Transcript Ch. 35: The Nervous System

The Human Body
Systems
Chapters 35-40
Organization of the Body
• The level of organization in multicellular
organisms include: Cells Tissues
Organs Organ Systems.
• Humans have 11 organ systems
– Functions of Organ Systems: Maintains
homeostasis in the body as a whole.
Organization of the Body
• Cells
– The Basic Unit of Structure
– Specialized structures: uniquely suited to perform a
particular function
• Tissues – a group of cells that perform a single
function
– Four Basic Types:
• Epithelial Tissue: Cover the interior and exterior of body
surfaces
• Connective Tissue: Connects and Supports
• Nervous Tissue: Transmits nerve impulses
• Muscle Tissue: Enable the body to move
Organization of the Body
• Organs – Group of tissues that work
together to perform a single function
• Organ systems – groups of organs that
perform closely related functions.
– Humans have 11 organ systems
• Functions of Organ Systems: Maintains
homeostasis in the body as a whole.
Human Organ Systems
Nervous System
Integumentary System
Skeletal System
Muscular System
Circulatory System
Human Organ Systems
Respiratory System
Endocrine System
Digestive System
Reproductive System
Excretory System
Lymphatic/Immune Systems
Maintaining Homeostasis
• Homeostasis: The process which
organisms keep internal conditions
relatively constant despite changes in
external environment
– Feedback inhibition: The process in which a
stimulus produces a response that opposes
the original stimulus
Negative Feedback
The Skeletal System
• Skeletons provide support for an organisms and the
skeletal system is composed of bones and connective
tissue (called cartilage and ligaments).
• The Skeleton
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Functions of the skeleton:
Supports the Body
Protects internal organs
Allows Movement
Stores Minerals
Site for blood cell formation
• Adult human skeleton had 206 bones
The Structure of Bones
• Bones are a solid network of living cells
and protein fibers that are surrounded by
calcium deposits.
• Types of Bone cells:
– Osteocytes - mature bone cells
– Osteoclasts - break down bone
– Osteoblasts - produce bone
Development of Bones
• Skeleton of an embryo is made up of
cartilage.
• Ossification: The process of replacing
cartilage with bone
– Begins about 7 months before birth.
Types of Joints
• Joint: The place where one bone attaches to
another.
• Ligaments: Hold bones together in a joint
• Three Types:
– Immovable Joints
• Allow no Movement/bones are interlocked
– Skull
– Slightly Moveable Joints:
• Allow small amount of Movement
• Bones separated from each other
– Two bones of lower leg meet.
Types of Joints
• Freely movable Joints:
– Permit movement in one or more directions
– Most Common Types:
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Ball-and-socket: Movement in many directions
Hinge: Back and Forth motion
Pivot: One Bone rotates around another
Saddle: One bone to slide in two directions
Types of Joints
The Muscular Tissue
• This system is required for bones to
move.
• Three types of Muscle Tissue:
– Skeletal
– Smooth
– Cardiac
Types of Muscle Tissue
• Skeletal Muscle:
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Attached to bones
Responsible for Voluntary Movement
Striated
Consciously Controlled
Large with many nuclei/long and slender
often called muscle fibers.
Types of Muscle Tissue
• Smooth Muscle
– Not under voluntary control
– One nucleus and not striated
– Found in Stomach, intestines, and blood
vessels
– Can function without nerves stimulation
Types of muscles
• Cardiac Muscle
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Found only in the heart
Small Cells, Striated
One or two nuclei
Not under direct control of the Brain.
Types of Muscles
How Muscles and Bones Interact
• Tendons: Join skeletal muscles to bones
• Most Skeletal muscles work in pairs.
When one contracts the other relaxes.
Muscle and Bone Interactions
The Integumentary System
• Latin word integument means “to cover”
• Skin and its related structures (hair,
nails, and glands) make up the
integumentary system.
• Function: barrier against infection, helps
regulate body temp, removes waste,
protects from UV rays.
The Skin
• Skin is the largest organ in the body.
– Two main layers:
• Epidermis
• Dermis
• Epidermis
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Outer layer of skin
Outside of epidermis is dead skin cells
Inner Layer is living cells
Contains melanin
No Blood Vessels
The Skin
• Dermis
– Inner Layer of Skin
– Contains blood vessel, nerve endings, glands,
sensory receptors, hair follicles, and smooth
muscles.
– Major Glands: Sweat and Sebaceous (oil)
• Sweat cools your body when it evaporates
• Oil keeps skin flexible and waterproof.
The Circulatory System
• The circulatory and respiratory systems,
together, deliver oxygen to the entire
body.
• Humans have a CLOSED circulatory
system  blood is contained within
vessels
• Components: Heart, blood vessels, and
blood.
The Heart
• Located at the center of the chest.
– Structure of heart:
• Made up of muscle
• Myocardium: Thick layer of muscle in the heart
• Divided into four chambers
– 2 Atria and 2 Ventricles
» Atria receive blood
» Ventricles pump it out
• Has valves: flaps of connective tissue that prevent
backflow.
Structure of the Heart
Circulation through the body
• The heart functions as two separate
pumps
– Pulmonary Circuit: Blood pumped to the
lungs
– Systemic Circuit: Oxygen-rich blood returns
to the heart and is pumped out to the body.
Circulation
Heartbeat
• How do all the cells in a heart know when to
contract?
• How do they do it at the same time?
• Every Contraction begins in a specific area of
the heart called the sinoatrial node (SA node).
The signal then spreads but pauses for split
second at another node (the AV node). Why?
– To make sure the atria and ventricles alternate
contractions!
Blood Vessels
• Aorta: Largest blood vessel that lead blood to
the rest of the body.
• Three types of blood vessels:
– Arteries: carry blood away from the heart
• Most are oxygen rich
• Have thick walls to withstand pressure
– Capillaries: smallest blood vessels
• The place where gas and nutrient exchange happens
• Surround cells and Tissues
– Veins: Carry blood to the heart
Blood Vessels
Blood Pressure
• Blood Pressure is the force of blood on the walls
of the arteries.
• Systolic/Diastolic
– Systolic: Force in arteries when ventricles contract
– Diastolic: Force in arteries when ventricles relax
• Typical reading for a healthy person: 120/80
Blood
• The human body has 4-6L of blood.
– 45% are blood cells
– 55% is plasma
• Blood Cells
– Three types of cells:
• Red Blood Cells
• White Blood Cells
• Platelets
Blood Components
• Red Blood Cells: Erythrocytes
– Transport Oxygen
– Hemoglobin: iron-containing protein in
RBC’s
– Nuclei forced out during development
– Very Numerous
Blood Components
• White Blood Cells: Leukocytes
– Much less common
– Contain nuclei
– Attack bacteria, fight parasites, guard
against infection
– Lymphocytes: Type of WBC that produces
antibodies to help destroy pathogens
– Part of the immune system
Blood Components
• Platelets: Cell Fragments
– Makes Clotting Possible
– Positive Feedback system
Blood Components
The Respiratory System
• Respiration: the process of gas exchange
– Release of Carbon Dioxide and uptake of
Oxygen
• The Human Respiratory System
– Function: to bring about the exchange of
oxygen and carbon dioxide
– Structures: nose, pharynx, larynx, trachea,
bronchi, and lungs.
The Human Respiratory System
• Air moves through the nose to a tube called the
pharynx (or throat)
• From the pharynx, the air moves into the
trachea, or windpipe.
– A flap of tissue called the epiglottis covers the
entrance to the trachea when you swallow
• At the top of the trachea, air passes through the
larynx, the voice box.
• From the larynx, air passes into two large
passageways called bronchi.
The Human Respiratory System
• The bronchi divide into bronchioles
which further divide into alveoli.
– Alveoli: Membrane sacs containing the
capillaries for gas exchange
– Alveoli is where gas exchange occurs!
• Hemoglobin: oxygen-carrying protein
– Makes this process very efficient because
oxygen binds very well to it.
Breathing
• Breathing is the movement of air into and
out of the lungs
– No muscles in the lungs
• Diaphragm: Large flat muscle at the
bottom of the chest cavity.
Respiratory Structures
How Breathing is Controlled
• Breathing can be voluntary
• It is controlled by the medulla oblongata
in the brain.
Digestive System
• Food and energy
– Energy is measured in calories.
• calorie: The Amount of heat needed to raise 1
gram of water by 1 degree celsius.
• Calorie: equal to 1000 calories. (The Dietary
Calorie)
– Nutrition: The study of food and its effect on
the body
Nutrients
• Nutrients: Substances the supply energy
and raw materials for growth
– Nutrients the body needs:
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Water
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Nutrients
• Water
– The most important nutrient because of the body’s
processes take place in water
– Should drink at least 1 liter a day
• Carbohydrates
– Main source of energy for the body
– Simple (sugars) and complex (starch)
• Fats
– Formed from a triglyceride
– Two Types: Saturated and Unsaturated
Nutrients
• Proteins
– Supply raw materials for growth and repair of
structures
– Made up of Amino acids (there are 20)
• Vitamins
– The organic molecules that regulate body processes
– Two Types: Fat-Soluble (KADE) and water soluble.
• Minerals
– Inorganic nutrients that the body needs
The Process of Digestion
• Function: convert food into simpler
molecules that can be distributed to cells
• Parts of the digestive system: mouth,
pharynx, esophagus, stomach, small
intestine, and large intestine
• Accessory structures: salivary glands,
pancreas, and liver.
The Mouth
• Mechanical Digestion: Physical Change
– Teeth: Cutting, tearing, and crushing food
• Chemical Digestion: Chemical Change
– Saliva contain an enzyme that begins
digestion of carbohydrates (Amylase).
Esophagus
• After chewing and slight chemical breakdown,
the food (bolus) goes down the throat into the
esophagus
– Esophagus: Food tube connecting the pharynx to
the stomach
• Contractions of smooth muscles pull the food
down, not gravity.
– Peristalsis: Contractions of the smooth muscles that
moves food down to the stomach.
The Stomach
• Stomach: a large muscular sac
• Chemical Digestion:
– Pepsin: enzyme that breaks down proteins
– HCl in stomach creates acidic environment
• Mechanical Digestion:
– Stomach muscles contract to churn and mix
fluids and food
– Chyme: mixture in stomach
The Small/Large Intestine
• The Small Intestine
– All of the absorption takes place in the small
intestine.
– Villi: fingerlike projections lining the walls of the
small intestine
– After absorption of nutrients, cellulose and other
indigestible items remain.
• The Large Intestine
– Removes water from undigested material
– Bacteria living there produces Vitamin K
Excretory System
• Excretion: The process by which
metabolic wastes are eliminated
• Removing waste is part of maintaining
homeostasis.
• Organs:
– Lung, Skin, Liver, and Kidney
The Kidney
• The principal Organ of excretion
• Function: Kidneys remove urea from the
bloodstream, maintain blood pH, regulate
water content of blood, and regulate blood
volume
• Ureter: A tube that leaves each kidney carrying
urine to the bladder.
• Urinary bladder: Saclike organ where urine is
stored before being excreted.
Kidney Structure
• Nephrons: The Functional Unit of the Kidney
• Two process of blood purification:
– Filtration: passing a liquid or a gas through a filter to remove
waste.
• Filtrate – the materials filtered through the blood (Ex: Glucose,
salts, amino acid, water, urea and vitamins)
– Reabsorption: the process by which liquid is taken back into a
vessel.
• After reabsorption, the remaining materials are called
urine.
• Urine is stored in the bladder until it is released
through a tube called the urethra.
Drugs and the Kidney
• Drugs often remain in Urine, which is
why antibiotics and medications wear off
after a while. It is also why drug tests are
routinely performed on urine samples.
The Endocrine System
• The Endocrine System is made up of gland that
release their products into the bloodstream that
deliver messages throughout the body.
– Hormones – the chemicals released in one part of
the body that travels through the bloodstream and
affects the activities of cells in other parts of the
body.
• Glands – an organ that produces and releases a
substance or secretion
The Endocrine System
• Hormone Action – hormones belong to one of
two groups:
– Steroid Hormones
• Bind to DNA directly
• Cause Dramatic Changes
– Nonsteroid Hormones
• Bind to cell membrane.
• Wide range of activities.
• Prostaglandins (local hormones) – Hormonelike substance produced by all cells that affect
only nearby cells and tissues.
Control of the Endocrine System
• Regulated by feedback mechanisms that
function to maintain homeostasis
– Controlling Metabolism
• Thyroid
– Maintaining Water Balance
• Kidneys
– Calcium Levels
• Parathyroid
Human Endocrine Glands
• Pituitary Gland
– Two parts: Anterior and Posterior
– Secretes Nine Hormones
– Master Gland
• Hypothalamus
– Attached to the Posterior Pituitary
– Controls the secretions of the pituitary
• Thyroid Gland
– Located at the base of the neck and wraps around the trachea.
– Regulates Metabolism
Human Endocrine System
• Parathyroid Glands
– Four Glands located on the back of the surface of
the thyroid gland.
– Maintains calcium levels
• Adrenal Glands
– Two pyramid-shaped structures that sit on top of
the kidneys
– Use to deal with stress
– Fight or Flight hormone, epinephrine, is created in
the adrenals.
Human Endocrine Glands
• Functions as an exocrine gland by
releasing hormones into the small
intestine for digestion. Also functions as
an endocrine gland by releasing
hormones into the body
– Maintain Blood Sugar Levels
• Abnormalities can lead to Diabetes Melitus.
Human Endocrine System
• Reproductive Glands
– Gonads serve two important functions: the
production of gametes and the secretion of
sex hormones
– Ovaries, for females, produces eggs, as well
as progesterone and estrogen.
– Testes, for males, produce sperm and
testosterone.
Endocrine Structures
The Immune System
• Disease is any change, other than an
injury, that disrupts the normal functions
of the body. Some are produced by
pathogens, called infectious diseases.
Agents of Disease
• The human body provides the right conditions
for many pathogens to grow:
– Suitable Temperature
– A watery environment
– Plenty of Nutrients
• Pathogen causes disease by:
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Releasing Toxins
Blocking Blood Flow
Removing Nutrients
Disrupting bodily functions
Disease Chart
Pathogen
Types
Viruses
Bacteria
Protists
Worms
Fungi
Chickenpox
Agent That Causes
Disease
Rhinovirus
Two types (A, B),
plus subtypes
Varicella
Measles
Paramyxovirus
Tuberculosis
Mycobacterium
tuberculosis
Neisseria meningitidis
Vibrio cholerae
Clostridium tetani
Trypanosoma
Disease
Common cold
Influenza
Meningitis
Cholera
Tetanus
African sleeping
sickness
Malaria
Amoebic dysentery
Schistosomiasis
Beef tapeworm
Athlete’s foot
Ringworm
Plasmodium
Entamoeba histolytica
Schistosoma
Taenia saginata
Imperfect fungi
Imperfect fungi
Method of
Transmission
Airborne; direct contact with infected person
Airborne; droplet infection; direct contact with
infected person
Airborne; direct contact with infected person
Droplets in air; direct contact with secretions of
infected person
Droplets in air; contaminated milk and dairy products
Direct contact with a carrier
Contaminated drinking water
Contaminated wound; usually puncture wound
Spread by tsetse fly
Spread by Anopheles mosquitoes
Contaminated drinking water
Freshwater streams and rice paddies
Contaminated meat
Contact with infected person
Exchange of hats, combs, or athletic head gear with
infected person
Examples
The Immune System
• Function: The Immune System fights
infection through the production of
specialized cells that inactivate foreign
substances or cells.
Nonspecific Defenses
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Include physical and chemical barriers.
1. First line of Defense – to keep pathogens
out of the body.
2. Second Line of Defense – the inflammatory
response, which is a nonspecific defense
reaction to tissue damage caused by injury
or infection
1. The Immune system also releases chemicals
that increase the core body temperature,
resulting in a fever.
Specific Defenses
• An immune response will occur if a
pathogen is able to get past the body’s
nonspecific defenses.
• A substance that triggers this is called an
antigen, such as a virus, bacteria, or
other pathogen.
Specific Defenses
• Two types of lymphocytes recognize these
specific antigens:
– B cells – provide immunity against antigens
and pathogens in body fluids (out of body)
– T cells – provide a defense against abnormal
cells and pathogens inside living cells.
Acquired Immunity
• Over 200 years ago, smallpox was one of the
deadliest diseases of the day. Edward Jenner
noticed that people who contracted a similar
disease, cowpox, were immune to the smallpox
disease.
• His Experiment: He injected a young boy with
cowpox and watched him develop a the disease.
Two months later he injected the same boy with
smallpox and the boy did not develop the
disease.
Acquired Immunity
1. Active Immunity – a person develops
antibodies to a certain pathogen
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Can Occur when recovering from a disease
or getting a vaccine.
Vaccination – the injection of a weakened
or mild form of a pathogen to produce
immunity
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Stimulates the production of millions of plasma
cells ready to produce specific antibodies.
Immune System Disorders
• Allergies
– Allergies are the most common overreactions
of the immune system to antigens.
– Allergen: Antigens that cause allergic
reactions
AIDS, an Immunodeficiency
Disease
• AIDS results from a viral infection that
destroys helper T cells.
• The Virus that causes AIDS – HIV
(Human Immunodeficiency Virus)
• Because T cells are destroyed, the body
cannot fight pathogens very well.
– Opportunistic diseases – diseases that attack
a person with a weakened immune system.
The Nervous System
• The Nervous System controls and
coordinates function throughout the body
and responds to internal and external
stimuli
– Ex. Body Temperature and Infection
(Internal)
– Ex. Burns and Environmental conditions
(External)
Neurons
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Messages are sent through the body in
the form of electrical impuleses.
Neurons: the cells that transmit
electrical impulses.
Three types of Neurons:
1. Sensory
2. Motor
3. Interneurons
Neurons
1. Sensory – Carry impulses from the
sense organs to the spinal cord and
brain
2. Motor – carry impulses from the brain
and spinal cord to muscles and glands
3. Interneurons – connect sensory and
motor neurons.
Neurons
• Structure of a neuron:
– Cell Body: largest part, contains nucleus
– Dendrites: branched extensions of cell body
that carry impulses in toward cell body
• Can have many dendrites
– Axon: long fiber that carries impulses away
• Only have one axon
– Myelin Sheath: insulating membrane around
axon
• Has gaps called nodes
Diagram
Nucleus
Axon terminals
Cell body
Myelin sheath
Nodes
Axon
Dendrites
• The message jumps from node to node as it is
passed down the axon.
The Nerve Impulse
• A neuron is at a resting state until it
receives a stimulus large enough to start
a nerve impulse.
• An impulse begins when a neuron is
stimulated by another neuron or by
another neuron or by the environment.
The Nerve Impulse
• The impulse causes the movement of ions
across the cell membrane through gates
(channels).
• The reversal of charges (or nerve
impulses) is an action potential.
• The action potentials move down the
axon sending the message.
The Synapse
• At the end of the neuron, the impulse
reaches an axon terminal. Here the
message is sent to another cell very close
to the axon terminal.
– Synapse: The location at which a neuron can
transfer an impulse to another cell
The Synapse
• The axon terminal contains tiny sacs filled with
chemicals that neurons use to transmit an
impulse across the synapse to other cells. These
chemicals are called neurotransmitters.
• The neurotransmitters diffuse across the
synaptic cleft (the space) and attach to
receptors on the receiving cell. This cues the
gates to open for Na+ to come in and cause
another action potential.
Divisions of the Nervous System
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Neurons are joined together to form a
complex system called the Nervous
System.
Two major divisions:
1. Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
Central Nervous System
• The control center of the body
• Function: Relays messages, processes
information, and analyzes information
• Structure: Brain and Spinal Cord (which
are protected by the skull and vertebrae)
The Brain
• Made up of about 100 billion neurons!!!
• Structure
– Cerebrum
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Largest region with large surface area
Controls voluntary activities
Divided into right and left hemisphere
Hemispheres are divided into lobes
Each hemisphere deals with the opposite side of the body
Cerebrum has two layers  gray matter and white matter
Brain
Brain PET
The Brain
• Cerebellum
– Second largest region
– Located at the back of the skull
– Coordinates actions of muscles so movement is
smooth
• Brain Stem
– Connects the brain and spinal cord
– Two regions: pons and medulla oblongata
– Regulates info passing between brain and spinal
cord
The Brain
• Thalamus
– Between brain stem and cerebrum
– Receives messages from sensory receptors in body
and relays info
• Hypothalamus
– Just below the thalamus
– Control center for recognizing hunger, thirst,
fatigue, anger, and body temp
– Coordinates the nervous and endocrine system
The Spinal Cord
• Function: Main communication link between
brain and the rest of the body
• 31 pairs of spinal nerves branch out from the
spinal cord sending messages to diff. parts of
the body.
• Some information is processed in the spinal
cord (not the brain)
– Ex. Reflex: quick, automatic response to a stimulus
Peripheral Nervous System
• Function: Receives information from the
environment and relays commands from the
CNS to organs and glands.
• Divided into two divisions:
– Sensory: Transmits impulses from the sense organs
to the CNS
– Motor: Transmits impulses from the CNS to muscles
and glands
• Further divided into somatic nervous system and
autonomic nervous system
Peripheral Nervous System
• Somatic Nervous System
– Movement of skeletal muscles
– Conscious Control
• Autonomic Nervous System
– Regulates involuntary
– Ex. Heart Rate Increasing
– Two Parts: sympathetic and
parasympathetic
Sympathetic Vs. Parasympathetic
The Senses
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Sensory Receptors: Neurons that react to a
specific stimulus such as light or sound
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Located throughout the body but concentrated in
the sense organs  eyes, inner ears, mouth, nose,
and skin.
Five general categories of sensory receptors:
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Pain receptors (Nocireceptors)
Thermoreceptors
Mechanoreceptors
Chemoreceptors
Photoreceptors
Vision
• Structure of the eye:
– Cornea – focuses light
– Iris – colored part of the eye
– Pupil – small opening in the iris, regulates
the amount of light passing into the eye
– Lens – changes shape to adjust focus
– Retina – inner layer of eye that contain the
photoreceptors
Vision
• Two types of photoreceptors
– Rods: see black and white
– Cones: see color and detail
• The place in your eye where the optic
nerve goes to the brain there are no rods
or cones  blind spot
The Eye
Vitreous humor
Muscle
Lens
Fovea
Aqueous humor
Cornea
Pupil
Optic nerve
Iris
Blood vessels
Ligaments
Retina
Choroid
Sclera
Rods and Cones
Hearing and Balance
• Function of ear: Hearing and Positional
change associated with movement
(balance)
Hearing
• Sound is vibration in the air
– Ears distinguish the pitch and loudness of the vibrations
• Structure of the ear:
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Auditory Canal: place where vibrations enter
Tympanum (eardrum): vibrates
Bones: three small bones pick up vibrations from eardrum
Cochlea: fluid-filled place in ear, lined with hairs that move
from vibrations transmitted there.
• The hairs moving produce nerve impulses that go to the
brain.
Balance
• Semicircular canals: Three tiny canals
above the cochlea
– They monitor position of your head
Ear
Anvil Stirrup
Hammer
Oval
window
Semicircular canals
Cochlear nerve
Cochlea
Bone
Auditory canal
Tympanum
Round window
Eustachian tube
Smell and Taste
• Chemoreceptors in your nasal
passageway detect chemical and send
impulses to your brain.
• Taste is also a chemical sense
– Taste buds: sense organs that detect taste
• Located on surface of tongue and mouth
• Much of taste has to do with smell also
Tongue and Taste