Revision sheet: Animal Tissues

📋 Course Outline

1. Epithelial Tissue Types
2. Connective Tissue Functions
3. Blood Bone Ligament Adipose
4. Muscular Tissue Fibres
5. Nervous Tissue Structure

📖 1. Epithelial Tissue Types

🔑 Key Concepts & Definitions

• Epithelial tissue : Forms the outer protective layer of most animals and lines surfaces such as the mouth, blood vessels, lungs, alveoli, and kidney tubes.
• Squamous epithelium : A thin, flat, semipermeable tissue suited for gas exchange and found in the lining of the oesophagus and mouth.
• Stratified squamous epithelium : Consists of multiple layers of squamous epithelial cells and forms the skin.
• Columnar epithelium : Consists of elongated, pillar-like cells that line organs involved in absorption and secretion, such as the intestine.
• Cuboidal epithelium : Consists of cuboidal cells lining salivary glands and kidney tubules, providing mechanical support and contributing to gland formation.

📝 Essential Points

• Ciliated columnar epithelium has cilia on its cells and occurs in the respiratory tract, fallopian tubes, and bronchioles.

💡 Memory Hook

Thin squamous tissue exchanges substances, whereas stratified squamous tissue protects.

📖 2. Connective Tissue Functions

🔑 Key Concepts & Definitions

• Connective tissue : Contains scattered living cells embedded in an abundant matrix that connects, binds, packs, and supports animal body structures.
• Blood : Blood is a fluid connective tissue that flows inside blood vessels through the pumping activity of the heart, and its pH is 7.4.

★ Must-know

• The major functions of connective tissue are:

  • binding structures
  • supporting structures
  • packing materials

• Blood consists of 55% fluid plasma and 45% blood cells.

Further detail

• The three types of blood cells are:
  • red blood cells or erythrocytes
  • white blood cells or leucocytes
  • platelets or thrombocytes

💡 Memory Hook

BSP: binding, supporting, packing.

📖 3. Blood Bone Ligament Adipose

🔑 Key Concepts & Definitions

• Bone : A very long, rigid, solid, and non-flexible tissue whose living cells are embedded in a hard matrix composed of calcium and phosphorus compounds.
• Ligament : A ligament binds one bone to another and allows bending and rotation around a joint because the tissue is very elastic.

★ Must-know

• Bones:
  • form the endoskeleton
  • support soft body parts
  • protect delicate tissues and organs

Further detail

• Adipose tissue: stores fat in reserve, forms a thick absorbing cushion around internal organs, provides shape to various body parts

💡 Memory Hook

Bone is rigid, ligament is elastic, and blood is fluid.

📖 4. Muscular Tissue Fibres

🔑 Key Concepts & Definitions

• Muscular tissue : Contractile tissue containing contractile proteins inside cells held together by connective tissue, and its cells are called muscle cells.
• Striated muscle fibres : Striated muscle fibres are long, cylindrical, unbranched cells with alternating light and dark bands that work under voluntary control.
• Smooth muscle fibres : Smooth muscle fibres are spindle-shaped, unbranched, non-striated cells with a centrally placed single oval or spindle-like nucleus that are not under voluntary control.
• Cardiac muscle fibres : Cardiac muscle fibres are branched, striated, involuntary, and non-fatiguing fibres found in the wall of the heart.

★ Must-know

• Contraction and relaxation of cardiac muscle fibres produce the pumping activity of the heart, and these fibres beat continuously and rhythmically without fatigue.

Further detail

• Striated muscle fibres occur in:

  • arms
  • legs
  • hands
  • feet
  • neck
  • body wall
  • tongue

• Smooth muscle fibres occur in:

  • posterior oesophagus
  • stomach
  • intestine
  • blood vessels
  • urinary bladder

💡 Memory Hook

Striated is voluntary, smooth is involuntary, and cardiac combines striations with involuntary action.

📖 5. Nervous Tissue Structure

🔑 Key Concepts & Definitions

• Nervous tissue : Transmits stimuli and impulses and, with connective tissue cells, forms the brain, spinal cord, and nerves.
• Neuron : A neuron is an individual nerve cell with a cell body, many short dendrites, and one long axon, and it can reach up to a metre in length.
• Cell body : The cell body or cyton contains the nucleus and cytoplasm, called neuroplasm, and lacks centrioles.

★ Must-know

• The nervous system: responds to stimuli, controls and coordinates body activities, supports learned behaviour, intelligence, memory, and reasoning

• Dendrites pick up impulses and transmit them toward the cyton, while the axon carries impulses away from the cell body.

Further detail

• The axon is a long, generally uniform-thickness process that lacks Nissl granules but contains neurofibrils.

💡 Memory Hook

Dendrites → cyton → axon: impulses arrive, pass through, then leave.

📊 Synthesis Tables

Comparison of Muscle Fibres

Type	Structure	Control and function
Striated	Long, cylindrical, unbranched, with light and dark bands	Voluntary; occurs in limbs and body wall
Smooth	Spindle-shaped, unbranched, without striations	Involuntary; prolonged contraction in internal organs
Cardiac	Branched and striated	Involuntary; rhythmic heart pumping without fatigue