Chapter 12: NEURAL TISSUE, PPT

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1

Cell body

integrate incoming signals that Contains an abundance of mitochondria, fixed and free ribosomes and RER (Nissl bodies), but lack centrioles

2

Dendrites

  • Act as ‘receptors’
  • Extend out from the cell body and branch into dendritic spines; account for 80-90% of the total surface area of a neuron
3

Axon (“nerve fiber”)

  • Propagates electrical impulses known as action potentials
4

Axon (“nerve fiber”) associated

Initial segment, Axon collaterals, Telodendria, Synaptic knob

5

Initial segment of axon

joins the cell body at the axon hillock

6

Axon collaterals

branches of an axon; enable communication with more than one cell

7

Telodendria

terminal, finger-like projections of the axon

8

Synaptic knob

at the end of a telodendrion; contain vesicles full of neurotransmitters

9

Synaptic knob includes

  • Presynaptic neuron

• Postsynaptic neuron

• Neuromuscular junction

• Neuroglandular junction

10

Sensory

Roughly 10 million sensory neurons transmit electrical impulses along afferent fibers from sensory receptors in the PNS into the CNS

11

sensory ganglia

Cell bodies in collections outside of the CNS

12

Interoceptors

monitor respiratory, digestive, cardiovascular, reproductive, and urinary systems; deep pressure, distension and pain

13

Exteroceptors

monitor stimuli from outside the body, i.e. pressure, temperature, touch, smell, vision, hearing, taste and equilibrium

14

Proprioceptors

monitor position and movement of skeletal muscles and joints

15

Motor neuron

Roughly 500,000 motor neurons transmit electrical impulses along efferent fibers from the CNS through the PNS to effectors (i.e. muscle, glands, adipose tissue)

16

nuclei (nucleus)

Cell bodies in collections inside of the CNS

17

Interneurons

Roughly 20 billion, most of which are found in the CNS

  • Distribute sensory input and coordinate motor output
18

Sensory (afferent) division includes

Somatic and Visceral

19

Sensory - Somatic

signals from receptors in skin, muscle, and joints

20

Sensory -Visceral

signals from receptors in heart, lungs, digestive organs, bladder

21

Motor (efferent) division

Somatic and Visceral (autonomic)

22

Motor-Somatic

signals to skeletal muscles for voluntary contraction and involuntary somatic reflexes

23

Motor- Visceral (autonomic)

signals to glands, cardiac, and smooth muscle; primarily involuntary:

  • Sympathetic: fight or flight division
  • Parasympathtic: rest and digest division