T1 - human nervous system organization

Question 1

The brain (general)

Answer 1

Central control organ for all arbitrary and automatic action sequence.
Recording, integration and storage of all sensory information, control of behaviour and motor skills
Area of emotions, motivation, thoughts, planning, problem-solving, consciousness, memory and learning abilities
Unanswered questions about the fundamental organization and function of the human brain.

Question 2

The brain can be examined on different levels that span
6 orders of magnitude:

Answer 2

• Macroscopic (about 100 regions)
• Microscopic (about 1000 different types of neurons)
• cell body, processes, myelin
• Electron microscopic coping: synapses and vesicles
• Submicroscopic: channels and other proteins

Question 3

Autonomic Nervous System (ANS)

Answer 3

Controls involuntary bodily functions. Regulates processes that occur automatically, such as heart rate, digestion, breathing, and glandular activities. It’s responsible for maintaining homeostasis (balance in the body’s internal environment).

Question 4

You do not consciously decide to increase your heart rate or …

Answer 4

adjust digestion; the body regulates these functions automatically

Question 5

what does the autonomic nervous system control? (example)

Answer 5

Controls smooth muscles, cardiac muscles, and glands. These muscles are found in the walls of organs (e.g., stomach, intestines, blood vessels, heart).

Question 6

Somatic Nervous System (SNS)

Answer 6

Controls voluntary movements. It is responsible for the conscious control of skeletal muscles, allowing you to perform movements like walking, talking, or picking up objects.
You consciously decide to move your arm or walk
Controls skeletal muscles, which are involved in voluntary movements like running, lifting, or speaking

Question 7

SYMPATHETIC VS PARASYMPATHETIC

Answer 7

The sympathetic and parasympathetic systems are two branches of the autonomic nervous system (ANS), responsible for regulating involuntary bodily functions. Although both systems work together to maintain homeostasis, they often have opposite effects on the body.

Question 8

Sympathetic Nervous System (SNS) (general)

Answer 8

Prepares the body for “fight or flight” responses during stressful or dangerous situations. It activates processes that help you respond quickly, enhancing alertness and physical capability.

Question 9

Sympathetic Nervous System (SNS) (effects)

Answer 9

Increases heart rate and force of contraction to pump more blood.
Dilates pupils to enhance vision.
Inhibits digestion to divert energy to muscles.
Dilates bronchioles in the lungs to increase oxygen intake.
Stimulates the release of glucose from the liver for quick energy.
Inhibits saliva and tear production (dry mouth during stress).
Causes sweating to cool the body.

Question 10

Parasympathetic Nervous System (PNS) (general)

Answer 10

Promotes “rest and digest” activities. It helps the body relax and conserve energy, controlling functions needed for maintaining calm and internal balance when there’s no immediate danger.

Question 11

Parasympathetic Nervous System (PNS) (examples)

Answer 11

Decreases heart rate to conserve energy.
Constricts pupils for normal light levels.
Stimulates digestion by increasing gastric activity and enzyme release.
Constricts bronchioles to return breathing to normal.
Promotes glucose storage in the liver.
Stimulates saliva and tear production, aiding in digestion and comfort.
Inhibits sweating, promoting relaxation

Question 12

Gross division of the brain

Answer 12

Gross anatomy structures and organs of the body observed with the naked eye, without a microscope. It contrasts with microscopic anatomy, which involves the examination of tissues and cells at the microscopic level.

Question 13

Gross division of the brain (methods)

Answer 13

Dissections: The dissection of human cadavers or animal specimens.

Models and imaging: Studying anatomical models or medical imaging techniques like X-rays, MRIs, and CT scans. medicine, biology, and physical therapy, as it provides the understanding of the human body’s from and structure

Question 14

Gray & White Matter

Answer 14

Gray matter: dark regions, cell bodies and capillary blood
White matter: light regions, fibers with fatty covering
Reticular matter: both cellular bodies and fibers.

Question 15

Cerebellum (general)

Answer 15

Contains largest proportion of neurons.
Communicates with the brain through massive input and output nerve tracts (cerebellar peduncles)
Crucial for motor function: maintaining balance, walking, performing coordinated movements, eye movement, and motor learning
Also implicated in attention, language, learning and mental imagery.

Question 16

Cerebellum (function)

Answer 16

Coordination of Movement: voluntary movements are smooth, accurate, and coordinated by fine-tuning motor commands from the cerebral cortex.
Balance and Posture: Maintains posture by integrating sensory information from the inner ear and muscles, ensuring that the body stays balanced during movement.
Motor Learning: motor learning-> tasks that require practice and repetition (e.g., learning to ride a bike or play a musical instrument).

Question 17

Midbrain (mesencefalon) (general)

Answer 17

Crucial part of the brainstem that plays a role in motor movement, particularly eye movement, and in auditory and visual processing.
Contains cranial nerve ganglia and important structures including:

Superior colliculus: locating and orienting toward visual objects appearing in the periphery.
Inferior colliculus: locating and orienting toward auditory stimuli.

Question 18

Midbrain (mesencefalon) (function)

Answer 18

Vision and Eye Movement: The superior colliculi coordinate reflexive eye movements, such as tracking moving objects or adjusting the eyes in response to sudden visual stimuli.
Auditory Processing: The inferior colliculi are part of the auditory pathway, helping to localize sounds and initiate reflexive responses to auditory stimuli, like turning your head toward a sound.
Motor Control: The substantia nigra and red nucleus play key roles in controlling voluntary movements and motor coordination. The degeneration of neurons in the substantia nigra leads to motor disorders like Parkinson’s disease.
Pain Modulation: The periaqueductal gray (PAG) is involved in modulating pain and defensive behaviors. It influences the body’s response to pain through the release of endogenous opioids.
Arousal and Consciousness: The reticular formation in the midbrain contributes to regulating wakefulness, attention, and the sleep-wake cycle.

Question 19

Thalamus (general)

Answer 19

Small, egg-shaped structure located deep within the brain, near the centre of the brain just above the brainstem.
It sits on top of the midbrain and is part of the diencephalon, which also includes the hypothalamus and other related structures.
Acts as a relay and processing centre for sensory and motor information.
The thalamus plays a vital role in sensory perception, motor function, consciousness, sleep, and alertness.
Divided in two parts (LH and RH) and several nuclei
“Gateway to the cortex”: relays all primary sensory information (except for olfaction)
Lateral geniculate nucleus (vision)
Medial geniculate nucleus (audition)
Reorganization and shutting of information

Question 20

Thalamus (function)

Answer 20

A) Sensory Relay Station: brain’s sensory relay station, as it processes and transmits sensory information to the cerebral cortex.
- All sensory inputs (except smell), such as touch, pain, temperature, vision, hearing, and taste, first pass through the thalamus before reaching the appropriate areas of the cerebral cortex for further processing.
Example: Visual information from the eyes travels to the lateral geniculate nucleus of the thalamus before reaching the visual cortex in the occipital lobe.

B) Motor Control
- motor signals between the basal ganglia, cerebellum, and the motor cortex, helping to coordinate voluntary movement.
- It integrates motor information and plays a role in motor planning and execution.

C) Regulation of Consciousness and Alertness
- maintaining consciousness and alertness. It helps regulate the sleep-wake cycle by interacting with the reticular formation in the brainstem.
- During wakefulness, the thalamus facilitates communication between various brain regions, keeping the mind alert and focused.
- In sleep, the thalamus regulates the transmission of sensory signals, contributing to the transition between different sleep stages.

D) And many others

Question 21

Hippothalamus (general)

Answer 21

“Primitive structure”
Controls autonomic system and maintains homeostasis.
Main link between the nervous system and the endocrine system, hormone production and control.
Pituitary gland: releases hormones to control thirst, hunger, fatigue and circadian rhythms.
Lesions produce fatal disruptions.

Question 22

Hipotálamo (functions A & B)

Answer 22

A wide variety of autonomic and endocrine functions that are vital to maintaining the body’s internal balance:
A) Regulation of the Endocrine System
Controls the pituitary gland regulates hormone release from other endocrine glands (thyroid, adrenal, reproductive glands, etc.).
The hypothalamus secretes releasing hormones (e.g., CRH, TRH, GnRH) that stimulate the pituitary to release hormones It also produces oxytocin and vasopressin (antidiuretic hormone, ADH), which are stored and released by the posterior pituitary.

B) Temperature Regulation
body’s thermostat, detecting changes in body temperature and triggering responses to maintain it within a narrow range.
When body temperature rises: The hypothalamus initiates cooling mechanisms, such as sweating and vasodilation (widening of blood vessels).
When body temperature drops: It triggers heat-producing responses like shivering and vasoconstriction (narrowing of blood vessels).

Question 23

Hipotálamo (functions C-G)

Answer 23

Control of Hunger and Thirst
Circadian Rhythms and Sleep-Wake Cycle,E. Autonomic Nervous System Control
Emotional and Behavioral Regulation
Water and Electrolyte Balance
Sexual Behaviour and Reproduction

Question 24

Basal ganglia (general)

Answer 24

Collection of interconnected nuclei: caudate nucleus, putamen, globus pallidus, subthalamic nucleus and substantia nigra.
Striatum: caudate nucleus + putamen
Abundant in DA receptors
Involved in action selection, action gating, motor preparation, timing, fatigue, and task switching.
Damage results in failure to initiate voluntary movement.

Question 25

Diseases that affect the basal ganglia

Answer 25

Parkinsons disease (PD): degeneration of substantia nigra inputs to the striatum. Patients show impaired probabilistic learning (weather prediction task) but spared declarative memory about the task.

Huntington’s disease (HD): degeneration of the striatum. Patients show impaired procedural learning independent from severity of motor deficits.

Question 26

limbic system

Answer 26

It is widely used nebulous concept (different uses of the term, not all scholars employ it).

Question 27

hippocapus

Answer 27

It is a bilateral structure that has an important role in learning and memory.

Memory:
Episodic and autobiographic memory but not procedural memory
Damage can lead to amnesia (anterograde and/ or retrograde)

Spatial processing and navigation:
Place or grid cells: population of cells that form cognitive maps (representation of space)

Question 28

Amygdala

Answer 28

It is a bilateral structure that is also involved in memory, and it is important for emotional regulation.
Fear processing:
Involved in triggering fight-or-fight response.
May be overactive in anxiety disorders
Resection produces kluver-bucy syndrome: reduced level of aggression and fear expression.

Question 29

Cortex (gyri and sulci)

Question 30

Cortex (gyri and sulci)

Answer 30

The cerebral cortex contains many convolutions and infoldings which are called:
Gyri: bumps
Sulci: grooves
Fissure: larger or deeper sulci

Functions of folding:
Effective packing
Shorter distance between neurons (faster communication)
Shorter distance between regions.

Question 31

Cortex (Brodmann areas)

Answer 31

The German neuroanatomist korbinian Brodmann divided the cerebral cortex into about 52 areas based on its cytoarchitecture (cell structure).
The different Brodmann areas (BA) have been correlated to different functions.
For example, BA6 and BA4 are mainly involved with motor functions.

Question 32

Frontal lobe (prefrontal cortex)

Answer 32

Prefrontal cortex:

Regions:
Dorsolateral prefrontal cortex (DLPFC)
Ventrolateral prefrontal cortex (VLPFC)
Orbitofrontal cortex (OFC)
Medial prefrontal regions: anterior, cingulate cortex (ACC)

Executive functions: planning, organizing, and executing behaviour.

Question 33

Frontal lobe (motor cortex)

Answer 33

Regions:
Primary motor cortex (M1) (BA4)
Premotor cortex (BA6)
Supplementary motor area (SMA)

Action planning and execution

Question 34

Parietal lobe (somatosensory area)

Answer 34

Regions:

Primary somatosensory cortex (S1)
Somatotopic organization:
- Somatosensory processing is carried out mostly by primary somatosensory cortex (S1) I the parietal lobe.
- Using electrical stimulation in awake patients, Dr. Penfield determined which areas of S1 were most responsive to the parts of the body, creating a somatotopic map or homunculus (which has been perfected over the years).
- Body parts are scaled as a function of the surface cortex area dedicated to its processing, which in turn is linked to their importance.
Secondary somatosensory cortex (S2)

Integrates sensory information about touch, pain, temperature sense… from thalamic inputs.

Question 35

Occipital lobe

Answer 35

Visual processing areas:
Regions:
Striate cortex or visual area (V1) (BA17)
Extrastriate visual cortex (BA18 and BA19)

Cortical coding for visual features (luminance, spatial frequency, orientation motion…)

Question 36

Association areas

Answer 36

Neocortical regions that are neither the sensory nor the motor cortex.
Each sense has its association area.
Receives and integrates information from many cortical areas.
Involved in high mental processes including language processing, metal imagery or abstract reasoning.

Question 37

Spinal cord (general)

Answer 37

Cylindrical bundle of nerve fibers and associated tissues that extends from the brainstem down through the spinal column.
It serves as a critical part of the central nervous system (CNS), connecting the brain to the rest of the body.
The spinal cord is responsible for transmitting sensory information from the body to the brain and sending motor commands from the brain to the body.
It also coordinates reflexes independently of the brain.

Question 38

Spinal cord (functions - Transmission of Sensory and Motor Information)

Answer 38

Transmission of Sensory and Motor Information

Ascending tracts carry sensory information from the body to the brain. This includes sensations like touch, pain, temperature, and body position (proprioception).

Descending tracts carry motor commands from the brain to the muscles, allowing voluntary and involuntary movement.
Some major tracts include:
Dorsal columns: Transmit information about fine touch, vibration, and proprioception to the brain.
Spinothalamic tract: Transmits pain and temperature sensations.
Corticospinal tract: Carries motor signals from the brain to control voluntary movements.

Question 39

Spinal cord (functions - reflexes and autonomic functions)

Answer 39

Reflexes
- The spinal cord is the center for reflex actions, which are fast, involuntary responses to stimuli. Reflexes bypass the brain and are processed directly in the spinal cord for quicker reactions.
- The knee-jerk reflex is triggered when the patellar tendon is tapped, sending a signal to the spinal cord, which then sends a motor signal to the leg muscles to contract.

Autonomic functions
the bladder, bowel, and some sexual functions.

Question 40

Afferent (or ascending), sensory input:

Answer 40

Autonomic:
Stretch, chemo and baro-receptors form lungs, heart, digestive tract and arteries (nerves 1, 2, 7, 8, 9 and 10).

Somatic:
Pain, temperature and touch (nerves 5, 6, 9 and 10)

Question 41

Efferent (or descending), motor output:

Answer 41

Autonomic:
Involuntary smoot muscle (nerves 3, 5, 6, 7, 9 and 10)

Somatic:
Skeletal muscles (nerves 3, 4, 6 and 12)

Question 42

divisions of the autonomic nervous system

Answer 42

Innervates glands, smooth muscle and cardiac muscle.

Central control: hypothalamus and solitary tract nucleus (medulla).

Sympathetic and parasympathetic division:
Parallel but antagonistic control.
Not all tissues have dual innervations.

Question 43

somatic nervous system

Answer 43

The somatic nervous system controls skeletal muscle and is involved in voluntary movement and reflex movements.

Question 44

Sensorimotor integration

Answer 44

Sensorimotor integration is the process by which:
The brain and nervous system integrate sensory information with motor actions to produce coordinated and appropriate responses.
Tis integration enables organisms to interact effectively with their environment by perceiving stimuli (ex. Touch, vision, sound) and responding through movement.
It plays a crucial role in daily activities like walking, grasping objects and maintaining posture.