NDA Biology · Human Physiology
Body Tissues — the Building Blocks
A tissue is a group of similar cells doing one job; the body builds every organ from four tissue types — epithelial (covering), connective (support), muscle (movement), and nervous (signalling).
Why this matters
Start here — every organ system later in the chapter is made of these tissues, so the NDA tests them directly (8 PYQs). The connective-tissue family is the highest-yield cluster: blood, cartilage, bone, tendon and ligament are all connective, and the bank loves to swap tendon with ligament or ask where cartilage is NOT found. All EASY or MODERATE — pure recall.
Concept 1 of 4: Levels of organization — cells to organ systems
Definition
The structural hierarchy of the body, smallest to largest:
- Cell — the basic unit of life.
- Tissue — a group of similar cells performing a common function (four types: epithelial, connective, muscle, nervous).
- Organ — different tissues working together (heart, stomach, kidney).
- Organ system — organs sharing one overall job (circulatory, digestive, excretory).
Worked example
Concept 2 of 4: The four types of animal tissue
Definition
Four primary animal tissues, classified by function. Note the surprises the bank tests: blood is a connective tissue (fluid matrix), and the contractile proteins actin and myosin are found only in muscle tissue.
| Tissue type | Function | Examples |
|---|---|---|
| Epithelial | Covering and lining of surfaces; protection, absorption, secretion | Skin surface, lining of mouth, oesophagus, intestine, glands |
| Connective | Support, binding, transport; cells in a matrix | Blood, bone, cartilage, tendon, ligament, adipose (fat) Blood is a CONNECTIVE tissue — fluid matrix (plasma) with cells (RBC, WBC, platelets) suspended in it. |
| Muscle | Contraction and movement; contains actin + myosin | Skeletal, smooth, cardiac muscle |
| Nervous | Conducting electrical signals | Neurons (brain, spinal cord, nerves) |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 2 · Human Physiology · Connective and Epithelial Tissues
Blood is connective tissue, not 'a fluid' of its own
Concept 3 of 4: The connective-tissue family — tendon, ligament, cartilage, bone
Definition
Members of the connective-tissue family and the facts the bank tests:
- Tendon — connects muscle to bone; made of tightly packed collagen fibres (high tensile strength).
- Ligament — connects bone to bone at a joint; more elastic than tendon.
- Cartilage — flexible support; found in the nose, ear (pinna), larynx, trachea, and joints (knee). NOT in the urinary bladder (smooth muscle) and NOT in the bronchioles (only the larger bronchi have cartilage).
- Bone — rigid calcified connective tissue; the skeleton.
- Blood — fluid connective tissue (plasma + cells).
| Tissue | Connects / role | Key fact |
|---|---|---|
| Tendon | Muscle to bone | Made of collagen; high tensile strength |
| Ligament | Bone to bone | Elastic; holds joints together |
| Cartilage | Flexible support | In nose, ear, larynx, trachea, knee NOT in the urinary bladder or the bronchioles. |
| Bone | Rigid framework | Calcified; the skeleton |
| Blood | Transport | Fluid matrix (plasma) + cells |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 3 · Human Physiology · Connective and Epithelial Tissues
Tendon ↔ ligament — the direction is the answer
'Cartilage is NOT found in ___' — know the exceptions
Concept 4 of 4: Epithelium and skin
Definition
Epithelial types by cell shape, plus the skin's UV defence:
- Squamous — flat, scale-like cells; line surfaces where smooth flow or thin diffusion is needed (oesophagus, alveoli, blood vessels).
- Cuboidal / Columnar — cube-shaped / tall cells; line glands and the intestine (absorption, secretion).
- Melanin — the brown skin/hair/iris pigment; it absorbs ultraviolet (UV) radiation, protecting cells from UV-induced DNA damage.
| Feature | Detail |
|---|---|
| Squamous epithelium | Flat cells; lines the oesophagus, alveoli, blood vessels |
| Columnar epithelium | Tall cells; lines the intestine and stomach (absorption/secretion) |
| Skin pigment | Melanin — gives colour to skin, hair, iris |
| Melanin's role | Absorbs ultraviolet (UV) radiation — not infrared, X-ray or radio NDA 2017 — melanin protects against ULTRAVIOLET radiation specifically. |
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 4 · Human Physiology · Connective and Epithelial Tissues
Melanin blocks UV, not infrared or X-rays
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (3)
The four types of animal tissue4 rows
| Tissue type | Function | Examples |
|---|---|---|
| Epithelial | Covering and lining of surfaces; protection, absorption, secretion | Skin surface, lining of mouth, oesophagus, intestine, glands |
| Connective | Support, binding, transport; cells in a matrix | Blood, bone, cartilage, tendon, ligament, adipose (fat) Blood is a CONNECTIVE tissue — fluid matrix (plasma) with cells (RBC, WBC, platelets) suspended in it. |
| Muscle | Contraction and movement; contains actin + myosin | Skeletal, smooth, cardiac muscle |
| Nervous | Conducting electrical signals | Neurons (brain, spinal cord, nerves) |
The connective-tissue family — tendon, ligament, cartilage, bone5 rows
| Tissue | Connects / role | Key fact |
|---|---|---|
| Tendon | Muscle to bone | Made of collagen; high tensile strength |
| Ligament | Bone to bone | Elastic; holds joints together |
| Cartilage | Flexible support | In nose, ear, larynx, trachea, knee NOT in the urinary bladder or the bronchioles. |
| Bone | Rigid framework | Calcified; the skeleton |
| Blood | Transport | Fluid matrix (plasma) + cells |
Epithelium and skin4 rows
| Feature | Detail |
|---|---|
| Squamous epithelium | Flat cells; lines the oesophagus, alveoli, blood vessels |
| Columnar epithelium | Tall cells; lines the intestine and stomach (absorption/secretion) |
| Skin pigment | Melanin — gives colour to skin, hair, iris |
| Melanin's role | Absorbs ultraviolet (UV) radiation — not infrared, X-ray or radio NDA 2017 — melanin protects against ULTRAVIOLET radiation specifically. |
Watch out for (4)
- Blood is connective tissue, not 'a fluid' of its own→ The four types of animal tissue
- Tendon ↔ ligament — the direction is the answer→ The connective-tissue family — tendon, ligament, cartilage, bone
- 'Cartilage is NOT found in ___' — know the exceptions→ The connective-tissue family — tendon, ligament, cartilage, bone
- Melanin blocks UV, not infrared or X-rays→ Epithelium and skin
Test yourself on Human Physiology
15 past NDA questions from this chapter, timed at 15 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.