Transcript File

Human Body Systems
Part 3
7th grade
The Skin
• A. The skin is the largest organ of your
body, the sense organ – it can shrink or it
can enlarge itself.
• B. The skin has 3 layers
– 1. epidermis – outer layer
– 2. dermis- below the epidermis it contains
blood vessels
– 3. fatty layer – insulates the body
• C. Melanin – a chemical that protects your
body and gives it color
– 1. Exposure to the sun, increases melanin
and darkens the skin.
• D. Skin Functions
– 1. protection
– 2. sensory response – touch a hot stove your
hand instantly responds and pulls away
– 3. formation of vitamin D
-4. regulation of body temperature
a. hot – sweat
b. cold- goose bumps
-5. ridding the body of heat waste and
sweating
-6. glands- secrete fluids to destroy some
bacteria
– 7. retains fluids – from water lose in tissues• A. dehydration- the skin discolors and wrinkles, it
loses its elasticity- can cause organ damage
E. Skin Injuries and Repair
1. your skin can be:
a. bruised
b. scratched
c. burned
d. ripped
e. exposed to harsh weather
– 2. Epidermis produces new cells continuously
– 3. Dermis repairs tears
– 4. Bruises are tiny blood vessels that have
burst under the skin
• A. shades of blue, red, and purple healing turn
yellow, greenish
II. The Muscular System
• A. Muscle Control
– 1. Voluntary muscles, you can control: legs,
arms, hands, face.
– 2. involuntary muscles, you cannot control:
blood pumping through body, food moving
through digestive system.
B. Muscle tissue, Three types
1. Skeletal- voluntary muscles that move bone
2. Smooth – involuntary muscles in intestines,
bladder, organs
3. Cardiac – involuntary, only found in heart
• III The Skeletal System
– A. Functions of your skeletal system
• 1. it gives shape and support
• 2. it protects your internal organs
• 3. major muscles are attached to bones and help
them move
• 4. red blood cells are made in the Marrow. 2-3
million cells per second.
• 5. the skeleton contains calcium and phosphorous
that makes bones hard.
• B. Bone Structure
– 1. bones have bumps, edges, round ends,
rough spots, pits and holes.
– 2. Periosteum- a tough membrane on bone’s
surface.
– 3. cartilage- a smooth, slippery, thick layer of
tissue on the end of bones.
– 4. joints – where two or more bones come
together, held together by a band called
ligament.
• C. Two types of joints
– 1. immovable joints – allows little or no movement.
Ex. Skull, pelvis however, a baby’s skull is flexible to
move through the birth canal.
– 2. movable joints – allows body to make wide range
of motion.
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A. Ball – and – socket = shoulder
B. gliding – wrist, ankles
C. hinge – knee
D. pivot- turning head
IV. The Nervous System
• A. Stimulus – how your body responds to
changes in the environment whether
external or internal ex: external, sudden
loud noise
• B. Nerve cells or Neurons – basic
functioning units of the nervous system,
called nerve cells
– 1. messages carried by neurons are called an
impulse
• C. Four parts of the Neuron
– 1. Dendrite
– 2. Soma, cell body with nucleus
– 3. Axon
– 4. Axon terminals
• D. Three types of Neurons
– 1. sensory neurons
• A. receives information and sends it to the brain or
spinal cord.
2. Motor neurons
a. conducts impulses from the brain or spinal cord
to muscles or glands.
b. detects stimuli in the skin and eyes
– 3. Inter-neurons
• A. transports information from the sensory to
motor, in the spinal column in brain
• E Synapses
– 1. A small space between neurons where impulse
moves.
– 2. Chemical is released to create movement.
• F. Two divisions of the Nervous System
– 1. CNS – Central Nervous System
• A. includes brain and spinal cord
• B. there are billions of neurons in the brain
• C. the spinal cord is made up of bundles of
neurons
• D. sensory neurons go to the CNS
2. PNS- Peripheral Nervous System
a. all nerves outside of the CNS
b. cranial nerves – 12 pairs
c. spinal nerves – 31 pairs
d. There are two divisions of PNS
1. Somatic system – controls voluntary
actions, from CNS to skeletal muscles.
2. Autonomic system – control of
involuntary actions, heart rate, breathing,
digestion.
• G. The senses – sense organs are
adapted for intercepting stimuli, such as
light sound, heat, chemicals, or pressure
and converting them into impulses for the
nervous system.
– 1. Vision
• A. Eyes have two structures that refract light,
cornea and lens.
• 2. Retina – the part of the eye that light is finally
focused on.
• C. optic nerve carries impulse to brain where brain
interprets image.
– 2. Hearing
• A. sound waves stimulate nerve cells deep inside
of ear.
• B. Ear – three sections
– 1. outer ear, funnels sound to middle ear
– 2. middle ear, eardrum, anvil, hammer, stirrup
– 3. inner ear, cochlea, semicircular canals, balance.
– 3. Smell
• A. food molecules move into air.
• B. stimulates olfactory nerve cells
– 4. Taste
• A. taste buds, major sensory receptors for taste
• B. 10,000 taste buds
• C. five taste sensations: sweet, salty, sour, bitter,
and MSG (monosodium glutamate).
V. The Endocrine System
• A. Fight or flight
• B. The Endocrine and Nervous System
are the body’s control system
• C. Endocrine Glands
– 1. Hormones – chemicals produced by the
endocrine system
• A. the endocrine gland releases the hormone
directly into the blood.
• B. the blood transports the hormone to the target
tissue.
• D. Glands
– 1. Pineal gland – produces melatonin.
Regulates wake/sleep patterns.
– 2. Pituitary gland – affects growth to
reproduction.
– 3. Thymus gland- production of infection –
fighting cells.
– 4. Thyroid gland- hormones that regulate
metabolic rate.
– 5. Adrenal glands - helps
• 6. Ovaries – female, produce hormones
called estrogen and progesterone
reproductive cycle.
• 7. Testes – male, reproductive organs
testosterone, production of sperm
VI. The Reproductive System
• A. Male and female reproductive systems
are adapted to lead to the birth of a baby.
• B. Female sex hormones create breast
development and eggs in ovaries.
– 1. ovaries – female sex organ
– 2. eggs develop in the ovary
– 3. egg is fertilized in the oviduct
– 4. embryo develops in the uterus
• C. Male sex hormones create facial hair
and sperm.
– 1. testes and sperm – male sex organ
– 2. semen – mixture of sperm and fluid
VII. Human Life Stages
• A. Zygote – sperm has entered the egg
and attaches itself to the uterus wall
• B. Period of development, pregnancy
• C. Embryo – after zygote attaches to wall
• D. Amniotic sac forms around embryo.
– 1. amniotic fluid, clear liquid acts as a cushion
for embryo and stores nutrients and waste.
• E. Fetus, after first two months of
pregnancy.
– 1. ninth month, fetus develops a white greasy
coating which helps the movement of the
baby through the birth canal.
• F. The Birthing Process
– 1. Labor, muscular contractions of the uterus.
– 2. Amniotic sac breaks
– 3. Baby is pushed out
G. Stages After Birth
1. infancy – newborn to 18 months
2. childhood – last until puberty
3. adolescence – puberty until 18 years old
H. Adulthood – final stage of development.