Test 4: Neuro and Endo

Neuron

The basic functional units of the nervous system, specialized for excitability, conductivity, and secretion to transmit electrical and chemical signals.

Neuroglia

Supportive cells that outnumber neurons 10 to 1, providing structural support, myelination, immune defense, and metabolic support in the CNS and PNS.

Saltatory Conduction

The process by which myelinated axons conduct neural signals more efficiently, allowing for rapid transmission of action potentials.

Resting Membrane Potential

The stable charge/voltage of the plasma membrane of a neuron in an unstimulated state, typically around -70mV.

Action Potential

A dramatic change in membrane polarity produced by voltage-gated ion channels that represents an all-or-nothing response.

Depolarization

The process of the membrane potential becoming more positive; occurs when Na+ ions enter the neuron.

Repolarization

The process of returning the membrane potential to its resting state after depolarization, involving K+ ions exiting the neuron.

Hyperpolarization

A state where the membrane potential becomes more negative than the resting potential due to K+ ions leaving the cell.

Graded Potentials

Localized changes in a cell’s membrane potential that can vary in magnitude and strength based on stimulus intensity.

Voltage-gated Channels

Channels that open and close in response to changes in membrane potential, primarily found along the axon.

Ligand-gated Channels

Channels that open when a specific chemical (ligand) binds to the channel, primarily found on dendrites and the soma.

Local Potential

Short-range changes in membrane voltage that occur at stimulated sites and can influence action potentials.

Sodium-Potassium ATPase Pump

A membrane protein that maintains the resting membrane potential by moving 3 Na+ ions out of the cell for every 2 K+ ions it brings in.

Threshold Potential

The level of depolarization that must be reached to trigger an action potential.

Summation

The process by which multiple graded potentials combine to influence the likelihood of an action potential being generated.

Define the nervous system

The bodies primary communication network, responsible for transmitting, processing, and responding to information via CNS and PNS

What is apart of the Central Nervous System?

Brain and Spinal Cord

What is the goal of the CNS?

Integrate sensory input and coordinates motor output

What is the Peripheral Nervous System made of?

All nerves outside of the CNS

What is the goal of the PNS?

Transmits sensory information to and from the CNS

What is the CNS?

The control center for the body, processing information and orchestrating responses

What does the Brain and Spinal Cord do for the CNS?

Integrates sensory information and generates an appropriate motor response

EX: Burn Hand —> receptors tells CNS —> CNS makes hand pull away

What is the brain responsible for?

• processing sensory information

• controlling movements

• regulating emotions, memory, and decision making

What are the 4 major regions of the brain

• Cerebrum

• Cerebellum

• Brainstem

• Diencephalon

  • Thalamus and Hypothalamus

What is the largest region of the brain

The Cerebrum, divided into 2 hemispheres connect by Corpus Callosum

How is the the Cerebrum divided into lobes?

Frontal, Parietal, Occipital, and Temporal

What does the Frontal lobe do?

Controls decision making, problem solving, speech, and voluntary motor control

What does the Parietal lobe do?

Processing sensory information

What does the Occipital lobe do?

Visual processing center

What does the Temporal lobe do?

hearing, language conprehension, and memory

Where is the Cerebellum located?

beneath the cerebrum and behind the brainstem

10% of brain volume but less than 50% of neurons

What does the cerebellum do?

coordinates

• fine muscle movements to ensure smooth and precise movements

• maintains equlibrium for balance and posture

• able to learn new motor skills and adapting movements based on experience

• involved in attention, language, and emotional regulation for cognitive roles

Where is the brain stem located?

At the base of the brain

Connects the cerebrum and cerebellum to the spinal cord

How is the brainstem broken into sections?

Midbrain, Pons, and Medulla Oblongata

What does the midbrain do?

Visual and auditory processing

contains tectum (reflexes and auditory) and tegmentum (motor control and arousal)

what does the pons do?

regulates breathing rhythm and relays sensory information

what does medulla oblongata do

controls heart rate, blood pressure, and digestion

reflex centers for swallowing, sneezing, and coughing

What are the brainstem functions?

Regulates involuntary physiological processes (autonomic) in the body

• Ex: breathing, heartbeat, blood pressure, sweating, etc.

Pathway for sensory and motor signals

Mediates reflexes for posture, balance, and protective responses by regulating reflex actions

Origin of most cranial nerves controlling facial sensation, eye movement, swallowing, etc.

Where is the diencephalon located?

deep in the brain between cerebrum and brainstem

what does the diencephalon do?

relay and control center for sensory, motor, and autonomic functions

What are the 2 minor structures of the diencephalon

Epithalamus and Subthalamus

What does the hypothalamus do?

Links nervous system to endocrine system

integral to maintaining homeostasis and regulating autonomic and endocrine functions

What are the hypothalamus functions?

Homeostasis

endocrine function

autonomic nervous system control

hunger and being satiated

circadian rhythms

emotion and behavior

Where is the thalamus located?

above the hypothalamus

paired, egg shaped structure

What does the thalamus generally do?

Relays sensory and motor signals and plays a role in consciousness and alertness

What are the thalamus functions?

sensory relay

• transmit information to cortical areas

Motor relay

• regulate voluntary movement

Consciousness and arousal

• maintain alertness and sleep - wake cycles

Integration

• integrate and filters sensory signal to precent overload

Emotion and memory

• contributes to emotional responses and memory formation

Where is the Epithalamus located?

Located in the doral part of the diencephalon, above the thalamus

What does the Epithalamus do

regulates circadian rhythms and emotional responses

What is the Epithalamus made up of?

Pineal gland, habenular nuclei, and posterior commissure

What does the pineal gland do?

produced meletonin and regulates sleep wake cycles

what does the habenular nuclei do?

modulates emotional responses to odors

regulates behaviors related to reward and aversion

what does the posterior commissure do?

small band of fibers involved in visual reflexes and eye movement

What are the epithalamus functions?

Regulates sleep wake cycle

plays a role in emotional and olfactory responses

modulates reward processing and aversive behaviors

Where is the subthalamus located

ventral to the thalamus, by hypothalamus and basal ganglia

What is the general function of the subthalamus

Integrates to motor control and regulation of movement

Inhibits inappropriate motor signals, ensuring smooth volentary movement

• Parkinsons Disease is linked to dysregulation

What is the subthalamus comprised of

Subthalamic nucleus (suppressing unwanted motor activity) and Zona Incerta (linked to limbic and sensory processing)

What is the spinal cord?

Cylindrical structure extending from the brainstem to the lumbar region of the cerbral column

How is the spinal cord protected?

via Vertebrate, meninges, and CSF (cerebrospinal fluid)

T/F The spinal cord is the primary communication highway between brain and body

True

What are the key features of gray matter in the spinal cord?

Central region shaped like a butterfly

Contains cell bodies, dendrites, and unmyelinated axons

divided into horns

What are the 3 horns of gray matter and their functions

Dorsal Horn: Receives sensory input

Ventral Horn: sends motor output

Lateral Horn: involved in autonomic functions

What are the horns of white matter functions

Surrounds gray matter

Composed of myelinated axons

• Ascending tracts: transmit sensory information to the brain

• Descending tracts: transmit motor commands from the brain

What are the regions of the spinal cord

• Cervical

• Thoracic

• Lubar

• Sacral

• Coccygeal region

What does the Cervical region do?

Innervates neck, shoulders, arms, and hands

what does the thoracic region do

innervates trunk and upper abdomen

What does the lumbar region do?

innervates hips, thighs, and legs

what does the sacral region do

innervates pelvis, buttocks, genitals and lower limbs

What does the coccygeal region do?

innervates skin over tail bone region

What is the Medulla Oblongata

a cylindrical structure extending from the brainstem to the lumbar region of the vertebral column

What does the Medulla Oblongata regulate

Cardiovascular system

• Heart rate and blood pressure

respiratory system

• rhythm and depth of breath

reflex centers

• swallowing, vomiting, coughing, sneezing, hiccupping

What are some additional spinal cord features?

• Meninges

• CSF (Cerebral spinal fluid)

• Ventricular system

• Reflex arcs

What is meninges

Protective layers of connective tissue surrounding the brain and spinal cord

What is CSF

clear fluid produced by the choroid plexus in the ventricles of the brain

What is the Ventricular system

• A series of interconnected fluid filled cavities in the brain that extend into the spinal cord as the central canal

• Lined with ependymal cells that produce and circulate CSF

What is Reflex arcs

neural pathways in the spinal cord that mediate reflex actions without direct brain involvement

What are Glial Cells role

Support neurons in the CNS and PNS

What are the glial cells in the CNS

Astrocytes: maintain blood brain barrier

Microglia: immune defense

Oligodendrocytes: Produce myelin for CNS axons

Ependymal cells: CSF production and circulation

What are the components of PNS

Cranial nerves from the brain

• sensory & motor function of the head and neck

Spinal nerves

• sensory and motor functions of the cervical, thoracic, lumbar, sacral, and coccygeal

Ganglia

What are the different PNS divisions

Sensory (afferent)

Motor (efferent)

What does the Afferent division do

Transmits sensory information from receptors in the body to the CNS

Somatic sensory (touch, temp, pain) and visceral sensory (interal organs) inputs

What does the Efferent division do

Carries motor commands from the CNS to the effectors (muscles/glands)

• Further subdivided into

• Somatic nervous system division: controls voluntary movement of skeletal muscle

• Autonomic nervous system division

What does the Autonomic nervous system

Regulates involuntary functions

• Heart rate, digestion, gland activity • Further sub-divided

• Parasympathetic division

• “Rest and digest”

• Sympathetic division

• “Fight or flight”

What is the parasympathetic division

Division of the autonomic nervous system that promotes restorative processes and conserves energy

what are the functions of the parasympathetic division

Conservation of Energy, Digestive Function, Urinary Function, Respiratory Function, Ocular Function

What is the sympathetic division responsible for

Responsible for preparing the body for action during stressful and emergency situations

• Mobilizes energy and resources for immediate physical activity

What are the functions of the sympathetic division

• Increased Cardiovascular Activity

• Respiratory Effects

• Metabolic Effects

• Inhibits Nonessential Functions

• Enhanced Sensory Perception

• Sweat and Temperature Regulation

What are neurons

Basic functional units of the nervous system

Specialized for transmitting electrical signals

what are the key parts of neurons

• dendrites

• Soma (cell body)

• Axon

What are the neuron properties

• Excitability

  • Respond to environment changes called stimuli

• Conductivity

  • Respond to stimuli by producing electrical signals that are quickly conducted to other distant cells

• Secretion

  • when electrical signal reaches the end of a nerve fiber, chemical neurotransmitters are secreted to influence the next cell

What are the neuron classes?

Sensory (afferent) neurons

• Detect stimuli and transmit information about them toward the CNS

Interneurons

• Receive signals from many neurons and carryout integrative functions (make decisions on responses)

  • Only within CNS connecting motor and sensory pathways (about 90% of all neurons)

Motor (efferent) neuron

• Send signals out to muscles and gland cells (the effectors)

What is the Soma?

• Control center of the neuron

• Cytoplasm contains most of the typical organelles

• No centrioles present (cannot generate new neurons via Mitosis)

What are Dendrites

• Branches from the Soma

• Primary site for receiving signals from other neurons

• More = more information received

What is the Axon?

• Cylindrical nerve fiber from Soma (specifically Axon Hillock)

• Primary features include Axon collaterals, Axoplasm, Axolemma

What is Axon collaterals

• Branches within the axon

• Most occur on the distal end

• Specialized for rapid signal conduction

What is axoplasm

cytoplasm of axon

What is axolemma

plasma membrane of the axon

What are the functions of Neuroglia

• Protect neurons & aid in function

• bind neurons together to from framework for nervous tissue

• Help guide migrating neurons to fetuses

What are the Neuroglia of the CNS

• Oligodendrocytes

• Ependymal cells

• Microglia

• Astrocytes

What does Oligodendrocytes do

Form myelin sheaths in CNS that speed signal transmission

• Arm like that wrap around the axon

What does Ependymal cells do

Line internal cavities of the brain, secrete and circulate cerebral spinal fluid

• Cuboidal epithelium with cilia on apical surface