MEMBRANES Membranes are sheets of tissues that cover or line surfaces or that separate organs or parts(lobes) of organs from one another. - PowerPoint PPT Presentation

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MEMBRANES Membranes are sheets of tissues that cover or line surfaces or that separate organs or parts(lobes) of organs from one another.

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Title: MEMBRANES Membranes are sheets of tissues that cover or line surfaces or that separate organs or parts(lobes) of organs from one another.


1
MEMBRANESMembranes are sheets of tissues that
cover or line surfacesor that separate organs or
parts(lobes) of organs from one another.
  • Types of membranes
  • 1-Epithelial membranes
  • 2-Connective tissue membranes

2
EPITHELIAL MEMBRANES
  • two types of epithelial membranes
  • serous
  • and mucous.
  • Each type is found in specific locations
  • within the body and secretes a fluid.
  • These fluids are called
  • -serous fluid
  • -and mucus.

3
Mucous Membranes
  • Mucous membranes line the body systems that have
    openings to the environment. (respiratory,
    digestive, urinary, and reproductive).
  • The epithelium of a mucous membrane (mucosa)
    varies
  • - mucosa of the esophagus and of the vagina is
    stratified squamous
  • mucosa of the trachea is ciliated epithelium
  • mucosa of the stomach is columnar epithelium

4
Mucous Membranes
  • Mucosa is composed of epithelium resting on a
    loose connective tissue membrane called a lamina
    propria
  • The mucus secreted keeps the lining epithelial
    cells wet and acts as lubricant

5
Serous Membranes
  • Serous membranes are sheets of simple squamous
    epithelium that line some closed body cavities
    and cover the organs in these cavities
  • 1-pleural membranes are the serous membranes of
    the thoracic cavity.
  • The parietal pleura lines the chest wall.
  • and the visceral pleura covers the lungs.
  • It secrete serous fluid, which prevents
  • friction between them

6
2-pericardium
  • The heart, has its own set of serous membranes.
  • The parietal pericardium lines the thorasic
    cavity
  • the visceral pericardium,
  • or epicardium, is on the surface of the heart
    muscle
  • Serous fluid is produced to prevent
  • friction as the heart beat

7
3-Peritoneal Membranes
8
Pleural Pericardial Membranes
9
CONNECTIVE TISSUE MEMBRANES
  • These are made of connective tissue with no
    epithelial cells at all
  • It cushions organs moving against each other
    during muscle activity

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The Integumentary System
  • consists of
  • -the skin,
  • - its accessory structures such as hair and
    sweat glands,
  • -and the subcutaneous tissue below the skin.
  • The skin is considered an organ.

13
Functions of the skin
  • 1-Protects deeper tissues from
  • -mechanical damage
  • -chemical damage (acids bases)
  • -bacterial damage
  • -ultraviolet radiation (sunlight)
  • Thermal (heat or cold) damage
  • -desiccation (drying out)

14
Functions of the skin (cont.)
  • 2-aids in heat regulation
  • -in cold vasogonstriction
  • -in hot vasodilatationsweat
  • 3-aids in excretion of urea uric acid
  • 4-synthesize vitamin D

15
STRUCTURES OF THE SKIN
  • two major layers the epidermis dermis.
  • The epidermis
  • made of stratified squamous keratinizing
  • epithelial tissue and is thickest on the palms
    and soles. The cells that are most abundant are
    called keratinocytes, and there are no
    capillaries present between them.

16
The epidermis
  • Although the epidermis may be further
  • subdivided into four or five sublayers, two of
    these are of greatest importance
  • the innermost layer, the stratum
  • germinativum,
  • and the outermost layer, the stratum
  • corneum .

17
Stratum Germinativum (BASALE)
  • To germinate means to sprout or to
  • grow. Basal means the base or lowest part.
  • The stratum germinativum is the base of the
    epidermis, the innermost layer in which mitosis
    takes place. New cells are continually being
    produced, pushing the older cells toward the
    skin surface. These cells produce the protein
    keratin, and as they get farther away from the
    capillaries in the dermis, they die.

18
Stratum Corneum
  • the outermost epidermal layer,
  • consists of many layers of dead cells all that
    is left is their keratin which is a fibrous
    protein that makes the epidermis
  • - a tough protective layer
  • - relatively waterproof (prevent evaporation,
    prevents the entry of water).
  • -a barrier to pathogens and chemicals.
  • Stratum Corneum rubs and flakes slowly leading
    to totally new epidermis every25-45 days

19
Langerhans Cells
  • are also called dendritic cells(branched
    appearance ) .These cells originate in the red
    bone marrow, and are quite mobile.
  • They are able to phagocytize foreign
    material, such as bacteria that enter the body
    through breaks in the skin. With such ingested
    pathogens, the Langerhans cells migrate to lymph
    nodes and present the pathogen to lymphocytes.
    This triggers an immune response such as the
    production of antibodies.

20
Melanocytes
  • Another type of cell found in the lower epidermis
  • Melanocytes produce another protein, a pigment
    called melanin.
  • In people with dark skin, the melanocytes
    continuously produce large amounts of melanin.
    The melanocytes of lightskinned people produce
    less melanin. The activity of melanocytes is
    genetically regulated.

21
Melanin
  • In all people, melanin production is increased by
    exposure of the skin to ultraviolet rays, which
    are part of sunlight and are damaging to living
    cells.
  • People with dark skin already have good
    protection against the damaging effects of
    ultraviolet rays.
  • Melanin also gives color to hair,iris choroid.

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DERMIS
  • It is a strong stretchy envelope that hold the
    body together
  • It is made of an irregular type of fibrous
    connective tissue.
  • . Fibroblasts produce both collagen and elastin
    fibers.
  • Collagen fibers are strong, and elastin fibers
    are able to recoil after being stretched.
  • Strength and elasticity are two characteristics
    of the dermis.
  • With increasing age, however, the deterioration
    of the elastin fibers causes the skin to lose its
    elasticity.

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papillary layer of dermis
  • IT is the uneven junction of the dermis with the
    epidermis
  • Capillaries are abundant here to nourish not only
    the dermis but also the stratum germinativum.
  • N.B. The epidermis has no capillaries of its own.
  • Within the dermis are the accessory skin
    structures
  • hair and nail follicles, sensory receptors, and
    several types of glands.

27
Colour of skin
  • Three pigments contribute to skin golour
  • 1-melanin
  • 2-karotine
  • 3-oxyhemoglobin

28
Appendages of the skin
  • 1-Hair folliclesmitosis takes place in the hair
    root new cells produce keratin, die, and become
    the hair shaft.
  • Hair of the scalp provides insulation from
  • cold for the head eyelashes keep dust out of
    eyes
  • nostril hairs keep dust out of nasal cavities

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  • 2. Nail folliclesat the ends of fingers and
    toes mitosis takes place in the nail root the
    nail itself is dead,keratinized cells.
  • -Nails protect the ends of the fingers and toes,
    enable the fingers to pick up small
  • objects, and provide for efficient scratching

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  • 3. Receptorsdetect changes in the skin touch,
    pressure, heat, cold, and pain provide
    information about the external environment that
    initiates appropriate
  • responses.
  • sensitivity of the skin depends on the number of
    receptors present.

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  • 4. Sebaceous glands(oil glands) secrete sebum
    into hair follicles or to the skin surface.
  • sebum inhibits the growth of bacteria and
    prevents drying of skin and hair.
  • If its duct is blocked by sebum,whitehead
    appears,with oxidation become blackhead
  • Active infection leads to acne

34
  • 5. Ceruminous glandssecrete cerumen in the ear
    canals.
  • cerumen prevents drying of the eardrum.

35
  • 6. Apocrine sweat glandsmodified scent glands in
    axillae and genital area
  • activated by stress and emotions
  • Their secretions contains fatty acids and
    proteins
  • Secretion is odorless
  • Begins function at puberty
  • Minimal role in thermoregulation

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  • 7. Eccrine sweat glandsall over the body, most
    numerous on face, palms, soles.
  • Activated by high external temperature
  • or exercise sweat on skin surface is
    evaporated by excess body heat.
  • Excretion of small amounts of NaCl and
  • urea is a very minor function.

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  • 8. Arteriolessmooth muscle permits constriction
    or dilation.
  • Vasoconstriction in cold temperatures
  • decreases dermal blood flow to conserve heat in
  • the body core.
  • Vasodilation in warm temperatures increases
    dermal blood flow to bring heat to the surface to
    be lost.
  • Vasoconstriction during stress shunts blood away
    from the skin to more vital organs, such as
    muscles, to permit a physical response, if
    necessary.

38
Subcutaneous Tissue
  • Subcutaneous Tissuealso called the superficial
    fascia connects skin to muscles
  • 1. Areolar tissue, called loose connective
    tissue
  • the matrix contains tissue fluid and WBCs that
    destroy pathogens
  • 2. Adipose tissue stores fat as potential energy
    cushions bony prominences provides some
    insulation from cold.

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AGING AND THEINTEGUMENTARY SYSTEM
  • become thinner as mitosis slows and fibroblasts
    die and are not replaced repair is slower.
  • becomes wrinkled as collagen and elastin fibers
  • deteriorate.
  • - Sebaceous glands and sweat glands become less
    active the skin becomes dry, and temperature
    regulation becomes more difficult.
  • Hair follicles become inactive and hair thins.
  • Melanocytes die so white hair
  • Less fat in subcutaneous tissue so more
    sensitivity to cold

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