Functions, anatomy, Glia, Meninges Flashcards
nervous system functions
voluntary movement, perception, homeostasis, higher functions.
cerebral anatomy
forebrain, brain stem, cerebellum, spinal cord
Where does Voluntary movement occur in the brain and what are type of neurons does it recruit?
Motorneuros.
In spinal cord for body movements, in brain stem for head and above movement
Neuros anatomy
Body/soma, dendrites/ arbor, axons, synaptic terminal, synapses
What is produced in the body/some of the neuron?
Protein
What are dendrites responsible for?
collecting information locally and sending it to axons
Axon function
transport information throughout the body to the next cell
What is a synaptic terminal, what’s it’s function and where is it located?
Part of a neuron located at the end of an axon. It contains vesicles filled with neurotransmitters, which are chemical messengers. When an action potential reaches the synaptic terminal, it triggers the release of these neurotransmitters into the synapse.
What is the electric signal called (information) that reaches synaptic terminal and triggers the release of the neurotransmitters?
action potential/ spike.
What is the small gap in between neurons called?
synaptic cleft.
What is a synapse and what is it made of?
The entire junction where communication occurs between 2 neurons (or a neuron and another cell, like a muscle cell).
The presynaptic terminal,
The synaptic cleft,
The postsynaptic membrane.
What is the postsynaptic membrane?
contains receptors on the receiving neuron or target cell that bind to the neurotransmitters.
How are neuros different from one another?
- Structure - different shapes, sizes
- Function - sensory, motor, interneurons
- Neurotransmitter type - dopaminergic, seratonergic, cholienergic
- location - cortical, spinal, cerebral
- firing patterns - tonic, phasic.
- myelination
- synaptic connections - diverging circutis, converging circuits.
- plascticity
Multipolar Neurons
Have many dendrites and one axon. Common in the brain and spinal cord, they are involved in motor control.
Bipolar Neurons
Have one dendrite and one axon. Found in sensory organs like the eyes and ears, these are involved in transmitting sensory information.
Unipolar (or Pseudounipolar) Neurons
Have one projection that splits into two branches. Common in sensory pathways, they transmit information from the body to the spinal cord.
Sensory Neurons
Carry signals from sensory receptors (like skin or eyes) to the brain or spinal cord.
Motor Neurons
: Transmit signals from the brain or spinal cord to muscles or glands, initiating movement or action.
Interneurons
Found within the brain and spinal cord, these neurons connect other neurons and are involved in processing information, reflexes, and decision-making.
Dopaminergic Neurons
Release dopamine and are involved in reward, motivation, and movement.
Serotonergic Neurons
Release serotonin, playing a key role in mood regulation, sleep, and appetite.
Cholinergic Neurons
Release acetylcholine, important for muscle activation and cognitive functions.
Cortical Neurons
Found in the cerebral cortex, involved in higher-order functions like thinking, perception, and decision-making.
Spinal Neurons
Located in the spinal cord, these are critical for transmitting signals between the brain and the rest of the body.
Cerebellar Neurons
Located in the cerebellum, these neurons help coordinate movement and balance.
Tonic Neurons
Fire steadily and maintain a consistent output of action potentials.
Phasic Neurons
Fire action potentials in bursts, usually in response to specific stimuli.
Myelin and its function
a fatty, insulating layer that surrounds the axons of many neurons in the nervous system.
Its main function is to increase the speed at which electrical impulses, or action potentials, travel along the axon. Myelin acts like insulation on a wire, preventing electrical signals from leaking out and allowing them to move more efficiently.
Diverging Circuits
Some neurons send signals to many other neurons, spreading information.
Converging Circuits
Others receive input from many neurons, integrating various signals.
Glial cells (or glia) and role
non-neuronal cells in the nervous system that provide support, protection, and nourishment to neurons. While neurons are responsible for transmitting electrical signals, glial cells play essential roles in maintaining the health and functionality of the nervous system.
Types of glia
astocytes (cns), olygodendrocytes (cns), Shawn cells (pns), microglia (cns)
Astrocytes function
structural support, regulate the blood-brain barrier (which controls the passage of substances from the bloodstream into the brain), and maintain the chemical environment around neurons by absorbing excess neurotransmitters.
Oligodendrocytes function
produce the myelin sheath in the CNS, wrapping around axons to speed up signal transmission.
Schwann cells function
produce the myelin sheath in the peripheral nervous system (PNS), insulating and protecting axons to increase the speed of nerve signals.
Microglia
act as the immune cells of the CNS. They protect against infections and clear away dead or damaged cells by engulfing them (a process called phagocytosis).
describe Myelinated Axons
These axons are covered by a myelin sheath, a fatty layer produced by oligodendrocytes (in the CNS) or Schwann cells (in the PNS). The myelin is not continuous but is segmented, with small gaps known as nodes of Ranvier.
The presence of myelin significantly increases the speed of signal transmission. The electrical impulses “jump” from one node of Ranvier to the next in a process called saltatory conduction, allowing signals to travel much faster.
These have much faster conduction velocities, with some reaching speeds of up to 120 meters per second (m/s). This is critical for rapid reflexes and coordinated movement.
Because myelinated axons only need to propagate action potentials at the nodes of Ranvier, they use less energy. Fewer ions are moved across the membrane, reducing the workload on the sodium-potassium pumps that restore ion balance after each impulse.
These are generally found in parts of the nervous system where rapid, precise communication is essential, such as in motor neurons controlling muscles, or sensory neurons transmitting information to the brain.
describe Unmyelinated Axons
These axons lack a myelin sheath, although they may still be associated with Schwann cells, they are not wrapped in layers of myelin. In these axons, the Schwann cells support the axon but do not provide the same insulating properties.
the nerve impulse travels continuously along the axon in a slower process called continuous conduction. The absence of myelin means the signal moves more gradually.
Signals move much slower, typically around 0.5 to 2 m/s. These are involved in slower processes, like transmitting pain or regulating internal organs.
require more energy because the entire length of the axon must propagate the action potential, leading to more ion movement and increased activity of sodium-potassium pumps.
are typically involved in slower processes, like regulating body functions (e.g., digestion, heartbeat) or transmitting chronic pain signals.
Are generally smaller in diameter, which also contributes to their slower conduction speed.
Meninges and the layers
Protectice layer between the brain and spinal cord. Dura, arachnoid, pia
PNS
includes all the nerves outside the brain and spinal cord, has a much greater capacity for regeneration.
CNS
includes the brain and spinal cord, has a very poor capacity for regeneration.
