L04 Anatomy of the Nervous System Flashcards
PNS
Peripheral Nervous System
Division of the brain located outside the skull & spine. It is composed of 2 divisions:
- SNS (somatic nervous system)
- ANS (autonomic nervous system)
CNS
Central nervous system
Division of the nervous system located in the skull & the spine. It is composed of 2 divisions:
- brain
- spinal cord
SNS
Somatic Nervous System
Division of the PNS that interacts with sensory environment.
Made of afferent nerves (think approach, arrive) that carry the sensory signals from the skin, skeletal muscles, joints, eyes & ears to the CNS.
Sensory signals from the environment (travel through the PNS) ——> CNS
Made of efferent nerves (think exit, escape) that carry motor signals from the CNS to the skeletal muscles.
Motor signals from CNS ——> (travel through the PNS) to skeletal muscles
ANS
Autonomic Nervous System
Division of the PNS that regulates the body’s internal environment.
Made of afferent nerves (think approach, arrive) that carry sensory signals from internal organs to the CNS.
Sensory signals from internal organs (travel though the PNS ——-> CNS
Made of efferent nerves (think exist, escape) that carry motor signals from the CNS to internal organs.
Motor signals from CNS ——> (travel through the PNS) to internal organs
Afferent nerves
Aka sensory nerves (think approach & arrive)
Carry sensory signals from the external environment or from internal organs to the CNS.
Found in the PNS. Input.
Efferent nerves
Aka motor nerves (think exit or escape)
Carry motor signals from the CNS to the skeletal muscles or to internal organs.
Found in the PNS. Output.
Describe the procedure that occurs when you see a bear?
Stimulus > picked up by the periphery via eyes > sensory signals sent by the PNS afferent nerves > travels to the CNS > received by CNS > efferent nerves send back a motor signal to the PNS > action carried out once it reaches the skeletal muscle
Sympathetic nerves
PNS —-> ANS —–> efferent nerves—–>
2 kinds of these autonomic motor nerves
- fight or flight
- second stage neurons (that get synapses on) are far away from the target neuron (because the target is short)
- innerviates into the spinal cord in the middle 2 portions: thoracic & lumbar
Parasympathetic Nerves
PNS—–> ANS——> efferent nerves——>
2 kinds of autonomic motor nerves
- rest & restore
- second stage neuron (that is synapses on) is very close to the target neuron (because the target neuron is longer)
- innerviates into the spinal cord at the high and low regions of the neck and the bottom: cranial & sacral
What is the pudendal nerve and example of?
PNS nerve in the SNS that causes “the endless O”
- nerve randomly fires
- stimulation to the clitoral dorsal nerve goes into overdrive
Decrease in secretion of salivary gland
Sympathetic
Increase in secretion of the salivary gland
Parasympathetic
Acceleration of heart rate
Sympathetic
Slow of heart rate
Parasympathetic
Blood vessels constricted
Sympathetic (blood vessels not intuitive RE: Forum post)
Blood vessels dilate
Parasympathetic
Penis ejaculates
Sympathetic response
Penis erection
Parasympathetic
Pupil contracting from iris sphincter muscle
Parasympathetic
Pupil dilates from iris radial muscle
Sympathetic (Think wide eyed when scared)
Tear gland no effect
sympathetic (too scared to cry)
Tear gland stimulated to secrete tears
Parasympathetic (emotions)
Sweat gland stimulated to secret
Sympathetic (think running)
Sweat gland no effect
Parasympathetic (relaxing not fricken sweating here)
Stomach & intestine stimulating secretion of bile and digestion
Parasympathetic
Stomach inhibiting digestion and secretion of bile
Sympathetic (think blood away from digestive)
Lungs bronchioles dilated / relaxed
Sympathetic (so that you can breathe more)
Lungs bronchioles constricted and inhibition of mucous
Parasympathetic
Arrector pili muscles erect hair & goosebumps
Sympathetic
Dermatomes & importance
Map that shows which part of the skin is controlled by specific area in spinal cord.
- important for diagnosing multiple sclerosis or nerve damage to know where to look for spinal cord/brain lesions or damage corresponding to what you feel
Most nerves project from the spinal cord except for the:
12 cranial nerves which innerviate directly into the brain.
Are the 12 cranial nerves sensory or motor?
Mixed
Exception: olfactory nerve and the optic nerve (think smell and sight)
Longest nerve in the body?
Vagus nerve
Spinal cord anatomy: grey matter
Blue butterfly
- made of cell bodies
- middle of spinal cord
Spinal cord anatomy: white matter
- around the blue butterfly
- made of myelin
Spinal cord anatomy: Dorsal horn
Skinny top
- sensory processing
Spinal cord anatomy
Ventral horn:
- motor processing
Spinal reflex
Evolved as a protection so that the sensory signal can be intercepted faster by the spinal cord and a decision can be made by the spinal cord to perform a motor action to protect yourself. Example pain from heat.
Reflexes are a good indication of how your spinal cord is functioning.
White matter & grey matter in the brain
Is opposite to that of spinal cord.
- White matter inside
- grey matter outside
Unipolar neurons
Seen in insects (simple)
Bipolar neurons
In sensory system
Multipolar cells
Most common neuron that we label
Interneuron
Close together because no axon
Glial cells
~ as many glia as neurons not 10:1
4 types of glia
- astrocytes
- Oligodendrocyte
- Schwann cells
- microglia
- glial cells play a large role in neurodegenerative diseases (ALS, Parkinson’s, Alzheimer’s)
- einstein brain has much more glia
Astrocytes
Type of glia:
- shaped like a star
- anchor neurons to blood vessel
- stop certain chemicals in the blood from passing to the CNS (BBB)
Oligodendrocyte & Schwann cells
Type of glial cell:
- Myelination for protection & faster conduction
- create myelin sheaths
- OLIGO in CNS
- Schwann in PNS
Microglia
Type of glial cell:
- respond to injury & disease to protect neurons
- immune response kind of
Parts of a cell
- nucleus
- mitochondria
- Golgi apparatus
- ER (endoplasmic reticulum)
- ribosomes
- cytoplasm
- microtubules
Nucleus
Contains the cell DNA
Mitochondria
Provide cell energy through sites of aerobic energy release (need oxygen).
Golgi complex
Connected system of membranes folded on each other that packages molecules in vesicles
ER endoplasmic reticulum
System of folded membranes in the cell body.
Rough ER - associated with synthesis of proteins
Smooth ER - associated with synthesis of fats
Ribosomes
Intracellular structures on which proteins are formed on. Located on the ER.
Cytoplasm
The intracellular fluid that surrounds the cell body
Microtubules
Long skinny tubes responsible for the transport of cell material throughout neurons
Synaptic vesicles
Spherical membrane packages holding neurotransmitter molecules ready to be released upon synapse
Neurotransmitters
Molecules released from active neurons and influence other cells
NG2 glia
Found a specific type of glia that once removed from the brain, model organism displayed signs of depression.
2 strains of model organism (susceptible and resilient populations) were found once induced into depression.
Mice in the susceptible population had small amounts NG2 glia and other types of glia where resilient populations seemed unaffected in glia cells.
Shows that glia cells may be a precursor to other cells and the interaction between these glia cells is crucial to preventing depression symptoms.
Applications to future:
- what we know now as the cause of depression may only be a symptom and we may have to dig deeper to design a treatment
- compare the resilient vs susceptible populations more closely to see if we can prevent the susceptible population symptoms from occurring in the first place
Golgi stain
Only 1% of the neurons pick up the stain which is good so that we can see the individual neurons at full length
- silhouette (no internal details)
- tells us about the shape
Nissl stain
- credal violet stain
- RNA (negatively charged) turns blue
- because they proteins are synthesized on the ribosomes which are in the rough ER, the ER turns most blue (picks up the stain)
- neuron counting (esp when removing)
Electron microscopy
- high magnification
- great details
- uses beam of electrons
- very expensive and need to be trained
Tracing
- developed in the 90s
- fluorescent materials/protein into virus to infect the neuron to see where it’s expressed
-shows us where the cells are communicating
