Tutorial 2

• Tissues


  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Epithelial tissue


  • Covers most internal and external organs

  
• Connective tissue


  • Binds tissues and organs together
  • Supports organs in their location
  • Storage site for nutrients
• Muscle tissue


  • Enables voluntary and involuntary movement
• Nervous tissue


  • Highly specialised cells that receive and transmit electrical impulses
• Epithelial tissue


  Covers body surfaces, forms glands and lines hollow organs, body cavities and ducts

  
• Epithelial tissue functions


  • Protection
  • Sensory
  • Secretion
  • Absorption
  • Excretion
• Epithelial tissue characteristics


  Avascular: contains no blood vessels
• Epithelial tissue types


  • Simple squamous
  • Simple cuboidal
  • Simple columnar
  • Pseudostratified (columnar)
  • Stratified squamous - Keratinised
  • Stratified squamous - Nonkeratinised
  • Transitional
• Connective tissue is the most abundant and widely distributed tissue
• Connective tissue functions


  • Bind tissues together
  • Support and strengthen tissue
  • Protect and insulate internal organs
  • Compartmentalise and transport
  • Energy reserves and immune responses

  
• Connective tissue types


  • Areolar
  • Adipose
  • Reticular
  • Dense regular collagenous
  • Elastic dense regular
  • Hyaline cartilage
  • Fibrocartilage
  • Bone
  • Blood

  
• Muscle tissue types


  • Skeletal
  • Smooth
  • Cardiac
• Nervous tissue functions


  • Rapidly regulates and integrates
  • Detects changes in the body
  • Responds by generating nerve impulses
• Membranes


  Thin sheet-like structures that cover and protect surfaces and interiors of the body
• Membrane types


  • Epithelial
  • Connective tissue

  
• Epithelial membrane types


  • Cutaneous
  • Mucous
  • Serous

  
• Serous membranes


  • Thin, slippery double-layered membranes
  • Visceral layer: covers the organs within cavities
  • Parietal layer: lines cavity walls
  • Serous fluid: separates the layers to reduce friction and allow movement

  
• Mucous membranes


  • Produce a film that protects and coats underlying cells
  • Protects and lubricates
  • Located where the body is most likely to interact with microorganisms from the external environment

  
• Parts of the integumentary system

  • Skin
  • Accessory structures
  • Hair
  • Nails
  • Glands
  • Blood vessels
  • Muscles
  • Nerves

  
• Skin


  • The largest body organ by surface area and weight
  • Approx. 2 square meters and it weighs 4.5–5kg
  • 0.5–4 mm thick, thinnest on the eyelids, thickest on the heels
• Skin tissue types


  • Epithelial
  • Connective
  • Muscle
  • Nervous

  
• Skin structure


  • Epidermis
  • Dermis
  • Hypodermis

  
• Epidermis


  • Thin, superficial layer
  • Composed of epithelial tissue
• Dermis


  • Deep, thicker layer
  • Composed of connective tissue

  
• Hypodermis


  • Subcutaneous later
  • Composed of areolar and connective tissue
  • Attaches skin to underlying tissues and stores fat

  
• Epidermis composition


  • Consists of keratinised stratified squamous epithelium
  • Avascular
  • New cells produced in the lower layer, pushing older cells further away from basement membrane
  • Loss of contact with blood vessels as they are pushed further away means the cells die
• Stratum corneum


  • Outer layer of 20-30 layers of dead, overlapping cells
  • Cells are very thin, flat membrane enclosed packages of keratin that non longer contain nucleus/organelles
  • Cells continually shed and replaces
  • Protective layer – prevents deeper layers from injury and microbes

  
• Stratum basale

  • Specialised cells of the epidermis
  • Keratinocytes – produce keratin
  • Melanocytes – produce melanin
  • Keratin protects the skin and underlying tissue from heat, microbes and chemicals
  • Keratin provides a waterproof sealant
  • Melanin contributes to skin colour and absorbs damaging ultraviolet (UV) light. Production is increased when cells are being damaged.

  
• Over-exposure to UV radiation


  The single most important risk factor for skin cancer
• Dermis


  Contains sebaceous glands, dermal arterioles, and hair follicles
• Dermal arterioles


  • Dilate in hot weather increasing heat loss from skin
  • Constrict in cold weather preventing heat loss
• Skin colour


  Three pigments normally affect skin colour: Melanin, Carotene, Haemoglobin
• When a patient is oxygen insufficient


  The skin appears bluish
• Less blood in the skin

  Provides a pale hue
• Functions of the skin

  • Protection
  • Sensory
  • Excretion
  • Vitamin D synthesis
  • Stores blood
  • Temperature regulation
• Hair growth


  • Starts in the matrix
  • Supplied with capillaries that provide hormones, chemicals and nutrients to stimulate hair growth
  • Cells in matrix divide actively
  • As new cells produced older cells push up, keratin increases, and they fuse together when cells die
  • Hair grows in cycles (we lose 90 hairs/day)
• Causes of hair loss

  • Advancing age
  • Severe burns
  • Genetics
  • Fever
  • Emotional trauma
  • Protein deficiency
  • Breast feeding
• Nail structure and growth

  • Formed by epidermal cells at the ends of fingers and toes fill with keratin
  • Visible portion called nail body and the portion beneath the cuticle is the nail root
  • Abundant supply of blood vessels
  • Nail body slides over nail bed producing growth
• Age-related skin changes


  • Wrinkling
  • Melanocytes decrease in number
  • Hair loss
  • Reduced sweat production
  • Sebaceous gland atrophy
  • Blood vessel walls thicken
  • Poor skin healing