Transcript Cells and Systems

Cells and Systems
Unit Review
Living Organisms
• the basic unit of life is called a CELL
– cells are organized into tissues and organs to perform
different functions
• unicellular organisms → single-celled
• multicellular organisms → many-celled
• all organisms
–
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–
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need energy from the sun or food
respond and adapt to their environment
reproduce so life goes on
grow
produce wastes (by-product of using energy)
Value of Microscopes
• made of small lenses
• magnify objects so we can see them
• Leeuwanhoek made the first one
– magnified things 300x
– he saw single cell organisms
• today
– compound light microscopes can magnify something
2000x
– electron microscopes can magnify something
2,000,000x
Parts of a Compound Microscope
Structures
of a Cell
Cell Membrane – containment
Cell Wall – structure
Cytoplasm – distribution
(food, oxygen)
Nucleus – control centre
Vacuole – storage containers
Chloroplast – photosynthesis
Cell Functions
• cells need a constant supply of oxygen,
water and food to work
• they also need to get rid of waste products
• everything that comes into or goes out of a
cell must pass through the cell membrane
– the membrane is selectively permeable →
allows some substances and stops others
Fluid Movement in Cells
• diffusion - spreading out of particles from
an area of more concentration to areas of
less concentration
– food, oxygen, etc. move into cell
– waste product move out of the cell
• osmosis – diffusion of water through a
selectively permeable membrane
Fluid Movement in Plants
• plants need a lot of water to make food by
photosynthesis
• water comes into the plant by through the root
hairs (by osmosis)
• air (oxygen) comes in through openings on
leaves called stomata
• water is lost from the plant by transpiration (a
types of evaporation)
• 2 types of vascular tissues that transport things
around inside the plant:
– phloem tissues transport sugars made in leaves, to
the rest of the plant
– xylem tissues transports water and minerals from
roots to other parts of the plant
Cell Specialization & Organization
• cells are specialized for particular tasks
• cells with the same structure and function are
grouped into tissues
– e.g. muscle tissue, nerve tissue, skin tissue
– e.g. phloem and xylem tissue
• groups of different tissues form organs
– e.g. stomach, lungs, heart, eyes
– e.g. roots, stems, leaves
• organs work together in systems
– e.g. digestive system, circulatory system
– e.g. root system (below ground) and shoot system
(above ground)
• multi-cellular organisms have advantages
over single-celled organisms:
– can grow large
– can live in a variety of environments
– can get energy from a variety of foods
– can work more efficiently
Human Body Systems
System
Digestive
Respiratory
Circulatory
Nervous
Excretory
Functions
breaks down food, absorbs food particles,
eliminates waste
exchanges oxygen and carbon dioxide
circulates blood which transports food
particles, dissolved gases and other
materials
controls and co-ordinates body activities;
senses internal and external changes
regulates blood composition and gets rid
of waste fluids
Body Systems & Human Health
• 8% of adult body is made up of blood
Component % of Blood
Volume
Main Function
plasma
55%
carries nutrients, waste products,
hormones & blood cells
carry oxygen
red blood
cells
44%
white blood
cells
<1%
defend body against infection &
disease
platelets
<1%
cause blood to clot at wounds to
prevent blood loss
Disorders in Human Body Systems
System
Digestive
Disorders
•low fibre, high fat, to much sugar, to much salt, smoking,
alcohol, etc can cause problems such as ulcers in stomach,
bowel disease, cancers, etc.
Respiratory
•smoking and pollution irritate lining of lungs resulting in cough
& difficulty breathing; can lead to lung cancer
Circulatory
•disorders of circulatory system are the leading cause of death
in North America
•most common problem is high blood pressure which affects
circulation and can lead to heart attach (damage to heart
muscle) and strokes (brain damage)
•smoking, poor diet, and lack of exercise contribute to the
problem