Nervous System: Structure and Function

The Nervous System

• The nervous system's cells function to transmit signals
• Neurons have distinct structures for signal transmission
• The nervous system has specialized divisions
• Neuronal communication involves electrochemical signals
• Synaptic disruption can lead to neurological disorders

Major Components

• The central nervous system (CNS) includes the brain and spinal cord
• The peripheral nervous system (PNS) includes ganglia and nerves

Sensory Information

• The nervous system receives sensory information from both outside and inside the body

Information Processing

• The nervous system processes information and formulates an appropriate response

Response Information

• The nervous system sends response information out, controlling behaviors like doing nothing, eating, and moving

Nervous Tissue

• Nervous tissue makes up the brain, spinal cord, and nerves
• It transmits electrical signals throughout the body

Main Cell Types

• The two main types of cells are neurons (nerve cells) and glial cells (support cells)

Neuron Function

• Neurons transmit electrical impulses and communicate information throughout the body

Glial Cell Function

• Glial cells support and protect neurons
• They provide nourishment, remove waste, and maintain homeostasis

Tissue Location

• Nervous tissue is found in the brain, spinal cord, and nerves throughout the body

Predominant Location

• Mostly in the brain and spinal cord

Glial Abundance

• Glial cells outnumber neurons by a ratio of 9:1

Glial Significance

• Take up more than half the volume of the brain

Glial Cell Types

• Major types include astrocytes, oligodendrocytes, microglia, and ependymal cells

Astrocytes

• Maintain the blood-brain barrier
• Provide nutrients for neurons
• Regulate blood flow
• Assist in repairing and scarring after injury

Oligodendrocytes

• Form myelin sheaths around neurons in the central nervous system
• Aid in the conduction of electrical impulses

Microglia

• Act as the immune cells of the CNS
• Clear away dead cells, debris, and pathogens
• Play a role in immune responses

Ependymal Cells

• Line the ventricles of the brain and the central canal of the spinal cord
• They produce and circulate cerebrospinal fluid (CSF)

Neuron Parts

• Main parts are the cell body (soma), dendrites, axon, and axon terminals

Cell Body (Soma)

• Contains the nucleus and other organelles
• Integrates signals received from the dendrites

Dendrites

• Receive electrical signals from other neurons and transmit them to the cell body
• Signals can stimulate nerve impulses that are then conducted away from the cell body by an axon

Axon

• Carries electrical signals away from the cell body to other neurons, muscles, or glands

Myelin Sheath

• A fatty layer that covers the axon
• Speeds up the transmission of electrical impulses
• Produced by oligodendrocytes in the CNS and Schwann cells in the PNS

Axon Terminals

• Small branches at the end of the axon that release neurotransmitters to communicate with other neurons, muscles, or glands

Synapses

• Form connections with other cells or neurons

Node of Ranvier

• A gap in the myelin sheath where action potentials are transmitted
• Speeds up the electrical signal through saltatory conduction

Neuron Cell Bodies

• Most are found close to the central nervous system

PNS Axon Bundles

• Bundles of axons are nerves

CNS Axon Bundles

• Bundles of axons are tracts

Myelin

• A fatty wrapping found around some axons

Myelin Function

• Greatly increase the speed of signal conduction along axons

Myelin Formation

• Formed by glial cells

PNS Myelin

• Schwann cells form myelin around axons

CNS Myelin

• Oligodendrocytes form myelin around axons

Nodes of Ranvier

• Gaps in the myelin sheath that facilitate fast signaling, allowing action potential to jump from node to node

Nervous System Function

• Coordinate and regulate the activities of the body
• Enable communication between different parts of the body
• Respond to stimuli

Sensory Input

• Sensory receptors collect information from both external and internal environments
• Transmitted to the central nervous system

Integration

• The nervous system processes and interprets sensory input
• Combines information from different sensory sources to form an understanding of the environment or body state

Motor Output

• The nervous system's response to processed information
• Sends signals to muscles, glands, and other effectors to produce a response or action

Communication

• Transmits electrical signals (action potentials) through neurons
• Enables quick transmission of information across the body

Sensory Neurons

• Carry information from sensory receptors to the central nervous system for processing

Interneurons

• Process and integrate information within the CNS
• Allow for decision-making and coordination between sensory input and motor output

Motor Neurons

• Carry the processed response from the CNS to effectors (such as muscles and glands), triggering a physical response or action

Sensory Input Involvement

• Sensory receptors collecting information from both outside and inside the body
• Information is then sent to the nervous system

Sensory Neuron Involvement

• Sensory neurons are involved in collecting and transmitting sensory information from the receptors to the central nervous system

Integration/Processing

• Integrates and processes information from various sensory sources to interpret and formulate appropriate responses

Interneuron Functions

• Integrating and processing information within the central nervous system

Motor Output Involvement

• Sends outgoing responses based on processed information to effectors (muscles, glands, etc.) for action

Motor Neuron Actions

• Carrying response signals from the CNS to generate a response

Nervous System Function (Summarized)

• Sensory input – collecting information from internal and external sources
• Integration/processing – Analyzing and interpreting information
• Motor output – Sending responses to effectors (muscles and glands)

Nervous System Divisions

• Central nervous system and peripheral nervous system

Central Nervous System

• Includes the brain and spinal cord

CNS Function

• Interprets incoming information, integrates it, and issues corresponding outgoing instructions to control body functions

Peripheral Nervous System

• Nerves extending from the brain and spinal cord that connect the rest of the body

Cranial Nerves

• The 12 cranial nerves carry information to and from the brain
• Enable communication between the brain and head/neck regions

Spinal Nerves

• The 31 spinal nerves carry information to and from the spinal cord
• Allow communication between the spinal cord and the body

PNS Pathways

• Divided into afferent (sensory) and efferent (motor) pathways

Afferent Division

• Carries information towards the CNS via sensory neurons

Afferent Nerves

• Somatic nerves (sensory information from the skin, skeletal muscles, and joints)
• Visceral nerves (sensory information from the internal organs)

Efferent Division

• Carries signals away from the CNS via motor neurons to effectors (muscles and glands)

Efferent Subdivisions

• Somatic nervous system (voluntary control over skeletal muscles)
• Autonomic nervous system (involuntary control over smooth muscles, cardiac muscles, and glands)

Autonomic Nervous System (ANS)

• Part of the efferent division of the PNS
• Controls involuntary functions, such as the regulation of smooth muscles, cardiac muscles, and glands

ANS Divisions

• Sympathetic and parasympathetic divisions

Sympathetic and Parasympathetic

• Exert antagonistic effects on the same organs

Sympathetic Division

• Prepares the body for fight-or-flight response
• Increases heart rate, dilates airways, and inhibits digestion

Parasympathetic Division

• Promotes rest-and-digest activities, slowing the heart rate, stimulating digestion, and promoting energy conservation

Sympathetic Activation

• Vital during situations that require alertness, such as when a person needs to fight or run away

Sympathetic Effects

• Shunts blood to skeletal muscles
• Accelerates the heartbeat and increases the strength of heart contractions
• Dilates bronchi to allow more oxygen intake
• Prepares muscles by ensuring they have a ready supply of glucose and oxygen

Sympathetic's Impact

• Activation inhibits the parasympathetic division

Parasympathetic Name

• Sometimes called the “housekeeper” division because it promotes relaxation and internal responses associated with a calm state

Parasympathetic Effects

• Causes pupils in the eyes to constrict
• Promotes digestion of food
• Slows the heart rate
• Decreases the strength of cardiac contractions

Parasympathetic's Impact

• Activation inhibits the sympathetic division, promoting relaxation and a focus on rest-and-digest activities rather than fight-or-flight responses

Neuronal Communication

• Membrane potential: The voltage across a cell membrane due to the polarization of the cell, which results from differences in ion concentration inside and outside the cell

Polarization Cause

• Created by the difference in ion concentration across the cell membrane
• Controlled by membrane proteins and channels

Resting Potential

• The resting membrane potential of a nerve cell is approximately -70 mV

Ion Distribution

• Concentration of Na+ ions is high outside the cell
• Concentration of K+ ions is high inside the cell

Ion Concentration Maintenance

• Maintained by the Na+/K+ ATPase
• A membrane protein that actively pumps 3 Na+ ions out of the cell and 2 K+ ions in

Channel Status

• Voltage-sensitive Na+ and K+ channels are closed, preventing the flow of ions across the membrane

Action Potential

• A sudden change in the cell membrane potential that allows the transmissions of a nerve signal within a neuron, from the dendrite to the axon terminal

Action Potential Purpose

• Transmit nerve signals along the axon of a neuron
• Enable communication between neurons or between neurons and muscles/glands

Resting Neuron: mV

• -70 mV

Neuron Stimulation

• The membrane potential reaches the threshold (around -50 mV) which generates an action potential

Action Potential Stages

• Depolarization
• Repolarization
• Hyperpolarization

Action Potential Event

• An all-or-nothing event, meaning that once the threshold is reached, the action potential will occur fully, without partial responses

Reaching Threshold

• (~-50mV) causes an action potential which triggers the process of depolarization to begin

Depolarization Phase

• Voltage sensitive Na+ channels open, allowing Na+ ions to diffuse into the cell
• Causes the membrane potential to increase to around +30 mV and reversing the polarization

Repolarization Phase

• The Na+ channels close and voltage-sensitive K+ channels open
• Allowing K+ ions to diffuse out of the cell.
• Causes membrane potential to decrease back toward its resting state

Hyperpolarization

• The excess K+ efflux (K+ leaving the cell) causes the membrane potential to drop below the resting membrane potential, making it more negative than usual

Refractory Period

• A phase after an action potential where the neuron cannot generate another action potential due to the membrane potential being too low (during hyperpolarization)

Synapse

• A connection between neurons and other cells
  • One neuron to another neuron
  • One neuron to an effector cell (e.g., muscle or organ)

Synaptic Cleft

• A tiny gap that separates neurons at the synapse
• Allows for transmission of signals

Presynaptic Neuron

• Carries the action potential toward the synapse, sending the signal to the next cell

Postsynaptic Neuron

• The neuron carries the action potential away from the synapse to continue signal transmission

Synapse Types

• Excitatory synapses help generate an action potential in the postsynaptic neuron, promoting signal transmission
• Inhibitory synapses prevent an action potential in the postsynaptic neuron, stopping signal transmission

Axon Terminal Arrival

• It causes an influx of Ca2+ ions into the axon terminal
• Triggers the release of neurotransmitters into the synaptic cleft

Synaptic Transmission

• The presynaptic neuron induces an influx of Ca2+ ions in the axon terminal
• Causes the neurotransmitters to be released from vesicles into the synaptic cleft, allowing communication between the presynaptic and postsynaptic neurons

Neurotransmitters

• Bind to receptors on the postsynaptic neuron which may either excite or inhibit the postsynaptic neuron, influencing whether it generates an action potential

Synaptic Summation

• Summation is the net outcome of the combined effects of excitatory and inhibitory synapses
• Determinines whether the postsynaptic neuron generates an action potential to continue signal transmission

Neurotransmitter Removal Importance

• Remove neurotransmitters from the synaptic cleft to stop the signal
• Prevent continuous stimulation of the postsynaptic neuron

Removal Methods

• Reuptake by the presynaptic neuron
• Enzyme breakdown of the neurotransmitter
• Astrocytes cleaning up the neurotransmitter from the synaptic cleft

Reuptake

• The process by which the presynaptic neuron reabsorbs the neurotransmitter from the synaptic cleft, terminating the signal

Enzyme Contribution

• Enzymes break down the neurotransmitters in the synaptic cleft, deactivating them and stopping the signal transmissions

Astrocyte Role

• Help clean up the neurotransmitters from the synaptic cleft
• Assist in their removal and helping maintain synaptic function

Neurological Disorders

• Often involve the disruption of signaling at synapses
• Can lead to abnormal communication between neurons

Abnormal Neurotransmitter Levels

• Can lead to disruptions in normal neuronal signaling, causing symptoms of neurological disorders

Therapeutic Goals

• Normalize the level of the appropriate neurotransmitter or alter the activity of the neurotransmitter at the synapse to restore proper signaling

Dopamine's Role

• An inhibitory neurotransmitter in a region of the brain called the substantia nigra
• its inhibitory effect plays an important role in the precise control of movements

Decreased Dopamine

• Disrupts movement control
• Leads to Parkinson's Disease
• Charecterized by symptoms like involuntary tremors

Parkinson's Cause

• The decrease in dopamine levels, which impairs the ability to control smooth and voluntary movements

Levodopa

• A common treatment for Parkinson's Disease
• Helps manage symptoms by increasing dopamine levels in the brain

Levodopa Contents

• Contains L-dopa, a building block that brain cells use to manufacture dopamine

Levodopa Process

• Provides brain cells with L-dopa, which they use to produce more dopamine
• Compensates for the reduced dopamine levels caused by Parkinson's Disease

Serotonin (5-HT)

• An excitatory neurotransmitter that plays a key role in functions such as appetite control, sleep, memory and learning, mood, and behaviour (including sexual and hallucinogenic behaviour), cardiovascular function, muscle contraction, and endocrine regulation, among others

Decreased Serotonin

• Linked to clinical depression, leading to mood changes and other related symptoms

Prozac

• It is a selective serotonin reuptake inhibitor (SSRI)
• Works by blocking the reuptake of serotonin back into the presynaptic neuron, leading to an increase in serotonin levels in the synaptic cleft

Prozac's Activity

• By blocking reuptake, Prozac causes serotonin to remain in the synapse longer
• Enhances its activity and increasing serotonin signaling in the nervous system

Prozac's Effects

• Results in increased serotonin activity, which can help alleviate symptoms of depression and other mood-related disorders by prolonging the presence of serotonin between cells

Central Nervous System

• The spinal cord is composed of grey matter and white matter

Structural Component

• White matter: Contains myelinated axons that run together in bundles called tracts, and the myelin gives the axons a shiny, white appearance

Structural Component

• Grey matter: Contains soma (cell bodies) and short, non-myelinated axons, which lack the myelin that gives white matter its appearance

White Matter Location

• Forms the outer periphery of the spinal cord

Grey Matter Location

• Resides in the center of the spinal cord, and it has a characteristic butterfly shape

Grey Matter Neurons

• Portions of sensory neurons, motor neurons, and interneurons

Spinal Cord Entry/Exit

• Sensory neurons enter the spinal cord through the posterior (dorsal) side
• Motor neurons exit the spinal cord through the anterior (ventral) side

Spinal Cord Function

• Limited processing functions are primarily involved in basic reflexes
• Transmits of signals between the brain and body

Ascending Tracts

• Carry sensory afferent information from the body to the brain
• Allowing the brain to process sensory input

Ascending Location

• Generally located in the posterior white matter of the spinal cord

Descending Tracts

• Carry motor efferent information from the brain to the body
• Allowing the brain to control motor functions

Descending Location

• Generally located in the anterior white matter of the spinal cord

White Matter Variance

• The cervical section of the spinal cord has a higher percentage of white matter compared to the sacral section

Decreasing White Matter

• As tracts descend the spinal cord, more peripheral nerve branches exit
• Leaving behind a smaller proportion of white matter in the lower sections.

Reflex

• Involuntary and nearly instantaneous response to a stimulus
• Often acting as a protective mechanism to maintain homeostasis and protect the body from harm

Homeostasis

• Reflexes are essential for homeostasis, helping maintain normal organ function
• Protecting the body from external threats.

Reflex Types

• Cranial reflexes – involve only the brain
• Spinal reflexes – involve only the spinal cord

Cranial Reflex Examples

• Blinking reflex
• Sneezing reflex
• Blushing reflex

Spinal Reflex Examples

• Withdrawal reflex
• Knee jerk reflex
• Stretch reflex

Babinski Reflex

• Occurs in infants when the sole of the foot is stroked, causing the toes to extend upward instead of curling down

Adult Babinski

• The Babinski reflex is normal in infants up to 2 years old

Reflex Development

• reflex may disappear as early as 12 months of age, but is usually gone by the time the child reaches 2 years old.

General Brain Composition

• The brain is composed of grey matter and white matter
• Grey matter found lining the periphery and white matter forming the deep tissue structures

Grey Matter Location

• On the outer surface of the brain
• Forms the cortex and some deep structures like the basal ganglia

White Matter Location

• Deeper within the brain
• Forms structures such as tracts that connect different brain regions

Brain Protection

• Skull
• Meninges
• CSF
• BBB

Meninges

• Protective membranes that wrap around the spinal cord and brain
• Helping to cushion and protect the central nervous system

Meninge Layers

• Dura mater (outer layer)
• Arachnoid mater (middle layer)
• Pia mater (inner layer)

Dura Mater Function

• A tough outer layer that provides structural protection to the brain and spinal cord

Arachnoid Mater Function

• The middle layer that acts a cushion, with a subarachnoid space filled with cerebrospinal fluid to further protect the brain and spinal cord

Pia Mater Function

• The inner layer that closely adheres to the surface of the brain and spinal cord
• Proving a thin protective covering and containing blood vessels that supply nutrients

Dura Mater Composition

• The outermost layer of the meninges
• Tough, white, fibrous connective tissue that lies deeper to the skull and vertebrae

Singular Dura Mater

• Made up of two separate membrane layers that are generally fused together
• In some areas, the layer separates to form the dural venous sinuses

Dural Venous Sinuses Function

• Collects venous blood from the brain and excess cerebrospinal fluid within the CNS
• Returning both to the systemic cardiovascular system

Arachnoid Mater Composition

• The middle layer of the meninges, located deeper than the dura mater
• A spider-web-like appearance made of connective issue

Subarachnoid Space

• It includes the subarachnoid space, which is filled with cerebrospinal fluid

Pia Mater

• Thin and follows follows contours of brain and spinal cord

Meningitis

• The inflammation of the meninges, the protective membranes surrounding the brain and spinal cord

Meningitis Cause

• Can be caused by either bacteria or viruses

High Risk

• Higher risk of meningitis in individuals, especially high school or college age students

Meningitis Symtoms

• Headache
• Fever
• Stiff neck

Meningitis Consequences

• Severe forms of meningitis can lead to paralysis, coma, or death

Meningitis Diagnosis

• X-ray
• CT scan
• Spinal tap (lumbar puncture)

Cerebrospinal Fluid

• A clear liquid that surrounds and cushions the brain and spinal cord
• Provides protection and removing waste

CSF Creation

• Formed by ependymal cells, a type of glial cell, which are found in structures called choroid plexus

CSF Formation Location

• Choroid plexus are blood vessel-rich tissues found in all four brain ventricles

CSF Production and Flow

• CSF is continually produced in the ventricles of the brain and flows between them
• Then fills the central canal of the spinal cord and the subarachnoid space around the brain

Excess CSF

• Drained into the dural venous sinuses
• Returns to the cardiovascular system

CSF Composition

• Similar to blood plasma
• Provides a protective cushion around the central nervous system

CSF Function

• To protect the brain and spinal cord from mechanical impacts by acting as a cushion

CSF Role

• Nourishes the brain and helps in the removal of waste products, such as carbon dioxide

CSF Regulating

• Tightly regulated by astrocytes that surround CNS blood vessels
• Forms a barrier to maintain the proper environment for the brain an spinal cord

Blood-Brain Barrier

• Isolates the CAN from the rest of the body
• Protects from harmful substances while allowing essential molecules to pass through

BBB Transmittance

• Water
• Some gases
• Lipid-soluble molecules (by passive diffusion)

Gas Permeability

• Oxygen
• Carbon dioxide

Lipid-Soluble Permeability

• Alcohol
• Nicotine
• Caffeine
• Anesthesia agents

Spinal Cord Protection

• Vertebrae
• Meninges
• CSF
• SCBB

Hydrocephalus

• Occurs when the flow of CSF is blocked, leading to the enlargement of the ventricles due to CSF accumulation

Infant Hydrocephalus

• The skull can expand, but if left untreated, the brain tissue between the ventricles and skull will be compressed which can result in brain damage and can be fatal

Adult Hydrocephalus

• The skull cannot expand, so the condition worsens dramatically leading to death

Cerebrum

• Largest portion of the brain and is responsible for higher cognitive functions

Sensory/Motor Cerebrum

• Last center to receive sensory input and carry out integration before commanding voluntary motor responses

Cerebrum Functions

• Communicates, coordinates, and integrates activities from other parts of the brain
• Including processes like learning, memory, language, and speech

Cerebrum Halves

• Divided into two halves called the left and right hemispheres

Longitudinal Fissure

• Separates the left and right cerebral hemispheres

Communication

• Hemispheres are connected by a bridge of white matter called the corpus callosum

Cerebral Cortex

• The outer layer of the cerebrum, made of grey matter, and is located within the highly folded structures called gyri

Cortex Purpose

• Responsible for information processing, including sensation, voluntary movement, and thought processes like learning, memory, emotions, reasoning, and language

Cell Count

• One billion cell bodies are interconnected and responsible for various cognitive and motor functions

Crotex Divisons

• Frontal lobe
• Parietal lobe
• Occipital lobe
• Temporal lobe

Primary Motor Cortex Location

• Lies in the pre-central gyrus, anterior to the central sulcus in the frontal lobe

Voluntary Function

• Responsible for the voluntary control of skeletal muscles
• Each body part being controlled by a specific area in the cortex

Contralateral Control

• The right primary motor cortex controls the left side of the body
• The left primary motor cortex controls the right side

Descending Tract

• Decussation occurs in the medulla oblongata

Somatosensory Function

• Located in the post-central gyrus, posterior to the central sulcus in the parietal lobe
• Receives sensory information from the skin and skeletal muscles

Contralateral Receive Sensory

• The left primary somatosensory cortex receives sensory information from the right side of the body
• The right primary somatosensory cortex receives sensory information from the left side

Deccusation

• The crossing of nerve fibers from one side of the body to the opposite side
• In the context of the brain and spinal cord, it often describes the point where motor and sensory pathways cross over to the opposite side of the body
• Occurs in the medulla oblongata

Association Areas

• Brain Regions with Integration between lobes where memories are stored
• Process and interpret sensory information

Somatosensory function

• Processes and analyzes sensory information from the skin and muscles
• Interprets touch, pressure, and body position

Visual function

• Associates new visual information with memories of previously received visual data
• Recognizes and interpret what we see

Auditory function

• Associates sound information with memories
• Perceives sounds as language, music, or other types of sound

Broca's Location

• Motor speech area
• Located in the left frontal lobe

Broca's Function

• Involved in speech production and syntax
• Coordinates signals that help produce speech by controlling respiratory and oral movements through the primary motor cortex

Damage From Broca

• Results in Broca's Aphasia where speech is non-fluent and not proper

Wernicke's Location

• Located in the left parietal lobe
• Overlaps into the temporal lobe

Wernicke's Function

• Involved in language comprehension
• Includes both spoken and written language

Damage From Wernicke

• Results in Wernicke's Aphasia
• Hinders a person's ability to interpret written/spoken messages, even through speaking and vocabulary are maintained

Diencephalon

• Part of the brain located between the brainstem and the cerebrum
• Plays a critical role in sensory/ motor signal relay, as well as in autonomic functions

Diecephalon Structurers

• Thalamus, hypothalamus, epithalamus, and subthalamus

Thalamus Function

• Relay station for sensory and motor signals
• Transmits information to the appropriate areas of the cerebral cortex
• Pairs of grey matter tissue located around third ventricle

Hypothalamus Function

• Responsible for regulating vital functions such as hormone release, body temperature, hunger, thirst, and sleep
• Plays a key role in the autonomic nervous system

Epithalamus Function

Includes the pineal gland, which produces the hormone melatonin Regulates sleep-wake cycles and habituates emotions and reward processing

Subthalamus

• Involved in the regulation of motor control
• influences movement and muscle tone in conjunction with the basal ganglia

Thalamus Information

• All sensory information like visual, sound, touch, and taste, passes through it before processing by cerebral cortex except for sense of smell.

Thalamus Processing

• Integrates and prioritizes sensory information
• Then sends to appropriate functional region of cerebral cortex for further processing

Hypothalamus Location

• Forms the floor of the third ventricle of the brain

Hypothalamus Role

• Regulates various processes related to homeostasis
• Such as hunger, sleep, thirst, body temperature, and water balance

Hypothalamus Interaction

• Produces hormones secreted by the posterior pituitary gland
• Secretes hormones that control the release of hormones from the anterior pituitary gland

Limbic Function

• Involved in memory and emotion as part of the limbic system
• Influences emotional responses and behaviour

Brain Stem

• Connects the spinal cord to the cerebrum
• Responsible for many vital functions such as breathing, heart rate, and basic bodily reflexes

Brain Stem Partition

• Midbrain
• Pons
• Medulla oblongata

Mid brain Role

• Involved in visual and auditory processing, motor control
• Plays a role in the regulation of sleep and alertness

Pons Role

• Serves as a bridge between the cerebrum and the cerebellum
• Controls breathing, sleeping, and motor control
• Relays signals between different parts of the brain

Medulla oblongata

• Controls autonomic functions such as heart rate, blood pressure, breathing
• Reflexes like cough, sneezing, and swallowing

Brain Stem Survival

• Regulates essential functions for survival, including heart rate, breathing
• Reflexes that keep the body safe and maintain homeostasis

Cranial Relationship

• Cranial nerves connect to the brainstem
• Provides sensory input and motor output to the head and neck regions

Overlapping Functions

• The structures of the brainstem have overlapping functions because of their extensive connections with various parts of the brain
• Allows for coordinated control over vital functions

Mid brain Role

• Functions as Relay station for tracts
• Passes between the cerebrum and the spinal cord or cerebellum
• Contains reflex centers for visual, auditory, and tactile responses

Mid brain Function

• Reflex centers for visual, auditory, and tactile responses
• Allowing for the brain to process sensory stimuli and trigger quick reactions

Pons Role

• Bridge with tracts that travel between the cerebellum and the rest of the CNS
• Regulates breathing rate alongside the medulla oblongata

Pons: Head Movement

• Contains reflex centers control head movements: respond to visual and auditory stimuli
• Helps the body to orient itself based on sensory input

Medulla's Location

• Located just superior to the spinal cord Critical connection between the brain and spinal cord

Medulla Function

• Involuntary functions: heart rate, heartbeat strength, and maintaining homeostasis

Medulla Reflex Centers

• Vital functions such as swallowing, coughing, vomiting, and sneezing

General Brain Information

Around 90% of medulla oblongata tracts cross the midline: left side of brain controls right side of body vice versa

Reticular formation location

• Web of gray matter running through brainstem Its Role: Controls sleep/wake state

Sensory

It Processes sensory stimuli: sounds, sights, and touch to keep us mentally alert

Function

• It helps to rouse a sleeping person and promote/maintain alertness

Consequence

• It causes coma
• Disrupts body’s conscious state

Cerebellum

• Commonly referred to as the little brain
• structure at back the brain

Primary Function

It Coordinates voluntary movements, balance posture,motor learning (helps fine tune/smooth out movements)

Motor control

Integrates sensory input to adjust/refine motor movements

Position

Located posterior to the brainstem and inferior to the cerebrum

Position

lies at the base of cerebrum Posterior to fourth ventrical Size of a plum

Neuron pack density

Densely packed than all other brain regions combined

Sensory input type

• Receives sensory input from eyes etc. to monitor body present position

Coordinate Motor Output

receives motor output: cerebral cortex regarding where parts should and motor impulses to skeletal muscles for it to adjust

Muscle Movement

• Ensures that all muscles work to produce smooth, coordinated movements
• Fine-tuning

Initiation and Assistance

Voluntary movements originate in primary motor cortex: cerebellum ensures movement smoothly

skill memory Role

Helps store skill memory: assisting learning new motor skills

Limbic Components

• Amygdala involved in emotions
• Hippocampus involved in storage
• Thalamus processes memories Hypothalamus contains autonomic responses/hormonal sections relations to emotions/ memories

Amygdala

plays role in emotions particularly for aggression and pleasure

Hippocampi

It is responsible for storing memories and its involved in long term memory

###Thalamus Contribution Process and relay sensory information to cerebral cortex: including aspects memory

Hypothalamus

Autonomic responses and secretes Hormones: relating to memorys and emotion

Sort vs long memories

Short: hold few bits of information for seconds Long: Larger things more Permanently

Memory Retention

Emotions play a key role: helps move Term into Long: making it emotional

Epinephrine

help transfer Term memories: enhancing associations with emotional experiences

N-D and D

N-skill= repetition:persistent and does not require attention * D facts/impressions: conscious

Cerebellum Role

Non-D skill memories that require skill

###Temporal Role D facts / conscious

Amygdala role

Screams emotional content and sends for further processing with hippocampus

N-Declarative Difference

Automatic: DO requires conscious Skills: Declaration Conscious: