Lesson 5: The Nervous System

Question 1

Two Principal Divisions

Answer 1

• CNS (Central Nervous System)

- PNS (Peripheral Nervous System)

Question 2

Central Nervous System

Answer 2

• Composed of the brain and spinal cord

- Most decidedly “central” in the body

Question 3

Peripheral Nervous System

Answer 3

• Consists of nerves that “reach out” into the periphery of the body
• Has a subdivision and it plays a critical part in keeping us alive

Question 4

Autonomic Nervous System (ANS)

Answer 4

• What keeps our heart beating, our digestive system digesting, and our glands secreting

Question 5

Nervous System

Answer 5

• Is composed of nervous tissue made up of two different kinds of cells: neurons and glia

Question 6

Neurons

Answer 6

• Are nerve cells that consist of three different parts

- Main part is the cell body which has projections that extend from the cell body called dendrites

Question 7

Glia or Neuroglia

Answer 7

• Are cells that support neurons in some way
• Neurons do the communication work of the nervous system but they aren’t able to function without support from other cells
• Have an overall coordinating function
• These cells also provide physical and immune supports
• Glia are found in both the CNS and PNS

Question 8

Dendrites

Answer 8

• These transmit nerve pulses toward the cell body

Question 9

Axon

Answer 9

• Are longer projections that transmits nerve impulses away from the cell body
• Are wrapped in an insulating, fatty layer called myelin
• A bundle of axons is what we refer to as nerves in the PNS

Question 10

Types of Neurons

Answer 10

• First type of neuron transmits nerve impulses to the brain and spinal cord from all around the body called sensory neurons or afferent neurons. These are the nerves that allow us to sense what is happening in our environment
• Second type are nerves that transmit nerve impulses away from the brain and spinal cord are called motor neurons or efferent neurons. These are the nerves that allow us to give instructions to muscle and glandular tissue
• Third type of neuron connects other types of neurons, transmitting nerve impulses from on to another which are called Interneurons that connect sensory and motor neurons with each other to form networks of nerve fibres

Question 11

Sensory Neurons or Afferent Neurons

Answer 11

• Nerves that transmit nerve impulses to the brain and spinal cord
• These are the nerves that allow us to sense what is happening in our environment

Question 12

Motor Neurons or Efferent Neurons

Answer 12

• Nerves that transmit nerve impulses away from the brain and spinal cord
• These are the nerves that allow us to give instructions to muscle and glandular tissue

Question 13

Interneurons

Answer 13

• Connect sensory and motor neurons with each other to form networks of nerve fibres
• Connects other types of neurons, transmitting nerve impulses from one to another

Question 14

Glia found in the CNS

Answer 14

• Oligodendrocytes
• Astrocytes
• Microglia

Question 15

Oligodendrocytes

Answer 15

• Holds nerve fibres in the CNS together and are the source of the myelin sheaths that characterize nerve fibres of the brain and spinal cord
• Insulate nerve fibres in the myelin
• Myelin is important for long nerve fibres as the insulation it provides allows nerve impulses to travel faster over those longer distances
• Loss of Myelin in the CNS can lead to the development of myelin disorders, the most common of which is multiple sclerosis (MS)

Question 16

Astrocytes

Answer 16

• Type of glial cell attaches neurons to blood vessels and moderates the environment around neurons including the level of neurotransmitters available
• Offer physical and metabolic support and influence neural activity

Question 17

Microglia

Answer 17

• Type of CNS glial cell functions as the immune cells of the nervous system
• Act as the immune cells of the CNS
• They do this in the same way as macrophages and other phagocytic cells: they engulf and digest pathogens and damaged cells

Question 18

Glia of the PNS

Answer 18

• Schwann Cells

Question 19

Schwann Cells

Answer 19

• Provide myelin “insulation” for peripheral nerves

- These cells are the oliogodendrocyte- equivalents of the PNS, as they wrap axons in myelin

Question 20

Brainstem

Answer 20

• Connects the brain to the spinal cord, starting at the medulla oblongata, superior to the medulla oblongata is the pons which is inferior to the midbrain
• Passes information between the brain and the peripheral nervous system
• In charge of basic functions such as respiration, the heart rate and blood pressure, swallowing, bladder control, consciousness etc..

Question 21

Cerebellum

Answer 21

• Second largest structure in the brain and the most densely packed with neurons
• Plays a critical role in motor function specifically facilitating our coordinated movements such as is required for walking upright

Question 22

Diencephalon

Answer 22

• Anterior to the cerebellum, and superior to the brainstem
• It is subdivided into the pineal gland, the thalamus and the hypothalamus
• Structure has three divisions including one that excretes a hormone important for sleep

Question 23

Pineal Gland

Answer 23

• Plays a critical role in promoting sleep through it excretion of the hormone melatonin in response to variations in visual stimuli specifically cycles of light and dark

Question 24

Cerebrum

Answer 24

• Largest part of the brain and its the part of the brain that makes us, us
• The characteristic ridges (gyri) and grooves (sulci) of the cerebrum give it its characteristic appearance and allow a lot of brain to fit into a relatively small space

Question 25

Hypothalamus

Answer 25

• Structure within the diencephalon exerts control over all internal organs.
• Helps control the heartbeat, vasoconstriction and peristalsis

Question 26

Pons

Answer 26

• Midsection of the brainstem

- Structure influences respiration

Question 27

Melatonin

Answer 27

• Hormone regulates the body’s “clock” and promotes sleep

Question 28

Medulla Oblongata

Answer 28

• Most inferior part of the brainstem

- Structure is cardiac, respiratory and vasomotor control centre

Question 29

Midbrain

Answer 29

• Most superior portion of the brainstem

- Structure is important for the transmission of visual and auditory nerve impulses

Question 30

Pineal Gland

Answer 30

• Glandular structure secretes a hormone that regulates the body clock

Question 31

Thalamus

Answer 31

• Superior to the hypothalamus
• Structure relays sensory information, associates sensations with emotions, regulates consciousness and plays a role in motor reflexes

Question 32

Stroke

Answer 32

• Also called a cerebrovascular accident
• Involves damage to neurons due to a cessation of blood flow
• If the resultant oxygen deprivation lasts long enough, the effected neurons will die
• A stroke commonly results in loss of control of some voluntary motor functions

Question 33

Concussion

Answer 33

• Type of traumatic brain injury due to a shock or sudden deceleration of the brain wherein the brainstem bends and causes temporary changes to brain chemistry
• Can be characterized by headaches, difficulty with concentration, memory loss, disordered mood, sleep disruption, nausea, and light sensitivity

Question 34

Seizure Disorders

Answer 34

• These disorders involve temporary changes to brain function due to short periods of abnormal neuronal activity
• Range in severity from barely noticeable to violent and jerky muscle contractions that result in temporary loss of normal control of bodily movement and functions
• Epilepsy is a seizure disorder involving recurring or chronic seizures

Question 35

Cerebral Palsy

Answer 35

• Caused by maternal infection, head trauma experienced by an infant before, during or after their birth, exposure to toxins, or an oxygen deprived brain
• This disorder is called cerebral palsy, often involves spastic paralysis which is characterized by involuntary muscle movement

Question 36

Dementia

Answer 36

• This brain disorder is caused by the progressive degeneration of neurons and the connections between them
• It effects memory, attention span, and intellectual ability
• It can cause changes to personality and progressive loss of motor function
• Alzheimer’s Disease is a common form of dementia associated with old age
• Huntington’s Disease starts as problems with motor function before middle age, and progresses to severe dementia and early mortality
• Chronic Traumatic Encephalopathy which involves loss of motor function similar in Parkinson’s disease, along with reduced cognitive function as seen in other forms of dementia. Those suffering from repeated traumatic brain injury such as in contact sports or those who suffer from physical abuse.

Question 37

Autonomic Nervous System

Answer 37

• Has an impact on cardiac muscle, smooth muscle, and glandular tissue
• The aim is to make adjustments to the human body’s involuntary and automatic functions to allow it to respond to environmental changes and to maintain homeostasis
• ” Fight or flight” response
• It is divided into the sympathetic division and the parasympathetic division each having an opposition to the other

Question 38

Specific Health Concerns Related to Chronic Stress

Answer 38

• Heart disease including hypertension
• Digestive Issues including colitis and ulcers
• Stress hormones reduce immune response, prolonged and repeated stress- related episodes leave those so affected at greater risk for infectious diseases and chronically- elevated levels of norepinephrine can speed the spread of cancer