Lecture 7 - Brain Anatomy

Question 1

What are the two main parts of the nervous system?

Answer 1

The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Question 2

What does the Central Nervous System (CNS) include?

Answer 2

Everything in the brain and spinal cord.

Question 3

What is the role of the Peripheral Nervous System (PNS)?

Answer 3

The purpose of the Peripheral Nervous System (PNS) is to relay sensory information from the body to the central nervous system (CNS) and to carry motor commands from the CNS to the muscles and glands, enabling coordination and response to the environment.

It includes any part of the nervous system outside of the brain and spinal cord.

Question 4

What cells create myelin in the CNS?

Answer 4

Oligodendrocytes.

Question 5

What cells create myelin in the PNS?

Answer 5

Schwann cells.

Question 6

What does the blood-brain barrier do?

Answer 6

It prevents certain substances in the bloodstream from entering the brain and spinal cord.

Question 7

What are small holes in blood vessels responsible for?

Answer 7

They allow the liquid part of blood (blood plasma) to leak out, forming extracellular fluid (also called interstitial fluid).

Selective permeability is important for ensuring that cells receive the necessary substances to function properly while removing waste products, ultimately maintaining overall health and homeostasis in the body.

Question 8

What is the role of extracellular fluid in the body?

Answer 8

It flows around cells, providing nutrients and collecting waste.

Question 9

How does the blood-brain barrier affect capillary walls in the brain?

Answer 9

The capillary walls in the brain are tightly joined, unlike those in the body which have gaps.

Question 10

What is extracellular fluid, and where does it come from?

Answer 10

It is the liquid part of blood (blood plasma) that leaks out of small holes in blood vessels, providing nutrients and collecting waste.

Question 11

What fluid does the brain create instead of allowing blood plasma to leak?

Answer 11

Cerebrospinal fluid (CSF).

Question 12

What is cerebrospinal fluid made of and what is it for?

Answer 12

Cerebrospinal fluid (CSF) is made from blood plasma, specifically by selectively extracting necessary substances from the blood. It serves to protect the brain and spinal cord, provides nutrients, removes waste, and maintains homeostasis within the central nervous system.

Question 13

What are projection neurons?

Answer 13

Projection neurons are neurons with long axons that connect and communicate with distant regions of the brain, facilitating coordination between different brain areas.

Question 14

What are interneurons?

Answer 14

Interneurons are a type of neuron that connects with and sends signals to other nearby neurons, instead of sending signals over long distances. They have short axons and play a crucial role in processing information within a specific area of the nervous system, helping coordinate responses and reflexes.

Question 15

What are efferent fibers?

Answer 15

Outputs/axons that bring information away from the CNS, typically associated with motor neurons.

Question 16

What are afferent fibers?

Answer 16

Inputs/axons that bring information toward the CNS, typically associated with sensory neurons.

Question 17

How many pairs of spinal nerves do humans have?

Answer 17

31 pairs.

Question 18

How many pairs of cranial nerves are there?

Answer 18

12 pairs.

Question 19

What is the principal function of the spinal cord?

Answer 19

To bring sensory information to the brain and to send motor fibers to effector organs.

Question 20

What does the term “neuroaxis” refer to?

Answer 20

The imaginary line that runs along the length of the CNS.

Question 21

What are the two divisions of the Peripheral Nervous System (PNS)?

Answer 21

Somatic and autonomic nervous systems.

Question 22

What does the somatic nervous system (SNS) do?

Answer 22

It interacts with the external environment, controlling skeletal muscles and processing sensory information.

Question 23

What is the role of the autonomic nervous system (ANS)?

Answer 23

It regulates the body’s internal environment, controlling smooth muscle, cardiac muscle, and glands.

Question 24

What are the two parts of the autonomic nervous system?

Answer 24

Sympathetic and parasympathetic divisions.

Question 25

What is the function of the sympathetic division of the ANS?

Answer 25

It primes the body for action, especially in life-threatening situations.

Question 26

What is the role of the hypothalamus?

Answer 26

It regulates autonomic nervous system activity and behaviors related to survival (feeding, fighting, fleeing, mating).

Question 27

What is the function of the limbic system?

Answer 27

It regulates emotions and the formation of episodic memories

Question 28

What is the lymphatic system?

Answer 28

A part of the immune system that collects extracellular fluid into lymph vessels, which carry it to lymph nodes and organs to detect and destroy foreign particles.

Question 29

Describe the cycle involving blood, extracellular fluid, lymph, and back to blood.

Answer 29

Blood → Extracellular fluid → Lymph → Blood

Blood: The process starts with blood moving around the body through blood vessels. Blood carries important things like oxygen and nutrients to all the cells.

Extracellular Fluid: As blood travels through tiny vessels called capillaries, some of the liquid in the blood (called blood plasma) seeps out through small openings in the vessel walls. This liquid forms a fluid that surrounds the cells, known as extracellular fluid (or interstitial fluid). This fluid helps provide nutrients and oxygen to the cells and collects waste that the cells produce.

Lymph: Any extra fluid that doesn’t get used by the cells, along with waste, is picked up by tiny vessels called lymphatic capillaries. This collected fluid is called lymph. The lymphatic system helps keep the body balanced and also works as part of the immune system to fight off germs.

Return to Blood: The lymph eventually flows back into the bloodstream, specifically into the veins. This allows the nutrients and other substances gathered from the extracellular fluid to go back into the blood, finishing the cycle.

This cycle ensures that cells receive the nutrients they need while removing waste products, maintaining homeostasis in the body.

Question 30

Why doesn’t the CNS participate in the lymphatic system?

Answer 30

There are no holes in the blood vessels that pass through the brain and spinal cord, which is known as the blood-brain barrier.

Question 31

What happens to blood plasma in the circulatory system of the brain?

Answer 31

Instead of leaking directly into the brain, blood plasma is processed by the brain to create cerebrospinal fluid.

Question 32

How does extracellular fluid contribute to nutrient delivery and waste collection?

Answer 32

It flows around cells, delivering nutrients and gathering waste products for removal.

Question 33

What are the main components of the lymphatic system?

Answer 33

Lymph vessels, lymph nodes, and lymph organs.

Question 34

What is the significance of the blood-brain barrier?

Answer 34

It protects the brain by preventing free passage of substances, maintaining a controlled environment for the CNS.