Download Control and Coordination

Control and Coordination
LS Chapter 18
The Nervous System
• Group of organs that gathers, processes and responds to
information gathered through the senses
• Acts very quickly
• Can be less than 1 second between gathering and responding
• Touching something hot
• The information gathered is called a stimulus
• Can be a sight, sound, taste, smell or a feeling (touch)
• The reaction to the stimulus is called a response
• If the response is involuntary, it is a reflex
• Vital in the maintenance of homeostasis
• Keeps body’s internal conditions correct, no matter what is going on outside
• Split into 2 parts-The Central Nervous System (CNS) and the
Peripheral Nervous System (PNS)
Neurons
• Neurons are the functioning unit of the nervous system
• Work to relay sensory information to and from the brain
• 3 main parts of a neuron
• Dendrite-Receives information
• Cell body-Processes information
• Axon-Transmits information
• 3 types of neuron
• Sensory-Send information from senses to the brain or spinal cord
• Motor-Sends information from the brain and spinal cord to tissues and organs
• Interneurons-Connect sensory and motor neurons
Information Transmission
• The area between neurons is called a synapse
• Neurons relay information by releasing chemicals called neurotransmitters
• These neurotransmitters travel across the synapse from an axon of one neuron
to a dendrite of another
The Central Nervous System
• The CNS includes the brain and spinal cord
• Receives, processes, stores, and transfers information
The Brain
• Control center of the body
• Receives and sends information. Also processes and stores information.
• 3 main divisions:
• Cerebrum- Controls memory, language, and thought
• Broca’s Area-Language center of the brain
• Cerebellum- Controls voluntary muscle movement and balance
• Muscle memory
• Brain Stem- Controls involuntary actions
• Heart, breathing, etc.
• Connects brain to the spinal cord
Lobes of the Cerebrum
• 4 lobes that have different functions
• Frontal Lobe
• Problem solving, emotion, reasoning, speaking, voluntary motor actions
• Parietal Lobe
• Sensation, reading, body orientation
• Occipital Lobe
• Vision, color perception
• Temporal Lobe
• Understanding language, behavior, memory, hearing
The Spinal Cord
• Tube-like structure of neurons that extends from the
brain stem
• Transmits information to and from the brain
• Protected by the vertebrae
The Peripheral Nervous System
• Connects the CNS to the rest of the body
• 2 parts
• Somatic (SoNS)- Controls skeletal muscles and voluntary actions
• Autonomic (ANS)- Controls smooth and cardiac muscles (involuntary)
• Think: Autonomic=Automatic
Damage to the Nervous System
• Physical injuries
• Concussions- Traumatic injury to the brain
• Can impair ability to think, concentrate, or remember
• Can cause headaches and blurry vision
• Can, in rare cases, change personality, and increase anxiety, anger, or loss of
interest in usual activities
• Huge problem in sports
• Paralysis- inability to control parts of the body, or loss of sensation
• Especially common in spinal cord injuries (broken neck/back)
• Drugs kill neurons and impair abilities
• Unlike most cells, neurons do not regrow or repair
Sensory System
• Part of the Nervous System that detects or senses the environment
• Humans have 5 senses
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Sight
Hearing
Smell
Taste
Touch
• The information is collected by specialized structures called
receptors
• Each sense uses different receptors
Vision
• Eye collects and transmits to the brain
• Parts of the eye
• Cornea-outer membrane. Collects light and directs it into the eye.
• Changes the direction to focus it
• Iris and Pupil- Iris is the colored portion of the eye. Pupil is the black circle.
• The iris controls the size of the pupil to adjust the amount of light entering.
• Pupil decreases in size when bright, and dilates (increases in size) when dark to
collect more light
• Lens- Changes the direction of light again to focus it on the retina
• Retina-area at the back of the eye that contains cells called photoreceptors
• Photoreceptors, called rods and cones, send the information as electrical signals
through the optical nerve to the brain
Vision Problems
• Nearsightedness- Trouble focusing objects that are
far away
• The eye is longer, and focuses the image in front of the
retina
• Farsightedness- Trouble focusing on objects that are
near
• The eye is shorter than normal, and focuses the object
behind the retina
• Astigmatism- Irregular curvature of cornea or lens
• Doesn’t bend light correctly, making image blurry
• All can be corrected with corrective lenses
Hearing
• Done by the ear
• Sound waves are collected and transferred via auditory nerve to
the brain
• 3 parts of the ear
• Outer Ear- Collects and directs soundwaves to the eardrum (tympanic
membrane)
• Middle Ear- Contains 3 tiny bones that are vibrated by the tympanic
membrane
• Called the malleus (hammer), incus (anvil), and stapes (stirrup)
• These bones vibrate and transfer the sound to the inner ear
• Inner Ear- Contains the cochlea, which is filled with fluid
• The fluid moves and disrupts tiny hair cells, which connect to the auditory
nerve
The Ear and Homeostasis
• The ear is responsible for your sense of balance
• As you move, fluid within the inner ear moves hair cells, which send
information to your brain
• Your brain interprets them and helps you maintain balance
• This is also why you may get dizzy if you have an ear infection
Smell
• Chemoreceptors in the nose collect sent particles from the air
Taste
• Chemoreceptors in the mouth (a.k.a. taste buds) collect tastes
and transfer them to the brain
• Main tastes: Bitter, salty, sweet, sour, and umami
• Umami is a savory taste
• Especially MSG in processed foods
• Not all taste buds sense all tastes
• There are not certain regions of the tongue for each
Touch
• Touch receptors in the skin feel temperature, pressure, and pain
• Different receptors allow for feeling light touches (tickles) and harder
touches (pokes or jabs)
• There are more receptors in some areas than others
• (where are you most ticklish?)
The Endocrine System
• A group of organs and tissues that release chemicals (called
hormones) into the blood
• Slower than the nervous system
• Endocrine glands release the hormones and they travel to other
areas of the body
• They bond to specific cells (lock and key)
Major Endocrine Glands
• Hypothalamus and Pituitary Glands in the brain
• Hypothalamus receives information from the body and signals the pituitary
gland to release hormones
• The Pituitary Gland releases hormones that regulate body functions and control the
rest of the endocrine system
• It also releases growth hormone which allows the body to grow
• The Thyroid Gland regulates how the body uses energy (metabolism)
• Located in the throat
• The Thymus Gland, located in the chest, signals the body to fight
infections
More Endocrine Glands
• Adrenal Glands in the abdomen release adrenaline to help respond
to stress
• The Pancreas secretes insulin to control blood sugar
• In females, ovaries release estrogen and produce egg cells
• In males, testes release testosterone and produce sperm
The Endocrine System and Homeostasis
• The glands of the endocrine system respond to stimuli and release
hormones
• Helps to regulate internal conditions
• Feedback Loops
• Negative Feedback-The glands release hormone only when needed
• Continually happening in the body
• Positive Feedback- The release of a hormone causes more to be released
• Not as common
• Childbirth, secretion of breastmilk