Nerve tissue

Question 1

What is nervous tissue and what is its function?

Answer 1

-Main tissue component of NS
-Neural communication within the body via neurons - neurons generate, conduct and recieve info via electrical signals and generate appropriate response signal

Question 2

What is the CNS composed of and does it contain connective tissue?

Answer 2

-Comprised of brain (encephalon) and spinal cord
-No connective tissue except meninges and walls of large blood vessels

Question 3

What is the PNS comprised of?

Answer 3

-The branching peripheral cranial and spinal nerves and relay centres (ganglia)

Question 4

What can the PNS be subdivided into?

Answer 4

-Somatic NS
-Autonomic NS

Question 5

What is the Somatic NS?

Answer 5

-Under voluntary control
-Transmits signals from brain to end organs e.g skeletal muscle

Question 6

What is the Autonomic NS

Answer 6

-Controls involuntary functions e.g heart rate blood pressure
-Smooth muscle, cardiac muscle, glands

Question 7

What are the 2 basic types of cells in nervous tissue?

Answer 7

-Neurons - receive and transmit impulses
-Neuroglia - support, protect and assisr neurons in neural transmission - do not receive or transmit impulses

Question 8

What are the 3 functional classifications of neurons?

Answer 8

-Sensory neurons
-Motor neurons
-Interneurons

Question 9

What is the structural classification of neurons?

Answer 9

-Multipolar
-Bipolar
-Pseudounipolar

Question 10

What are sensory neurons and what do they do?

Answer 10

Originate in sensory receptors
-Conducted via sensory (afferent) neurons to the CNS
-Sensory receptors detect taste, pressure, pain, touch, temp, sight, smell, hearing, body postition

Question 11

What are motor neurons?

Answer 11

-Originate in the CNS
-Conducted via motor (efferent) neurons from CNS to the peripheral ns, muscle tissue or glands

Question 12

What are interneurons?

Answer 12

-Form connections between neurons in CNS

Question 13

What is the basic neuronal structure?

Answer 13

-Cell body
-Multiple dendrites
-Single axon

Question 14

Note on Cell body/perikaryon/soma

Answer 14

-Contains nucleus and perinuclear cytoplasm
-Large, spherical to ovoid nucleus, centrally located
-RER and polyribosomes (rER+polyribosomes= nissl body)
-single axon and one or more dendrites extend from soma

Question 15

What are Nissl bodies?

Answer 15

rER + polyribosomes

Question 16

What is the axon hillock?

Answer 16

Region where axon arises

Question 17

What is the cell body?

Answer 17

-Main nutritional and metabolic region of the neuron
-Receives signals from other cells and sends them towards the axon

Question 18

What are dendrites and what are their functions?

Answer 18

-Most neurons have multiple dendrites
-Branching results in synaptic terminals
-Synaptic terminals allow a neuron to receive and integrate multiple impulses
-Dendrites function as the major sites of info input INTO the neuron
-Receives signals coming in from other cells and sends towards axon

Question 19

What does the axon arise from?

Answer 19

Axon hillock

Question 20

What is the initial segment?

Answer 20

Portion of axon from origin at axon hillock to the beginning of myelin sheath

Question 21

What are terminal boutons?

Answer 21

Axons terminate on other neurons, effector organs as small branches ending in swellings called terminal boutons - form a synapse

Question 22

What is the function of an axon?

Answer 22

-Conducts an action potential from soma
-Axonal transport of materials beztween soma and axon terminals
-Can be myelinated or unmylinated

Question 23

What does anterograde vs retrograde mean?

Answer 23

Anterograde - from soma to axon terminal
Retrograde - axon terminal to soma

Question 24

Grey vs white matter

Answer 24

Grey matter - cell bodies and dendrites (group of cell bodies = in CNS nucleus, in PNS ganglion)
White matter - axons

Question 25

What are bipolar neurons?

Answer 25

-Single dendrite and single axon -Located in vestibular and cochlear ganglia, olfactory epithelium of nasal cavity

Question 26

What are unipolar (pseudounipolar) neurons?

Answer 26

-One process which branches into central and peripheral branch -Originate as bipolar neurons but processes partially fuse during embryonic development

Question 27

What are multipolar neurons?

Answer 27

-Most common -Multiple dendrites, single axon

Question 28

What happens at a chemical synapse?

Answer 28

-Most common -Presynaptic membrane releases neurotransmitters into synaptic cleft -Neurotransmitter diffuses across synaptic cleft to gated ion-channel receptors -Binding results in ion channels opening, allowing passage of ions - reverses membrane potential

Question 29

What are the different types of synaptic contacts between neurons?

Answer 29

-Axodendritic synapse - between axons and dendrite -Axosomatic system - between axon and soma -Axoaxonic synapse - between 2 axons -Dendrodentritic synapse - between 2 dendrites

Question 30

What happens if there is a maintenence of hyperpolarisation?

Answer 30

inhibitory

Question 31

What is the most common neurotransmitter chemical?

Answer 31

Acetylecholine