Bio Quiz 2 Flashcards
BRAIN DIVISION
Corpus callosum:
white nerve fibers that connect the right and left hemispheres
Allows for communication and increased processing speed
Glial cells:
hold neurons in place, supply nutrients, repair damage to NS
Half the volume of CNS
BRAIN DIVISION
Meninges:
Dura, Arachnoid, Pia
Cerebral Spinal Fluid (CSF):
Clear fluid that provides cushioning for the brain
Produced in the ventricles
Fills subarachnoid space, canal of spinal cord, and the cerebral ventricles
1) CEREBRAL VENTRICLES and Flow of CSF
Ventiricles:
series of hollow, interconnected chambers filled with CSF
CSF:
Extracted from blood, similar to blood plasma
Manufactured continuously by choroid plexus
Total amount- 125 mL, half-life 3 hours
Flows from ventricles to subarachnoid space where it is reabsorbed by blood supply
Diminishes pressure on base of brain
Role: Added layer of protection for the brain, keeping the brain from resting directly on the skull
Created by lateral ventricles and choroid plexus which filters CSF out from the blood
Flows through the third and fourth ventricles to the subarachnoid space where it diffuses over brain and spinal cord
Brain produces roughly 500 mL of cerebrospinal fluid per day
This fluid is constantly reabsorbed, so that only 100-160 mL is present at any one time
Since the subarachnoid space around the brain and spinal cord can contain only 135 to 150 ml, large amounts are drained primarily into the blood
Drainage of CSF occurs through arachnoid granulations (protrusions of arachnoid through the dura), allowing drainage into the superior sagittal sinus (a blood vein)
CSF turns over about 3.7 times a day
LOBES OF THE BRAIN
FRONTAL LOBE
Temperol Lobe
PARIETAL LOBE
OCCIPITAL LOBE
OCCIPTAL LOBE
Back of the brain
Primarily vision
Injury can lead to visual field cuts
Most specialized lobe
Optic chiasm
PARIETAL LOBE
Responsible for processing somatosensory information
Speech, pain, spatial orientation Integrates sensory information for movement
Note taking, eating, brushing your teeth Injury can present as agraphia, poor muscle control, inability to move
TEMPORAL LOBE
Includes the limbic cortex, amygdala, and hippocampal formation
Important in hearing, processing auditory information, processing affective tone of nonverbal cues, memory, and recognition
Lateralization in left and right temporal lobes
THE SYNAPSE
ACETYLCHOLINE (ACH)
First identified neurotransmitter
Released by neurons connected to the voluntary muscles (causes them to contact)
Links motor neurons to muscles
Found in many brain regions
Thought to play important role in attention, memory, and sleep
FRONTAL LOBE
1/3 of the cortex
Higher-order cognitive processes: • Problem solving
Planning
Organization
Inhibition
What makes humans unique!
Includes premotor cortex, motor cortex, and prefrontal regions
SEROTONIN
Present in many tissues
Plays important role in transmission of other
neurochemicals (the catecholamines)
Switches affecting various mood-states- regulation of mood
Role in sleep, eating, arousal
Regulation of pain
CATECHOLAMINES
Dopamine, epinephrine, norepinephrine
Arise in sequence from tyrosine
Help the body prepare for fight or flight responses
Adrenal glands make a large amount of catecholamine in response to stress
CATECHOLAMINES: DOPAMINE
Inhibitory or excitatory depending on receptor
Produced in substantia nigra
Controlling movements, regulating hormonal response, and causing psychotic symptoms
Found in individuals who are experiencing:
Muscle rigidity
• Tremors
• Parkinson’s disease • Schizophrenia
Movement, attention, learning, reinforcing effect of abused drugs
Parkinson’s Disease
CATECHOLAMINES: NOREPINEPHRINE
Synthesized from dopamine
Increases arousal & vigilance
Influences reward system
Known to play a role in psychiatric disorders • Attention deficit disorder and Depression
ANS-Sympathetic
CATECHOLAMINES: EPINEPHRINE
Also known as adrenaline
Acts on nearly all body tissue
Rapidly prepares the body for action when necessary
Quickly increases blood and oxygen supply to brain and muscles
Simultaneously diminishes other bodily processes that aren’t as important for a stressful situation (digestion, immune system)
Dilates pupils, increases heart rate, constricts GI tract
CATECHOLAMINES: GLUTAMATE
Excitatory neurotransmitter
Regulates cortical and subcortical functioning
Important for cognitive functioning
Overstimulation can lead to cell damage and death
Brain injury & stroke
CATECHOLAMINES: GAMMA AMINO BUTRIC ACID (GABA)
Inhibitory neurotransmitter
Decreases activity
Lowers arousal
High concentration in cortex
Regulates seizure activity through inhibition
Benzodiazepines aim to increase this receptor activity
Peripheal NS
Divided into:
1) Somatic nervous system:
Responding to environmental stimuli by connecting voluntary skeletal muscles with cells that respond to sensations
Afferent and efferent nerve cells
2) Autonomic nervous system
Neurons connecting the CNS to internal organs Regulates response of the body
Subdivided into:
Sympathetic: regulates arousal
Parasympathetic:conserves energy during relaxed state
2) Autonomic NS: Parasympathetic & Sympathetic
Sympathetic (arousal)
Releases adrenaline in response to fear, danger, excitement
Regulates arousal by mobilizing energy during stress and high arousal
Breathing becomes faster, irregular
Heart rate increases
Digestion decreases
Circulation focused toward major organs and muscles, away from extremities (hands become cold, sweaty)
Muscles tense
Parasympathetic (calming, return to homeostasis, conserves energy during relaxed state)
Lowers metabolic rate
Important for sleep, digesting food, restoring blood pressure, heart rate
3) Electrochemical neural transmission
RTSSHPCVNNPLR
Resting potential:
Resting potential of a neuron is -70 mV
Trigger:
Action potential signal arrives at axon hillock
Sodium channels open:
Local depolarization causes sodium channels along axon, which are voltage-gated, to open
Sodium enters/diffusion:
When channels open they allow inward flow of sodium ions because concentration is greater outside cell than inside
Related to principle of diffusion
Hyperpolarization:
Influx of positively charged ions move down axon as voltage-gated channels open
Potassium channels open:
Neuron reaches +35 mV
Potassium channels activate causing outward current of potassium ions (depolarization)
Calcium channels are opened:
Action potential reaches terminal button
Voltage-gated calcium channels are opened
Calcium enters
Vesicles migrate and merge:
Calcium binds with vesicle walls
Causing them to move towards presynaptic membrane and merge
Neurotransmitters released:
Once this merge occurs neurotransmitters inside vesicle are released into synapse
Neurotransmitters bind and receptors open: Neurotransmitters diffuse into the synapse
Some bind at receptor sites on postsynaptic cell triggering opening of receptors
Postsynaptic action potential is triggered:
When receptors open, voltage of postsynaptic neuron changes and action potential is triggered
Leftover neurotransmitters destroyed or reuptaked:
Leftover neurotransmitters destroyed by enzymes in the synapse or re-uptaked into presynaptic cell
Refractory period:
In presynaptic cell, there is brief over-correction (refractory period), taking polarization down past -70 mV, preventing an action potential from travelling back the way it just came
Return to resting potential:
In presynaptic cell, sodium-potassium pumps and diffusion of ions through cell membrane both assist in returning neuron to resting potential of -70 mV
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