In biology, the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body. A cell has three main parts: the cell membrane, the nucleus, and the cytoplasm. The cell membrane surrounds the cell and controls the substances that go into and out of the cell. The nucleus is a structure inside the cell that contains the nucleolus and most of the cell’s DNA. It is also where most RNA is made. The cytoplasm is the fluid inside the cell. It contains other tiny cell parts that have specific functions, including the Golgi complex, the mitochondria, and the endoplasmic reticulum. The cytoplasm is where most chemical reactions take place and where most proteins are made. The human body has more than 30 trillion cells.
Body Tissues
Tissue is a group of cells that have similar structure and that function together as a unit. A nonliving material, called the intercellular matrix, fills the spaces between the cells. This may be abundant in some tissues and minimal in others. The intercellular matrix may contain special substances such as salts and fibers that are unique to a specific tissue and gives that tissue distinctive characteristics. There are four main tissue types in the body: epithelial, connective, muscle, and nervous. Each is designed for specific functions.
Human Organs
An
organ
is a collection of tissues joined in a structural unit to serve a common function. Organs exist in most multicellular organisms, including not only humans and other animals but also plants. In single-celled organisms such as
bacteria
, the functional equivalent of an
organ
is an
organelle
.
Tissues in Organs
Although organs consist of multiple
tissue
types, many organs are composed of the main
tissue
that is associated with the
organ
’s major function and other tissues that play supporting roles. The main
tissue
may be unique to that specific
organ
. For example, the main
tissue
of the
heart
is the
cardiac muscle
, which performs the
heart
’s major function of pumping
blood
and is found only in the
heart
. The
heart
also includes nervous and connective tissues that are required for it to perform its major function. For example, nervous tissues control the beating of the
heart
, and connective tissues make up
heart
valves that keep
blood
flowing in just one direction through the
heart
.
Vital Organs
The human body contains five organs that are considered vital for survival. They are the
heart
,
brain
, kidneys,
liver
, and lungs. The locations of these five organs and several other internal organs are shown in Figure 10.4.2" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; font-size: 17.6px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">10.4.210.4.2. If any of the five vital organs stops functioning, the death of the
organism
is imminent without medical intervention.The
heart
is located in the center of the chest, and its function is to keep
blood
flowing through the body.
Blood
carries substances to cells that they need and also carries away wastes from cells.The
brain
is located in the head and functions as the body’s
control center
. It is the seat of all thoughts, memories, perceptions, and feelings.The two kidneys are located in the back of the abdomen on either side of the body. Their function is to filter
blood
and form
urine
, which is excreted from the body.The
liver
is located on the right side of the abdomen. It has many functions, including filtering
blood
, secreting
bile
that is needed for
digestion
, and producing proteins necessary for
blood
clotting.The two lungs are located on either side of the upper chest. Their main function is exchanging oxygen and carbon dioxide with the
Answers & Comments
Answer:
In biology, the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body. A cell has three main parts: the cell membrane, the nucleus, and the cytoplasm. The cell membrane surrounds the cell and controls the substances that go into and out of the cell. The nucleus is a structure inside the cell that contains the nucleolus and most of the cell’s DNA. It is also where most RNA is made. The cytoplasm is the fluid inside the cell. It contains other tiny cell parts that have specific functions, including the Golgi complex, the mitochondria, and the endoplasmic reticulum. The cytoplasm is where most chemical reactions take place and where most proteins are made. The human body has more than 30 trillion cells.
Body Tissues
Tissue is a group of cells that have similar structure and that function together as a unit. A nonliving material, called the intercellular matrix, fills the spaces between the cells. This may be abundant in some tissues and minimal in others. The intercellular matrix may contain special substances such as salts and fibers that are unique to a specific tissue and gives that tissue distinctive characteristics. There are four main tissue types in the body: epithelial, connective, muscle, and nervous. Each is designed for specific functions.
Human Organs
An
organ
is a collection of tissues joined in a structural unit to serve a common function. Organs exist in most multicellular organisms, including not only humans and other animals but also plants. In single-celled organisms such as
bacteria
, the functional equivalent of an
organ
is an
organelle
.
Tissues in Organs
Although organs consist of multiple
tissue
types, many organs are composed of the main
tissue
that is associated with the
organ
’s major function and other tissues that play supporting roles. The main
tissue
may be unique to that specific
organ
. For example, the main
tissue
of the
heart
is the
cardiac muscle
, which performs the
heart
’s major function of pumping
blood
and is found only in the
heart
. The
heart
also includes nervous and connective tissues that are required for it to perform its major function. For example, nervous tissues control the beating of the
heart
, and connective tissues make up
heart
valves that keep
blood
flowing in just one direction through the
heart
.
Vital Organs
The human body contains five organs that are considered vital for survival. They are the
heart
,
brain
, kidneys,
liver
, and lungs. The locations of these five organs and several other internal organs are shown in Figure 10.4.2" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; font-size: 17.6px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">10.4.210.4.2. If any of the five vital organs stops functioning, the death of the
organism
is imminent without medical intervention.The
heart
is located in the center of the chest, and its function is to keep
blood
flowing through the body.
Blood
carries substances to cells that they need and also carries away wastes from cells.The
brain
is located in the head and functions as the body’s
control center
. It is the seat of all thoughts, memories, perceptions, and feelings.The two kidneys are located in the back of the abdomen on either side of the body. Their function is to filter
blood
and form
urine
, which is excreted from the body.The
liver
is located on the right side of the abdomen. It has many functions, including filtering
blood
, secreting
bile
that is needed for
digestion
, and producing proteins necessary for
blood
clotting.The two lungs are located on either side of the upper chest. Their main function is exchanging oxygen and carbon dioxide with the
blood
.