve what function in the cell?
form the skeletal structure of the axon
The route for transporting materials down the axon is called the….
axoplasmic transport
This part of the cell takes glucose and O2 to make ATP
mitochondria
The rough endoplasmic reticulum does what?
holds ribosomes from the nucleolus and is the site of protein production
also makes NT
The smooth endoplasmic reticulum does what?
produces primarily lipids for the membrane
This organelle packages secretions in a membrane known as “synaptic vesicles” which travel along the axon. This organelle also produces lysosomes that break down unnecessary substances .
Golgi Bodies
Where are NTs produced from?
Rough ER in soma
from ribosomes housed there
What are the 3 steps of a simple reflex?
- A stimulus is detected by a sensory cell
- The sensory neuron transmits it to the spinal cord via the interneuron
- The spinal cord processes the signal and signals the muscles to contract
What are the 4 basic functions of the “Glial Cells”?
- Hold neurons in the CNS together
- Controls the supply of nutrients for survival
- Don’t let the NTs travel too far from the synapse
- Destroys and removes dead neurons
Astrocytes in the CNS perform these 4 functions…
- Actively absorbs and releases substances around neurons to keep their environment stable
- Wraps around both capillaries and dendritic/somatic membranes
- Provides nourishment
- Disposes of waste/dead neurons (phagocytosis)
Oligodendrocytes perform what function
Supports the axon by wrapping around the axons to form myelin sheaths and digest dead axons
What 2 functions does the Microglia do?
- Performs phagocytosis (ingesting dead neurons
- Protect neurons against disease by causing swelling
What do Schwann Cells do?
- Do exactly the same thing as the oligodendrocytes but only in the PNS
- Also regrow channels in the PNS
What is the difference between Schwann and Oligodendrocytes?
Schwann in PNS and Oligodendrocytes in CNS. Also, Schwann can regrow the axons, not in the CNS
The Blood Brain barrier performs what function?
A membrane in the brain which prevents certain harmful substances out and some in.
Why are there some fenestrations (gaps) in the blood brain barrier?
Because the brain can detect potentially really harmful substances and make us throw up to expel them. Area Postrema controls vomiting
What are the 5 things that can pass into the blood brain Barrier? What must be transported
Lipid solubles, O2 and CO2,
Glucose and amino acids must be transported
What is the resting potential of a neuron?
-70 mV
What are the 4 steps for a sodium potassium pump?
- 3 NA ions bind to the pump
- ATP is used to activate the pump
- Pump releases sodium ions outside of the cell
- 2 potassium ions bind to the pump and are transferred to the cell
(NB: when action potential happens, sodium is entered into the cell, the pump is used to remove NA and return it to the resting state)
What are the steps for Action Potential?
- Excitation of the cell occurs, NA channels open and NA starts to enter the cell
- Potassium channels ion and began to leave the cell
- Sodium channels become refractory, no more NA enters the cell
- K+ continues to leave the cell causing the cell to need to return to resting level
- Channels close, extra K+ diffuses away
This is the period in which stimulation cannot produce AP because the Na+ channels are closed
Absolute refractory period
This is the period in which a super threshold stimulus is required to cause an AP while the K+ channels are closed
Relative Refractory Period
Where does the AP occur?
the axon hillock
What is the rate law?
The intensity of a muscle contraction is associated with the rate of “firing” (not the intensity of the charge).
Ex: a quick jerk would be a bunch of firing
How is action potential conducted down the neuron?
Action potential is conducted down the neuron by the myelin sheaths and re-energized by the nodes of Ranvier
This type of synapse is the axon closest to the dendrite
Axodendritic
This type of synapse is the axon closest to the soma
axosomatic
This type of synapse is axon to axon
axoaxonic
These types of neurons increase AP
EPSP (Excitatory post-synaptic potentials)
These types of neurons decrease AP
IPSP (inhibitory post-synaptic potential)
This is the process where the presynaptic membrane pinches off the excess membrane into recycling for synaptic vesicles
pinocytosis
This type of receptor allows NT to dock on the receptor allowing for a flow of ions.
- Ionotropic receptors
This type of receptor, when the NT docks activates the G protein sending out the alpha molecule which docks on the channel
metabotropic receptors
If a neuron is depolarized (-65mv) then, _____ > _____ (Cl- flows in making the neuron more negative
diffusion, electrostatic
If the neuron is hyperpolarized (say, -75 mV), then ______ > _____ (Cl- flows out making the neuron less negative)
electrostatic, diffusion
What stops synpatic stimulation?
Re-uptake
The combined influence of many NT releases at different locations on the postsynaptic membrane at a particular moment in
time is called…
Spatial summation
The combined effects of NT release over time; occur when stimuli occur close enough in time that their effects are additive is called…
Temporal summation
