Table of Contents
Chapter 1
Characteristics
of Life
How Humans fin into the Natural
World
Science is both a body of
knowledge and a Process
Sources of Scientific
Information vary in Style and Quality
Learning to be a Critical
Thinker
The Role of Science in Society
Chapter 2
All
Matter Consists of Elements
Atoms
Combine to form Molecules
Life
Depends on Water
The
importance of the Hydrogen Ions
The
Organic Molecules of Living Organisms
Carbohydrates:
Used for Energy and Structural Support
Lipids:
Insoluble in Water
Proteins:
Complex Structures Constructed of Amino Acids
Enzymes
Nucleic
Acids Store Genetic Information
APT
Carries Energy
Chapter 3
Cells are Classified According to their Internal
Organization and Cell Structure Reflects Cell Function
A
plasma Membrane Surrounds the Cell
Molecules
Cross the Plasma Membrane in Several Ways
Internal
Structures Carry out Specific Functions
Cells have Structures for support
and movement
Cells Use and Transform Matter and
Energy
Chapter 4
Tissues
are Groups of cells with a Common Function
Epithelial Tissues cover body
Surfaces and Cavities
Connective Tissue Supports and
Connects Body Parts
Muscle Tissue Contract to Produce
Movement
Nervous Tissue Transmits Impulses
Organs and Organ Systems Preform
Complex Functions
The Skin as an Organ System
Multicellular Organisms Must
Maintain Homeostasis
Chapter 1 Bio
Characteristics of Life
Although all living and non-living things are
made up of almost the same 100 different elements living things are very
different. Living things have a unique
molecular composition that is considered the molecules of life. All living things are made up of cells. They are able to grow and reproduce. Living things can respond to the environment around
them making them unique to non-living things.
They can also maintain homeostasis which means the internal body
regulates everything that happens within it.
All living things evolve enabling them to survive. Lastly, living things
require energy, and besides plants, all living things need food and water.
How Humans fin into the
Natural World
I have discovered that how humans
fit into the natural world is a lot more in depth than I had originally
realized. First it is best understood
when starting at the beginning. Living
things are grouped by characteristics and placed into three domains and are
then classified into kingdoms. Domain
Archaea is a single celled prokaryote (no membrane found nucleus) and is in
Kingdom Archaea. Domain Bacteria is also
a single celled prokaryote (no membrane found nucleus) and is in Kingdom
Bacteria. Domain Eukarya have a nucleus and are single or multi cellular. Domain Eukarya has four kingdoms: Kingdom
Animalia (have organs and must eat), Kingdom Plantae (plants who use the sun to
photosynthesize), Kingdom Fungi (recycles waste into food) and Kingdom Protista
(single complex cells). Humans are
classified in the Kingdom Animalia and are in the subgroup vertebrates. Within vertebrates humans are mammals. Down to primates and the scientific name is
Homo Sapien meaning thinking man. Species is the smallest unit of the
classification system and the second smallest is genus. All humans belong to
both the genus and species classification.
Humans have defining features
that separate us from other animals.
Humans have a large brain in proportion to their bodies. There are many theories as to why humans
brains evolved but no one knows for sure.
Another feature that makes humans unique is opposable thumbs. Even though other primates have thumbs,
humans are the only animals who have the right muscles to precisely pick up tiny
objects. Humans are the only mammals who
walk upright on two legs called bipedalism (excluding birds). The last defining feature of humans is the
capacity both written and spoken language.
All animals communicate but humans are the only ones who have two
complex forms of communication.
Science is both a body of
knowledge and a Process
Science is the study of the
natural word and can be divided into two groups. The first group is knowledge about the world
and the second is the process in which to acquire knowledge. The second is also known as the scientific
method and is used to test ideas. There
are five steps that might have to be repeated in the scientific method. Step 1 Is to observe and generalize
(inductive reasoning). Step 2 Is to come up with a hypothesis which is a
tentative explanation for an observation, phenomenon, or scientific problem
that can be tested by further investigation.
(http://www.thefreedictionary.com/hypothesis,
9 Febuary 2012, Page 1) Step 3 is to make a testable prediction that is both
ethical and reproducible (deductive reasoning).
Step 4 Experiment and observe (inductive reasoning). Step 5 if necessary modify and repeat the
hypothesis as many times as needed. A
hypothesis can never be proved true, only supported or disproved. Experiments are well planned and performed
under controlled conditions. Many
controlled experiments are conducted to make sure a medicine or product is safe
for consumers. Controlled experiments take into account all the variables
except for the controlled variable. A group of people are specifically chosen
to take part in the experiment. That
group is then split into two groups. The
people in the experiment don’t know which group is receiving the placebo and
what group is receiving treatment. Then
observations and data is recorded on the two groups of test subjects. At the end of the experiment the results are
compared between the two groups of test subjects. This is only the start to supporting the
hypothesis. Many more experiments will be done to make sure all the information
is complete enough to release a safe product.
(http://images.search.yahoo.com/images,
8 Feb 2012)
Sources of Scientific Information vary in
Style and Quality
There are many different
information sources out there. The
source that is very popular right now is the internet. On the internet you have to be careful that
you are receiving correct information.
Due to the vastness of the internet it is hard to regulate and control
if the information is accurate. Other
sources of scientific information are magazines and newspapers. These sources are used to disperse new
information quickly so many people can receive it. Then there is books and science magazines that
target a specific group of individuals who are educated enough to grasp what
the author is saying. Lastly, in
peer-reviewed journals scientists often communicate with other scientists. These journals are written very technical and
the main goal is to be able to communicate with other scientists.
Learning to be a Critical
Thinker
I believe learning to become a
critical thinker will benefit many aspects of my life. Being skeptical will allow me not to necessarily
always believe what I am told but question the information given. To find any evidence that can back up the
information being offered. By using
statistics we are able to have confidence in what is being presented. It is also very helpful to be able to read
and understand graphs. This is important
because the information is sometimes shown in a way that is deceiving unless
you can point it out. Scientific evidence is defined as …..
Anecdotal evidence is different because it is short and unverified. For example if a book was written guaranteeing
you something but didn’t really know if they would deliver although some might
get the intended results. Another thing to consider when
receiving information is to question who will profit from the information being
given. How are facts and conclusions
different? Facts are defined as
something that has really occurred or is actually the case. The usual test for
a statement of fact is verifiability that is whether it can be shown to correspond
to experience. Standard reference works are often used to check facts. (http://en.wikipedia.org/wiki/Fact,
page 1, 9 January 2012) Where conclusions are the close or last part; the end or finish, the
result or outcome of an act or process. Or a judgment or decision
reached after deliberation. (http://www.thefreedictionary.com/conclusion, 9 January 2012, Page 1) Next is to
understand the difference between correlation and causation. When someone gets bit by a shark this doesn’t
mean that because people go to the beach that sharks will bite them
(correlation). Where in causation there
is direct cause and effect. For example
someone who smokes cigarettes could get a health related problem directly
caused by smoking.
The Role of Science in Society
Science has done so much for us
(humans) from helping us to better understand a more efficient way to grow
food, harvest wind energy, and the
tsunami warning system in our oceans to name a few. Science does have limits because it can’t
determine what is morally right and wrong. Most humans have some sort of faith or
religion believed in but there isn’t any proof it exists. We as humans use our minds and experiences to
create our truth. When making informed choices
science defiantly helps us do this. We
use science all day long with decisions like what we are going to eat, smoking,
using risky behavior ect. What we decide
is all because science has given us the knowledge to make informed choices. (pic of tsunami warning systems and wind
energy)
Chapter 2
All Matter Consists of Elements
Matter is anything that has mass and occupies space. Chemistry is the study of matter and matter
is made up of elements. Elements cannot
be broken down to simple form and all known elements are listed on the periodic
table. The smallest unit of an element
is called an atom. Atoms have a nucleus
that is the core. They have positive
charged protons and have mass. The shell
surrounds the nucleus and is sometimes called a cloud or mist. Electrons have a negative charge and lack
mass (there is some mass that I haven’t learned about yet).
Atoms have an atomic symbol containing one or two
letters. In neutral atoms the number of
protons will be equal with the number of electrons. Atomic mass is roughly equal to the number of
protons plus neutrons. Atoms that have
either more or less neurons than the usual number are called isotopes. These isotopes have the same atomic number
but have a different atomic mass.
Unstable isotopes are called radioisotopes and they give off energy
particles (radiation). Some
radioisotopes have been useful to scientists and people in the medical field. They have been used in cancer treatment, used
for dating fossils, in diagnostic imaging, and in cardiac pacemakers power
supply.
Atoms Combine to form Molecules
A molecule forms when two or more atoms are in a firm
link. Energy is what fuels life’s
activities and is the capacity to do work.
There are two types of energy.
Kinetic energy is the body in motion and potential energy which is
stored energy. Potential energy is
energy that can be turned into kinetic energy.
Electrons have potential energy and each shell matches to a specific
level of potential energy. Shells that
are farther away from the nucleus contain electrons with more potential
energy. Atoms that have a full shell are
most stable and atoms will interact with each other in hopes of filling their
shells. Chemical bonds link atoms to
form molecules. Chemical bonds are the
attractive forces that hold atoms together.
There are three types of chemical bonds 1. Covalent bonds 2. Ionic bonds
3. Hydrogen bonds. Covalent bonds form
when atoms share an electron. An example
is water H2O. A nonpolar covalent bond
has electrons that aren’t shared. Ionic
bonds are electrically charges atoms or molecules. Ionic bonds have attractive forces between
oppositely charged ions. A negatively
charged ion forms when an atom or molecule gains electrons. Positively charged ions form when an atom or
molecule loose electrons. Hydrogen bonds
form between polar molecules where electrons are not equally shared. Polar molecules have polar covalent bonds
with unequal electrons. They have an
uneven charge distribution but overall are electrically neutral.
Life Depends on Water
We couldn’t survive without water and not only that but 60%
of our body weight is made up of water.
Water molecules are polar. Water is liquid at our body temperature; it
can also absorb and hold heat energy.
Water helps to regulate body temperature and is a biological
solvent. A solvent is liquid in which
other substances dissolve. Solute is any
dissolved substance. Hydrophilic are
polar molecules that are attracted and interact with water. Hydrophobic is nonpolar neutral molecules
that don’t like water and try to stay away from it. Water pushes away molecules that aren’t
polar.
The importance of the Hydrogen Ions
The hydrogen ion is one the most important ions in the
body. The covalent bonds between
hydrogen and oxygen in water are strong and rarely break. An acid can donate hydrogen ions (protons)
and increase hydrogen ion concentrations in solutions. A common acidic drink is orange juice and
soda. Bases can accept hydrogen ions and
lower hydrogen ion concentrations in solutions (alkaline). The pH scale measures the hydrogen ion
concentration. The pH range is between 0-14 with the neutral at 7. Acidic solutions are higher than 7 and
alkaline solutions are below 7. Carbonic
acid and bicarbonate act as one of the bodies most important pair of
buffers. Their job is to minimize the pH
change within the body and help to maintain a stable pH level within body
fluids.
The Organic Molecules of Living Organisms
Although organic molecules were once believed to only
originate from living organisms scientists now know this isn’t true. Carbon is the building blocks of all living
things. Carbon is abundant in the human
body but is much rarer in the natural world.
Carbon is diverse because it can form single or double bonds. There is no size limit of organic molecules
derived from carbon. Macromolecules
consist of thousands + smaller molecules of carbon and are made and broken down
within cells. Macromolecules are built
within the cell by a process called dehydration synthesis. In this process by removing a water molecule
this in turn links molecular units.
Dehydration synthesis builds macromolecules from smaller subunits but it
does require energy to do so. Sometimes
macromolecules need to be broken down in a process called hydrolysis. This process actually releases energy and
uses water to break the macromolecules apart.
(Dehydration is the opposite of hydrolysis)
Carbohydrates: Used for Energy and Structural Support
General formula: Cn(H2O)n
Carbohydrates have the same number of carbons as oxygens as
hydrogen molecules. Lots of living
things use carbohydrates as energy. The
simplest form of sugars is called monosaccharide. Monosaccharide includes glucose, fructose,
galactose, ribose and deoxyribose.
Dehydration synthesis can link monosaccharaides together called
disaccharides. Polysaccharides are
composed of thousands of monosaccharide by chains and branches. This makes it so cells can stock pile energy
to be used later. Plants make and store
starch to be used by plants later.
Animals store and make glycogen for animals to use at a later time. Cellulous is made by plants to be used for
structural support but can be used by animals for energy.
Lipids: Insoluble in Water
There are three important classes of lipids. Triglycerides are energy storing
molecules. Triglycerides are known as
fats or oils. Saturated is fats and
unsaturated is in oils. Triglycerides are stored in adipose tissue and are
energy storing molecules. Phospholipids
make up the main components of the cell membrane structure. One end of the phospholipid is hydrophobic
and the other end is hydrophilic.
Steroids are carbon based and made of four rings. One type of steroid is cholesterol which
hormones, estrogen, testosterone, and pigments are made from.
(http://images.search.yahoo.com/search/images?_adv_prop=image&fr=yfp-t-435-17&sz=all&va=lipids, 12 Feb 2012)
Proteins: Complex Structures Constructed of Amino Acids
Proteins are made up of long chains of amino acids made by
the dehydration synthesis. There are
twenty different types of amino acids that are connected by peptide bonds. Every protein has a specific function that
depends critically on its construction.
The simple primary structure of a protein is represented by the amino
acid sequence. Secondary structure is
in an alpha helix (twisted) form.
Alpha Helix
(http://images.search.yahoo.com/images,
13 Feb 20120
It can also be in a
beta pleated form (like a fan) stabilized by hydrogen bonds. Tertiary structures are 3D and stabilized by
other bonds such as disulfide and hydrogen bonds. The grooves and pockets created by the three
dimensional figure create polar and non-polar areas within the molecule. Quaternary structure is two or more tertiary
structures together.
Enzymes
Enzymes are proteins and function as biological
catalysts. They speed up chemical
reactions but can’t change reactions.
Without enzymes many biological reactions couldn’t take place quick
enough to sustain life. The functional
shape of an enzyme depends on temperature, pH, ion concentration, and the
presence of inhibitors.
Nucleic Acids Store Genetic Information
Two types: DNA deoxyribonucleic acid and RNA ribonucleic
acid
Nucleic acids function is to store genetic information. DNA provides instructions for making
RNA. RNA provides instructions for
making proteins. Proteins direct most of life’s processes. Nucleotides are the building blocks of nucleic
acids. The nucleotides are made of a
sugar base and one or more phosphate group.
The structure of DNA is double stranded and in the nucleotides is
deoxyribose (sugar). The nitrogenous
bases of adenine + thymine and guanine +cytosine are paired together. Sugar and phosphates are the backbone of the
structures and hydrogen bonds in the middle make the structure strong.
(http://freelancingscience.com/molecular-renderings/,
2 Feb 2012)
RNA ribonucleic acid is single stranded. The nucleotides contain ribose and nitrogen
bases. The nitrogen bases are adenine,
guanine, cytosine, and uracil.
APT Carries Energy
ATP is a universal energy source. Bonds between phosphate groups contain potential
energy. When bonds break energy is
released (a+p=ADP + P + energy).
( http://images.search.yahoo.com/images,
12 Feb 2012)
Chapter 3 Bio
Cells are Classified According to their Internal Organization
and Cell Structure Reflects Cell Function
The cell doctrine is the theory that cells form the fundamental structural and functional units of all living organisms (http://dictionary.reference.com/browse/cell+doctrine, 10 February 2012, page 1). The cell doctrine is made up of 3 principles:
1. all living things are made up of cells 2. A single cell is the smallest unit
that displays all the characteristics of life 3. All cells come from
preexisting cells.
There are two different cell
types that are classified by their internal organization. A Prokaryotic cell has a plasma membrane, do
not have a nucleus, and has jelly like cytoplasm without any true organelles. Eukaryotic cells have a plasma membrane and
have an information center called the nucleus. They too have a cytoplasm but do
have organelles that perform functions like digesting nutrients or shipping
waste. Eukaryotic cells are very
important to us because all human cells are eukaryotic. Eukaryotic cells come in many shapes and
sizes. Muscle cells are made up of many
organelles because muscles require extra energy. Nerve cells are long and thin enabling them
to carry impulses for long distances.
Needless to say, human cells vary in many different shapes but stay
small to be efficient. This is efficient
because with a higher surface area the volume ratio can get rid of cell waste
and acquire nutrients easier. Cells are
so small that they can’t be seen without a microscope. There are three types of microscopes 1. Light
microscope that has been used for a few hundred years. 2. A transmission
electron microscope that has greater clarity at any magnification. 3. Scanning electron microscope gives amazing
images of the cells and the outer surface of the cell.
A plasma Membrane Surrounds the Cell
Cells are surrounded by a plasma membrane which is the cells
house. It is a barrier that protects the
inside of the cell regulating temperature.
The cell membrane also controls what comes inside the cell and what
doesn’t. When looking at what makes up
the plasma membrane we find it is a lipid bilayer. The lipid bilayer is made up of phospholipids
that have non polar tails that aren’t attracted to water and a polar head that
is attracted to water. There is also
cholesterol that helps make the plasma membrane firm. Proteins provide transport through the plasma
membrane and regulate what is allowed in or out.
(http://www.molecularstation.com/molecular-biology-images/504-cell-biology-pictures/17-cell-membrane-figure-plasma-membrane.html,
12 Feb 2012)
Molecules Cross the Plasma Membrane in Several Ways
Molecules cross the plasma membrane in a few different
ways. They can pass by passive transport
through means of diffusion and osmosis where the cell doesn’t use any
energy. There is passive transport that
moves with the concentration gradient.
Concentration gradient is defined as the graduated difference in
concentration of a solute per unit distance through a solution http://www.thefreedictionary.com/concentration+gradient,
10 February 2012). This can happen
through protein channels, diffusion through the lipid bilayer and by
facilitated transport where no energy is used. Another means of transport is
active transport where the cell must use energy. In active transport substances
are moved from an area of lower concentration to an area of higher
concentration. This requires a plasma
membrane protein to transport and either ATP or a different energy source. Lastly, bulk transport is used when molecules
are too large or used to move molecules in bulk. Endocytosis is bulk transport moving
molecules into the cell. Exocytosis is
bulk transport moving molecules out of the cell. Receptor proteins span over the plasma
membrane gathering and giving information.
Receptor sites on the receptor proteins interact specifically with
signal molecules. When a signal molecule
fixes itself to a receptor site changes within the cell are triggered. Different types of cells have different types
of receptor sites. When determining what
comes and goes, a sodium potassium pump helps to maintain cell volume. It also gets rid of unwanted ions and
maintains the ions that are needed. For
instance when a cell gets rid of 3 sodium ions, 2 potassium ions are brought
into the cell. The sodium potassium pump
can increase cell volume by decreasing pumping and allowing more sodium
inside. The pump can decrease cell
volume by increasing pumping and getting rid of more sodium.
Internal Structures Carry out Specific Functions
The nucleus is the information center of the cell. The outer layer of the nucleus is the double
layered nucleus membrane. Inside the
nucleus is the nucleolus where components of ribosomes are created. Ribosomes are responsible for making certain
proteins by connecting amino acids in certain sequences. Ribosomes that are attached to the
endoplasmic reticulum release their proteins into the folds of the endoplasmic
reticulum. They are industrial plants
making materials that are not in their final form. The materials are polished and packaged by
the Golgi apparatus. Then the products
are put in the vesicles to go to their final destination. There are many different types of vesicles.
Two powerful vesicles that have potent enzymes are peroxisomes and lysosomes.
Peroxisomes destroy waste within the cell including alcohol. Lysosomes have great digestive enzymes that
digest bacteria and large particles, cellular waste and debris. The power plant of the cell is the
mitochondria. The more energy a cell
needs the more mitochondria will be present.
Mitochondria can generally make ATP when needed but some cells also
store raw energy. One way cells store
energy is in fat (lipids). When you work
out and get thinner you are not reducing the amount of fat but rather making
your fat cells skinny.
(http://www.rkm.com.au/CELL/animalcell.html,
10 Feb 2012)
Cells have Structures for support and movement
The plasma membrane is soft and flexible. Structural elements support the plasma
membrane and enable cells to move. The
cytoskeleton is made up of protein and fibers called microtubules and
microfilaments. These fibers create the supports
and anchors within a cell. Some cells
have hair like cilia or flagella on one surface of the cell. Cilia are common on cells that line airways
and certain ducts within the body. The
flagella are only found on sperm cells enabling them to move relatively
quickly. The last cell structural
support is centrioles. These centrioles
are very important in cell division because they align and divide all the
genetic material.
(http://micro.magnet.fsu.edu/cells/ciliaandflagella/ciliaandflagella.html, 10 February 2012)
Cells Use and Transform Matter and Energy
All the chemical reactions that happen within living cells
is called metabolism. Within a single
cell thousands of different chemical reactions happen which are called the
metabolic pathways. There are two types
of metabolic pathways; the first is anabolism in which molecules are made into
larger molecules using energy. The second is catabolism where larger molecules
are broken down and energy is made.
Cells need energy (ATP) and can use a variety of fuels. Glucose is the most available source of fuel
but cells can use fats or proteins as well.
We eat and glucose is usually always available throughout our
bodies. When glucose isn’t available our
energy reserves are mostly fat and some protein. This is when fat is broken down in our
bodies.
Chapter 4
Tissues are Groups of cells with a Common Function
Tissue(s) is made up of cells that arrange themselves in a
way to function as a whole.
Epithelial Tissues cover body Surfaces and Cavities
One of the four tissue types is epithelial tissue. It is formally called Glandular
Epithelia. It lines body cavities and
also our skin. Other epithelial tissues
line the bladder, blood vessels, lungs, digestive tract and tubules of kidneys. There are many layers to epithelial
tissue. There are three shape classifications
for epithelial cells. The first is
squamous cells that are flat, line the body’s surface, line the lungs and
vessels. Second are cuboidal cells that
are cube shaped and form the lining of tubules and gland tissue. Lastly are columnar cells that are column
shaped, line the respitory tract, digestive tract and reproductive glands. There are single layers (simple) of
epithelial tissue that are adapted to diffusion and line the glands, respitory,
digestive and reproductive systems.
There is also multiple layers (stratified) that provide protection to
the skins surface. Underneath the
epithelial tissue is the basement membrane.
This membrane provides support and attaches the epithelial tissue to the
tissues under it. Types of junctions
hold epithelial cells together. Gap
junctions are in the form of protein channels for the direct transfer of water
and ions between cells. Adhesion
junctions anchor two cells together allowing some movement between cells. Tight junctions don’t let anything pass
between cells. Depending on where the
epithelial cells are determines the type of junctions between the cells.
(http://images.search.yahoo.com/images,
12 Feb 2012)
Connective Tissue
Supports and Connects Body Parts
Connective tissue is a very diverse tissue and is made up of
cells, ground substrate, and protein fibers.
Connective tissue supports softer organs, connects and cushions parts of
the body, stores fat and produces blood cells.
There are two types of connective tissue. The first is Fibrous which also has four
types 1. Loose- surrounding organs 2. Dense- making tendons and ligaments 3.
Elastic- surrounds the stomach and bladder 4. Reticular- makes up the frame
work to the liver and lymph system. The
other type of connective tissue is called special. There are specialized connective tissues that
have special functions including blood, bone, cartilage, and adipose
tissue. Blood is made of red and white
blood cells, platelets and a fluid matrix of plasmas. Bone is an inorganic matrix with calcium
salts for hardness. Cartilage doesn’t
have any blood vessels and contains a high amount of collagen. Some cartilage turns to bone and other
cartilage remains flexible. Adipose
tissue store energy, help protect, and store energy in the form of fat. The amount of adipose tissue someone has is
due to genetics.
(http://images.search.yahoo.com/images/view,
12 Feb 2012)
Muscle Tissue Contract to Produce Movement
Muscles are made up of cells that are tightly fit together
called fibers. These fibers line up
parallel and are tight together. There
are three different types of muscle tissues in the human body. First is skeletal muscle which connects to
tendons then connecting to bones. They
are controlled muscles , multinucleated, with many nuclei. Second is the cardiac muscle that contains a
single nucleus. These muscles are only
found in the heart and are an involuntary muscle. Last are smooth muscles that contain a single
nucleus and is an involuntary muscle.
These muscles surround hollow organs and tubes and are found in the
bladder, uterus, blood vessels, and digestive tract.
Nervous Tissue Transmits Impulses
Nervous tissue forms fast communication throughout the
body. Nervous tissue is located in the
brain, spinal cord, and within the nerves that transmit information from one
place to another. The electrical
impulses are called neurons. Neurons can
be very long so the body can receive impulses from other parts of the
body. They have three main structural
components; the cell body, dendrites (that receive impulses) and the axon (that
transmit impulses). The glial surrounds
and protects neurons giving them the nurturance they need.
Organs and Organ Systems Preform Complex Functions
Organs have two or more tissue types joining together to
preform specific functions. An organ
system is a group of organs that preform a common purpose. A few types of organ systems are mouth,
throat, esophagus, stomach, and intestines.
All the organs have to work together to accomplish their overall
functions.
There are four tissue membranes. First is serous membrane that reduces the
friction between the organs. The second
is mucous membrane that lubricates surfaces and catches debris. Third is synovial membrane that lines the
spaces in all movable joints. Last is
the cutaneous membrane which is our skin.
Serous tissue membrane lines our body cavities. Humans have a thoracic cavity (lungs and
heart), abdominal cavity, cranial cavity (brain), spinal cavity, and pelvic
cavity.
(http://www.newworldencyclopedia.org/entry/Body_cavity,
12 Feb 2012)
There is a unique language used to accurately describe a
certain part of the body. It is best shown in the picture below.
(http://images.search.yahoo.com/images/view,
12 Feb 2012)
The Skin as an Organ System
Many would not think of the skin as being an organ system
but it is. The proper name is the
integumentary system that includes not only the skin but also hair, nails and
glands. The skins functions are to
prevent the body from any injury, prevent dehydration, regulates the body
temperature, makes vitamin D, helps defend against microorganisms, and to
provide sensation. The outermost layer
of the skin is called the epidermis. The
layer of skin under the epidermis is called the dermis. The dermis provides protection
and supports tissues under it. There are
some accessories to the dermis like sweat glands that help to regulate body
temperature. Blood vessels supply
necessary nutrients and remove waste.
There are also sensory nerve endings that can detect hot and cold,
pressure, and touch. The skin in an
amazing organ that is overlooked at times.
(http://health.allrefer.com/pictures-images/skin-layers.html,
12 Feb 2012)
Multicellular Organisms Must Maintain Homeostasis
Homeostasis is defined as the
ability or tendency of an organism or cell to maintain internal equilibrium by
adjusting its physiological processes. (http://www.answers.com/topic/homeostasis, 11 Feb 2012)
So whenever conditions become abnormal in the body the negative feedback
control system flies into action. The
parts of a negative feedback control system are a sensor, controlled variable,
control center, and an effector. The
negative feedback control center keeps all changes within the body at suitable
limits.
