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
Intuition
The body is built in a hierarchy. Similar cells group into a tissue; different tissues combine into an organ; organs that share a job form an organ system. Knowing the ladder tells you what KIND of thing each exam term is — 'epithelium' is a tissue, 'stomach' is an organ, 'digestive system' is an organ system.
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
Place these in order from smallest to largest unit: stomach, digestive system, muscle tissue, a single gland cell.
- A single gland cell is one cell — the smallest unit.
- Muscle tissue is a group of similar cells — one level up.
- The stomach is an organ — built from several tissues (muscle, epithelial, connective, nervous).
- The digestive system is an organ system — the stomach plus mouth, intestine, pancreas, etc.
Answer:Gland cell → muscle tissue → stomach → digestive system.
Concept 2 of 4
The four types of animal tissue
Intuition
Every tissue in the human body is one of four kinds. Each has a signature job: epithelium covers and lines, connective tissue supports and binds, muscle contracts, and nervous tissue carries signals. Most NDA tissue questions just ask 'which type is this?' — so learn the one-line job of each.
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) |
The 'odd one out' answers the bank tests: blood = connective, not a fluid of its own category; contractile proteins = muscle only.
Practice this conceptself-check · 4 quick reps
Try it yourself
Classify each into a tissue type: (a) blood, (b) the lining of your intestine, (c) the biceps, (d) a nerve carrying touch signals.
Practice — Level 1 (4 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Which tissue type is blood?
- 2.Which tissue type contains contractile proteins?
- 3.What tissue lines the inside of the intestine?
- 4.Which tissue type carries electrical signals?
From the bank · past-year question
Blood is a type of
[Q78 · Sep · 2019]
Blood is connective tissue, not 'a fluid' of its own
A classic distractor lists blood as epithelial, muscular or nervous. It is connective — defined by cells suspended in a non-living matrix, which for blood is the plasma. Bone and cartilage are connective for the same reason.
Concept 3 of 4
The connective-tissue family — tendon, ligament, cartilage, bone
Intuition
Connective tissue is the body's support department, and the NDA mines it for recall questions. Two facts carry most marks: tendon connects MUSCLE to BONE while ligament connects BONE to BONE, and cartilage appears in specific named places (nose, ear, larynx, trachea, knee) but NOT in others. Get the tendon/ligament direction right and the cartilage locations memorised and this cluster is free.
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
Try it yourself
A sprinter tears the tissue joining her shin bone to her thigh bone at the knee, and separately strains the tissue joining her calf muscle to her heel bone. Name each tissue.
Practice — Level 1 (4 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Tendons connect ___ to ___.
- 2.Ligaments connect ___ to ___.
- 3.Name three places cartilage is found.
- 4.Is cartilage found in the urinary bladder?
From the bank · past-year question
Which one among the following tissues help to connect two bones ?
[Q53 · Sep · 2024]
Tendon ↔ ligament — the direction is the answer
Tendon = muscle to bone (think: 'Tendon Tugs the muscle'). Ligament = bone to bone. The bank swaps these constantly; if you only remember one, remember tendon = collagen, muscle-to-bone.
'Cartilage is NOT found in ___' — know the exceptions
Cartilage IS in the nose, ear, larynx, trachea and joints. It is NOT in the urinary bladder (2020) or the bronchioles (2024) — the small airways lose their cartilage even though the larger bronchi keep it.
Concept 4 of 4
Epithelium and skin
Intuition
Epithelial tissue covers the body and lines its tubes and cavities. It is named by cell shape — squamous (flat, scale-like), cuboidal (cube), columnar (tall). The skin is the body's largest epithelial organ, and its pigment melanin is a recall favourite: it blocks ultraviolet radiation.
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
Try it yourself
Why does the oesophagus have flat squamous cells lining it, and what pigment protects skin from sun damage?
Practice — Level 1 (3 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Which epithelium lines the oesophagus?
- 2.Melanin protects the skin against which radiation?
- 3.Melanin gives colour to which three structures?
From the bank · past-year question
Squamous epithelial cells are found in the inner lining of
[Q71 · Apr · 2021]
Melanin blocks UV, not infrared or X-rays
The distractors offer infrared, X-ray and radio radiation. Melanin's job is specifically ultraviolet absorption — the band of sunlight that damages DNA and causes sunburn.
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 'odd one out' answers the bank tests: blood = connective, not a fluid of its own category; contractile proteins = muscle only.
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
Mastery check — 5 interleaved questions
Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.
Which one of the following types of tissues will have contractile proteins?
[Q92 · Apr · 2018]
In which part or organ of human body cartilage is NOT found ?
[Q86 · Sep · 2024]
Melanin is the natural pigment that gives colour to human skin, hair and the iris. It provides protection against
[Q65 · Sep · 2017]
Tendons through which muscles are connected to bones are tightly compacted bundles of which one of the following long fibrous protein?
[Q63 · Sep · 2017]
Cartilage is NOT found in
[Q127 · Apr · 2020]
Drill every past-year question on this subtopic
8 questions from the bank — paginated, with cart and Word-export support.