The Nervous System

Central and Peripheral Nervous System

2 main parts of the nervous system

Central Nervous System

The command center of the body. It processes information and controls all the activities in your body, both voluntary like moving your hand and involuntary like breathing.

Peripheral Nervous System

Made up of all the nerves that are outside the CNS. These nerves branch out from the brain and spinal cord and reach all parts of your body like a network of telephone lines connecting every area to the main control center

Brain

The control center for the entire body.

It processes sensory information, thoughts, emotions, and controls body functions like movements

Spinal cord

Acts as a highway for information traveling between the brain and the body.

It sends instructions from the brain to the body and carries sensory information back to the brain.

It also coordinates reflexes, which are fast, automatic responses to stimuli

Somatic and Autonomic Nervous System

Two main division of PNS

Somatic Nervous System

Controls voluntary movements of the muscles and sends sensory information to the CNS

Afferent Nerves

Sensory

Efferent Nerves

Memory

Autonomic Nervous System

Regulates involuntary functions like heart rate, digestion, and breathing

Sympathetic Nervous System

THoracic and lumbar

Prepares the body for stressful or emergency situations, also known as the “fight or flight” response

It increases heart rate, widens airways, and slows down digestion to give the body more energy and focus in dangerous or stressful movements

Parasympathetic Nervous System

Cranial and Sacral

Helps the body relax and recover after stress. This is called the “rest and digest” response

It slows the heart rate, promotes digestion, and helps the body conserve energy.

Sensory input, Integration, and Motor Output

Key functions of the Nervous System

Sensory Input

A key function of the nervous system that collects information from the external environment through sensory receptors

Integration

A key functions of the nervous system that processes and interprets the sensory information to make decisions about how to respond

Motor output

A key functions of the nervous system that sends signals to muscles or glands to make the body respond

Skull, meninges Cerebrospinal Fluid

Physical protection of the brain from toxic substance

Blood-Brain Barrier

Chemical protection of the brain

It is also a tightly-packed cells of blood vessel walls prevent entry of many molecules

Neurons

Specialized cells for the reception, conduction, and transmission of electrochemical signals

It comes in variety of shapes and sizes

Cell body

The metabolic center of the neuron; also called the soma

Cell membrane

The semipermeable membrane that encloses the neuron

Dendrites

The short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons

Axon hillock

A corn shaped region at the junction between the axon and the cell body

Axon

The long, narrow process that projects from the cell body

Myelin

The fatty insulation around many axons

Nodes of Ranvier

The gaps between sections of myelin

Buttons

The buttonlike endings of the axon branches, which release chemicals into synapses

Synapses

The gaps between adjacent neurons across which chemical signals are transmitted

Synaptic vesicles

Spherical membrane packages that store neurotransmitter molecules ready for release near synapses

Neurotransmitters

Molecules that are released from active neurons and influence the activity of other cells

Unipolar, Bipolar, and Multipolar Neuron, and Multipolar interneuron

Classes of neuron

Unipolar Neuron

One process extending from its cell body

Bipolar neuron

Two processes extending from its cell body

Multipolar neuron

More than two processes extending from its cell body

Multipolar interneuron

Integrate neural activity within a single brain structure

Horizontal Slice

A slice parallel to the ground

Frontal

Slicing bread or salami

Sagittal

A midsagittal section separates the left and right halves

Telen, Dien, Mesen, Meten, and Myelencphalon

The five major divisions of the brain

Telencephalon

Main parts: Cerebral cortex, Basal ganglia, and Limbic system

Primary Functions: Voluntary movement, Sensory perception, Cognition reasoning, Emotion & Memory

It also the largest brain division

Diencephalon

Main parts: Thalamus, Hypothalamus, Epithalamus

Primary Functions: Sensory relay station (thalamus), Homeostasis (hypothalamus), Endocrine control, and Sleep-wake regulation

Links nervous and endocrine systems

Mesencephalon

Main parts: Tectum, Tegmentum, and Cerebral peduncles

Primary Functions: Visual $ auditory reflexes, motor coordination, and consciousness/arousal

It also acts as a relay between forebrain and hindbrain

Metencephalon

Main parts: Pons and Cerebellum

Primary Functions: Coordination of movement, balance and posture, bridge between medulla and higher centers

The cerebellum stores procedural memories

Myelencephalon

Main parts: Medulla oblongata

Primary Functions: Autonomic control

Vital for life-sustaining functions-centers (coughing, sneezing)