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LS12 - Life Sciences > Nervous system > Flashcards

Flashcards in Nervous system Deck (23)
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0
Q

Two types of coordinating system in humans

A
  • Nervous system
  • Endocrine system (hormones)
  • These two work together.
1
Q

Stimulus

A
  • Any internal or external change
  • To which an organism responds
2
Q

Homeostasis

A
  • Tendency to maintain a stable equilibrium between interdependent factors.
  • Especially important for organisms that function within a specific range of conditions.
3
Q

Nervous coordination

A
  • Impulses conducted in nerves
  • For rapid responses
4
Q

Chemical coordination

A
  • Hormones (chemical messengers) are transported in the blood
  • Relatively slower responses
5
Q

Two main systems of the human nervous system

A
  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
6
Q

Generalised process of responding to stimuli

A

Stimulus -> detection -> processing and integration -> response

7
Q

How a stimulus is detected

A

Receptors detect stimuli and convert them into nerve impulses

8
Q

How a response is actioned

A

Effectors (muscles and glands)

9
Q

Components of nervous tissue

A
  • Nerve cells called neurons
  • Connective tissue called neuroglia
10
Q

Main parts of a neuron

A
  • Dendrites
  • Cell body (cytoplasm and nucleus)
  • Axon (with myelin sheath)
  • Terminal branches of axon (synaptic knobs)
11
Q

Dendrites

A
  • Conduct impulses to the cell body
  • One or more dendrites may be present in a neuron
12
Q

Axons

A
  • Carry nerve impulses away from the cell body
  • Forms a number of terminal branches
  • Synaptic knobs at the tips
13
Q

Myelin sheath

A
  • Nerve fibres outside CNS enclosed by myelin
  • Insulates the nerve fibres and accelerating impulse transmission
  • Formed by specialised Schwann cells
  • these wrap spirally around nerve fibres
  • myelin is a white fatty protein found in the cell membrane
14
Q

Nodes of Ranvier

A
  • Gaps in the myelin sheath between Schwann cells
  • Speed up transmission as impulses jump from one node to another
15
Q

Neurilemma

A
  • Outermost membrane of myelin sheath
  • Assist in repairing and regenerating damaged PNS neurons
  • (unmyelinated fibres and axons of the CNS cannot regenerate or be repaired)
16
Q

Neuron structural classification

A

Depends on number of outgrowths from cell body:

  • Multipolar (more than two)
  • Bipolar (two)
  • Unipolar (one)
17
Q

Neuron functional classification

A
  • Sensory (afferent) neurons - impulses from receptor to CNS
  • Motor (efferent) neurons - impulses from CNS to effectors
  • interneurons (connector neurons) - neurons of the CNS
18
Q

Synapse

A

The gap between an an axons synaptic knob and a dendrite

19
Q

How an impulse crosses a synapse

A
  • neurotransmitter chemicals
  • e.g. serotonin
20
Q

Where neurotransmitters are formed and how they are released

A
  • synaptic vesicles alongside many mitochondria providing required energy
  • Impulses cause the vesicles to burst at the surface of the pre-synaptic membrane
  • The neurotransmitter is released into the synaptic cleft
21
Q

How the nerotransmitter passes on an impulse to the dendrite.

A
  • The neurotransmitter moves across the synaptic cleft
  • It attaches to the post-synaptic membrane
  • This generates electric signals that are conducted as nerve impulses to the cell body of the next neuron
22
Q

The significance of a synapse

A
  • Signals only move in one direction
  • Impulses can be transmitted to many neurons, afecting more than one effector
  • Insignificant stimuli can be filtered out
  • The synapse filters out weak signals, preventing overloading of the CNS