nervous system

Question 1

What is the role of the nervous system?

Answer 1

It senses changes in the environment and coordinates an appropriate response.

Question 2

How does the nervous system work with the endocrine system?

Answer 2

Together, they regulate our physiology and allow us to take action.

Question 3

What are the main components of the nervous system?

Answer 3

The nervous system includes:

Central Nervous System (CNS): Composed of the brain and spinal cord.

Question 4

What is the Peripheral Nervous System (PNS)?

Answer 4

It connects the CNS to the rest of the body and transmits signals between them.

Question 5

What are the main functions of the brain?

Answer 5

The brain learns, retains memories, maintains balance, interprets sensory information, and decides on body responses.

Question 6

How many neurons does the brain have, and how do they interact?

Answer 6

The brain contains about 100 billion neurons, and each neuron communicates with thousands of other neurons.

Question 7

What are the main functions of the spinal cord?

Answer 7

The spinal cord coordinates involuntary reflexes and serves as the main connection between the Peripheral Nervous System (PNS) and the brain.

Question 8

What is the Afferent System in the PNS?

Answer 8

The Afferent System receives sensory data from receptors and transmits it to the Central Nervous System (CNS) for processing.

Question 9

What is the Efferent System in the PNS?

Answer 9

The Efferent System receives messages from the CNS and transmits them to effector cells to take action.

Question 10

What is the role of receptors in sensory organs?

Answer 10

Receptors detect changes in the environment, with different receptors specialized to detect different stimuli.

Question 11

What are the two main divisions of the autonomic nervous system?

Answer 11

The sympathetic division (fight or flight) and the parasympathetic division (rest and digest).

Question 12

What is the difference between the somatic system and the autonomic system?

Answer 12

The somatic system controls voluntary actions, while the autonomic system controls involuntary actions

Question 13

What are the two main subsystems of the PNS?

Answer 13

The Afferent System (sensory) and the Efferent System (motor).

Question 14

What are glial cells and their functions?

Answer 14

Glial cells are non-conducting cells in the nervous system that provide structural support, protect neurons, form myelin, and digest dead cells.

Question 15

What are nerve cells (neurons) and their function?

Answer 15

Nerve cells (neurons) are conducting cells of the nervous system that send messages in the form of electrical signals throughout the body.

Question 16

What are dendrites and their function?

Answer 16

Dendrites are highly branched extensions of a neuron that receive signals from other neurons.

Question 17

What is an axon and its function?

Answer 17

The axon is a long extension from the cell body that transmits signals to synapses at the axon terminal, where the message is spread to other cells. It may have a myelin sheath.

Question 18

What is a sensory neuron (afferent neuron) and its function?

Answer 18

A sensory neuron “senses” information from the environment and relays it to the central nervous system. Its dendrites do not branch from the cell body.

Question 19

What is a motor neuron (efferent neuron) and its function?

Answer 19

A motor neuron relays information from the central nervous system to effectors, such as muscles, organs, or glands.

Question 20

What are interneurons and their function?

Answer 20

Interneurons connect sensory neurons to motor neurons and perform complex functions such as decision making and “thinking”.

Question 21

What are oligodendrocytes and Schwann cells and their function?

Answer 21

Oligodendrocytes (in the CNS) and Schwann cells (in the PNS) are glial cells that form myelin sheaths around the axons of many vertebrate neurons.

Question 22

What is the myelin sheath and its function?

Answer 22

The myelin sheath, composed of fat-containing cells, surrounds the axon, insulating it and speeding up the transmission of signals.

Question 23

What are some symptoms of Multiple Sclerosis (MS)?

Answer 23

Symptoms of MS may include double or blurred vision, fatigue, loss of balance and coordination, speech, bladder, bowel, and short-term memory problems, and partial or complete paralysis.

Question 24

What is the function of an astrocyte?

Answer 24

Astrocytes provide structural and metabolic support for neurons, regulate extracellular concentrations of ions and neurotransmitters, and help sweep up debris.

Question 25

What is a reflex arc?

Answer 25

A reflex arc is the neural pathway that controls a reflex, where the reaction is controlled by the spinal cord before the brain receives the message.

Question 26

What is a characteristic of reflexes?

Answer 26

Reflexes are very fast and occur without conscious thought.

Question 27

How do muscles work in opposing pairs during a reflex?

Answer 27

In opposing muscle pairs, one signal relaxes the triceps (inhibitory signal) while another signal flexes the biceps (excitatory signal).

Question 28

What is the resting potential of a neuron?

Answer 28

The resting potential is -70mV, meaning the inside of the neuron is more negative compared to the outside.

Question 29

What happens when a neuron is at rest?

Answer 29

In a resting neuron, the plasma membrane maintains a resting potential with more positive ions outside and negative ions inside.

Question 30

How is the nervous system similar to an electrical circuit?

Answer 30

The nervous system is like an electrical circuit because sending signals requires charged particles (ions), similar to how electric currents work.

Question 31

What is the resting potential in neurons dependent on?

Answer 31

The resting potential depends on the ionic gradient across the membrane, with high [Na+] outside the cell and high [K+] inside the cell, along with other anions (A-) that cannot pass through.

Question 32

How do sodium-potassium pumps maintain the resting potential of a neuron?

Answer 32

Sodium-potassium pumps use 1 ATP to pump 3 Na+ ions out of the neuron and 2 K+ ions into the neuron, maintaining the resting potential.

Question 33

What is the result of the sodium-potassium pump’s action on the neuron’s charge?

Answer 33

The result is a negative charge inside the neuron and a positive charge outside, creating a resting potential.

Question 34

What happens during an action potential in a neuron?

Answer 34

During an action potential, positive charges (Na+) move inside the neuron, reversing the resting potential.

Question 35

Q: What is depolarization in a neuron?

Answer 35

A: Depolarization is the raising of the membrane potential, occurring when it reaches the threshold potential of about -55mV from the resting -70mV.

Question 36

What happens when Na+ channels open during an action potential?

Answer 36

When Na+ channels open, Na+ ions rush into the neuron, causing the membrane potential to rapidly become more positive.

Question 37

What happens during repolarization of a neuron?

Answer 37

During repolarization, when the neuron’s potential reaches +30mV, sodium channels close, and potassium channels open, allowing K+ ions to exit, restoring the negative membrane potential.

Question 38

What happens to the membrane potential during repolarization?

Answer 38

The membrane potential lowers as K+ ions diffuse out of the neuron, restoring the negative charge inside the cell.

Question 39

What happens after repolarization in the neuron?

Answer 39

Na+/K+ pumps restore the resting potential while potassium channels slowly close, causing the membrane to become briefly hyperpolarized.

Question 40

What causes the neuron membrane to become briefly hyperpolarized after an action potential?

Answer 40

The slow closure of potassium channels after repolarization causes the membrane to become briefly hyperpolarized. Na+/K+ pumps then restore the resting potential.

Question 41

What is the refractory period in neuron activity?

Answer 41

The refractory period is the time after an action potential when the neuron’s threshold for generating another action potential is much higher until it reaches its resting potential again.

Question 42

What is meant by the “all or nothing” response of an action potential?

Answer 42

The action potential is an all or nothing response to a stimulus. If the threshold potential is not reached, no action potential occurs. There are no weaker or partial impulses.

Question 43

How does an action potential travel down the axon?

Answer 43

The impulse travels down the axon as each section of the membrane that reaches its action potential depolarizes sections of the membrane downstream from it.

Question 44

Where is the action potential generated in a neuron?

Answer 44

The action potential is generated at the axon hillock, where an electrical current depolarizes the neighboring region of the axon membrane.

Question 45

How does the speed of an action potential increase in vertebrates?

Answer 45

The speed of an action potential increases with the diameter of the axon and the presence of myelination. The myelin sheath insulates the axon, and the Nodes of Ranvier, which are gaps in the myelin, allow for ion exchange that speeds up the action potential.

Question 46

What is the synaptic cleft?

Answer 46

The synaptic cleft is a small gap between the axon terminal of the presynaptic neuron and the dendrite of the postsynaptic neuron where neurotransmitters are released.

Question 47

What triggers the release of neurotransmitters from synaptic vesicles?

Answer 47

The nerve impulse triggers the release of neurotransmitters from the synaptic vesicles. The average neuron has 1,000 synapses with other neurons.

Question 48

What is the process of neurotransmitter release and reception at a synapse?
A:

I

Answer 48

1. impulse from action potential opens ion channels for Ca²⁺.
2. Increased Ca²⁺ concentration in the axon terminal triggers the release of neurotransmitters (NT).
3. NT crosses the synaptic cleft and attaches to a protein receptor on the dendrite.
4. Interaction of NT and receptor opens ion channels for Na⁺ in the postsynaptic membrane.

5.After transmission, NT is either degraded by an enzyme or taken back into the presynaptic membrane by a transporter or reuptake pump.

Question 49

How do neurotransmitters like acetylcholine affect target cells?

Answer 49

Acetylcholine has different effects depending on the type of receptor:
- Excitatory response on skeletal muscle

-Inhibitory response on cardiac muscle

Question 50

How do different neurotransmitters affect skeletal muscle?

Answer 50

• Acetylcholine has excitatory effects on skeletal muscle.
• Noradrenaline has inhibitory effects on skeletal muscle.