1.3 How do cells work
together in the human
body?
SNC2P1
Unit #1: Biology
Levels of Biological Organization
CELLS
Single-Celled ORganismS
• Like all single-celled organisms, the AMOEBA relies on the
organelles in just ONE CELL to perform all of its life’s functions
Amoebas are plentiful in nature. They can strive in salt
or freshwater, but are often found in mud beneath the
water than floating in the water itself. The common
amoeba species, are often found attached to the
underside of leaves of water plants such as mosses.
There are also about a dozen parasitic amoeba species
that live inside the digestive tract of human beings and
most animals.
Multi-cellular Organisms Need
Specialized cells
•
However, larger organisms with many cells need
specialized cells to perform specific functions. They also need to
work together (as a tissue) to carry out specific tasks
.
Specialized
construction
workers are need
to carry out the
different jobs at a
construction site.
Specialized cells in the human body are
needed to do different jobs
Therefore, the definition of
Cell Specialization is….
•
CELL SPECIALIZATION: refers to the fact that different types of cells have different structures and
abilities that enable them to perform their functions efficiently.
•
 In total there are 200 different types of cells in the human body…below is a list of just a handful.
Specialized
Cells
How Structure Influences Function
Muscle Cells
•
•
•
Long and thin structure allowing the cells to change shape when they
contract
Some have a branching pattern, which increases muscle strength
Cells have several mitochondria to supply energy
Nerve Cells
(called
neurons)
•
Cells have long, threadlike branches that help them to receive and transmit
signals from one cell to another
Red Blood
Cells
•
Doughnut-like shape with a sunken middle to provide a large surface area to
carry oxygen
Bone Cells
•
Have a framework of hard material containing minerals that provide strength
and support to hold the cells together
Skin Cells
•
Thin, flat, and layered cells that form a gap-free barrier to keep out invaders
(viruses and bacteria) and to keep in moisture.
So the next question is then… HOW
do cells becomes specialized????
• ANSWER: CELL DIFFERENTIATION: which is the series of events
through which stem cells develop into specialized cells.
• All cells start out as identical cells called STEM CELLS
• Each stem cell then has the potential to become SPECIALIZED
• Cells become specialized through the process of DIFFERENTIATION
Cell Differentiation
Stem Cells
Internal/External
Signals
Gene Regulation
Cell Specialization
Why are Scientists interested in
STEM CELLS?
•



Stem Cells are Interesting to Scientists because….
Stem cells have the potential to differentiate into any specialized cell
Stem cells offer the potential to treat diseases
TWO types of stem cells
 Embryonic Stem Cells
 Can make all cell types
 Wider range of medical treatments are possible
 Ethical Issues (they come from embryos/babies)
 Adult Stem Cells
 Can make only a few cell type
 Fewer medical treatments possible
 Ethically not a concern (come from our own tissues)
VIDEO: Stem Cells Explained (3min8sec)
https://www.youtube.com/watch?v=uC0fLXdu56g
TISSUES
Tissues:
A tissue is specialized cells working together to
perform a function
Cells
Tissues
Organs
Introductory Video: Specialized Cells and Tissues (4m26s)
http://www.youtube.com/watch?v=I8uXewS9dJU&feature=youtu.be
Four Major Tissue Types
1.
Epithelium
• Function: Covers the external and internal body surfaces
• Ex. skin, gut, glands, hair, lining of the gut
2.
Connective Tissue
• Function: Strengthens, supports or connects cells and tissues
• Ex. bone, blood, fat, ligaments and tendons
1.
Muscle
• Function: Enables the body to move, exert force or change
shape
• Ex. muscle cells in the stomach, heart, and arm (voluntary and
involuntary muscle)
1.
Nervous Tissue
• Function: Senses, conducts and transmits information
• Ex. brain, nervous tissue and sense cells
Tissues, and Their Cell Types