SKIN AND BODY
MEMBRANES – PART 1
Chapter 4
Body Membranes

Body Membranes – Cover
surfaces, line body cavities,
and form protective sheets
around organs.
 Two
major groups of body
membranes:
1. Epithelial membranes
2. Connective tissue
membranes
Epithelial Membranes

Include:
1.
2.
3.


Cutaneous Membranes
Mucous Membranes
Serous Membranes
All contain an epithelial
sheet combined with an
underlying layer of
connective tissue.
These membranes are
actually simple organs.
Cutaneous Membranes

Cutaneous Membrane – Skin
 Its
superficial epidermis is composed of a
keratinizing stratified squamous epithelium.
 The underlying dermis is mostly dense
connective tissue.
 Is exposed to air and is a
dry membrane.
Mucous Membrane


Mucous Membrane
(Mucosa) – Lines all
body cavities that open
to the exterior (digestive,
urinary, respiratory).
Composed of epithelium
resting on a loose connective
tissue membrane.
 Most
contain either stratified
squamous epithelium or simple
columnar epithelium.
Mucous Membranes

They are “wet” or moist
membranes that are always
continuously bathed in the
secretions or urine.
 Mucosae
of the digestive and
respiratory tracts secrete mucus.
 Mucosae of the urinary tract
produces urine.

Often adapted for absorption
or secretion.
Serous Membranes

Serous Membranes – Line body cavities that
are closed to the exterior.


Exceptions: Dorsal body cavity and joint cavities
Composed of a layer of simple squamous
epithelium resting on a thin layer of areolar CT.
Serous Membranes

Occur in pairs
1.
2.
The parietal layer lines
a specific portion of the
wall of the ventral
cavity.
The parietal layer folds
in on itself to form the
visceral layer, which
covers the outside of the
organs in that cavity.
Serous Membranes

Similar to you pushing your fist into a limp
balloon.
Visceral Serosa = Part of the balloon that
clings closely to your fist.
 Parietal Serosa = Outer wall of the balloon.

Serous Membranes

The serous layers are separated by a thin,
clear fluid called serous fluid.
 Serous
fluid is secreted by both membranes.
 Two layers lie very close to each other. The
fluid allows the layers to slide easily across the
cavity walls and one another.
Serous Membranes: Examples
1.
2.
3.
Peritoneum – Serosa lining the
abdominal cavity and covering
its organs.
Pleura – Serous membrane
that surrounds the lungs.
Pericardium – Serous
membrane that
surrounds the heart.
Connective Tissue Membranes

Synovial Membranes –
Composed of soft areolar
CT and contain no
epithelial cells at all.

Cushion organs moving
against each other during
muscle activity (such as
the movement of a tendon
across a bone’s surface).
Where are Synovial Membranes
Located?
1.
Line the fibrous capsules
surrounding joints.
 Provide
a smooth surface
and secrete a lubricating
fluid.
2.
Also line small sacs of CT
called bursae and the
tubelike tendon sheaths.
Integumentary System (Skin)
Skin (Integument) – Cutaneous membrane;
External covering of the body.
 Integumentary System – The skin and its
derivatives (sweat and oil glands, hairs, and
nails).

Skin
Absolutely essential because it keeps water
and other precious molecules in the body.
 It also keeps water and other things out.
 Pliable, yet tough, which allows it to take
constant punishment from external agents.
 Without our skin, we would quickly fall prey to
bacteria and perish from water and heat loss.

Functions of the Skin
1.
Protects the entire body from:





2.
mechanical damage (bumps and cuts)
chemical damage (such as from acids and
bases)
thermal damage (heat and cold)
ultraviolet radiation (sunlight)
bacteria
Insulates and cushions the deeper organs.
Functions of the Skin (Continued)
3.
Acts as a mini-excretory system.

4.
5.
Urea, salts, and water are lost through sweat.
Manufactures several proteins important to
immunity and synthesizes vitamin D.
Sensory receptors provide us with a great
deal of information about our external
environment.
The Main Layers of Skin
1.
2.
3.
Epidermis
Dermis
Hypodermis or
Subcutaneous
Tissue
The Main Layers of Skin
1.
Epidermis


2.
Dermis


3.
The outer layer of the skin.
Made up of stratified squamous epithelium that is
capable of keratinizing, or becoming hard and tough.
The inner layer of the skin.
Made up of dense CT.
Hypodermis or Subcutaneous Tissue


Subcutaneous layer of fat and loose connective tissue
that help insulate the body and acts as a shock absorber.
Not considered part of the skin, but it does anchor the
skin to underlying organs.
Blisters

The epidermis and dermis are firmly
connected.
 Friction
or a burn may cause them to separate
and results in a blister.