Download Chapter 4 The Human Body

ASA
Chapter 4
The Human Body
ALABAMA 7TH GRADE SCIENCE STANDARDS COVERED IN THIS CHAPTER INCLUDE:
Relate major tissues and organs of the skeletal, circulatory, reproductive,
muscular, respiratory, nervous and digestive systems to their functions.
3
:
•
Sc
.
••
you think of the human body as a team, then the organ
systems within it would be the players This team must work
together in order for the body to maintain homeostasis
•
:.
INKS
.l.LJI4M;_44cIwI F
ACO65
Let’s review the definition of homeostasis It is the process
of maintaining a constant internal environment, despite
changing environmental conditions. It is how we “regulate ourselves.” Here are a
few examples:
.
.
.
Sweating cools us and helps us maintain a constant internal temperature.
We drink water to remain hydrated and maintain our body’s water balance.
We excrete waste products to maintain a clean bloodstream.
To accomplish homeostasis, the combined efforts of cells, organs and organ systems
are required. We won’t look at every part of our “human body team,” but we will
examine several “star players.”
.
Co
In
Co
CO
Co
C?
ui
C)
0
D
0
I-
0
z
0
0
(U
E
0
C)
0
0
C
(U
I.)
0
E
©
0)
>‘
0.
0
C)
Figure 4.1 The Human Body Team
37
The Human Body
Table 4.1 Overview ofHuman Body Systems
System
Major Parts and Organs
Respiratory
nose, trachea, bronchial tubes, lungs, alveolus and diaphragm
Circulatory
heart, veins, arteries and capillaries
Digestive
tongue, teeth, salivary glands, esophagus, stomach, pancreas,
liver, gall bladder, small intestine, appendix and large intestine
Skeletal
skull, vertebral column, sternum, ribs, humerus, radius, ulna,
carpals, metacarpals, phalanges, pelvic girdle, femur, patella,
tibia, fibula, tarsals and metatarsals
Immune
lymphatic system, spleen, tonsils, thymus, leukocytes and bone
marrow
Lymphatic
lymph nodes, tonsils, thymus and spleen
Muscular
involuntary (smooth muscles), heart (cardiac muscle) and
voluntary (striated muscles)
Nervous
brain (cerebrum, medulla, cerebellum), spinal cord and nerve
cells
Excretory
kidney, blood vessels, bladder, ureter, urethra, skin and sweat
glands
Reproductive
male: testes, vas deferens, seminal vesicle and penis
female: ovary, oviduct, uterus, cervix and vagina
REsPIRAToRY SYSTEM
p.
C?
w
The respiratory system allows our
bodies to obtain oxygen from the
air. Respiration refers to the
movement of air in and out of the
lungs. Respiration happens when
we breathe in (inspiration). To
take a breath, a special muscle
called the diaphragm must
contract. The diaphragm is a flat
muscle that runs across the body
cavity below the lungs. When the
diaphragm contracts, it increases
0
-J
0.-
0
z
0
0
E
0
0
0
0
ro
0
E
©
Figure 4.2 Respiratory System
0.
0
0
38
Chapter 4
the total overall volume of the lungs, causing air to rush into the body. When the
diaphragm relaxes, it decreases the volume of the lung cavity, causing air to leave the
body. During inspiration, air enters the nose or mouth, where it passes through the
trachea (a hollow tube made of cartilage), bronchial tubes and into the alveoli.
are air sacs rich in blood vessels, where gases exchange between lungs and blood.
Oxygen then diffuses into the cells, and carbon dioxide diffuses out of the cells.
Alveoli
When we breathe out, we rid our bodies of carbon dioxide. Breathing out is called
leave the body, air reverses the path it used to enter.
expiration. To
CIRCULATORY SYSTEM
The circulatory system is a transport system for many
substances, most notably, blood. Blood is essentially
made up oftwo parts: cells and plasma. Blood
is a yellowish fluid that suspends the cells. It is similar
to the broth in chicken noodle soup; it provides a liquid
for the cells and other nutrients. Plasma is about 55%
of total blood volume and carries important dissolved
salts, water, fats and amino acids.
plasma
(to the heart,
depleted)
oXygen
Blood cells can be one ofthree main types: red blood
cells, white blood cells or platelets.
are responsible for transporting oxygen. They contain
an iron rich protein called hemoglobin, which gives
these cells their red color. Red blood cells are the most
attack
harmful microorganisms (bacteria, viruses or
Figure 4.3 Circulatory System
parasites) and aid in immunity. Platelets are blood
cells that form clots. Platelets, along with white blood cells, stop the bleeding at the site
of a wound and eventually lead to the formation of a scab.
Red
.
Circulatory System
‘ems
common type
blood
cells
of blood cell. White blood cells
The heart is the pump of the circulatory system. It is a hollow muscular organ located
between the lungs. It has four chambers that perform two primary functions. The heart:
.
!
.
collects deoxygenated (without oxygen) blood from the body and pumps it to the
lungs, and then...
collects oxygenated blood from the lungs and pumps it throughout the body.
.
The respiratory system and circulatory system work closely together, because your body
needs to take in oxygen and send it to your cells.
.
©
.
0.
0
Q
39
The Human Body
Oxygenated blood has passed through the lungs to
pick up oxygen, and is ready to travel through the body
to deliver the oxygen to cells. Oxygenated blood
moves through the arteries. Arteries are the blood
Vein
vessels that carry blood “away” from the heart. Blood
ThsueCells
Capillaries
vessels are hollow tubes that transport blood. There are
Figure 4.4 Capillanes
large vessels, like the aorta which measures roughly
2.5 cm, and small vessels, measuring 5 10 tm (that’s about 0.0005 cm). Really small
blood vessels are called capillaries. The walls of a capillary are only one cell layer
thick. This allows molecules and elements like oxygen, glucose and carbon dioxide to
pass through. Capillaries are what actually bring the nutrients to individual cells.
Capillaries
‘
.
.
.
—
Deoxygenated blood has traveled through the body and has already delivered oxygen
to your cells via the capillaries. Deoxygenated blood travels in blood vessels called
veins. Veins bring blood back to the heart and lungs.
DIGESTIVE SYSTEM
The digestive system breaks down food into smaller pieces that can be used by your
cells. The digestive system is made up of several organs located in your mouth and
inside your body. Some important organs involved in digestion include the esophagus,
stomach, liver, small intestine and large intestine.
Digestion can happen two ways: mechanically and chemically. Mechanical digestion
occurs when food is physically broken into smaller pieces. Mechanical digestion
occurs when you chew your food, and during movement of the stomach. Chemical
digestion happens when chemicals inside your body break down food. One example of
chemical digestion is stomach acid dissolving food. The digestive system works with
the circulatory and excretory system to bring nutrients to cells and remove wastes.
Co
U)
CD
C1
CO
Co
C?
w
The mouth is where
the digestive system
begins. Food is placed
inside the mouth,
where your teeth,
tongue, saliva and jaw
muscles chew it. food
is then swallowed, or
ingested, down a tube
called the esophagus.
0
-J
Digestive System
esophagus
D
I
I-
0
z
0
0
Co
0.
gall bladder—
pancreas
small intestines .e::::
large
appendix
E
0
0
0
0
Co
(3
0
E
Figure 4.5 Digestive System
©
0.
0
0
40
Chapter 4
The esophagus is a tube of smooth muscle tissue that transports food to the stomach.
The
stomach is a bag-like organ that receives the large pieces of food from the mouth.
The stomach chemically and mechanically breaks down large food pieces into much
smaller pieces. The stomach has strong acids, a pH of 1 2, that chemically break down
large food particles into much smaller pieces. In fact, acids inside the stomach are so
strong, if placed on skin they could cause a chemical bum. In the first part of the small
intestine (the duodenum), secretions from the pancreas neutralize stomach acids. Also
in the duodenum, the liver secretes several chemicals that help break down fats. The
small intestine is a hollow, highly folded tube that absorbs nutrients from food as it
slowly moves the food to the large intestine. The last organ involved in digestion is the
large intestine. The main ffinctjons of the large intestine are to absorb water from
indigestible food and absorb vitamins released by bacteria living inside the large
intestine. Another function ofthe large intestine is to compact solid wastes (indigestible
food, also called feces).
—
h
SKELETAL SYSTEM
Skeletal System
The skeletal system includes
skull
r.—
Ije
e
and
bones, cartilage, tendons
sternum
:
scapula-_.,
ligaments. The skeletal system
k— humerus
jz
provides support and structure
b’
A
! :- veraI
for the body. This is
column
racsa
accomplished through the use of
:—-carpaLs
sacium
inetacarpa1s
/
bones. Bones are an organ made
3 1 ‘phalanges
\
pelvic girdle
up of hard connective tissues
i
i tèmur
1
(mostly of calcium phosphate).
¶; -_patella
Skeletal muscle attaches to
bones to allow for movement. inetarsals
Bones are also a source of phalanges -‘I
calcium for other organs in our
Figure 4.6 Skeletal System
bodies. Calcified bone tissue
renews itselfperiodically. When old bone breaks down, calcium and phosphorus move
into the bloodstream and are able to be used in other ways.
,.
1L
4W
-
•
%
‘
‘
•1
!
-
-
-
,
::
•
I
(
.
I
)
A place where two bones join is called a joint. Joints allow your skeleton to move.
Tough fibrous tendons attach muscles to bones and allow muscles to “pull” the bones in
different directions. Ligaments are a band of dense, fibrous connective tissues that
connect one bone to another. Ligaments function to stabilize joints. Cartilage, a tough
connective tissue, is found at mostjoints. Injoints, cartilage softens movement between
two bones. This allows a smooth, gliding action as the bones move past one another. In
other body organs, like your ear or nose, firm yet flexible cartilage forms the main
41
The Human Body
support structure. Cartilage lacks blood vessels resulting in a slow rate of repair, injury
to certain cartilaginous tissues often results in lifelong diseases. This is particularly true
ofknee or back cartilage injury.
Joints are classified by the type of movement they
allow and the types of tissues they have. The most
commonly accepted types of joints are fixed, hinge,
pivot, gliding and ball-and-socket. Fixedjoints, like in
your skull, do not move but serve to absorb shock
while protecting sensitive tissues underneath. Hinge
joints, like your knee, allow for two directional
nIovement and move like a door hinge. Pivot joints,
like your elbow, allow for rotational movement around
1 80° axes. Gliding joints, like your wrists, allow
slightly more rotational movement than pivot joints
Figure 4.7 Synovial Joint
and function as two bones glide past one another. The
movement allowed by this joint type is defined by the
shape ofthe bones involved. A ball-and-socketjoint, like your shoulder, allows the most
freedom of movement and permits bones to rotate a full 360°. Can you name another
ball-and-socket joint? Right your hip! Figure 4.7 shows a typical synovial joint, the
most common moveablejoint. It is called a synovialjoint because ofthe synovial tissues
located in and around it. An example of a synovialjoint is your knee.
—
IMMUNE SYSTEM
The immune system is a collection
of cells and tissues that defend the
;NKS human
body against invaders. The
immune system works with your
ABCO8O
dasese
skm, respiratory system and
digestive system to prevent
disease. It consists of the lymphatic system, spleen,
tonsils, thymus and bone marrow. Bone marrow makes
leukocytes, white blood cells, which defend against
infection and disease.
F..,
Sc
In
In
c.,1
In
In
Iw4grqwLw
.....
ui
..
.
0
aD
0
z
0
C
Figure 4.8 White Blood Cell
>
C
E
0
0
0
0
to
C
U
E
©
0)
0.
0
0
:
42
Chapter 4
LYMPHATIC SYSTEM
The lymphatic system is a network of the parts
of the immune system. It consists of lymph
vessels, lymph and lymphoid tissues (i.e.
lymph nodes, tonsils, thymus and spleen).
Lymph vessels transport lymph. Lymph is
composed of tissue fluid and white blood cells.
Tissue fluid is fluid that surrounds cells. It is
made up of water,. small molecules and lymph
cells.
Lymphatic System
Lymph nodes filter lymph fluid and prevent
Figure 4.9 Lymphatic System
foreign particles and microorganisms from
entering the bloodstream. As the lymphatic system fights these invaders, lymph nodes
can become swollen and sore.
The lymphatic system also plays a role in returning fluid to blood. Lymph vessels do not
have a pump (the heart) like arteries do. They operate like veins, relying on muscle
contractions to push fluid throughout the body. Exercise helps keep lymph moving. This
is one reason why people who regularly exercise seem to be sick less often!
MUSCULAR SYSTEM
The muscular system is used to move the body, help circulate blood and move food
through the digestive system. The three types of muscular tissue that accomplish these
tasks are skeletal, cardiac and smooth.
Skeletal muscle tissue is attached to bones by tendons. Skeletal muscles, also called
voluntary muscle, move the body. Voluntary muscle tissues are under the complete
control ofthe organism; you decide when to move your arms and legs. Cardiac muscles
are found only in the heart. These are a type of involuntary muscle. Involuntary
muscles contract automatically. You don’t have to think about making your heart beat;
it just happens! Mother type of involuntary muscle tissue is smooth muscle. Smooth
muscle is found in many organs like the esophagus, stomach and intestines.
43
The Human Body
NERVOUS SYSTEM
The nervous system is the control and communication
network of the body. It detects and responds to stimuli
both inside and outside the body. The five senses (smell,
touch, taste, sight and hearing). are controlled by this
system. A nerve is a bundle of nerve cells or neurons.
Neurons carry information from one place to another.
Nervous System
brain
spinal cord
The two main parts of the nervous system are the central
nervous system (CN$) and the peripheral nervous
system. The central nervous system is made up of the
brain and spinal cord. The CNS is the main control center
Figure 4.10 Nervous System
for the human body. The peripheral nervous system
consists of all other parts of the nervous system. The peripheral nervous system carries
nerve impulses from the brain and spinal cord to the body and back to the brain. The
nerves that detect heat in your fingers exemplify the peripheral nervous system.
.
The brain is the most important and
complex human organ. A complete
(Bodysensesorientation,
discussion of the brain is beyond the
visualand apaUni
percepUon)
scope of this text; however, it is
Occipft& Lobe
important to have a basic
Vialon)
Temporal Lobe
understanding of how the brain
(Hearing, music, understanding
Cerebellum
speech menroryfornomverbal
functions. It serves as the control
)Muac)e coordination)
events)
Brain Stern
Spinal Cord
Maintain homeostasis:
center for the entire human body. It
a.blood pressure
b. heartbeat
regulates behavior, blood chemistry,
mood, growth, heart rate, sleep
Figure 4.11 Parts ofthe Human Brain
cycles, reproduction orjust about any
other bodily function you can think of. The brain has a complex network of nerves (at
least 23 billion neurons) that interact closely with the spinal cord and sensory neurons.
The brain sends messages down the spinal cord, a long thin bundle of nerves running
the length of the vertebral column, to different parts of the body. The main function of
the spinal chord is to transport messages from the brain to the body’s nerves and vice
versa. The brain receives information from your senses (eyes, nose, etc.) and processes
this information to cause appropriate action. While your eyes merely perceive the words
on the page, your brain allows you to understand their meaning. Internal body signals
are also perceived by the brain. Changes in blood chemistry, like a buildup of CO2
during exercise, are detected by the brain. The brain then sends signals to the rest of the
body to increase both the heart and breathing rate.
Language Area
Judgment. initiation,
IHandukills sensory. reading.
abstract thought, speech)
writing, numbers)
.
‘
Co
L()
Co
c1
CO
Co
op
LU
0
-j
a.
I-
0•
z
0
0
CC
E
0
0
0
0
CC
U
CC
E
©
>
a-
0
0
44
Chapter 4
EXCRETORY SYSTEM
The excretory system removes wastes from the body. The
lungs and skin release some wastes through respiration and
sweating, but the majority of metabolic wastes are removed
through the urinary tract. The urinary tract consists of the
kidneys, ureters, bladder and urethra. The excretory system
removes wastes from cells in the body.
REPRODUCTiVE SYSTEM
The Urinary Tract
aorta
‘ena cava
kidney
1.111::.
ureters
(
bladder
urethra
Reproduction is necessary for the continuation ofa species.
figure
4.12
The
Uñnaiy
Tract
Human reproduction involves two parents: a male and a
female. The reproductive system allows humans to
reproduce. The organs in the reproductive system are different for males and females.
In males, the reproductive system is composed of the testes and the penis. In females,
the reproductive system includes the ovaries, uterus, vagina and breasts.
Males have two testes
glands that produce testosterone, the male sex hormone.
Upon sexual maturity, the amount of testosterone increases, and sperm are produced in
the testes. Sperm are male sex cells, or gametes, that move via flaggeflum. Males can
produce sperm throughout their lifetime. Sperm leave the body, in semen, through the
urethra. The urethra is the opening the head of the penis.
—
females produce ova, or eggs, which are housed in two
ovaries. Upon sexual maturity, one ovum forms
approximately every 28 days, when it is released from the
ovary and travels along the fallopian tube on its way to the
uterus. The uterus is a hollow organ that provides a place for
the embryo (an embryo is a developing baby) to develop.
During pregnancy, the uterus more than doubles in size.
g
If sperm and egg unite, fertilization occurs, resulting in a
zygote. The zygote develops into a fetus in the uterus until,
finally, a baby is born. The human female feeds the infant with
milk produced by mammary glands in the breasts.
female Reproductive System
Figure 4.13 Female
Reproductive System
Activity
Research the different organ systems using textbooks or the Internet. Determine
which body system (circulatory, digestive, skeletal, respiratory, immune,
lymphatic, muscular, nervous, excretory or reproductive) you could live without.
reparedtodefendyourposffionwithevidenceandJorlogical reasoning.
45
The Human Body
CHAPTER 4 REVIEW
1. What is one major function ofthe lymphatic system?
A
B
C
B
transporting oxygenated and deoxygenated blood
providing support and structure for the body
transmitting information from the environment to the brain
preventing foreign particles from entering the bloodstream
2. How does the stomach aid in digestion?
A
B
C
B
It mechanically breaks down fats.
It chemically and mechanically breaks down foods.
It mechanically breaks down sugars.
It chemically breaks down proteins.
3. The diaphragm contracts to
A
B
C
B
force air into the lungs.
force air into and out of the lungs.
move the stomach, assisting in the mechanical breakdown of food.
support the spinal column.
4. What is the main job of the respiratory system?
A
B
C
B
delivering carbon monoxide to the important parts of the body
pumping blood to the capillaries
taking in oxygen needed for respiration
taking in carbon dioxide and delivering it to the cells
5. What are the main components of the circulatory system?
A
B
C
B
bone marrow, ligaments and tendons i
heart, veins, arteries and capillaries
brain, spinal cord and neurons
stomach, esophagus and small intestine
,