Chapter 2: Nerve cells Flashcards
What are the two types of cells that nervous cells contain
Neurons
glia cells
number of neurons the human brain contains
approximately 100 billion individual neurons
How many neurons do we have
billions of them
the structure of animal cells
- Membrane
- Nucleus
- Mitochondria
- Ribosomes
- Endoplasmic reticulum
membrane
a structure that separates the inside of the cell from the
outside environmens
Nucleus
the structure that contains the chromosomes
Mitochondria
the structure that performs metabolic activities, providing the energy that the cell uses for all activities
Ribosomes
the sites within a cell that synthesize new protein molecules. Proteins provide building materials for the cell and facilitate chemical reactions
Endoplasmic reticulum
a network of thin tubes that transport newly synthesized proteins to other locations
structure of a neuron diagram
what is the difference between motor and sensory neurons
motor neuron Has its soma in the spinal cord, Conducts impulses along its axon to a muscle
sensory neurons specialized at one end to be highly sensitive to a particular type of stimulation (touch, light, sound, etc.)
motor neuron diagram
sensory neuron diagram
components of all neurons
- Dendrites
- Soma/cell body
- Axon
- Presynaptic terminals
Dendrites
Branching fibers with a surface lined with synaptic receptors
responsible for bringing information into the neuron
The greater the surface area of the dendrite, the more the information it can receive
Soma/cell body
Contains the nucleus, mitochondria, and ribosomes
Axon
The thin fiber of a neuron is responsible for transmitting nerve impulses toward other neurons, organs, or muscles
Maybe have a myelin sheath, an insulating material that
contains interruptions in the sheath known as nodes of Ranvier
Nods of renvier
the interruptions in the myelin sheet, play an important role in action potential of
neuron.
Presynaptic terminals
they are at the endpoints of an axon and they release
chemicals to communicate with other neurons
Myelin Sheaths
act as a protective film for the axons.
how many axons neurons have
Neurons have only one axon, but the axon may have branches.
The end of each branch has a swelling, called a presynaptic
Terminals
Afferent axon
refers to ADMITTING information into a structure: sensory
Efferent axon
refers to EXITING with information away from a structure: Motor
Interneurons or intrinsic neurons
whose dendrites and axons are completely contained within a single structure
interneurons are the ones in between - they connect the spinal motor and sensory neurons.
Do neurons vary in size and shape and why
Neurons vary in size, shape, and function,The function is closely
related to the shape of a neuron
Example: Purkinje cells of the cerebellum branch are extremely widely within a single plane
Types of glial cells
Astrocytes
Microglia
Oligodendrocytes
Radial glia
Astrocytes
astrocytes are star-shaped glial cells with many functions which include providing nutrients and support to neurons helping repair damaged nervous system tissue regulating communication between neurons and maintaining the blood-brain barrier which keeps potentially toxic substances in the blood from entering the brain
Microglia
Remove waste material, viruses, and fungi from the brain
Oligodendrocytes
is responsible for the myelination of neurons in the CNS
Schwann cells
are responsible for the myelination of neurons in PNS
Radial glia
are involved in neurogenesis and neural development they can give birth to new neurons and also serve as a scaffold along which new neurons can travel from their site of origin to their final destination in the brain
What is BBB and what its function
It’s a mechanism that protects the brain and surrounds it protecting it from harmful stuff getting into the brain, when neurons get affected by bacteria or virus etc. the immune system destroys he neuron and remove it, and because the neurons in the brain don’t regenerate it’s very vital that that is protected and that’s wat BBB does.
How does BBB work
Doesn’t let in large molecules or non-fat soluble, oxygen and co2 can travel easily for larger molecules it needs a special mechanism: Active transport
Sugar or glucose is one of the few nutrients that can pass through the blood-brain barrier and it’s the only one that crosses it in large quantities
Glucose and oxygen are essential for the neurons and the body needs thiamin to use the glucose, its deficiency can cause the death of neurons
Active transport
The protein-mediated process that expends energy to pump chemicals from the blood into the brain
Glucose, certain hormones, amino acids, and a few vitamins are
brought into the brain via active transport
what neurons depend for their nutrition
Vertebrate neurons depend almost entirely on glucose
A sugar that is one of the few nutrients that can pass through the blood-brain barrier
what is the only thing that can cross the BBB in large molecules
Glucose is the only nutrient that crosses the blood–brain
barrier in large quantities.
what does the body need to use glucose
The body needs a vitamin, thiamine, to use glucose
what does the deficiency of thiamin cause
Prolonged thiamine deficiency leads to the death of neurons as
seen in Korsakoff’s syndrome, a result of chronic alcoholism
Korsakoff’s syndrome is marked by severe memory impairment
Nerve impulse
is the electrical message that is transmitted down the axon of a neuron
Does not travel directly down the axon, but is regenerated at points along the axon so that it is not weakened
what is the speed of the nerve impulse
The speed of nerve impulses ranges from less than 1 meter/second to 100 meters/second
A touch on the shoulder reaches the brain more quickly than a
touch on the foot
