Lecture 3 - Nervous System 1

Question 1

What is homeostasis?

Answer 1

The state of stability brought by the body’s tendency to stay in equilibrium.

Question 2

What are the two major systems of the body that integrate and generate appropriate responses to maintain homeostasis?

Answer 2

Nervous System

Endocrine System

Question 3

What are the three basic functions are performed by nervous systems?

Answer 3

1) Takes input from sensory receptors
2) Performs integration at the CNS
3) produces a signal for motor output

Question 4

What are receptors and where are they found.

Answer 4

Receptors are the parts that would detect changes in the internal or external environmental for the body to react accordingly. Eyes, ears, tongue, tactile?

Question 5

Give examples of sensory input (both internal and external)

Answer 5

pH, temperature, light, taste, haptic

Question 6

Where is sensory information integrated?

Answer 6

In the Central Nervous System (Brain and Spinal Cord)

Question 7

What is the response?

Answer 7

The electrical/chemical signal that is sent by the CNS after integration to invoke the necessary motor action to be done by organs.

Question 8

What is the central nervous system composed of?

Answer 8

Brain & Spinal Cord

Question 9

What is the function of the CNS?

Answer 9

Takes the input signal and then creates the output signal based on experiences, reflexes and current conditions

Question 10

What is the peripheral nervous system composed of?

Answer 10

The surrounding nerves around the CNS are composed of ganglia, cranial nerves and spinal nerves.

Question 11

What is the function of PNS?

Answer 11

To send signals to the CNS and also conduct information between CNS and the organs.

Question 12

Define Ganglia?

Answer 12

Collection of nerve bodies

Question 13

Cranial nerves

Answer 13

Facial nerves found near the brain

Question 14

Spinal nerves

Answer 14

Nerves found near the spinal cord

Question 15

How many cranial nerves are there?

Answer 15

N/A

Question 16

What are the two subdivisions of the peripheral nervous system and what are their functions?

Answer 16

The afferent (sensory) division = collects signals from the receptors to send to the CNS
The efferent (motor) division = sends signals from the CNS to the organs to perform output

Question 17

What are the two subdivisions of the motor division?

Answer 17

1) Autonomic nervous system

2) Somatic Nervous System

Question 18

What are the two subdivisions of the autonomic nervous system and what are their functions?

Answer 18

1) Parasympathetic division (involved in “rest and digest” system)
2) Sympathetic division (fight or flight action)

Question 19

What are the two types of nervous tissue? Which is involved with transmitting signals and which can divide, which are far more numerous?

Answer 19

1) Neurons that transmit signals

2) Neuroglia that divides. Outnumbers neurons 10:1

Question 20

Define Oligodendrocytes?

Answer 20

forms myelin sheath to insulate the axons. Found in CNS.

Question 21

Define Microglia?

Answer 21

Phagocytes to protect CNS cells. (engulfs invaders)

Question 22

Define Astrocytes?

Answer 22

functions in exchange of nutrients in the capillaries and repair the nervous system in CNS

Question 23

Define Ependymal?

Answer 23

Cells that line the cerebral spinal fluid (CSF), excreted by the choroid plexus (types of ependymal cells)

Question 24

Define Schwaan

Answer 24

Produce the myelin sheath around a single axon

Question 25

Define Satellite?

Answer 25

thought to have the same function as astrocytes

Question 26

Generally describe the characteristics of a neuron?

Answer 26

Functional unit of the NS must serve you for life. High metabolic rate and cannot stay alive for long without oxygen. Function: generation and conduction of nerve impulse

Question 27

What is in the structure of a neuron?

Answer 27

1) Dandrites – short and diffused branches. Receptive (input) regions. Conveys information to the soma. Messages are in electric signals called graded potential. 2) Soma – cell body where nucleus is located. Contains usual organelles except centrioles. 3) Axon – a single long extension 4) Axon terminal branched at the tip

Question 28

What direction the impulse travels?

Answer 28

From dandrites to the axon terminal

Question 29

Define Nuclei, Ganglia, Tract, Nerve

Answer 29

Nuclei: clusters of cell bodies inside the CNS Ganglia: clusters of cell bodies in the PNS Tract: Axons in the CNS Nerve: Axons in the PNS

Question 30

What is the synapse?

Answer 30

...

Question 31

What is the myelin sheath?

Answer 31

Layering of fatty substance (myelin) and proteins to insulate nerves

Question 32

Which cells form the myelin sheaths in the CNS and PNS?

Answer 32

Schwaan cells

Question 33

Describe the formation of the myelin sheath by Schwann cells?

Answer 33

Rolling of layers by Schwaan cells

Question 34

What is the neurilemma?

Answer 34

The myelin sheath that is the outermost of the Schawaan cell that covers the nucleus

Question 35

What is the function of the myelin sheath

Answer 35

- Protects the axon - Electrically insulates the axon so that ions cannot enter/exit the axon - Speeds up nerve transmission

Question 36

What is a node of Ranvier and why is it necessary

Answer 36

Gaps in between Schwann cells on the axon. Necessary because there would be no current and action potentials would only occur because of such nodes.

Question 37

What is grey matter and white matter

Answer 37

White matter: nervous tissue that consist of myelinated axons (insulated by myelin sheath) Grey matter: contains cell bodies, unmyelinated axons, axon terminals.

Question 38

Know the structural classification of neurons (multipolar, bipolar and unipolar), which is most common, which is found only in some of the special sense organs –the eye, which is composed of a peripheral process and a central process and compose the cell type found in the PNS ganglia

Answer 38

1) Multipolar: very common. All motor and association neurons are this type. Found in CNS. 2) Bipolar: rare. Found only in some special receptor organs (the eye) 3) Unipolar: composed of a peripheral process and a central process and compose the cell types found in PNS ganglia

Question 39

Know the functional classification of neurons, which has cell bodies located in the sensory ganglia outside the CNS, which make up over 99% of the neurons of the body and which has a cell body in the CNS

Answer 39

1) Sensory neurons (sensory ganglia) 2) Interneurons: makes up 99% of neurons 3) Motor neurons: cell body in CNS