Cell Biology and Neuroscience Flashcards
What are the basic parts of a neuron?
Soma (Cell Body) - Nucleus and organelles
Nurites- Dendrites (Input)
Axon- Output
Describe what dendrites are
- Many dendrites extend from cell body
- Dendritic tree
- Receive input from other neurons
- Dendritic spines
- Smaller volume
- Isolate events triggered by neurotransmitters
How is the axon formed and what is it responsible for?
- Cell body gives rise to a single axon
- Branches = axon collaterals
- Axon begins at Axon hillock
- If voltage reaches threshold at axon hillock, an action potential is initiated and travels down axon
How are axon potentials produced and what is the typical voltage of them?
- Voltage-gated sodium channels in axon = action potentials
- Action potentials are large changes in voltage, about 100 mV
- Spike-initiation zone
Axon terminals form synapses with…
Dendrites of other neurons
How are neurotransmitters released?
- Neurotransmitter is released from synaptic vesicles in axon terminal
- Diffuse across synaptic cleft
- Bind to receptors on dendrite of postsynaptic cell
What does this picture represent? (What does the blue and yellow represent?)
Neurites in contact, not continuity. These neurites were reconstructed from a series of images made using an electron microscope. The axon (colored yellow) is in contact with a dendrite (colored blue).
What are Glia?
- Cells in nervous system that are not neurons
- Supporting functions- Myelinating Glia, Oligodendrocytes (Oligodendroglia), Schwann cells, Astrocytes
Describe what astrocytes are and responsible for
- Fill most of space in the brain not occupied by neurons or blood vessels
- Regulate chemical composition of cytosol surrounding neurons
- Ion concentrations very important for generating electrical signals
- Remove neurotransmitter after it’s been released
What is myelinating glia?
- Oligodendrocytes and Schwann Cells
- Myelin:
- Insulation
- Speeds up action potential
- Nodes of Ranvier
What are the differences between schwann cells and oligodendrocytes?
Schwann cells
- In peripheral nervous system
- Wrap only one axon
Oligodendrocytes (Oligodendroglia)
- In central nervous system
- Wrap up to 50 axons
What is multiple sclerosis?
- Demyelinating disease
- Autoimmune disorder
- Slower action potential velocity
- Symptoms (depends on which nerves affected):
- Numbness
- Muscle weakness
- Unsteady gait, lack of coordination
- Loss of vision, blurred vision, double vision, when optic nerve affected
What is in the Central Nervous System?
Cerebrum
Cerrebelum
Brain stem
Spinal cord
Describe the cerebrum?
- Two hemispheres
- Receive sensory information from, and control movement, on opposite side of body
Decribe the cerebellum
- “Little brain” Same number of neurons as cerebrum, harder texture
- Coordination of movement on same side of body
Describe the brain stem
- Regulation of vital functions
- Breathing, temperature, consciousness
Describe the spinal cord
•Information from body to brain and commands from brain to body
Describe the 3 parts of the human brain
(Weighs about 3 lbs)
- Cortex- Highly convoluted – large surface area
- Ventral view- Optic chiasm (x-shaped structure): visual pathways, Olfactory bulbs: smell
- Medial view- Pons: connections between cerebrum and cerebellum
What are the 5 physical characteristics of the spinal cord?
- Spinal nerves
- Dorsal root- Sensory axons, Cell bodies in dorsal root ganglion
- Ventral root- Motor axons, Cell bodies in ventral horn
- Grey matter- Cell bodies, interneurons
- White matter columns- Myelinated axons
For the meninges…
- Describe them from the skull to the brain
- What is meningitis?
- What is subdural hematoma?
- From skull to brain- Dura Mater, Arachnoid membrane, Pia Mater
- Meningitis-Inflammation of the membranes
- Subdural hematoma- Blood collects between dura and brain
What is bacterial meningitis?
Inflammation of the meninges due to bacteria, virus or fungus
•Swelling of membranes causes increased intracranial pressure that compress brain and nerves
- Severe headache
- Stiff neck
- Seizures
- Light sensitivity
- Hearing loss
•Spinal tap (lumbar puncture)
- Bacteria, virus, fungus in CSF
- Increased numbers of white blood cells
What is subdural hematoma?
•Bleeding from veins that cross subdural space
- Acute - due to trauma
- Chronic – slow bleed over days to weeks
- Blood collects in subdural space
- Increased intracranial pressure
What is the ventricular system?
- Brain floats in cerebrospinal fluid (CSF)
- Ventricles: CSF-filled caverns and canals inside brain
- Choroid plexus- Specialized tissue in ventricles that secretes CSF
- CSF circulates through ventricles; reabsorbed in subarachnoid space
- Concussion
How is a concussion caused?
- Rocking the brain back and forth
- Can cause severe damage if not treated with time
