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Chapter 11: Human
Types of Tissues
A tissue is composed of specialized cells
that perform a function in the body.
The human body has four major types of
Epithelial tissue
Connective tissue
Muscular Tissue
Nervous Tissue
Cancers are classified by the type of
tissue from which they arise:
Carcinomas – cancers of epithelial tissue
Sarcomas – cancers of connective tissue
Leukemias – cancers of blood
Lymphomas – cancers of lymphatic
Cancers are more likely to arise in
tissues in which cells divide rapidly.
Epithelial Tissue
Epithelial tissue (epithelium) is made of
highly packed cells that line the body
surface and inner body cavities.
Epithelial tissue functions in protection,
secretion, absorption, excretion, and
Epithelial tissue is classified according to
cell type.
Squamous epithelium is composed of
flattened cells and is found lining the
lungs and blood vessels.
Cuboidal epithelium contains cubeshaped cells and is found lining the
kidney tubules.
Columnar epithelium has elongated cells
with nuclei at the bottom of cells and is
found in the digestive tract.
Ciliated columnar epithelium is found
lining the oviducts.
Epithelial tissue is also classified
according to the number of layers in a
Simple means the tissue has a single
layer of cells.
Stratified means the tissue has layers of
cells piled on top of one another.
Pseudostratified means the epithelium
appears layered but is not.
Simple squamous epithelium
Simple cuboidal epithelium
Simple columnar epithelium
Pseudostratified ciliated
columnar epithelium
A basement membrane joins epithelium
to an underlying layer of connective
Some epithelial cells are glandular and
secrete a product.
A gland may be a single cell or contain
many cells.
Mucus-secreting digestive glands are
single goblet cells.
Exocrine glands secrete products into
ducts, while endocrine glands secrete
directly into the bloodstream.
Junctions Between Epithelial
Junctions that occur between cells help
cells function as a tissue.
A tight junction forms an impermeable
barrier between cells.
A gap junction allows material to pass
from one cell to the next.
Adhesion junctions adhere cells together
so tissues can stretch.
Connective Tissue
Connective tissue binds organs together,
provides support and protection, fills
spaces, produces blood cells, and
stores fat.
Connective tissue cells are separated by
noncellular matrix that ranges from
solid to semifluid.
The matrix houses fibers of three
possible types.
White collagen fibers contain the protein
collagen; these fibers are flexible and
Reticular fibers are very thin, highly
branched collagen fibers that form
delicate supporting networks.
Yellow elastic fibers contain the protein
elastin; these fibers are more elastic
and not as strong as collagen fibers.
Loose Fibrous and Dense
Fibrous Tissues
Loose fibrous and dense fibrous
connective tissues have cells called
fibroblasts in a matrix containing
collagen and elastic fibers.
Loose fibrous connective tissue supports
epithelium and many internal organs.
Dense fibrous connective tissue, packed
with collagen fibers, is found in
tendons and ligaments.
Loose fibrous connective tissue
Adipose Tissue and Reticular
Connective Tissue
In adipose tissue, fibroblasts enlarge and
store fat to be used for energy,
insulation, and organ protection.
Adipose tissue is found beneath the skin
and around certain internal organs.
Reticular connective tissue forms the
supporting meshwork of lymphoid
tissue in lymph nodes, the spleen,
thymus, and bone marrow.
Adipose tissue
Cartilage cells lie in small chambers
called lacunae separated by a solid but
flexible matrix.
Hyaline cartilage contains very fine
collagen fibers and is found at the ends
of bones, in respiratory passages, and
in the nose.
The fetal skeleton is made of hyaline
cartilage and is replaced by bone.
Hyaline cartilage
Flexible elastic cartilage has abundant
elastic fibers and is found in the
framework of the outer ear.
Fibrocartilage has a matrix with strong
collagen fibers.
Fibrocartilage is found in structures that
withstand tension and pressure, such
as the pads between the vertebrae in
the backbone and the wedges in the
knee joint.
Bone is the most rigid connective tissue
with its matrix of calcium and other
inorganic salts and protein fibers.
Compact bone makes up the shafts of
long bones and consists of cylindrical
units called osteons.
Osteons contain a central canal through
which blood vessels carry blood and
nutrients to bone tissue.
Compact bone
In compact bone, cells lie within lacunae
which are interconnected by tiny
nutrient-delivering canals called
The ends of long bones contain spongy
Spongy bone contains many bony bars
and plates located along lines of stress,
separated by irregular spaces.
Spongy bone is strong yet lightweight.
Blood is a fluid connective tissue
containing blood cells in liquid plasma.
Blood has many functions:
Keeps body chemistry within limits
Transports nutrients and wastes to cells
Distributes heat
Keeps pH and ions in balance
Protects against blood loss and disease
Blood, a fluid tissue
Components of Blood Plasma
Inorganic ions:
Plasma proteins:
Organic nutrients:
Nitrogenous wastes:
Na+, Ca2+, K+, Cl2,
HCO3-, HPO42+
O2, CO2
Albumins, globulins,
Glucose, lipids, amino
acids, phospholipids
Urea, ammonia
Formed elements of the blood include:
Red blood cells – small, biconcave, and
lacking nuclei, with hemoglobin that
transports oxygen
White blood cells – larger, nucleate, and
fight infection and produce antibodies
Platelets – fragments of larger cells that
form a plug in damaged blood vessels,
thus helping in the clotting process
Formed elements of blood
Muscular Tissue
Muscular tissue is made up of cells
called muscle fibers.
All muscular tissue contains actin
filaments and myosin filaments; the
interaction of these accounts for
Three types of vertebrate muscle are
skeletal, smooth, and cardiac.
Skeletal muscle, under voluntary control,
is attached by tendons to bones and
allows for movement.
Skeletal muscle fibers are long and
cylindrical with many nuclei just inside
the plasma membrane.
Actin filaments and myosin filaments
form a striated appearance in skeletal
Skeletal muscle
Smooth (visceral) muscle is involuntary
and nonstriated.
Long, tapered cells, each with a single
nucleus, form layers within the smooth
Smooth muscle is found in the walls of
the digestive tract and in blood vessels.
Smooth muscle contracts more slowly
than skeletal muscle but can remained
contracted for a longer period.
Smooth muscle
Cardiac muscle is found only in the walls
of the heart and functions to pump
Cardiac muscle has striations but is
Cardiac muscle fibers are branched and
have a single nucleus.
Cells are bound end to end at
intercalated disks, areas where plasma
membranes between cells contain
adhesion junctions and gap junctions.
Cardiac muscle
Nervous Tissue
Nervous tissue found in the brain and
spinal cord is made up of cells called
Neurons have three parts:
Dendrites – carry impulses to the neuron
Cell body – houses nucleus
Axon – carries impulse away from cell
Axons are insulated with myelin; axons
are bound together to form nerves.
In addition to neurons, nervous tissue
contains neuroglia, cells that support
and nourish neurons.
Three types of neuroglia are found in the
Microglia support neurons and engulf
bacteria and cellular debris
Astrocytes provide nutrients and secrete
a hormone called glia-derived growth
Oligodendrocytes form myelin.
A neuron and some types of
Body Cavities and Body
The human body is divided into the
ventral cavity and the dorsal cavity.
During development, the coelom
becomes the ventral cavity, which is
divided into thoracic and abdominal
The thoracic cavity contains the pleural
cavities each containing a lung, and the
pericardial cavity housing the heart.
Mammalian body cavities
The thoracic cavity is separated from the
abdominal cavity by the diaphragm.
The upper abdominal cavity contains the
stomach, liver, spleen, gall bladder, and
most of the intestines.
The lower abdominal cavity contains the
rectum, urinary bladder, and the rest of
the large intestine.
The dorsal cavity contains the cranial
cavity that houses the brain, and the
vertebral canal that contains the spinal
Body Membranes
Here the term “membrane” refers to a
thin lining of epithelium overlying a
layer of loose connective tissue.
Body membranes line cavities and
internal spaces of organs and tubes
that open to the outside.
There are mucous membranes, serous
membranes, synovial membranes, and
Mucous membranes line the tubes
of digestive, respiratory, urinary,
and reproductive systems.
Mucus secreted by goblet cells in
the epithelial layer of mucous
membrane protects the body from
invasion by bacteria and viruses.
Mucus also protects the lining of the
stomach from digestive juices.
Serous membranes line the thoracic and
abdominal cavities and the organs they
contain and secrete a watery fluid that
lubricates the membranes.
Serous membranes have specific names
according to their location:
Pleura - line pleural cavity and cover
Pericardium - lines pericardial cavity and
covers heart
Peritoneum - lines abdominal cavity
where it forms a double-layered
Synovial membranes line freely movable
joint cavities.
They secrete lubricating synovial fluid
into the joint cavity that helps bones
move freely.
The meninges are membranes in the
dorsal cavity that protect the brain and
spinal cord.
Meninges are composed of connective
tissue only.
Organ Systems
Organs work together in organ systems;
all body organ systems work together.
A single organ may be part of more than
one organ system.
The integumentary system is made up of
the skin, including an outer epidermis
and an inner dermis.
Skin covers and protects the body,
houses sensory receptors, and helps in
temperature regulation.
The integumentary system includes nails,
glands, sensory receptors, and hairs.
The digestive system consists of the mouth,
esophagus, stomach, small intestine, and
large intestine along with associated organs.
The digestive system receives and breaks
down food into nutrient molecules that are
distributed to cells.
The cardiovascular system, made up of the
heart and blood vessels, distributes
nutrients, oxygen, and heat throughout the
body, and helps to remove wastes.
The lymphatic system consists of lymphatic
vessels that transport lymph, lymph nodes,
and other lymphoid organs,
This system helps protect again disease by
producing and storing lymphocytes, collects
excess tissue fluid, and absorbs fats from
The immune system consists of all body cells
that protect against disease.
The respiratory system consists of the lungs
and branched tubes that carry air to them.
The respiratory system brings in oxygen and
removes carbon dioxide from the body, and
helps regulate pH.
The urinary system, made up of kidneys,
urinary bladder, and tubes that convey urine,
rids the body of nitrogenous wastes, and
regulates fluid balance and pH.
The bones skeletal system protect the body
and aid in movement; they also store
minerals and calcium and produce blood
cells in bone marrow.
The muscular system, made up of the skeletal
muscles, provides movement and generates
heat for the body.
Smooth muscle and cardiac muscle provide
movement of internal organs.
The nervous system, made up of the
brain, spinal cord, and nerves, receives
and processes information, and causes
the body to react to stimuli; the
nervous system regulates the activities
of the other organ systems of the body.
The endocrine system consists of
hormone-secreting glands, helps to
regulate the functioning of other body
The reproductive systems produce
sperm and egg cells, allowing humans
to produce more of their own kind.
Integumentary System
The skin and its accessory organs make
up the integumentary system.
Skin plays a significant role in
homeostasis by protecting underlying
tissues from trauma, infection, and
water loss, and by helping to regulate
The skin synthesizes vitamin D and
houses sensory receptors.
Regions of the Skin
The skin has two regions:
Outer epidermis made up of stratified
squamous epithelium, with waterproof
keratin, and pigment-producing melanocytes
Inner dermis made up of fibrous connective
tissue with collagen and elastic fibers, blood
vessels, and sensory receptors.
A subcutaneous layer, composed of loose
connective and adipose tissues, connects
the dermis to underlying organs.
Human skin anatomy
Accessory Organs of the Skin
Nails, glands, and hair are structures of
epidermal origin even though they are
located in the dermis.
Nails are a protective covering of the
ends of the fingers and toes; these
increase dexterity.
Nails grow from cells in the nail root;
these become keratinized as they grow
over the nail bed.
Nail anatomy
Hair follicles are in the dermis and extend
through the epidermis; arrector pili
muscles allow the hair to become erect.
Each hair follicle has oil (sebaceous)
glands that secrete moisturizing
Sweat (sudoriferous) glands are present
in all regions of the skin and play a role
in temperature regulation.
Homeostasis is the relative constancy of
the body’s internal environment.
Internal conditions fluctuate slightly in
dynamic equilibrium.
Illness results if internal conditions vary
to a great degree.
A homeostatic mechanism in the body
has a sensor, a regulatory center, and
an effector.
Negative Feedback
Negative feedback is the primary
homeostatic mechanism that keeps a
variable close to its set point.
A home heating system, with its
temperature set at 68oF (the set point),
operates by negative feedback; many
negative feedback mechanisms in the
body function in a similar manner.
Negative feedback
Regulation of Body Temperature
The regulatory center for body
temperature is located in the brain’s
When body temperature is below normal,
the hypothalamus sends nervous
impulses to the skin blood vessels and
they constrict, conserving heat.
If cooling continues, skeletal muscles are
signaled, shivering ensues, generating
heat and raising body temperature.
When body temperature is higher than
normal, the regulatory center directs
skin blood vessels to dilate, radiating
heat to the outside.
Sweat glands are also activated, and
evaporation helps to lower body
Temperature drops to normal, and the
regulatory center is inactivated.
Homeostasis and body
temperature regulation
Positive Feedback
Positive feedback mechanisms bring
about an ever greater change in the
same direction and does not achieve
relative stability; they may have a cutoff point.
Examples of positive feedback:
Childbirth and the hormone oxytocin
Blood clotting
Digestion of protein in the stomach
Certain fevers
Homeostasis and Body Systems
The internal environment of the body
consists of blood and tissue fluid.
The chemical composition of tissue fluid
remains constant only as long as blood
composition remains constant.
All systems of the body contribute
toward maintaining homeostasis and
therefore a relatively constant internal
Regulation of tissue fluid
Chapter Summary
Human tissues are organized into four
Epithelial tissues cover the body and line
its cavities.
Connective tissues bind body parts
Muscle tissue allows the enter body or its
internal organs to move and contract.
Nervous tissue conducts nerve impulses.
The internal organs occur within cavities.
Major body cavities include the ventral
cavity, with thoracic and abdominal
portions, and the dorsal cavity, which
includes the cranial cavity and
vertebral canal.
Body membranes line body cavities and
the internal spaces of organs, and
include mucous, serous, and synovial
membranes, and the meninges.
Organ systems provide coordinated
functions for the body.
Processing and transporting functions
are provided by the digestive,
cardiovascular, lymphatic, respiratory,
and urinary systems.
The musculoskeletal system supports
the body and permits movement.
The nervous system detects changes and
responds to stimuli and controls the
activities of other organ systems.
The endocrine system produces
hormones, some of which affect the
reproductive system.
Skin covers and protects the body,
houses sensory receptors, and helps in
temperature regulation.
Homeostasis is the relative constancy of
the internal environment.
Most homeostasic mechanisms are by
negative feedback, although some use
positive feedback.
All organ systems contribute to the
homeostasis of tissue fluid and blood.
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