Tissue

• Tissues - groups of cells that work together to perform specific functions in the body.
• The human body is composed of 4 main types of tissues:

  1. Epithelial

  2. Connective

  3. Muscular

  4. Nervous
• Epithelial Tissue

  • covers body surfaces, lines internal organs, and forms glands
  • composed of tightly packed tissues
  • Avascular yet regenerative
  • They have an apical surface and a basal surface.
  • Acts as a barrier to protect, absorb, filter, and secrete.
  • Categorized into 2 groups based on structure and function

  1. Lining: covers body cavities and body tubes
  2. Grandular: secretory organs
• Simple Epithelium: One layer of cells.
• Simple squamous:

  • Structure: single layer of flat thin cells

  • Function: diffusion and filtration

  • Location: alveoli, endothelium,mesothelium
• Simple cuboidal:

  • Structure: single layer of cube-shaped cells

  • Function: secretion and absorption

  • Location: kidney tubules, ducts of glands
• Simple columnar:

  • Structure: single layer of tall, column-like cells

  • Function: secretion, absorption, and movement of substances

  • Location: lining of the GIT, fallopian tubes, and parts of respiratory tract
• Pseudostratified:

  • Structure: single layer at varying levels

  • Function: secretion and movement of mucus

  • Location: upper respiratory tract and male reproductive ducts
• Stratified squamous:

  • Structure: multiple layers of flat cells

  • Function: protection

  • Location: skin, mouth, esophagus, vagina
• Stratified cuboidal:

  • Structure: multiple layers of cube-shaped cells

  • Function: protection

  • Location: mammary glands anorectal junction, large ducts of exocrine glands
• Stratified Epithelium: Multiple layers

  for protection.
• Stratified columnar:

  • Structure: multiple layers of tall,

  column-like cells

  • Function: protection

  • Location: eye conjunctiva,

  anorectal junctions, large ducts

  of exocrine glands
• Transitional:

  • Structure: from cuboidal to

  squamous

  • Function: protection and permits

  distension

  • Location: renal calyces, ureter,

  bladder, urethra
• CONNECTIVE TISSUE

  Contains cells scattered within an extracellular matrix, made up of fibers and ground substance.

  • Vascularity varies

  • Cell types: fibroblasts, adipocytes, and chondrocytes.
• CONNECTIVE TISSUE PROPER

  1. Loose

  2. Dense
• SPECIALIZED CONNECTIVE TISSUE

  1. Cartilage

  2. Bone

  3. Blood
• Loose/areolar connective tissue:

  • Structure: loose arrangement of

  fibers (collagen, elastin) and

  various cell types in a matrix.

  • Function: support and defense

  • Location: capillaries, skin
• Dense regular connective tissue:

  • Structure: tightly packed

  collagen fibers arranged in

  parallel bundles.

  • Function: strong attachment

  • Location: tendons, ligaments
• Dense irregular connective tissue:

  • Structure: collagen fibers

  arranged irregularly (non-

  parallel bundles)

  • Function: strong attachment

  • Location: dermis
• Adipose tissue:

  • Structure: adipocytes with very

  little extracellular matrix

  • Function: energy, insulation, and

  cushion

  • Location: hypodermis, abdomen
• Bone:

  • Structure: rigid extracellular

  matrix with collagen fibers and

  calcium salts.

  • Function: support, protection,

  storage, movement

  • Location: skeleton
• MUSCLE TISSUE Specialized for contraction and movement.

  • It is composed of cells that can shorten to produce force.

  1. Skeletal

  2. Cardiac

  3. Smooth
• Skeletal muscle:

  • Structure: long, cylindrical,

  multinucleated fibers with visible

  striations

  • Function: voluntary movement

  • Location: attached to bones
• Cardiac muscle:

  • Structure: branched,

  striated fibers with 1-2

  central nuclei; connected

  by intercalated discs.

  • Function: pump blood
• Smooth muscle:

  • Structure: spindle-shaped cells

  with no visible striations, single

  nucleus per cell.

  • Function: moves substances

  through hollow organs

  • Location: walls of blood vessels,

  digestive organs, airway
• NERVOUS TISSUE

  Specialized for transmitting electrical signals.

  • Consists of neurons (nerve cells) and supporting cells called glial cells.

  1. Neurons

  2. Glial cells
• Neurons:

  • Structure: consist of dendrites, a

  cell body, and an axon.

  • Function: transmit nerve impulse

  • Location: CNS & PNS
• Neuroglia:

  • Structure: supporting cells that protect, nourish, and insulate

  neurons.

  • Function: maintain homeostasis (signal transmission and repair)

  • Location: CNS & PNS
• Epithelial Tissue: Thin layers allow for absorption,

  secretion, and protection.
• Connective Tissue: The extracellular matrix provides

  support and binds tissues together.
• Muscular Tissue: The contractile fibers enable movement

  and force generation.
• Nervous Tissue: The long axons of neurons allow for the

  rapid transmission of signals across the body.
• TISSUE MEMBRANE

  Thin layers of tissues that cover surfaces, separate regions, and protect organs.

  1. Mucous membrane

  2. Serous membrane

  3. Synovial membrane
• Mucous membrane:

  • Structure: has epithelial layer and

  an underlying connective tissue

  layer (lamina propria).

  • Function: secretes mucus

  • Location: digestive, respiratory, and

  urogenital tracts.
• Serous membrane:

  • Structure: has simple squamous

  epithelium (mesothelium) and an

  underlying layer of connective

  tissue.

  • Function: secretes serous fluid

  • Location: pericardium, pleura,

  peritoneum
• Synovial membrane:

  • Structure: composed of connective

  tissue and lacks an epithelial layer

  • Function: secretes synovial fluid

  • Location: synovial joints