Transcript The Human Body Systems

The Human Body Systems
Chapters 35 -39
Levels of Organization
• Cells – basic units of structure.
• Tissues – groups of similar cells that
perform a single function.
• Organs – groups of tissues that work
together to perform a complex function.
• Organ systems – groups of organs that
perform related functions. (11 systems
make up the human body)
4 Types of Tissues
• Epithelial – tissue covers body
surfaces like internal organs.
• Connective – supports the body and
connects its parts.
• Nervous – carries messages throughout
the body.
• Muscle – enables the body to move.
Homeostasis
• Organ systems work together to maintain stable
conditions in the body.
• Homeostasis – is the process of maintaining
stable internal conditions.
• Feedback inhibition- process that enables
the body to maintain a stable temperature.
• Ex. The nervous system senses when the
body cools and signals the cells to produce
more heat.
Skeletal System
• Supports the body.
• Protects internal organs.
• Provides attachment sites for muscles
to move body parts.
• Stores mineral reserves.
• Provides a site for blood cell formation.
• There are 206 bones found in an adult
human skeleton.
Skeletal System
• 2 Parts:
– Axial – skull, spine, and ribs.
– Appendicular – all the bones associated with the
arms & legs, including bones of the shoulders, hips,
hands, & feet.
• Made up of:
– Periosteum – tough connective tissue.
– Compact bone – thick layer of tubes (Haversian
canals) which contain blood vessels & nerves.
– Bone marrow – cavities of soft tissue.
• Red marrow produces blood cells.
• Yellow marrow is fat.
Skeletal System
• Cartilage – type of connective tissue that
is tough but flexible.
• The skeleton of an embryo is
composed almost entirely of cartilage.
• Joint – place where one bone attaches to
another bone and permits the bones to
move w/o damaging each other.
Skeletal System
• 3 types of Joints:
– Immovable – skull, no movement.
– Slightly movable – spine, allow small/restricted
movement.
– Freely movable – movement in one or more
directions.
• Ball-and-socket joints – allow the widest range of
movement of any joint. Ex. Shoulder.
• Hinge joint – permit only back-and-forth movement. Ex.
Knee.
• Pivot joint – one bone rotates around another. Ex. Elbow.
• Saddle joint – one bone slides in two directions. Ex. Hand.
• Ligaments – strips of tough connective
tissue that connects bone to bone.
Skeletal System
• Arthritis – disorder that involves
inflammation of the joints.
• Osteoporosis – condition in which bones
weaken and could fracture or break.
Muscular System
• Muscle tissue is over 40% of the mass of the
human body.
• 3 Types:
– Skeletal – usually attached to bones; appear striped
(striated); responsible for voluntary movement. Ex.
Dancing, running.
– Smooth – line blood vessels & the digestive tract; not
striated and not under conscious control. Ex. move
food through the digestive tract & control the flow of
blood through the circulatory system.
– Cardiac – found only in the heart; not under
conscious control.
Muscular System
• Fibers – Skeletal muscle cells.
• Myofibrils – smaller structures of fibers.
• Filaments – even smaller structure of
myofibrils which can be thick or thin.
• A muscle contracts when the thin
filaments in the muscle fiber slide over
the thick filaments.
Muscular System
• Impulses from motor neurons in the nervous
system control the contraction of skeletal
muscles.
• The more muscle cells that are stimulated to
contract, the stronger the contraction.
• Tendons – tough connective tissues that
connect skeletal muscles to bones.
• Regular exercise helps maintain strength &
flexibility of muscles, strengthens bones, &
prevents injury.
Integumentary System
• The skin is the single largest organ of the
body.
• Serves as a barrier against infection
and injury.
• Helps regulate body temperature.
• Removes waste products from the
body.
• Provides protection against ultraviolet
radiation from the sun.
Integumentary System
• 2 Layers:
– Epidermis – outer layer which is made of flat,
dead cells.
• Produces keratin which is a tough, fibrous protein that
helps keep the epidermis flexible & waterproof.
• Contains melanocytes which produce melanin ( a dark
brown pigment that helps protect the skin from
ultraviolet rays).
– Dermis – inner layer.
• Contains nerves, blood vessels, glands, & other structures
not found in the epidermis.
• Works with other organs to maintain homeostasis.
• Regulates body temperature.
– Sweat glands produce sweat when the body gets too hot.
Sweat evaporates from the skin & cools the body.
Integumentary System
• Too much sunlight can produce skin
cancer.
• Protect yourself by wearing hats,
sunglasses, protective clothing, and
sunscreen with a sun protection factor
(SPF) of at least 15.
Integumentary System
• Other parts of this system:
– Hair
• Composed of keratin.
• On the head – protects scalp from sunlight and cold.
• In the nostrils & around eyes – prevents dirt from entering the
body.
• Produced by hair follicles in the dermis.
– Nails
• Composed of keratin.
• Grow from an area called the nail root.
• Protect tips of fingers & toes.
Nervous System
• Controls and coordinates functions throughout the
body.
• Responds to internal and external stimuli.
• Impulses – electrical signals that carry messages.
• Neurons – smallest structural & functional unit that
transmit impulses.
• Dendrites – short branches that carry impulses toward
the cell body.
• Axon – long fiber that carries impulses away from the
cell body.
• Synapse – at the end of an axon and is where a neuron
can transfer an impulse to another cell.
• Neurotransmitters – transmit impulses across the
synapse.
Nervous System
• 2 Major Divisions:
– Central Nervous System
•
•
•
•
control center of the body.
Relays messages.
Processes information.
Analyzes information.
– Peripheral Nervous System
• carries messages back & forth b/w the
environment & the central nervous system.
Nervous System
• Central Nervous System
– Brain – divided into several regions:
•
•
•
•
Cerebrum – controls voluntary (conscious) actions.
Cerebellum – controls actions of the muscles.
Brain stem – controls basic body functions.
Thalamus – receives impulses from the senses & sends
them to the cerebrum.
• Hypothalamus – connects the nervous & endocrine systems.
– Spinal cord – connects the brain & the rest of the
body.
• Processes certain kinds of information, reflexes.
• Reflex – a quick, automatic response to a stimulus.
• Ex. – sneezing.
Nervous System
• Peripheral Nervous System
– Sensory division – transmits impulses from
sensory neurons to the central nervous
system.
– Motor division – transmits impulses from the
central nervous system to the muscles &
glands.
• Somatic – voluntary actions.
• Autonomic - involuntary
Nervous System
• Sense Organs
– Sensory receptors are neurons that react to
stimuli in the environment & send impulses to
the central nervous system.
– 5 Types
•
•
•
•
•
Pain receptors – respond to pain.
Thermoreceptors – respond to temperature.
Mechanoreceptors – respond to pressure.
Chemoreceptors – respond to chemicals.
Photoreceptors – respond to light.
Nervous System
• Vision
– Pupil – light enters through this opening in
the front of the eye.
– Lens – light passes through.
– Retina – focuses the light.
• Photoreceptors are on the retina
– Rods are sensitive to dim light.
– Cones are sensitive to colors.
Nervous System
• Hearing
– Sound enters the ear
– Cochlea – fluid filled structure where the
vibrations create pressure waves.
• Sensory receptors are in the cochlea.
– Send impulses to the brain.
– Semicircular canals – 3 tiny canals that
help the central nervous system maintain
balance.
Nervous System
• Taste
– Taste buds - Sense organs that detect taste.
• Touch
– Skin – largest sense organ.
• Contains sensory receptors that respond to:
– Temperature
– Touch
– Pain
Nervous System
• Drugs – any substance, other than food, that changes the
structure or function of the body.
– Stimulants – speeds up actions controlled by the
nervous system. Ex. Heart rate.
– Depressants – slows down actions that are controlled
by the brain.
• Cocaine causes the sudden release of a substance in the
brain called dopamine.
– Opiates – act like natural brain chemicals called
endorphins (normally help overcome pain).
• Marijuana can cause memory and concentration problems.
– Alcohol – is a depressant that slows down the central
nervous system.
• During pregnancy it may cause fetal alcohol syndrome &
babies could have a birth defect.
Circulatory System
• Consists of the heart, blood vessels, &
blood.
• The human body contains 4 – 6 liters of
blood.
• With the respiratory system, it supplies the
body’s cells with nutrients & oxygen and
removes carbon dioxide & other wastes
form the body.
Circulatory System
• Heart
– Composed almost entirely of muscle.
– Myocardium – thick layer of muscle that forms the
walls of the heart; contracts and pumps blood.
– 4 chambers – 2 atria (top) & 2 ventricles (bottom).
– 2 halves
• Pulmonary circulation – Right; pumps blood from heart
to lungs.
• Systemic circulation - Left; pumps blood to the rest of
the body.
– Valves – prevent blood from flowing backward in
the heart.
Circulatory System
• Aorta – large blood vessel that leaves the heart
• 3 types of vessels:
– Arteries – large thick vessels that carry blood
away from the heart to capillaries.
– Capillaries - smallest vessels that bring
nutrients & oxygen to the cells & absorb carbon
dioxide & other wastes.
– Veins – blood from the capillaries enters these
large, thin vessels which return blood to the
heart.
Circulatory System
Blood Pressure – The force of the blood
in the arteries caused by the heart
pumping.
• It keeps the blood flowing through the
body.
• Controlled by the autonomic nervous
system and Kidneys.
Diseases of the
Circulatory System
• Cardiovascular Disease are the leading
causes of death.
– high blood pressure
– Atherosclerosis – fatty deposits build up in
the arteries.
– Lead to heart attack and stroke.
– Easier to prevent if you exercise
regularly, eat a low-fat diet, control
weight, & don’t smoke.
Blood & the Lymphatic System
• Plasma – fluid portion of the blood; 90%
water; helps clot blood & fight infections.
• Red blood cells – transport oxygen.
• Hemoglobin – found in red blood cells; binds
to oxygen & carries it throughout the body.
• White blood cells – guard against infection, fight
parasites, & attack bacteria.
• Lymphocytes – produce antibodies.
• Platelets – help blood clot.
Blood & the Lymphatic System
• As blood circulates, some fluid leaks from the
blood into surrounding tissues. This fluid is
called lymph.
• Lymphatic System consists of:
– Network of vessels
– Lymph nodes
– Organs (ex. spleen)
• The system collects lymph & returns it to the
circulatory system
• It also helps absorb nutrients & fight infections.