Tissues and the Integumentary System

Four Main Types Of Animal Tissue

• Epithelial Tissue

• Muscle Tissue

• Nervous Tissue

• Connective Tissue

Epithelial Tissue - Functions

• Protection

  • Covers external and internal body surfaces

  • Physical barrier

  • Protects underlying tissues from pathogen invasion, toxin exposure, thermal and mechanical trauma

• Absorption/Secretion

  • It allows absorption of nutrients, water, molecules from digested food (intestine) and blood (capillaries), secretion of enzymes, hormones and mucus (glands eg, liver, pancreas, thyroid)

Epithelial Cells- Functions

• Filteration/Excretion

  • Of waste products from blood (kidneys)

  • Filtration of inhaled air (lungs)

  • Excretion of sweat (skin)

• Regulation

  • Body temperature

  • Hydration etc

Apical-basal of epithelial cells

Apical- top

Basal - bottom

Apical-basal polarity of epithelial cells

Apical Membrane -

- Faces the inside of a cavity or the outside of the body

- Usually exposed to fluid or air

- Specialised for absorption,secretion and sensation

Basal Membrane-

- Faces the underlying cells

- Lies on top of the basement membrane

Apical- basal polarity of epithelial cells

Lateral Membrane-

• - In contact with surrounding cells through adhesion molecules (eg. Tight junctions)

• - These membranes hold the epithelium together and block paracellular diffusion

• - Epithelium offer a mechanical and chemical barrier against the toxic molecules and pathogens

Types of epithelial tissue

• Squamous Epithelium

• Cuboidal Epithelium

• Columnar Epithelium

• Simple Epithelium

• Stratified Epithelium

Squamous Epithelium

Flat and sheet like in appearance

Cuboidal Epithelium

Equal width, height and depth

Columnar Epithelium

Taller and wide

Simple Epithelium

• Single layer

• All cells are bound to the basement membrane

• Main functions: Absorption, secretion and Filteration

Stratified Epithelium

• Multiple layers of cells stacked

• Only cells in basal layer are bound to the basement membrane

• Main function: Protection

Types of Epithelial Tissue

Types of Epithelial Tissue 2

Function of muscle tissue

1. Production of body movements:

- Contains contractile proteins responsible for generating force and enabling body movements and locomotion

2. Stabilisation of the body position:

- Ensures posture and stability by constantly acting against the force of gravity

3. Storage and transport of substances within the body:

- Allows transport of blood, lymph and food.

- Stores carbohydrates in the form of glycogen

4. Heat generation: - 70-80% of energy generated during MC released as heat

Muscle cell- Myocyte

Contains 2 contractile proteins: Actin and Myosin

Skeletal Muscle- Striated or Striped muscle

-Myocytes are elongated, cylindrical in shape and contains more than one nucleus - arranged into bundles

-30-40% of total body mass

-Connected to the bones through tendons

-Voluntary contraction

Cardiac Muscle

• Found only in walls of the heart

• Not under voluntary control

• Striated but smaller than skeletal myosytes, branched and only has 1 nucleus (Uninucleated)

• Connected by intercalated discs that allow their synchronous contraction

Nervous Tissue - Functions