Lecture 4: Nervous Tissue Flashcards
Overview of Neurons
- receive, integrate, and transmit signals
- generate action potential
- 10% of neural cells are neurons
- found in CNS and PNS
Overview of Glial cells
- take care of neurons
- cannot generate action potential
- most neural cells are glial cells (90%)
- can undergo mitosis
- found in CNS and PNS
Neural signal
- excitable cells that can rapidly change their Em to send electrical signals
- signal travels very quickly over long distances
Four functional zones of a neuron
- signal reception at the dendrites and cell body
- signal integration at axon hillock
- signal conduction at axon and it’s schwann cells of myelin sheath
- signal transmission at the axon terminal and synapse
Signal Reception
-at cell body (soma) and dendrites, incoming signals are received and converted to a change in membrane potential (Em) aka graded potentials
Signal Integration
- at axon hillock
- Converts changes in Em (graded potentials) into Action Potentials
Signal Conduction
- at axon
- Action Potential (AP) travels along the axon to its terminal
Signal Transmission
- at axon terminal
- transmits signal at synapse via gap junction (electrical) or converted into a chemical signal called a neurotransmitter
Efferent Neuron
-sends signals from the brain to the body (motor)
Afferent Neuron
-sends sensory signals from body to the brain (sensory neuron)
Interneuron
forms connections between neurons
Neuron Classification based on structure: multipolar, bipolar, and unipolar
- multipolar: many processes
- bipolar: two processes
- unipolar: one process
Neuron Polarity
most neurons have one end specialized for signal reception and the other for transmission, this is known as signal polarity
Glial Cell Function:
- 90% of human brain
- glial cells cannot generate AP, but can have graded potentials
- they “take care” of the neurons
Glial Cells are found in ____ in PNS
-Schwann cells, which form myelin sheathes, remove cell debris, and regenerate damaged axons
