sections 1 and 4. levels of organization human body consists of cells- smallest unit tissues organs...
TRANSCRIPT
Levels of OrganizationHuman body consists of Cells- smallest unitTissuesOrgansOrgan systems- largest unit
CellsThe cell is the basic unit of
structure and functionComplex organisms are made of
many cellsHuman body contains about 100
trillion cellsNucleus directs the cell’s activitiesCytoplasm is made of clear,
jellylike substance containing many cell structures called organelles (the material within a cell apart from the nucleus)
Cheek Cells
TissueTissue- a group of specialized cells that
perform the same function4 basic types of tissues in the human
body: muscle tissue, nervous tissue, connective tissue, and epithelial tissue
Muscle tissue- contract or shorten to make part of your body move
Nervous tissue- carries electrical messages back and forth between the brain and other parts of the body
Connective tissue- provides support for your body and connects all its parts
Epithelial tissue- covers the surfaces of your body, inside and out (skin and lining of the digestive system)
Your skin is epithelial
tissue
Organs and Organ SystemsAn organ is a structure that is composed of
different kinds of tissue and does a specific job (like a stomach, heart, brain, lungs)
Organ System- is a group of organs that work together to perform a major function
Human body has 11 organ systems
Organs and Organ SystemsEach organ in your body is part of an organ system, which is
a group of organs that work together to perform a major function.
Integumentary System- hair, nails, skin- the body’s covering
Immune System- protects your body from disease•Pathogens- bacteria or viruses•Antibodies- proteins that destroy pathogens•Immunity- the ability to destroy pathogens before they can cause disease
Reproductive System- male and female systems that produce sex cells
HomeostasisThe different systems work together and depend on
each otherHomeostasis is the process by which an organism’s
internal environment is kept stable in spite of changes in the external environment. (Key concept)
No matter what the temperature around you your temperature stays the same (except when you are sick but it goes back to normal eventually)
Our body maintains homeostasis by sweating when we are hot or shivering when we are cold
Stress- the reaction of your body to potentially threatening, challenging, or disturbing events
Homeostasis is restored after the stress is gone
Machines and the BodyForce-is a push or a pull on an object as
described by its strength (or magnitude) and direction in which it acts
Standard unit for magnitude of force is newton (N)
Arrow represents the direction and strength of the force
Work- when you exert a force on an object that causes the object to move some distance in the same direction as the force
Work= Force x DistanceMachine- a device that allows you to do work in
a way that is easier or more effective
LeverLever- a rigid rod that is free to rotate around a fixed
pivot pointFulcrum- a fixed point that a lever rotates around
(the pivot point of a lever)
Effort Force
Resistance Force
Fulcrum
A lever makes work easier by changing the amount of force exerted, the distance over which the force is exerted, or the direction of the force. (key concept)
Effort force- the force that is exerted on the lever (the force applied to a machine)
Effort distance- the distance pushed downResistance force- the force that a lever exerts
on an objectResistance distance- the distance the lever
pushes up on an objectEffort force
Resistance force
Mechanical AdvantageThe number of times a lever increases a force
exerted on itComparing the effort force to the resistance
force you can find the advantageMechanical Advantage= Resistance Force
Effort Force
The Law of the LeverLever may be balanced when the effort force
and resistance force are differentEffort arm- the distance from the fulcrum to
the effort forceResistance arm- the distance from the
fulcrum to the resistance force
LeversLevers are classified according to the
location of the fulcrum relative to the input and output forces.
*hint- you might want to draw a stick figure similar to the third-class lever in figure 25 for the test
Simple Machines in the BodyMost of the machines in your body are levers
that consist of bones and muscles.
Example of a fulcrum for a first-class lever in your body is the joint at the top of your neck
Example of a fulcrum for a second-class lever is the ball of your foot
Examples of fulcrums for third-class levers are the thigh joint, wrist joint, shoulder joint, knee joint, elbow joint
Most common type of lever in your body is the third-class lever