Nervous system Flashcards
1
Q
What is the primary organ for coordinating the different functions of cells and organs
A
The brain
2
Q
What does the brain do (3)
A
- senses the need for activity (stimulus)
- regulates other cells and organs to achieve the activity (adaptive response).
- Uses nerves & hormones to mediate adaptive response and achieve homeostasis (optimum physiological states = health).
3
Q
What is coupling stimulus to response (Reflex arc) (3)
A
- Involves peripheral sensory nerve afferent signals, spinal cord, efferent signals and response
- Involuntary but conscious
- e.g. burning hand
4
Q
How do we couple stimulus to response via nerves (5)
A
- Peripheral sensory nerve activation (Afferent nerve → CNS)
- Afferent signal → spinal cord
- Sensory neurone comunicates to the somatic neurone
- Efferent signal → terminals of the axon releasing chemicals
- Chemicals activate the muscle
5
Q
What is the cough reflex (5)
A
- Peripheral sensory nerve activation
- Afferent signals → spinal cord via vagus nerve
- Central processing of inputs in the brainstem
- Efferent output via motor nerves
- Effector muscles of the diaphragm, thorax and larynx (cough response)
6
Q
What are the nervous tissue cell types (2)
A
- Neurones - main electrically excitable cells besides muscles and glands
- Gilia - metabolic, insulation & immune support to nerves, different in CNS/PNS
7
Q
What structures are in neurons (5)
A
- Dendrites - post-synaptic input sites
- Cell body - aka soma
- Axon hillock - initiates an action potential
- Axon - conducts
- Synaptic terminals - presynaptic output sites of neurotransmitter release
8
Q
What are the glia types in the CNS (4)
A
- Oligodendrocyte - insulates nerve processes
- Astrocyte - lines the blood-brain barrier
- Ependymal - produces cerebrospinal fluid of ventricles
- Micorglia - phagocytose immune role
9
Q
What are the glia types in the PNS (2)
A
- Schwann cell - myelin insulation of nerve axons
- Satellite cells - surround soma of peripheral nerves in ganglia (accumulations of soma)
10
Q
What is a collection of nerve bodies called in the CNS
A
nucleus
11
Q
What is a collection of nerve bodies called in the PNS
A
ganglion
12
Q
What is the blood-brain barrier (6)
A
- Collection of cells regulating access to most of the brain
- Endothelia
- Pericytes
- Basement membrane
- Macrophages
- Astrocytes
13
Q
What are circumventricular organs
A
Provide permeable routes of access for entry or sensory signals and exit of neuroendocrine signals
14
Q
What are the 3 types of nerves
A
- Monopolar - sensory afferent
- Bipolar
- Multipolar - most neurones (multiple dendrites)
15
Q
What is the basis of excitability (3)
A
- Impermeable membrane
- Na/K-ATPase pumps - establish ion gradients
- Different ion channel permeabilities - determine membrane voltage
16
Q
What are the different ion channel permeabilities (4)
A
- Leakage - non-gated, always active - potassium channels
- Transmitter activated - ligand operated, trigger action potentials
- Mechanically activated - generator potential sensory cell
- Voltage activated - voltage operated, Na+, K+, Ca++ or Cl- ions
17
Q
What are the types of membrane voltages (3)
A
- Resting
- Graded
- Action potential
18
Q
What is the resting membrane potential
A
-70mV
19
Q
What is the graded membrane potential (3)
A
- Potentials initiated by neurotransmitter receptors:
- Excitatory post-synaptic potentials (less negative membrane)
or
- Inhibitory post-synaptic potentials (more negative membrane)
20
Q
What is the action potential (5)
A
- All or nothing
- not graded
- → +
- Ions flowing across membrane
- Depolarisation and repolarisation
21
Q
How do we achieve electrical propagation and chemical transmission (5)
A
- Electrogenesis - hyperpolarised resting membrane potential, low [Ca]
- Inhibition/Excitation - synaptic inputs
- Conduction - depolarising (+) & repolarising (-) wave spreading across the axon by voltage-operated channels for Na+ and K+
- Synaptic chemical transmission - opens voltage-operated channels for Ca & Ca-dependent vesicle fusion and transmitter release into the synaptic cleft
- Response - intracellular communication due to ligand-operated channels
22
Q
What channels are at the pre-synapse and post-synapse
A
Pre-synapse = voltage-operated channels
Post-synapse = ligand-operated channels
23
Q
What effects do synaptic inputs have on chemical transmission (3)
A
- Inhibitory Post-Synaptic Potentials are hyperpolarising (maintaining -ve Vm)
- Excitatory Post-Synaptic Potentials are depolarising (less -ve; or +ve).
- IPSPs and EPSPs are integrated/summated to determine the size of a generator potential at the axon hillock. If high enough will initiate ‘all or none’ action potentials (Apd, impulse, spike)
24
Q
What are the types of neurotransmitters (6)
A
- Acetylcholine
- Catecholamines (noradrenaline, adrenaline, dopamine)
- Serotonin
- Gamma-aminobutyric acid
- Glutamate
- Substance P
25
What are the receptor types for acetylcholine and their function (4)
1. Nicotinic - excite
2. Muscarinic - inhibit
3. CNS = memory & cognition
4. PNS = Skeletal muscle & autonomic
26
What are the receptor types for noradrenaline & adrenaline and their function (4)
1. Alpha 1, beta 1 - excite
2. Alpha 2, beta 2 - inhibit
3. CNS = Opioid relief
4. PNS = Sympathetic NS
27
What are the receptor types for dopamine and their function (4)
1. DA 1 - Excite
2. DA 2 - Inhibit
3. CNS = motivation
4. PNS = BVs, GIT, renal
28
What are the receptor types for serotonin and their function (4)
1. 5-H1(1&5) - inhibit
2. 5-HT(2,3,4,6,7) - excite
3. CNS = sleep, mood
4. PNS = GIT, bone
29
What are the receptor types for gamma-aminobutyric acid and their function (3)
1. GABA(A & B)
2. inhibitory
3. Inhibits neurons from firing off
30
What are the receptor types for glutamate and their function (2)
1. NMDA, AMPA
2. Neurons fire off
31
What are the receptor types for substance P and their function (3)
1. NK1
2. Excitatory
3. pain & inflammation
32
What are the transmitter classes (5)
1. Amino acids - Glutamate (excite) & GABA (inhibit)
2. Amines - Catecholamines & indolamines (Serotonin 5HT)
3. Acetylcholine
4. Small molecule type - nitrate oxide, non-adrenergic, non-cholinergic
5. Peptide - Hypothalamic & peptide hormones & substance P
33
What are the responses evoked from transmitters (2)
1. Excitation - depolarising
2. Inhibition - hyperpolarising
34
What are the mechanisms of transmitters (2)
1. Direct - inotropic receptors, Nicotinic, glutamate, GABA-A, 5HT3R
2. Indirect - metabotropic receptors, all adrenergic
35
What does the CNS consist of (2)
1. Brain
2. Spinal cord
36
What does the PNS consist of (3)
1. SNS
2. ANS
3. Crainal & spinal nerves
37
What does the SNS consist of (3)
1. Motor nerves → skeletal muscle
2. Sensory nerves
3. Voluntary
38
What does the ANS consist of (4)
1. Sympathetic - Fight or flight
2. Enteric → cardiac & smooth muscle, glandular cell
3. Parasympathetic - Rest & digest
4. Involuntary
39
Why do drugs target the ANS nerve transmission (3)
1. The two systems are physiological antagonists
2. SNS and PsNS nerves provide opposing drives to target organs
3. e.g. adrenergic in SNS speeds up heart, cholinergic in PsNS slows the heart
