Lecture 1

Question 1

Central nervous system (CNS):
Consists of

Answer 1

brain and spinal cord

Question 2

Peripheral nervous system (PNS):
Consists of

Answer 2

nerve fibers that carry information between the CNS and other parts of the body (the periphery)

Question 3

PNS is further subdivided into

Answer 3

Afferent and Efferent divisions

Question 4

Afferent division:

Answer 4

Carries information to the CNS
Two branches:
Sympathetic
Parasympathetic

Question 5

Efferent division

Answer 5

Carries information away from CNS to effector organs
muscles and glands that carry out orders to bring about the desired effect

Question 6

Efferent division is divided into

Answer 6

• somatic ns
• Autonomic ns

Question 7

Somatic nervous system:

Answer 7

Consists of fibers of motor neurons that supply skeletal muscles

Question 8

Autonomic nervous system:

Answer 8

Consists of fibers that innervate smooth muscle, cardiac muscle, and glands
Two divisions:
Sympathetic nervous system
Parasympathetic nervous system

Question 9

Nervous System Organization

Question 10

Classification based on function

Answer 10

• motor neurons
• sensory neurons
• interneurons

Question 11

Motor neurons:

Answer 11

transmit from CNS to muscle or gland

Question 12

Sensory neurons:

Answer 12

transmit from sensory receptor to CNS

Question 13

Interneurons

Answer 13

(99% of all neurons)
transmit within the CNS

Question 14

Functional Classes of Neurons

Answer 14

• Afferent neurons
• Efferent neurons
• Interneurons

Question 15

Afferent neurons:

Answer 15

• Inform CNS about conditions in both the external and internal environment
• At its peripheral ending, there is a Sensory Receptor that generates Action Potentials in response to stimulus (frequency and amplitude)

Question 16

Efferent neurons:

Answer 16

• Carry instructions from CNS to effector organs – muscles and glands
• Lie primarily in PNS

Question 17

Interneurons:

Answer 17

• Found entirely within CNS
• Lie between Afferent and Efferent neurons
• Responsible for:
  Integrating afferent information and formulating an efferent response
  Interconnections between interneurons are responsible for higher mental functions associated with the “mind”

Question 18

Functional Classes of Neurons

Question 19

Classification based on polarity

Question 20

Neurons-functional unit
- In CNS: 100 billion
neurons

Question 21

Neuroglia

Answer 21

(90% of the cells within the CNS)
- Also called glial cells
- Unlike neurons, they do not initiate or conduct nerve impulses
> Do communicate with neurons and among themselves via chemical
signals
- Serve as Connective Tissue of CNS:
Physically, metabolically, and functionally support interneurons

Question 22

4 major types of Neuroglia cells:

Answer 22

Astrocytes
Oligodendrocytes
Microglia
Ependymal cells

Question 23

Astrocytes

Answer 23

Named for starlike shape (astro = “star”)
Most abundant glial cells
Main “glue” of CNS – holds neurons together
Guide neurons during fetal brain development (migration)
Induce capillaries of brain to undergo changes that aid in establishment of blood-brain barrier
Important in repair of brain injuries and in neural scar formation
> Play role in neurotransmitter activity
Take up and degrade Glutamate and GABA
Take up excess K+ from brain ECF
> Helps maintain optimal ion conditions for neural excitability
Along with other glial cells – enhance synapse formation and modify synaptic transmission

Question 24

Question 25

Neuroglia

Answer 25

Oligodendrogytes
Form myelin sheaths around axons in CNS (Multiple sclerosis)

(in PNS - Schwann cells - mylenation)

Question 26

Microglia

Answer 26

Immune defense cells of the CNS
In resting state release low levels of growth factors that help neurons and other glial cells survive and thrive

Question 27

Ependymal cells

Answer 27

Line internal, fluid-filled cavities of the CNS
In ventricles of brain, help form and circulate cerebrospinal fluid

Question 28

Neuroglia
- 90% = supporting cells ( neuroglia)

Question 29

Question 30

Metabolic requirements

Answer 30

Specialized metabolism
Constant supply of oxygen and glucose required
20% of O2 and 50% of glucose consumed by brain
No metabolite storage
High demand for ATP and oxygen (oxidative phosphorylationmitochondria required)
Substrate: glucose (or in starvation ketonbodies)
hypoglycaemia: confusion, irritability, coma, death

Question 31

High demand for oxygen

Answer 31

• Brain receives about 15% of the total blood
• Irreversible brain damage after 4-5 min O2 supply disruption and 10-15 mins glucose supply disruption
• Exception: Temp and metabolism
  If cold, slows down metabolism, can deal with stress for longer

Question 32

Stroke

Answer 32

Most common cause of brain damage: cerebrovascular accident/stroke (either vessel occlusion or rupture)
Initial blood deprived cells die by necrosis (bursting of cell)
The viable neighbor cells undergo apoptosis (programmed cell death) due to a signalling cascade resulting in additional neurotoxicity:
Excessive glutamate releasebinds to NMDA receptorstoxic activation and Calcium influxROS/free radical productionapoptosis

Question 33

The brain has a degree of plasticity:

Answer 33

• ability to change/functionally remodeled in response to the demands
• especially in the first few years of development
• Regions of the cortex maintain
  plasticity throughout life
• Δexperience –> Δsynaptic connections

Question 34

Network and emergent properties

Answer 34

• Neurons –> form circuits –> creating infinite nr of possible pathways
• Signalling within these patways: enables complex behaviours such as thinking, learning, memory
• Combination of neurons possess emergent properties not found at single cell level

Question 35

Simple and complex nervous systems

Question 36

Embryology: neural plate and neural tube

Question 37

Question 38

Question 39

4-6-11 weeks development