The Nervous System
Nervous
System
Central
Nervous
System
is the system that is made up of structures that control the actions and reactions of the body in
response to stimuli from the environment.
Consists of two parts: the central nervous system and peripheral nervous system
made up of the brain and spinal cord
Brain – is the body’s central command center.
The brain is made up of three parts: cerebrum, cerebellum, and brain stem
Cerebrum – is for thinking and problem solving and storing memories
Cerebellum – area where information from the body is processed such as, position and
coordination of movements.
Brain Stem – connects the brain to the spinal cord. The medulla is connected here. It
controls blood pressure, body temperature, heart rate and involuntary breathing.
Spinal cord – allows your brain to communicate with the rest of the body. Is made up of
bundles of nerves.
Peripheral
Nervous
System
there are two main parts: sensory and motor AND there are processes you have no control over
called involuntary processes like the beating of your heart. The processes you can control are
called voluntary like the movement of your arms.
How do
signals
move?
The nervous system works by receiving information from the outside environment and
translating that information into electrical signals. Those signals are sent from the brain to
the rest of the body by special cells called neurons (cell that moves messages in the form of fast
–moving electrical energy called impulses).
Neurons carry information from the body to the brain, and carry instructions from the brain
back to the rest of the body.
Neuron
Is a short, branched
extension of the cell body.
Extensions of
the neuron.
Main senses
Sight, touch, hear, taste, smell
The Endocrine System
Endocrine
hormones.
System
How do
hormones
work
Glands of
The Endocrine
System
controls body functions and helps maintain homeostasis by using
Hormones – is a chemical messenger made in one cell or tissue that causes
a change in another cell or tissue in a different part of the body.
Hormones are produced by endocrine GLANDS or tissues. GLANDS are a
group of cells that make special chemicals for your body.
hormones travel through the bloodstream. They travel from the endocrine
gland where
they were made and will go only to the target cell.
Pituitary gland – main control center of the endocrine system; stimulates
growth and
sexual reproduction.
Hypothalamus – is a gland in the brain that controls the release of
hormones from the pituitary.
Pineal Gland – produces hormones that control of sleep, aging,
reproduction, and body temperature.
Thyroid – control your metabolism
Parathyroid gland – controls calcium levels in the blood
Ovaries and Testes – makes hormones responsible for reproduction
Pancreas – regulates blood sugar levels.
Adrenal gland – control’s body’s fight or flight response
The Digestive System
Digestive
System
Mechanical digestion – Is the breaking, crushing, and mashing of food.
Causes a physical change in food because it changes shape.
Chewing is a type of mechanical digestion.
Chemical Digestion – process by which large food molecules are broken
down into smaller molecules so that they can pass through the
bloodstream. Enzymes help break down the large molecules.
Parts of
the digestive
System
Mouth – place where digestion begins; both mechanical and chemical
digestion occur here.
Esophagus – tube that leads into the stomach. Food is moved down by the
muscular contractions called peristalsis.
Stomach – a muscular bag that crushes food and contains acids and
enzymes for killing bacteria and breaking down proteins. The walls of the
stomach contain layers of smooth muscle so it can churn and mix food.
Small Intestines – after leaving the stomach the food mixture enters the
small intestine. The S.I. is a muscular tube where most chemical digestion
takes place. Most nutrients are absorbed into the bloodstream. Nutrients
are absorbed by the help of folds, villi, and microvilli. Folds increase the
surface area, the microvilli absorb nutrients.
Large Intestine – most water and nutrients are absorbed. Solid waste is left
over and eventually eliminated from the body. Cell walls of plants can’t be
absorbed so they are passed through.
The Excretory System
Excretory
System
Eliminates cellular wastes from the body through the lungs, skin, and
kidneys.
Urinary System
Kidneys – a pair of organs that remove waste from the blood. Fluid is
filtered from the blood. Water and the wastes filtered out of the blood is
called urine.
Ureters – Urine forms in the kidneys; urine then travels through the ureters
(tubes) to the bladder
Bladder – saclike organ that collects urine Voluntary muscles will squeeze
out urine when the time comes.
Urethra – a tube urine travels through to exit the body
How does the
urinary system
maintain
homeostasis?
The excretory and endocrine work together to help maintain homeostasis.
Chemical messengers called hormones signal kidneys to filter more or less
water or salt.
The Immune System
Immune System
External defenses – begins with the skin which is your body’s first line
of defense. Mucus in the nose and saliva in the mouth will wash the
pathogens away into the stomach where they are digested. Nails,
hair, and sweat and oil glands also help in keeping our bodies safe
from harmful organisms. These parts all make up the integumentary
system.
Internal Defense – should pathogens enter the body, the body
responds quickly to keep them out. Blood flow increases to an
injured area to repair it quickly, the body’s temperature may increase
to slow the growth of the bacteria. White blood cells will recognize,
attack, and destroy foreign substances in the body.