Nervous System 2 Flashcards
A synapse
Found at the axon terminal
A junction between:
- 2 neurons
Eg sensory neurons and interneurons
- neuron and an effector cell
Eg motor neuron and muscle cell
Postsynaptic membrane potentials
Are graded potentials
- they are added up
- if the net potential reached a threshold, an action potential will occur
Postsympatic Potential:
The 2 types
EPSP: excitatory postsynaptic potentials
• lead to depolarization
IPSP: inhibitory postsynaptic potentials
• lead to hyper plaition
Neural processing
Neurons work together in groups
Different connections between neurons form different circuits:
- Diverging: 1 input many outputs
- Converginf: Many inputs, 1 output
1 Reverberating: A signal travels through a chain of neurons, each feeding back into to previous ones
- Parallel are discharge circuit: a signal activates neurons arranged in parallel arrays that eventually converge into a single output cell, ex math
The withdrawal reflex is an automatic response that enables you to pull away from a painful stimulus. Which neural circuit does it utilize?
A. Diverging
B. Converging
C. Reverberating
D. Parallel after-discharge
D
Neurotransmitters(NTs)
Are c huh Nicola messengers that allow neurons to communicate
- over 50 are known
What is the neurotransmitter used at the synapse between a motor neuron and a muscle cell?
Acetylcholine(ACh)
The effect of acetylcholine can be stimulating or inhibiting. Which of the following gives the best explanation for why this is so?
A. Acetylcholine has many different forms.
B. Different postsynaptic cells will have different receptors.
C. Postsynaptic cells have a dynamic and changing metabolism and respond differently at different times.
D. Acetylcholine has a “dose effect.” Larger doses are stimulating while small doses inhibit.
B
Acetylcholine(ACh)
Made from acetic and choline
- degraded by enzyme acetylinesterase(AChE)
It binds to different receptors:
ACh is excitatory at neuromuscular junctions in skeletal muscle
• ACh is inhibitory in cardiac muscle
When acetylcholine acts as an excitatory neurotransmitter, which of the following is likely happening on the postsynaptic cell?
A. Chemically gated sodium channels will open.
B. Chemically gated chloride channels will open.
C. Chemically gated potassium channels will open.
D. Chemically gated sodium channels will be closed.
A
ACh binds
To cholinergic receptors:
The 2 types:
- Nicotinic Receptor (binds nicotine)
• Always stimulatory - Muscarinic Receptor (binds muscarine, a mushroom poision)
• Can be stimulatory or inhibitory
ACh binds
To cholinergic receptors:
The 2 types:
- Nicotinic Receptor (binds nicotine)
• Always stimulatory - Muscarinic Receptor (binds muscarine, a mushroom poision)
• Can be stimulatory or inhibitory
Biogenic Amines
are neurotransmitters have one or more amine groups
• Tyrosine: Dopamine, norepinephrine (NE), and epinephrine (E)
• Tryptophan: Serotonin
• Histidine: Histamine
Epinephrine(E) and Norepinephrine(NE)
Known as the catecholamines.
E and NE are excitatory in smooth muscle of blood vessels and lead to vasoconstriction (contraction).
E and NE are inhibitory in smooth muscle of bronchioles and lead to bronchodilation (relaxation).
Epinephrine and Norepinephrine differ
Structurally structurally by 1 methyl group (СН3).
Norepinephrine has greater effects on blood vessels and acts primarily as a NT.
Epinephrine has greater effects on the heart and metabolism and acts primarily as a hormone.
Norepinephrine
binds adrenergic receptors.
There are two types:
1. a (2 subtypes)
• a1 receptors leads to smooth muscle contraction
2. B (3 subtypes)
• B2 receptors leads to smooth muscle relaxation
