Cells, Tissues, and Organs

The organization of multicellular organisms

In this lesson, you will learn…

• The difference between unicellular and multicellular organisms

• that cells of similar structures are organized into tissues

• that several tissues may make up an organ

• that organs are organized into systems

Unicellular Organisms

Paramecium Amoeba

Unicellular Organisms

• Paramecium– Microscopic organism– Found on surface of water

(eg: pond, river)– Has hair surrounding the

body for movement– Has a mouth

Unicellular Organisms

• Amoeba– Often found at bottom of ponds

or under rocks– Does not move fast– No arms, legs, eyes, mouth– Eats by surrounding its prey with

its body – Lives only for 2 days – Reproduce by spliting itself into

2 new amoebas

Multicellular Organisms

• Have many different cells

• Different cells perform different functions

• Examples– Plants– Humans

Cells in a Human

• Examples– Red blood cell (transport

oxygen)

– Nerve cell (have nerve fibres to transmit signals to and from the central nervous system)

Cells in a Plant

• Examples

– Root hair cell

– Leaf guard cell

From cells to tissues

• Tissue

– Group of similar cells that are specialized to perform a particular function

Tissues in a Human

• Epithelial tissue– Covering or lining tissue

to protect structure beneath it

Connective tissue– Joins, stores or

supports all parts of an organism

Tissues in a Human

• Muscle tissue– Cause movement

• Nerve tissue– Carry messages

from one part of body to another by conducting electrical signals

Tissues in a Plant

• Epidermal tissue

– Protects plant against injury and losing too much water

• Vascular tissue

– Transports materials within a plant

Tissues in a Plant

• Photosynthesis tissue

– Carries out photosynthesis in a plant

From Tissues to Organs

• Organ

– Group of specialized tissues that are gathered in a certain part of the body to perform a particular function together

Organs in a Human

• Examples– Skin – Lungs– Heart

Organs in a Plant

• Examples– Leaves– Stem– Roots– Flowers

From Organs to Systems

• System

– Different organs working together to perform a major function in an organism

From Systems to Organisms

• Organism

– Made up of different systems working effectively in a coordinated manner

The Human Body

- An organism

CELLS

TISSUES

ORGANS

ORGAN SYSTEMS

ORGANISM

Division of Labor• Each cell in a multicellular organism

does not perform all the bodily functions.

• Each type of cell is specialized to perform one particular function.

• Different functions in a multicellular organism can be performed at the same time by dividing the work.

Division of Labor

• Division of labor

– Sharing different functions in an organism among its cells, tissues, organs and systems ensures smooth running and effective working of the different parts in an organism as well as the organism as a whole

Main Organ Systems in a Human

• Respiratory system

• Digestive system

• Skeletal system

• Blood circulatory system

• Excretory system

• Muscular system

• Nervous system

Respiratory System

• Respiration– Process in which cells release energy from

the food we eat– Oxygen is required– Carbon dioxide is removed

Respiratory System

Nasal Passage

Pharynx

Trachea

Bronchus

Larynx

Bronchioles

Alveoli

Respiratory System

• Mechanics of breathing

Exhalation

Inhalation

Digestive System

• Digestion

– Process in which large, insoluble food substances are broken down into smaller, soluble food substances for absorption into blood

Digestive System

Villi

Mouth

Liver

Pharynx

StomachLarge Intestine

Small Intestine

Oesophagus

Skeletal System

• Supports our body

• Gives us shape

• Protects our organs

• Enables movement

Skeletal System

Circulatory System

• Transports nutrients, gases, water and hormones to different parts of the body

• Include red blood cells, white blood cells, heart, blood vessels

Red blood cells

White blood cells

Blood Circulatory System

Excretory System• You must also get rid of fluids. The results of the

excretory system is urine. • Kidneys are the core organs involved in the excretory

system. Kidneys act as a filter. Eventually all of the blood in your body passes through the kidneys and they are able to do their filtering magic. The kidneys pull harmful molecules out of your bloodstream and leave the ones that are good for you.

• Related body parts include the ureters, bladder, and urethra. Once the urine passes through your urethra, it's out of your body.

Muscular System

• Enables movement by contraction and relaxation of muscles

• 3 muscle types:– Skeletal muscles– Smooth muscles– Cardiac muscles

Muscular System

DeltoidPectoralis major Biceps brachi

Gluteus maximus

Rectus femoris

Gastrocnemius

Nervous System

- Consists of the brain, spinal cord and nerves found throughout our body

- Controls and coordinates functions throughout our body

- Enables us to respond to changes around us

Nervous System

Cerebrum

Corpus callosum

Cerebellum

Thalamus

Hypothalamus

Midbrain

Pons

Medulla oblongata

Spinal cord

Plant Transport System