Tissues and Membranes

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Tissues and Membranes

• A tissue is a group of cells with similar
  structure and function.

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Types of Tissues

• Epithelial
• Connective
• Muscle
• Nerve

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Epithelial Tissues

• Found on surface as either coverings or linings
• Have no capillaries
• Receive oxygen and nutrients from the blood
  supply of connective tissues beneath them

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Epithelial Tissues

• Covers the body and many of its parts
• Lines the bodys serous cavities, blood vessels,
  and the respiratory, digestive and urinary tracts
• Forms the bodys glands
• Has close cellular arrangement with very little
  intercellular substance
• Contains no blood vessels

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Epithelial Tissues

• Receives oxygen and nutrients by diffusion upward
  from capillaries of the connective tissue which
  always lies beneath the epithelium
• Has a basement membrane which lies between the
  epithelial and connective tissue
• Undergoes mitosis continually to replace the
  upper layer of cells which are lost to normal
  wear and tear

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Types of Epithelial Tissues

• Simple squamous
• Stratified squamous
• Transitional
• Simple cuboidal
• Simple columnar
• Ciliated
• Glands

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Classification of Epithelium

• By the shape of the cells
• Squamous - Flat and scalelike
• Cuboidal Cu7belike
• Columnar Taller or longer than they are wide

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By the Layer Arrangement

• Simple A single layer
• Stratified Multiple layers

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Simple Squamous Epithelial

• A single layer of flat cells
• Very smooth
• The alveoli of the lungs are simple squamous
• The thinness of the cells permits diffusion of
  gases between the air and blood

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Simple Squamous Epithelial

• The capillaries , smallest blood vessel have
  these cells
• Walls are one cell thick
• Permits the exchange of gases, nutrients, and
  waste products between the blood and tissue
  fluid.
• Interior surface of the capillaries are very
  smooth because it prevents abnormal blood
  clotting within the blood vessel

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Stratified Squamous Epithelial

• Consist of many layers of mostly flat cells
• Mitosis take place in the lowest layer to
  continually produce new cells to replace those
  worn off the surface
• Make up the epidermis of the skin

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Stratified Squamous Epithelial

• Nonkeratinizing type lines the
• Oral cavity
• Esophagus
• Vagina
• A barrier to microorganisms because the cells of
  which it is made are very close together

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Transitional Epithelial

• A type of stratified epithelium
• Tolerates considerable stretching
• Found in regions of the urinary tract

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Simple Cuboidal Epithelium

• Cubelike
• Single layer
• Found in thyroid gland
• Found in salivary glands
• Function is secretion
• Arranged in small spheres

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Simple Columnar Epithelium

• Taller or longer than they are wide
• Specialized for secretion and absorption
• Found in the stomach lining
• Found in the lining of the small intestines
• Columnar cells of the small intestines have
  microvilli ( folds of the cell membrane)

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Columnar Epithelium

• Goblet cell is another type
• Is unicellular gland
• One cell
• Secrete mucus
• Found in the lining of the intestines and lining
  of part of the respiratory tract such as the
  trachea

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Glands

• Cells or organs that secrete something
• Secretions are classified according to location
• Examples
• Endocrine glands secretions are released into
  surrounding interstitial fluid and blood
• Secretions are called hormones
• Multicellular

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Glands

• Examples
• Exocrine Glands
• Produce secretions that are discharged onto
  epithelial surfaces
• Multicellular Gland
• Divided into major groups

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Connective Tissue

• Include tissues such as
• bones
• adipose
• blood
• areolar
• Fibrous
• Elastic
• Cartilage
• Reticular
• hemopoietic

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Connective Tissue

• Reticular
• Location spleen, lymph nodes, and bone marrow
• Function filters injurious substances from
  blood and lymph by the reticular network
  phagocytosis

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Areolar

• Loose/ordinary
• Location between other tissues, organs, and
  superficial tissues
• Function connects tissues

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Adipose

• Location under skin as padding
• Function protects, insulates, supports, and
  acts as reservoir for food

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Fibrous

• Location tendons, ligaments, deep fascia,
  dermis, scars, capsule of kidney
• Function flexible, but strong connecting tissue

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Bone (osseous)

• Location skeleton
• Function protects, supports

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Cartilage (elastic)

• Location Nasal septum, covering surface
  of bones, larynx rings in
• trachea, and bronchi vertebral discs,
  external ear
• Eustachian tube
• Function firm, but flexible support

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Hemopoietic

• Location
• Myeloid Bone Marrow
• Lymphatic Lymph nodes, spleen, tonsils and
  thymus

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Hemopoietic

• Function
• Myeloid Formation of red and white blood cells
  and platelets
• Lymphatic formation of lymphocytes and monocytes

Hemopoietic
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Blood

• Location blood vessels
• Function transportation, protection

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Elastic

• Location Walls of large arteries and is found
  surrounding the alveoli of the lungs
• Function to stretch and recoil

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Muscle Tissue

• Skeletal
• Visceral
• Cardiac

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Skeletal

• Striated, voluntary
• Attached to bones

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Visceral

• Nonstraited, smooth, involuntary
• Found in walls of hollow organs such as blood
  vessels, intestines, and uterus

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Cardiac

• Striated, involuntary
• Composes the walls of the heart

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Types of Nerves Tissue

• Neuron ( the nerve cell)
• Capable of generating and transmitting
  electrochemical impulses
• Make up the brain, spinal cord and peripheral
  nerves

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Membranes

• Sheets that cover or line surface or that
  separate organs or parts of organs from one
  another.

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Types of Membranes

• Epithelial Membranes
• Mucous line cavities or passages of the
  body that open to the exterior such
• as mouth, esophagus, digestive
  tract, respiratory
  passages and GU tract
• Function in protection, secretion of mucus, and
  absorption
• Serous line closed cavities of the body such as
  thoracic cavity (pleura),

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Serous (Cont)

• Abdominal cavity (peritoneum), and sac in which
  heart lies (pericardium)
• Also cover organs lying in those closed cavities
• Has two layers
• Visceral covers organs
• Parietal lines the cavity

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Serous (Cont)

• Potential space between the two layers is kept
  most by the secretion of a small amount of serous
  fluid which prevents friction when the two layers
  rub together

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Synovial Membranes

• Line joint, tendons, and bursae
• Secrete synovial fluid which prevents friction on
  the smooth, moist surfaces

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Cutaneous Membranes

• Covers the body
• Are continuous with mucous membranes
• Has essentially two layers
• Epidermis outer layer
• Dermis under layer

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Integumentary System

• Appendage Anything attached to a larger or
  major part
• Cerumen Wax-like soft brown secretion
  found in the external canal of the ear
• Dermis the inner, sensitive, vascular
  layer of the skin

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Terms

• Dermatology a branch of science dealing
  with the skin, its structures,
  functions, and diseases
• Epidermis the outer, non-sensitive,
  nonvascular layer of the skin

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Terms

• Integument something that covers or encloses as
  an enveloping layer such as skin or a membrane
• Keratin an extremely tough protein substance in
  hair, nails, and horny tissue.

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Terms

• Lumen The space within a tube, artery, vein, or
  intestine
• Melanin the dark brown or black pigment that
  gives color to hair and skin
• Sebum a fatty, oil secretion of the sebaceous
  glands of the skin

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Terms

• Tactile relating to the sense of touch

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Characteristics

• Largest organ of the body
• Varies in depth
• The bodys first line of protection against
  disease (if it is kept clean)
• Continuous with the mucous membrane
• Color depends upon deposits of varying amounts of
  melanin and upon changing amounts of blood
  supplied to the skin

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Functions of the skin

• Protects by acting as a mechanical barrier
  against microorganisms, sunlight, and chemicals
• Senses pain, heat, cold, and pressure through
  nerve endings in the skin
• Regulates body temperature by varying the amount
  of blood flowing through the skin and varying the
  amount of sweat excretion

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Function of the skin

• Acts as excretory organ through sweat glands
• Aids in maintaining fluid and electrolyte balance

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Blood Vessels

• Arterioles small arteries, and the small muscle
  in their walls permits them to constrict or
  dilate
• Important to maintain body temperature
• Blood carries heat which is a form of energy

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Blood Vessels

• Arterioles dilate which increases blood flow
  through the dermis, and brings excess heat to the
  body surface to be radiated to the environment
• vasodilation

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Blood vessels

• In a cold environment the arterioles constricts
  which decreases the flow of blood through the
  dermis and keeps heat within the core of the
  body.
• Vasoconstriction
• May occur during stressful situation

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Two main layers of skin

• Epidermis false skin thinner, outer surface
  layer
• Composed of stratified squamous epithelial
  tissue
• Is protective and the greater part of its
  thickness is made up of dead epithelial cells
  that are continually being scraped off and
  replaced by underlying daughter cells

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Epidermis

• Thickness varies in different parts of the body
• Thickest on soles of feet
• Thinnest on eyelids, forehead, and penis

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epidermis

• Has no blood or lymph vessels or nerve endings
  (nonvascular and non-sensitive)
• Has four layers of cells except on the palms of
  hand and soles of feet where there are five

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Layers of the Epidermis

• Stratum corneum outermost layer
• Horny layer
• Top layer where dead cells converted into keratin
  continually flake off
• Protein keratin is waterproof
• Prevent most evaporation of body water
• Barrier to pathogens and chemicals

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Epidermis

• Stratum Lucidum
• Translucent or clear layer
• Layer only found in palms or soles

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Epidermis

• Stratum granulosum
• Granular layer
• Layers where cells die and granules are present
  in the cytoplasm

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Epidermis

• Stratum Spinosum
• Prickle cell layer
• Layer of irregularly shaped cells

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Epidermis

• Stratum germinativum
• Bottom layer where columnar shaped cells undergo
  mitosis continually to make cells and to push old
  ones upward
• The base of the epidermis
• Mitosis take place

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Dermis

• True skin lies underneath the epidermis
• Compose of dense, fibrous connective tissue
• Blood capillaries and nerves pass freely through
  the dermis to supply the epidermis
• Contains nerve endings for five types of
  sensations

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Dermis

• Heat
• Cold
• pain
• Touch
• Pressure
• Contains all accessory appendages of the skin
• Has two layers

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Layers of the Dermis

• Papillary Layer
• Elevated into tiny projections and hollows
• Lies next to the germinal layer of epidermis
• Produces the familiar ridges of the skin which
  form a characteristic and unchangeable pattern
  for every individual

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Dermis

• Reticular Layer
• Lies beneath papillary layer
• Forms a network of interlacing cells and fibers

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Accessory appendages of the skin

• Hair
• Nails
• Skin glands

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Hair

• Found on all parts of the body except the palms
  of hands, soles of feet and penis
• Hair shaft is visible part of the hair
• Hair root is part of the hair that is embedded in
  the dermis
• Hair follicle is the cavity which contains the
  hair

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Hair

• Hair is kept soft and pliable by two or more
  sebaceous glands which secrete sebum
• Also attached to the hair follicle are small
  bundles of involuntary muscle called arrector
  pili muscles that cause the hair to stand on end
• Hair color is due to different amounts of pigment
  within the hair shaft
• Hair color is due to loss of this pigment

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Hair

• Hair grows about one-half inch a month
• A boil or furuncle is an infection of a hair
  follicle
• Hair found around eyes and in the ears and nose
  performs a protective function in keeping out
  some dust and insects
• Hair on the bulk off the skin has no apparent
  function

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Nails

• Consist of epidermis cells which have been
  converted to keratin
• Grow from epithelial cells lying under the white
  crescent (lunula) at the proximal end of the nail
• The subungual area is the area situated
• Underneath a nail
• Paronychia is a hangnail around the fingernail

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Receptors

• Most sensory receptors for the cutaneous senses
  are found in the dermis
• The cutaneous senses are touch, pressure, heat,
  cold, and pain
• Each sensation has a specific type of receptor

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Receptors

• Free nerve endings are receptors for
• pain
• Heat
• Cold

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Receptors

• Encapsulated nerve endings are for touch and
  pressure
• There is a cellular structure around the sensory
  nerve ending.
• The purpose of these receptors and sensations is
  to provide the central nervous system with
  information nad its effect on the skin

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Skin Glands

• Sebaceous glands
• Secrete sebum to lubricate the hair
• There are two more sebaceous glands per hair
  follicle
• Keep hair supple and skin soft and pliant
• Prevent excessive water evaporation and water
  absorption through the skin
• Lesson the amount of heat lost from the skin

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Skin Glands

• Sweat Glands (sudoriferous glands)
• Very small and numerous, especially on palms,
  soles, forehead, and axillae
• Located in deep layers of dermis and exit through
  pores
• A single square inch of skin on the palms of the
  hand contains 3,000 sweat glands
• Help maintain homeostasis of fluids and
  electrolytes and body temperature

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Skin glands

• Sweat Glands
• Excrete nitrogenous wastes
• Consists of tubes into a tiny ball surrounded by
  capillaries

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Sweat glands

• Two types
• Apocrine most numerous in the axillae and
  genital
• Active in stress and emotional situations
• Eccrine glands found all over the body
  especially forehead, upper lip, palms and soles

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Ceruminous GlandsModified sweat glands

• Located in external ear canals
• Secrete cerumen

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