- Internal regulation events - Communication - Organising behaviour (External) - Information storage (memory) - Sensation, Perception, emotions

Nervous System Flashcards by Basama Mahmood

What is Hyperpolarising ?

Current moves the MP further from ‘0’

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What is a Depolarising?

Current moves the MP nearer to ‘0’

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Action potential

This large change in MP

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What is the action potential amplitude is independent on?

stimulus intensity/ size of the stimulus

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What we call when MP reaches about –55mV

Threshold’ for opening of voltage-gated Na+ channels

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What happened when MP reaches about +35mV(peak)?

Na+ channels shut, and K+ channels open ( K+ leave the cell, making the MP more negative repolarisation)

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What happened At ‘threshold’

voltage-gated Na+ channels open
Na+ diffuse in → depolarisation

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How Refractory period occurs?

After an AP is initiated, the neuron cannot generate another AP until the first one has ended

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Myelin sheath

fatty layer formed by wrapping the membranes of ‘glial’ cells round the axon

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How we can improve AP conduction speed?

Increases the axon diameter
Myelination: wrapping a layer of myelin round an axon

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Chemical synapses occur between neurons and?

Neurons
Muscle cells
Gland cells

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The effects of transmitters on post-synaptic cell dependent on what?

-Type of receptors
-2nd messengers in post-synaptic cell

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Excitatory synapse

Transmitter causes depolarisation
Excitatory post-synaptic potential (EPSP)
Brings MP nearer to firing threshold

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Inhibitory synapse

Transmitter causes hyperpolarisation
Inhibitory post-synaptic potential (IPSP)
Takes MP further from firing threshold

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When post-synaptic cell will “fire”?

When it receives sufficient excitation to drive the MP beyond threshold
This occurs when it receives many excitatory inputs (and few inhibitory inputs) within a short time period

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Convergence

Neuron receives many inputs from other cells

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Divergence

Neuron synapses with many other cells

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Drug affects can enhance or supress synaptic activity via:

Synthesis, storage of Tx
Release of Tx
Action of Tx on receptor
2nd messenger system
Inactivation of Tx

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Functions of NS

Internal regulation events
Communication
Organising behaviour (External)
Information storage (memory)
Sensation, Perception, emotions

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Who is responsible for Myelin formation in CNS, PNS?

Schwann cells (PNS)
Oligodendrocytes (CNS)

Peripheral nervous system (PNS)

Spinal nerves
Cranial nerves

Central nervous system (CNS)

Spinal cord
Brain

Mention all spinal nerves

31 pairs across cord:
- Cervical - 8
- Thoracic - 12
- Lumbar - 5
- Sacral - 5
- Coccygeal -1

What we called the sensory axons that run to body surface?

Dermatomes

What we call the motor axons that supply blocks of muscle?

Myotomes

Afferent somatic Vs Afferent autonomic

Afferent somatic → Associated with sensation/perception Afferent autonomic (visceral) → From internal (viscera) organs

Efferent somatic Vs Efferent autonomic

Efferent somatic → Voluntary control of muscle Efferent autonomic (visceral) → ANS control of smooth muscle and glands

What activities dose the ANS controls?

Smooth muscle Cardiac muscle Various glands

The 2 division of ANS:

Sympathetic NS Parasympathetic NS

Where are the cell bodies of pre-ganglionic neurons in Parasympathetic divisions?

Brainstem: CN 3,7,9 - Head structures CN 10 - Thoracic & Abdominal organs Sacral spinal cord: S 2,3,4 - Pelvic organs

Where are the cell bodies of pre-ganglionic neurons in Sympathetic divisions?

T1 - L2 (Thoracic & Lumbar regions)

Who has Long pre-ganglionic neurons?

Parasympathetic NS

Ganglion near or in effector organ in which system?

Parasympathetic N

Role of Parasympathetic NS

discrete actions on single organs, in the body ‘core’: – salivary gland; heart Conservative, anabolic effects: – storing energy - digestion etc (cow in a field) – slowing heart

Role of Sympathetic NS:

Widespread actions, often affecting whole body -distribution of sympathetic nerves; circulating adrenalin Homeostasis: – Blood pressure,thermoregulation Fight, flight or fright: – meeting demands of active muscle – anxiety (dental treatment!)

Who control breathing?

Skeletal muscles and are controlled by somatic nerves

Types of Adrenergic receptor

Alpha: Contraction of smooth muscle (a-1) Beta: Relaxation of smooth muscle (b-2) Increase heart rate and contraction force (b-1) ‘beta blockers’ only affect b1 receptors (localised affect on heart)

Types of Cholinergic receptor

Muscarinic receptors - neuro-effector junctions (Post gang) (Blocked by Atropine) Nicotinic receptors - NMJ, Pre gang/post gang synapses neuromuscular junction

Protective 3 layers of CNS

- Dura mater - Arachnoid membrane - Pia mater

Segments of spinal cord

Cervical Thoracic Lumbar Sacral Coccygeal

The difference between gray matter and white matter in spinal cord?

Grey matter: contains neuron cell bodies and some axons. White matter: contains nerve axons

Where does the first and second order occur?

Dorsal horn (grey matter) 1st-order afferent neuron terminals → 2nd-order cell bodies of sensory neurons

Reflex pathway

(Stimulus) Sensory → Interneuron → Motor (Response)

3 major sections of brain:

- Forebrain - Midbrain - Hindbrain

Cerebrum function

- Sensory/motor function - Language - Memory - perceptions - sensory-motor inegration - emotions

Midbrain function

Connection between Mid-Hind Visual & auditory reflexes Pain control

Hindbrain

Containing: Pons, Cerebellum, medulla oblongata Vital centres - breathing, heart, blood vessels (Medulla) Control of balance and posture (cerebellum)

Diencephalon function

Thalamus: - Sensory processing Hypothalamus: - Homeostasis - Hormone production - associated with pituitary gland - circadian rhythms - Motivation - Emotional responses, stress