Psychobiology part 2 unit 3

Question 1

What is the primary function of the spinal cord?

Answer 1

The spinal cord serves as the primary communication pathway between the brain and the body, transmitting sensory and motor information. It also controls reflex actions independently of the brain.

Question 2

How many pairs of spinal nerves are there, and what is their role?

Answer 2

There are 31 pairs of spinal nerves, each corresponding to a segment of the spinal cord. These nerves are responsible for transmitting sensory information to the spinal cord and motor commands from the spinal cord to muscles.

Question 3

What is the difference between sensory and motor nerves in the spinal cord?

Answer 3

Sensory Nerves: Carry sensory information from the body to the spinal cord through the dorsal roots.
Motor Nerves: Carry motor commands from the spinal cord to muscles through the ventral roots.

Question 4

What is the difference between grey matter and white matter in the spinal cord?

Answer 4

Grey Matter: Composed of neuronal cell bodies and dendrites, located centrally in the spinal cord, responsible for processing information.
White Matter: Composed of myelinated axons that transmit signals between spinal cord segments and the brain.

Question 5

How is the spinal cord protected?

Answer 5

The spinal cord is protected by the spinal column (vertebrae), meninges (three layers of membranes), and cerebrospinal fluid (CSF), which cushions the cord.

Question 6

What are the cervical and lumbar enlargements of the spinal cord responsible for?

Answer 6

The cervical enlargement supplies the upper limbs, and the lumbar enlargement supplies the lower limbs.

Question 7

How are spinal nerves organized?

Answer 7

Each spinal nerve consists of a dorsal root (sensory nerves) and a ventral root (motor nerves), which join together to form a mixed spinal nerve that carries both sensory and motor information.

Question 8

What happens if the spinal cord is damaged at a specific segment?

Answer 8

Damage to a segment of the spinal cord can result in the loss of sensation and motor control from that segment and all regions below it.

Question 9

Whats the main pathway of
communication between the brain and the head?

Answer 9

Through cranial
nerves

Question 10

What do the terms dorsal and ventral refer to in the context of the spinal cord?

Answer 10

Dorsal: Refers to the back side of the body or spinal cord. The dorsal root of the spinal cord carries sensory information from the body to the spinal cord.

Ventral: Refers to the front or belly side of the body. The ventral root of the spinal cord carries motor information from the spinal cord to the muscles, enabling movement.

Question 11

What are ascending and descending pathways in the spinal cord?

Answer 11

Ascending Pathways: These pathways carry sensory information from the body to the brain. They transmit signals such as touch, pain, and temperature from the spinal cord to the brain for processing.

Descending Pathways: These pathways carry motor information from the brain to the spinal cord. They transmit signals that control voluntary movement from the brain to muscles in the body.

Question 12

What is the spinal column, and how does it protect the spinal cord?

Answer 12

The spinal column is a series of bones (vertebrae) stacked on top of each other. It protects the spinal cord, which runs through the center of these bones. The column is made up of:

Cervical vertebrae (neck)

Thoracic vertebrae (upper back)

Lumbar vertebrae (lower back)

At the bottom, the sacral and coccygeal vertebrae are fused together. The spinal cord passes through an opening in the middle of each vertebra called the spinal foramen.

Question 13

What are dorsal root ganglia?

Answer 13

Dorsal root ganglia are clusters of sensory nerve cell bodies located outside the spinal cord. They collect sensory information from the body and send it to the spinal cord.

Question 14

What is a dermatome in relation to the spinal cord?

Answer 14

A dermatome is a specific area of the body that is innervated by a single spinal nerve. Sensory information from each dermatome is carried back to the spinal cord via the corresponding spinal nerve.

Question 15

How do dermatomes overlap, and what does this mean for spinal nerve damage?

Answer 15

Dermatome divisions overlap slightly, so if one spinal nerve is damaged, sensation in the corresponding area of the body may not be completely lost, as neighboring dermatomes can still provide sensory input.

Question 16

What is the central canal in the spinal cord?

Answer 16

The central canal is a small, fluid-filled channel that runs through the center of the spinal cord. It is filled with cerebrospinal fluid (CSF) and helps cushion and protect the spinal cord.

Question 17

What are the four protrusions of the spinal cord?

Answer 17

The spinal cord has four protrusions where the grey matter expands into the horns of the spinal cord:

Dorsal Horn: Processes sensory information.
Ventral Horn: Contains motor neurons that send signals to muscles.
Lateral Horn: Found in thoracic and lumbar regions, involved in autonomic functions.
Central Canal: Contains cerebrospinal fluid and runs through the center of the spinal cord.

Question 18

What are Rexed’s laminae in the spinal cord, and how are they organized?

Answer 18

Rexed’s laminae are layers of cells in the dorsal and ventral horns of the spinal cord. They are numbered from I to X, running from dorsal to ventral, and are used to classify the organization of cell bodies based on their function and properties.

Question 19

What types of sensory information are processed in the dorsal horn of the spinal cord?

Answer 19

In the dorsal horn, the most dorsal laminae process somatosensory information (e.g., sensations from skin, joints, and muscles), while more ventral laminae process visceral sensory information (e.g., sensory signals from internal organs).

Question 20

What is the function of Lamina VII in the spinal cord?

Answer 20

Lamina VII spans both the dorsal and ventral horns of the spinal cord. The more dorsal and lateral portion contains preganglionic sympathetic neurons that project from the lateral horn in the middle segments of the spinal cord, while at sacral segments, it contains preganglionic parasympathetic neurons.

Question 21

What role does the ventral horn play in movement, and what happens in motor neuron disease?

Answer 21

The ventral horn contains motor neurons that control voluntary movement. These motor neurons are affected in motor neuron disease, which leads to muscle weakness, reduced muscle control, and muscle wasting.

Question 22

How is spinal cord white matter organized?

Answer 22

White matter in the spinal cord is organized into dorsal, lateral, and ventral columns, with axons grouped into ascending (sensory) and descending (motor) tracts that communicate between the spinal cord and other parts of the CNS.

Question 23

What do ascending tracts in the spinal cord carry, and how are they organized?

Answer 23

Ascending tracts carry different types of somatosensory information to the brain. For example, the spinothalamic tract carries pain, temperature, and touch information, while the fasciculus gracilis and fasciculus cuneatus carry proprioception and fine touch information.

Question 24

Does all ascending information reach consciousness?

Answer 24

No, some ascending information reaches consciousness (e.g., when it reaches the cerebral cortex), while other information does not (e.g., when it goes to the cerebellum).

Question 25

What are the spinothalamic tract, fasciculus gracilis, and fasciculus cuneatus?

Answer 25

Spinothalamic Tract: Carries pain, temperature, coarse touch, and pressure information from the body to the brain.

Fasciculus Gracilis: Located in the dorsal column, it carries information about proprioception (body position) and fine touch from the lower body.

Fasciculus Cuneatus: Also part of the dorsal column, it carries similar information about proprioception and fine touch, but from the upper body.

Question 26

What do descending white matter tracts control?

Answer 26

Descending white matter tracts originate in the cerebral cortex and brainstem, controlling movement, muscle tone, spinal reflexes, autonomic functions, and modulating sensory signals to the brain.

Question 27

How are the 2 descending tracts categorized in the spinal cord?

Answer 27

Lateral Column Tracts (e.g., lateral corticospinal, rubrospinal): Control voluntary limb movements.

Ventromedial Column Tracts (e.g., ventral corticospinal, tectospinal, vestibulospinal, reticulospinal): Control automatic movements, reflexes, and unconscious coordination for posture and balance.

Question 28

What is a reflex, and how does it work?

Answer 28

A reflex is an automatic, involuntary response to a stimulus. It occurs through the spinal cord without the need for conscious thought, involving a simple pathway known as the reflex arc.

Question 29

What are the main components of a reflex arc?

Answer 29

A reflex arc includes:

Sensory receptor (detects stimulus)
Afferent neuron (sends signal to spinal cord)
Interneuron (integrates information in the spinal cord)
Efferent neuron (carries motor command)
Effector organ (produces response, such as muscle contraction).

Question 30

What are the two main types of reflexes?

Answer 30

Monosynaptic Reflex: Involves only one synapse between the sensory and motor neuron (e.g., knee-jerk reflex).
Polysynaptic Reflex: Involves one or more interneurons between sensory and motor neurons (e.g., withdrawal reflex).

Question 31

What is the role of interneurons in reflexes?

Answer 31

Interneurons relay signals between sensory and motor neurons, particularly in polysynaptic reflexes, helping coordinate more complex reflex actions like withdrawal from pain.

Question 32

How does the withdrawal reflex work?

Answer 32

The withdrawal reflex is a polysynaptic reflex that occurs when a painful stimulus (e.g., touching something hot) triggers a rapid withdrawal of the affected body part, usually involving a reciprocal inhibition to relax the opposite muscle group.

Question 33

What are the main functions of the brainstem?

Answer 33

The brainstem controls basic life functions, such as breathing, heart rate, and sleep. It also acts as a relay center for sensory and motor pathways between the brain and spinal cord.

Question 34

What are the three main parts of the brainstem?

Answer 34

The brainstem consists of the midbrain, pons, and medulla oblongata, each playing a role in sensory processing, motor control, and autonomic functions.

Question 35

What is the role of the medulla oblongata in the brainstem?

Answer 35

The medulla oblongata regulates vital functions like heart rate, blood pressure, and respiration. It also controls reflexes such as swallowing and vomiting.

Question 36

What does the pons do in the brainstem?

Answer 36

The pons is involved in regulating sleep, respiration, and facial movements, and it connects the upper and lower parts of the brain.

Question 37

What is the function of the midbrain?

Answer 37

The midbrain plays a key role in vision, hearing, motor control, and regulating sleep/wake cycles. It connects the forebrain and hindbrain and is involved in processing auditory and visual information.

Question 38

What is the reticular formation and what role does it play?

Answer 38

The reticular formation is a network of neurons in the brainstem responsible for regulating arousal, alertness, and sleep. It acts as a filter, controlling the flow of sensory information to the cortex.

Question 39

What is the periaqueductal grey matter and its role in the brain?

Answer 39

The periaqueductal grey matter (PAG) surrounds the cerebral aqueduct and is crucial for pain modulation and defensive behavior. It plays a role in the body’s response to stress and pain, including the activation of the “fight or flight” response.

Question 40

What function does the substantia nigra serve in the brain?

Answer 40

The substantia nigra is involved in movement control and is a major part of the dopamine system. It is essential for voluntary motor coordination and is implicated in diseases like Parkinson’s due to its role in dopamine production.

Question 41

What are the key structures found in the midbrain?

Answer 41

The midbrain contains the superior colliculus (involved in visual processing) and the inferior colliculus (involved in auditory processing), both of which play roles in integrating sensory information and coordinating movement.

Question 42

What behavioral responses does the periaqueductal grey matter (PAG) influence?

Answer 42

The PAG is involved in the fight or flight response, defensive behaviors, and pain relief. It activates motor pathways to coordinate responses to stress, including freezing or fleeing from threats.

Question 43

What is the role of dopamine produced by the substantia nigra?

Answer 43

What is the role of dopamine produced by the substantia nigra?
A: Dopamine produced by the substantia nigra is critical for voluntary movement control, influencing motor coordination and the ability to perform smooth, purposeful movements.

Question 44

How does damage to the substantia nigra affect movement?

Answer 44

Damage to the substantia nigra, as seen in Parkinson’s disease, leads to a dopamine deficiency, resulting in symptoms such as tremors, rigidity, and difficulty initiating movements.

Question 45

What is the relationship between the midbrain and the brainstem?

Answer 45

The midbrain is a part of the brainstem, serving as the connection between the hindbrain and forebrain and playing an essential role in motor coordination, sensory processing, and regulating autonomic functions.

Question 46

How does the substantia nigra contribute to motor control in coordination with the basal ganglia?

Answer 46

The substantia nigra releases dopamine to the basal ganglia, which helps coordinate smooth, controlled voluntary movements. Disruption in this system, such as in Parkinson’s disease, impairs movement initiation and control.

Question 47

How many cranial nerves are there, and where do they originate?

Answer 47

There are 12 cranial nerves, and they originate from the brainstem, except for the olfactory and optic nerves, which are connected to the forebrain.

Question 48

What are the general functions of cranial nerves?

Answer 48

Cranial nerves are responsible for sensory functions (e.g., vision, hearing, taste) and motor functions (e.g., eye movement, facial expressions, swallowing). Some cranial nerves also regulate autonomic functions, like heart rate and digestion.

Question 49

What is the function of cranial nerve I (Olfactory nerve)?

Answer 49

The olfactory nerve (CN I) is responsible for the sense of smell. It transmits sensory information from the nasal cavity to the brain.

Question 50

What is the function of cranial nerve II (Optic nerve)?

Answer 50

The optic nerve (CN II) transmits visual information from the retina to the brain. It is crucial for vision.

Question 51

What is the role of cranial nerve III (Oculomotor nerve)?

Answer 51

The oculomotor nerve (CN III) controls most eye movements, pupil constriction, and eyelid elevation. It is essential for motor control of the eye muscles.

Question 52

What does cranial nerve IV (Trochlear nerve) control?

Answer 52

The trochlear nerve (CN IV) controls the superior oblique muscle of the eye, which allows for downward and inward eye movements.

Question 53

What is the function of cranial nerve V (Trigeminal nerve)?

Answer 53

The trigeminal nerve (CN V) has sensory and motor functions:

Sensory: Provides sensation to the face, including touch, temperature, and pain.

Motor: Controls muscles of mastication (chewing).

Question 54

What is the role of cranial nerve VI (Abducens nerve)?

Answer 54

The abducens nerve (CN VI) controls the lateral rectus muscle, allowing the eye to move laterally (away from the nose).

Question 55

What is the main function of cranial nerve VII (Facial nerve)?

Answer 55

What is the main function of cranial nerve VII (Facial nerve)?
A: The facial nerve (CN VII):

Motor: Controls facial expressions.

Sensory: Provides taste sensation to the anterior two-thirds of the tongue.

Autonomic: Controls tear production (lacrimal glands) and saliva secretion (salivary glands).

Question 56

What does cranial nerve VIII (Vestibulocochlear nerve) do?

Answer 56

The vestibulocochlear nerve (CN VIII) is responsible for hearing (via the cochlear branch) and balance (via the vestibular branch), transmitting auditory and equilibrium information.

Question 57

What is the function of cranial nerve IX (Glossopharyngeal nerve)?

Answer 57

The glossopharyngeal nerve (CN IX):

Sensory: Provides taste sensation to the posterior one-third of the tongue and sensation to the pharynx.

Motor: Involved in swallowing and saliva secretion from the parotid gland.

Autonomic: Helps regulate blood pressure and respiration through baroreceptors and chemoreceptors.

Question 58

What is the role of cranial nerve X (Vagus nerve)?

Answer 58

The vagus nerve (CN X) is involved in autonomic functions like heart rate, digestion, and respiratory rate. It also provides motor control of the larynx and pharynx and helps with swallowing and speech.

Question 59

What does cranial nerve XI (Accessory nerve) control?

Answer 59

The accessory nerve (CN XI) controls the sternocleidomastoid and trapezius muscles, allowing for head movement and shoulder elevation.

Question 60

What is the function of cranial nerve XII (Hypoglossal nerve)?

Answer 60

The hypoglossal nerve (CN XII) controls the muscles of the tongue, allowing for movement required for speech, swallowing, and food manipulation.