Nervous & Sensory Systems by: Cindy Quisenberry

How does the nervous system control your body? The nervous system directs the functions of all human body systems. Every activity is controlled by some of the more than 100 billion nerve cells in the body. CNS (Brain & Spinal Cord) – acts as a control center PNS (Nerves) – carry messages to and from this center

Neurons (Nerve cells) – Basic Element of the Nervous System Each nerve is a bundle of neurons (sends electrical messages to the body’s organs and muscles). Each neuron consists of 3 parts: The cell body – reach out to send or receive impulses. Dendrites – conduct nerve impulses toward the cell body. The axon – conducts nerve impulses away from the cell body.

Nerve Impulses What is the tissue called that covers the axon? What is the space called where impulses jump between neurons?

Nerve Impulses What is the tissue called that covers the axon? Myelin Sheath What is the space called where impulses jump between neurons? Synapse

Two Basic Properties of Neurons Excitability – the ability to respond to a stimulus Conductivity – the ability to transmit a signal

Three Types of Neurons Efferent or Motor – convey information to the muscles and glands from the CNS Afferent or Sensory – carry information from sensory receptors to the CNS Interneurons – carry and process sensory information

Electrical Impulses to Organs & Muscles Cells of the Body Release Electrical Energy After an External Stimuli or Stimulation from Internal Chemical Passes Through Nerve Cell Nerve Impulse Received by Tissues & Organs (Receptors) Transmitted to Other Receptors

Neuroglias Connect, protect, and remove debris from the system Do not transmit impulses Along with capillaries, these cells form the Blood Brain Barrier Blood Brain Barrier – permits some chemical substances to reach the brain’s neurons while blocking most others

The Central Nervous System – Center of Control Composed of brain and spinal cord. Receives and interprets all stimuli and sends nerve impulses Voluntary & Involuntary Movement Brain has 4 major divisions: Brainstem Cerebellum Cerebrum Diencephalon

Cerebrum – 2 Hemispheres & 4 Lobes Responsible for reasoning, thought, memory, judgment, speech, sensation, sight, smell, hearing, and voluntary body movement. Includes the: Frontal Lobe - voluntary motor movement, expression, moral behavior Parietal Lobe - interprets senses and taste Temporal Lobe - memory, equilibrium, emotion, and hearing Occipital Lobe - vision, some forms of expression Contains Cerebral Cortex (outer portion) – area of conscious decision making Start Claymation

Divisions of the Brain

Central Nervous System Brain Stem Midbrain – concerned with visual reflexes Pons – respiratory functions Medulla Oblongata – contains centers that regulate heart and lung functions, swallowing, vomiting, coughing, and sneezing Cerebellum Coordinates Musculoskeletal Movement

Central Nervous System Diencephalon Thalamus Hypothalamus Integrates with the ANS to control: HR BP Temp Water & Electrolyte Balance Digestion Behavioral Responses Grandular Activities

Cerebrospinal Fluid (CSF) Between the area of the brain and the cranium A water liquid that contains various compounds and flows throughout the brain and around the spinal cord Cradles and cushions the brain Ventricles in the brain also contain this fluid

Spinal Cord Extends from the base of the brain to near the first lumbar vertebra Contained within the vertebral column in a space called the vertebral canal Protected by: Vertebral Column CSF Spinal Meninges

Layers of the Meninges

The Meninges Dura Mater – outer layer, covers the entire length of the spinal cord and contains channels for blood to enter brain tissue Arachnoid Mater – middle layer, runs across the space containing CSF Pia Mater – innermost layer, thin membrane containing blood vessels to nourish the spinal cord

What can we inject Into the epidual space? Epidural Space - b/w the dura mater & the bones What can we inject Into the epidual space?

The Peripheral Nerves Twelve pairs of cranial nerves carry impulses to and from the brain. Thirty-one pairs of spinal nerves carry messages to and from the spinal cord and the body. Contains 2 subsystems: Somatic Nervous System Autonomic Nervous System (ANS)

The Peripheral Nerves The somatic nervous system receives and processes sensory input and excites the voluntary contraction of skeletal muscles. The autonomic nervous system carries impulses from the central nervous system to glands, various involuntary muscles, cardiac muscle, and various membranes. Divided into 2 Divisions Sympathetic Parasympathetic

The Peripheral Nerves The somatic nervous system receives and processes sensory input and excites the voluntary contraction of skeletal muscles. The autonomic nervous system carries impulses from the central nervous system to glands, various involuntary muscles, cardiac muscle, and various membranes. Divided into 2 Divisions Sympathetic Parasympathetic

Autonomic Nervous System – both divisions play opposite roles Sympathetic Division– operates under stress (fight or flight) Parasympathetic Division– operates to keep the body in homeostasis, under normal conditions

Autonomic Nervous System – both divisions play opposite roles What are the three parts of neurons?

Autonomic Nervous System – both divisions play opposite roles What are the three parts of neurons? Cell Body Dendrites Axon

Sensory System or Special Senses The sensory system includes any organ or part that perceives or receives stimuli from the outside world.

Sensory System Sight—the Eye Hearing and Equilibrium—the Ear Touch, Pain, and Temperature—the Skin Smell—the Nose Taste—the Tongue and Oral Cavity

Major Parts of the Sensory System Sight - the Eye Hearing – the Ears Touch - the Skin Smell - the Nose Taste - the Mouth

Sight – The Eye Outer Layer The sclera – supports the eyeball and nourishes the cornea Cornea – transparent layer where light is bent (refracted) as it enters the eye Middle Layer Choroid – focuses the eye Interior Layer Retina – decodes light waves and sends the info to the brain Rods – black and white Cones - color Optic Disk – where the retina connects to the nerve

Sight – The Eye

Chambers of the Eye Anterior Chamber Posterior Chamber Lies between the cornea and iris Nourishes the lens and cornea Maintains constant pressure of the eyeball Posterior Chamber Lies between the iris and the lens Vitreous Chamber – occupies about 80% of the space in the eyeball Nourishes parts of the eye and maintains structure to keep the eye from collapsing

Chambers of the Eye Eyelids Eyebrows and Eyelashes Lacrimal Glands

The Ear Major divisions of the ear The external ear, or pinna. The middle ear includes the eardrum, or tympanic membrane. The inner ear, which contains three semicircular canals and the cochlea.

The Ear

Smell – The Nose Olfactory relates to the sense of smell. The sense of smell is activated by receptors located at the top of the nasal cavity. The receptors are nerve cells covered with hairlike cilia that send messages to the brain

Taste - the Tongue and Oral Cavity Taste buds sense the taste of food. Located on the surface of the tongue in small raised structures called papillae. Four main types of taste buds to match taste sensations Sweet Sour Salty Bitter

Taste

The Sensory Which part of the eye decodes light waves and sends the information to the brain?

The Sensory Which part of the eye decodes light waves and sends the information to the brain? The retina