Physiology Test 2

Front 1

Synapse

Back 1

The functional connection between a neruon and a second cell

Front 2

Electrical Synapse

Back 2

-Requires that cells are electrically coupled through gap junctions.

- Most common in cardiac muscle
-Smooth muscles
-Allows for rhytmic contraction of large masses of muscle cells
- Some brain regions
-Between some glial cells
-Present in many embryonic tissues

Hint 2

Function and location

Front 3

Chemical Synapses

Back 3

-Chemicals called neurotransmitters released fromy presynaptic cells stimulate action potentials in postsynaptic cells
-Pressynaptic neuron stores neurotransmitters in synaptic vesivles at th eaxon terminal.
-Arrival of action potential at axon terminal opens voltage gated Ca2+ channels
- Rapid influx of Ca2+ into axon triggers fusion of synaptic vesivles with axon membrance and release of neurotransmitter into snaptic cleft by process of exocytosis
-Tetanus and botulism toxins effect the exocytosis of synaptic vesivles

Hint 3

Description of process by which chemical synapses work

Front 4

Neurotransmitter

Back 4

-Released into synaptic cleft bind to specific recptor proteins locatedo n the post synaptic membrane

Hint 4

What they do whne released

Front 5

Ion channels when released

Back 5

- Binding of the neurotransmitter to its receptor causes ion chanels to open in the postsynaptic membrance

Front 6

Post synaptic membrane potential

Back 6

-Opening of ion channels produces changes in postsynaptic membrane potential

Front 7

EPSP

Back 7

-Excitatory postsynaptic potential= depolarization
- Caused by Na+ ions
- Graded in magnitude (not all or none)
- No refractory period

Front 8

IPSP

Back 8

- Inhibitory postsynaptic potential = hyperpolarization
-Graded response ( not all or none)
- Cl- channels open

Front 9

Acetylcholine

Back 9

- ACh
- 2 receptor types:
1) Nicotinic ACh receptor (stimulatory)
2) Muscarinic ACh receptor (Stimulatory or inhibitory)
-Inactivation of ACh in the synaptic cleft is achieved through enzyme acetylcholinesterase (AChE)

Front 10

ACh in CNS

Back 10

-Cholinergic neurons use ACh as neurotransmitter
-Excitatory effects, EPSP
- Alzheimer's Disease, typically there is loss of cholinergic neurons that terminate in hippocampus and cermral cortex.

Front 11

ACh in PNS

Back 11

- Somatic motor neurons form synapses with skeletal muscle cells, EPSP
- Release of ACh produces action potentials in muscle fibers stimulating muscle contractions
-Autnomic motor neurons that have parasympathetic effects use ACh as their neurotransmitter
-Effects can be EPSP or IPSP

Front 12

Monoamines

Back 12

- Includes epinephrine, norepinephrine, dopamine, and serotonin.
- Derived from amino acids
- EPSP

Front 13

Inhibition of Monoamines stimulatory action

Back 13

1) reuptake by presynaptic neuron
2) degradation by monoamine oxidase (MAO) released by presynaptic neuron
3) degradation by catechal-O- methyltransferase in postsynaptic neron
-MAO inhibitors are common drugs

Front 14

Serotonin

Back 14

-5-hydroxytyptamine
-role in regulation of mood, behavior, appetite
-many different subtypes of receptors
-SSRIs= serotonin-s[ecific reuptake inhibitors
-anti-depressants, anti-anxiety drugs
- Prozac, Paxil, Zoloft, Luvox
these drugs leave serotonin in synapse for longer period of time

Front 15

Dopamine

Back 15

-dopaminergic neurons
-nigrostriatal dopamine system
-dopaminerging neurons in substantia nigra (region of brain) send axons to group of nuceli called the corpus striatum deep in cerebrum
-involved in initiation of skeletal movements

Front 16

Parkinson's Disease

Back 16

-Involves destruction of dopaminergic neurons in substantia nigra
- Muscle tremors and rigidity
- difficulty initiating movements and speech

Front 17

Mesolimbic dopamine system

Back 17

- Dopaminergic neurons in midbrain send axons into limbic system within forebrain
-involved in behcaior and reward
-Schizophrenia may involve overactivity of mesolimbic dopamine pathways
-Some addictive drugs activate dopaminergic pathways in limbic system:
nicotine, cocaine, morphine, amphetamines, alcohol

Front 18

Norepinephrine

Back 18

-Used by sympathetic neruons in PNS
-Varied effect depending on organ
- Involved in behavioral arousal in CNS (fight or flight)

Front 19

Amino Acids

Back 19

-Unmodified
- Glutamic Acid
- Glycine
-Gamma-aminobutyric acid (GABA)

Front 20

Glutamic Acid

Back 20

- Glutamate
- Excitatory neurotransmitter in CNS
- Bind to NMDA receptors
- Important in memory storage
- Excessive release may result in epilepsy and excitotoxicity of neurons

Front 21

Glycine

Back 21

- IPSP
- Opens Cl- channels to hyperpolarize postsynaptic cells
- Helps control and coordinate skeletal muscle movements

Front 22

Gamma-aminobutyric acid

Back 22

-GABA
- Most prevalent neurotransmitter in brain
-inhibitory neurotransmitter ISPS
- Similar to glycine in action (opens Cl- channels)
- Involved in motor control
- Huntington's Disease is caused by deficiency in GABA-releasing neurons, causing uncontrolled movements

Front 23

Polypeptides

Back 23

- Neuropeptides
-Endogenous Opioids
- Neuropeptide Y
- Nitric Oxide (NO)

Front 24

Endogenous Opioids

Back 24

- activated by stressors to block transmission of pain
-B-endorphin, enkephalins, dynorphin, cannabinoids
-may mediate reward and positive reinforcement pathways (euphoria, felling of well being)
-released during exercise

Front 25

Neuropeptide Y

Back 25

** Most abundant neuropeptide in brain**
-Variety of effects
-powerful stimulator of appetite
-leptin supresses appetite by inhibiting neuropeptide Y release

Front 26

Nitric Oxide

Back 26

-NO
- Acts as a neurotransmitter in both CNS and PNS
-In CNS, may be involved in learning and memory
- In PNS, causes smooth muscle relaxation in target organs:
blood vessels, gastrointestinal tract, penis, respiratory tract