Organization of
the Human Body
On the cellular level, the structure of the human body is very complex and
designed for efficiency. Every structure, from the different types of cells to
the different organs, has a specific and unique function that all work
together to maintain life. All of these functions are highly regulated and
interactive to provide the processes and chemical products that are
necessary to maintain life.
The basic unit of structure and function of life.
The cell is an organized system that is that made up of small structures, called
organelles. Organelles are found within cells and allow cells to carry out their
functions. Examples of organelles are:
• Nucleus: Control center of the cell, the genes decide which proteins the cell
makes.
• Cell membrane: allows certain substances to pass through into the cell.
• Mitochondria: carry out respiration and provide the cell with energy.
• Cell wall: allows the cell to keep its shape
• Vacuole: storage area for sugars and other minerals.
• Chloroplasts: contain chlorophyll which converts sunlight into sugars for food.
A group of cells of the same type, performing the same function
Tissues
Cells which all have a similar function are
grouped together to form tissues. For
example, muscles are made up of a group of
muscle cells, all specialized to work hard. This
group of cells forms muscle tissue. This
muscle tissue is kept alive by the blood that
supplies it. The blood is supplied through
blood tissue.
A group of tissues that work together to perform a function
Organs
An organ is made of a group of tissues all
working together to perform a specific
function. Examples of organs include the
heart, the lungs, the liver, the stomach, and
the brain.
A group of organs working together to accomplish the same, or similar functions.
The organ system is the highest level of internal organization for all
organisms. An organ system is a group of organs that work together to
perform a job. There are eleven systems in the human body. Example of a
system: the mouth, esophagus, stomach and intestines are part of the
digestive system. All of these organs all work to complete the common
goal of nutrient extraction and absorption.
Homeostasis, which is the body’s ability to maintain a stable
internal environment, is dependent on all of the systems functioning
properly and working together to create balance. There are certain
factors that must be maintained for life to continue. These factors
include temperature, blood glucose levels, blood pH, water balance,
oxygen and carbon dioxide levels.
The systems each functioning independently and normally, as well
in conjunction with other systems creates an internal environment
that is balanced, or in homeostasis.
An example of systems working together to maintain homeostasis is
the process of maintaining blood glucose levels. The digestive system
is responsible for extracting glucose, which is a sugar, from food. The
circulatory system then transports these sugar molecules to the cells, so
that they can create cellular energy that can be used for the different
types of cells to function. The respiratory system brings in the oxygen
that is needed for cellular respiration and removes carbon dioxide as a
waste product. If too much glucose is present, the endocrine system
prompts the pancreas to release insulin to reduce the level. If too little
glucose is present, the pancreas is stimulated to produce glucagon to
release stored glucose from the liver and kidneys. All of this is
ultimately regulated by the brain, which receives messages about
internal and external stimuli from the nerves and neurons.
Quick Review
Complete the following activities and practices to
review the concepts presented in this PowerPoint.
Order the words below in the following pyramid. Have the smallest level on
the bottom and work up to the largest.
Organelle
Organ
Organism
Cell
Organ System
Tissue
Order the words below in the following pyramid. Have the smallest level on
the bottom and work up to the largest.
Organism
Organ
System
Organ
Tissue
Cell
Organelle
Can you name any of the organ systems below?
Can you name any of the organ systems below?
Endocrine
Respiratory
Skeletal
Muscular
Digestive
Circulatory
Nervous
Determine if the following statements are true or false.
Tissues are made from only one type of cell.
Lots of organ systems work
together to make an organism.
An organelle is bigger than an organ
The circulatory system carries
electrical messages around the body
The spinal cord and brain are
organs in the Nervous System
Determine if the following statements are true or false.
Tissues are made from only one type of cell. True
Lots of organ systems work
together to make an organism. True
An organelle is bigger than an organ. False
The circulatory system carries
electrical messages around the body. False.
The spinal cord and brain are
organs in the Nervous System. True
Review Questions
1. What are the functions of these organelles:
a) Nucleus
b) Chloroplast
c) Mitochondria
2. What is the job of the digestive system?
3. What is the role of tissue?
4. What are the components of an organ system?
5. How is homeostasis maintained?
Review Questions
1. What are the functions of these organelles:
a) Nucleus- Control center of the cell
b) Chloroplast- Contain chlorophyll which converts sunlight into sugars for food
c) Mitochondria- Carry out cellular respiration and provide the cell with energy
2. What is the job of the digestive system? To extract nutrients from foods that we eat.
3. What is the role of tissue? Group of like cells that carry out a specific function.
4. What is an organ system? Group of organs and tissues that perform together to
accomplish a specific function.
5. How is homeostasis maintained? By the different systems functioning properly
independently and together as a group.