Lecture Exam 3 (Set 1)

Front 1

Synapses

Back 1

-specialized in structure and physiology
-in most cases, communication is one-way

Front 2

Two methods by which cell can communicate with other:

Back 2

Electrical and Chemical

Front 3

Two possibilities of responses:

Back 3

Excitatory and Inhibitory

Front 4

Electrical Synapses:

Back 4

-formed by gap junctions
-no delay
-only limit is size

Front 5

Electrical Synapse functions:

Back 5

-fast transmission/communication
-allows for synchronization of activity of all cells
-allow for stereotyped responses--always exactly same response
-almost all electrical synapses are excitatory

Front 6

Characteristics of chemical synapses:

Back 6

-most common type
-response of post synaptic cells is determined by what ion channel is open
-excitatory responses are anytime the ion movement takes membrane potential towards or above threshold
-inhibitory response is any synapse where ion movement prevents or takes membrane potential below threshold

Front 7

Steps of chemical synaptic transmission Part 1 (3 parts)

Back 7

Pre-synaptic events:
1. Action potential arrives at terminal and causes depolarization.
2. Depolarization causes voltage-gated calcium channels to open
3. Calcium enters terminal and causes synaptic vesicles to fuse with membrane
4. Neurotransmitter released into cleft
*above steps take .5 milliseconds

Front 8

Steps of chemical synaptic transmission Part 2 (3 parts)

Back 8

In The Cleft:
1. Neurotransmitter will diffuse to post synaptic cell (1 usec)
2. Neurotransmitter removed (2-5 usec)by:
a. Enzymatic breakdown
b. re-uptake into presynaptic neuron or other nearby cells
c. diffuses away

Front 9

Steps of chemical synaptic transmission Part 3 (3 parts)

Back 9

Post synaptic events:
1. Neurotransmitter will bind to membrane receptor
2. Causes receptor to change shape and open selective ion channel
3. Ions move through channel and change membrane potential
4. Channels close as neurotransmitter unbinds and is removed
*above steps take 1 usec

Front 10

Acetylcholine (ACh)

Back 10

-on skeletal--excitatory
-on cardiac--inhibitory
(two different responses because receptor is different)

Front 11

Acetylcholine (ACh)

Back 11

-released by motor neurons onto skeletal muscles
-also used by autonomica nervous system
-by brain stem
-diencephalon (thalamus & hypothalamus)
-cerebral cortex
-removed by enzymatic breakdown (acetylcholinesterase)

Front 12

Seratonin (5-HT)

Back 12

-found in brain stem
-send axons into diencephalon
-appear to be active in mood control and sensory perception
-inactivated by re-uptake

Front 13

Dopamine (DA)

Back 13

-located in thalamus, hypothalamus and spinal cord
-involved in emotional responses
-control of complex movements
-subconscious muscle movements
-inactivated by reuptake
-two diseases: Parkinson's and schizophrenia

Front 14

Norepinephrine (NE)

Back 14

-in brain stem and autonomic nervous system
-neurons that release are involved in arousal, dreaming, mood regulation
-inactivated by re-uptake

Front 15

Gamma-aminobutyric acid (GABA)

Back 15

-in amino acid, but not found in proteins
-always cause inhibition
-30% in cerebral cortex use this
-found in thalamus and hypothalamus
-inactivated by re-uptake
-Huntington disease

Front 16

Substance P

Back 16

-used by sensory neurons which signal pain into spinal cord
-inactivated by re-uptake

Front 17

Enkephalin

Back 17

-in thalamus and hypothalamus, limbic system and spinal cord
-natural opiate--inhibit pain perception
-removed by reuptake

Front 18

Synaptic responses

Back 18

-graded potentials
-excitatory post synaptic potentials (EPSP)
Na+
Na+ and K+ -->very quickly
-inhibitory post synaptic potentials (IPSP)
-ion channel that needs to be open: K+ and Cl-, can get spatial and temporal summation--happening at same time

Front 19

Responses:

Back 19

-sometimes not at threshold, nothing happens
-reach threshold, get one action potential
-reach and stay above--will get more than one action potential

Front 20

Pre synaptic facilitation:

Back 20

-responses keep getting bigger and bigger
-more channels open
-releasing more neurotransmitter
-pre synpatic cell forces it to make change

Front 21

Neuromodulator:

Back 21

Classical synaptic transmission and neuromodulation
-causes effects to last longer period of time
-can decreased membrane permeability
-can change threshold of cell
-activate "special electrical properties"

Front 22

Brain stem:

Back 22

-pathway between higher brain centers and lower brain centers and spinal cord
-many pathways cross over to opposite side of nervous system
-motor nuclei for cranial nerves
-control internal organs and involuntary functions
-where autonomic activity is started
-control of eye movements
-reticular formation located here:
1. involved in arousal and sleep
2. involved in coordination of breathing
3. involved in modulating pain

Front 23

Cerebellum:

Back 23

-regulates muscle tone-small amount of contraction of muscles
-helps maintain posture and balance
-involved in coordinating and planning skilled voluntary movements

Front 24

Hypothalamus:

Back 24

-regulates many homeostatic functions: body temp, thirst, urine output, food intake
-important link between nervous system and endocrine system
-helps maintain waking and sleeping states
-functions as oscillator that drives many biological rhythms
-emotional responses

Front 25

Thalamus:

Back 25

-relay station for all sensory inputs except smell to cerebral cortex
-relay station for motor commands from cerebral cortex down to spinal cord
-contributes to emotions and memory

Front 26

Basal Nuclei:

Back 26

-coordinating voluntary movements
-inhibits muscle tone
-suppresses useless patterns of movement
1. amygdala-emotions and memory
2. hippocampus-learning and memory

Front 27

Cerebral Cortex:

Back 27

Six layers:
1-3: connections between different parts of cortex
4: sensory inputs from thalamus
5: outputs to spinal cord
6: outputs to thalamus

Front 28

Functions of cerebral cortex:

Back 28

-voluntary control of movement
-sensory perception
-language
-personality traits
-sophisticated mental events, ex: creativity, memory

Front 29

Frontal lobe:

Back 29

1. voluntary motor control
2. location of personality
3. responsible for higher intellectual responses
4. location of verbal communication

Front 30

Parietal lobe:

Back 30

1. sensory perception of both skin and muscle sensations
2. understanding of speech and being able to formulate words to express thoughts and emotions
3. ability to interpret textures and shapes

Front 31

Temporal lobes:

Back 31

1. interpretation of auditory inputs
2. storage of memory of auditory and visual experiences

Front 32

Occipital lobe:

Back 32

1. perception of vision
2. integrates eye movements
3. correlates visual images with previous visual experiences and other sensory inputs

Front 33

Insula:

Back 33

1. perception of visceral sensations (ex: stomach ache)
2. plays role in memory

Front 34

Corpus callosum:

Back 34

-main connection between two hemispheres
left hemi-reading and producing language
right hemi-can interpret verbal language, but not generate speech, depth perception drawing

Front 35

Sensory receptors:

Back 35

transducers will convert sensory stimulus into a neural signal

Front 36

Five types of sensory receptors:

Back 36

1. mechanoreceptor: touch, respond to physial change in shape or position
2. chemoreceptor: smell and taste
3. photoreceptor: vision
4. nociceptor: pain
5. thermoreceptor: temperature

Front 37

sensory modality:

Back 37

will only detect that certain type of stimulus

Front 38

Receptive field:

Back 38

-region or place where sensory stimulation large enough that would cause a response in only one sensory neuron
-send info to brain in very ordered way

Front 39

labeled lines:

Back 39

sensory maps, pathways

Front 40

Receptor potentials:

Back 40

-caused when sensory stimulation of sensory cell stimulation reception comes
-summation-temporal and spatial
-decremental conductance-get smaller as they go
-size is graded, more light, more seen

Front 41

Receptor adaptation:

Back 41

-decrease in sensory cell response to continued stimulation

Front 42

Phasic receptors:

Back 42

exhibit adaptation, ex: touch, smell--perfume

Front 43

Tonic receptors:

Back 43

will continue to respond, ex: nociceptors

Front 44

Somatosensory cortex:

Back 44

part of parietal obe where you get sensations of skin and muscle

Front 45

Somatosensory homunculus:

Back 45

the sensory map, ex: lips have more area than knee, so you can sense things coming into mouth

Front 46

Peripheral nervous system

Back 46

Autonomic nervous system
-sympathetic
-parasympathetic

Front 47

Neurotransmitters

Back 47

-both preganglionic neurons release ACh
-different receptors (on postganglionic)

Front 48

Nicotinic receptors:

Back 48

nicotine will activate, open ion channels that let both Na+ and K+ through-depolarization

Front 49

Muscarinic receptors:

Back 49

-agonist, will change target cell-use G-protein
-in different targets, open ion channels with only K+ through--cell will hyperpolarize, inhibit that cell
-cause depolarization, but by closing a K+ channel or open a calcium channel

Front 50

Norepinephrine:

Back 50

-all work through G-protein
-sometimes will effect ion channels
-some will work through cAMP

Front 51

Functions of autonomic nervous system:

Back 51

involved in controlling involuntary targets, cardiac, smooth muscle and glands

Front 52

Functions of sympathetic nervous system:

Back 52

-active when body needs to adapt or cope with stresses-physiological and psychological
-produces wide effects, cannot pick and choose

Front 53

Functions of parasympathetic nervous system:

Back 53

-day to day stuff, negetative functions
-produces discrete response in one organ and leaves others alone

Front 54

Neuromuscular junction:

Back 54

-where motor neurons synapse onto skeletal muscle cell
-receptor in muscle cell is nicotinic receptor, both Na+ and K+ through channel will ALWAYS depolarize to threshold

Front 55

Actin:

Back 55

-main protein, two rows of actin molecules
-"strand of pearls" then twisted into helix

Front 56

Myosin binding site:

Back 56

where actin binds to myosin

Front 57

Thick myofilaments

Back 57

-made up of myosin
-actin binding site of myosin binds to myosin binding site

Front 58

ATP binding site:

Back 58

enzyme ATPase

Front 59

Sarcoplasmic reticulum (SR)

Back 59

-contains calcium ions, when stimulated it will release them

Front 60

T-tubules:

Back 60

part of plasma membrane, goes down deep into cell, carry stimulation down into cell

Front 61

Contraction: stimulation/excitation steps:

Back 61

1. action potential travels down motor neuron axon
2. ACh is released at the neuromuscular junction
3. ACh activates receptors that open ion channels that let both Na+ and K+ through
4. muscle membrane potential depolarized to threshold
5. muscle cell will produce action potential which will spread across the muscle cell membrane
6. action potential will travel down T-tubule into cell
7. Action potential will activate the SR

Front 62

Excitation-coupling steps:

Back 62

1. Once it's activated, the SR releases calcium ions
2. Calcium ions bind to troponin
3. Troponin and tropomyosin move out of the way and expose myosin binding sites of actin

Front 63

Contraction steps:

Back 63

1. Myosin cross bridge binds to actin
2. Myosin cross bridge will bend over in power stroke, pulling the myofilament towards the center of sarcomere and ADP and Pi are released
3. brand new ATP has to bind to myosin cross bridge and then will let go of actin
4. ATP broken down into ADP and Pi and myosin uses energy to move back to starting position
5. process continues until calcium is transported back to SR.