Anatomy
MBBS Anatomy question bank: general anatomy and osteology, regional gross anatomy (upper limb, lower limb, thorax, abdomen, pelvis, head and neck), neuroanatomy, histology and embryology.
12chapters144questions84High-Yield
Definition
Epithelial tissue is an avascular tissue that covers surfaces, lines cavities and forms glands; its cells are closely packed on a basement membrane.
Features
- Cells closely packed, little matrix
- Rests on a basement membrane
- Avascular (nourished by diffusion)
- Cellular polarity (apical / basal)
Classification by Layers
- Simple — single layer
- Stratified — multiple layers
- Pseudostratified
Classification by Shape
- Squamous, cuboidal, columnar
Epithelium is grouped by number of layers and cell shape. Type Example Simple squamous Alveoli Simple columnar Gut Stratified squamous Skin Transitional Bladder Applied
- Metaplasia (e.g. Barrett’s oesophagus)
- Carcinoma (epithelial cancer)
🔑KEY POINTS TO REMEMBER- Epithelium: avascular, on basement membrane, polarised.
- By layers (simple/stratified) & shape (squamous/cuboidal/columnar).
- Functions: protection, absorption, secretion.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Connective tissue supports, connects and protects other tissues; it consists of cells, fibres and ground substance.
Components
- Cells — fibroblasts, macrophages, mast cells, adipocytes
- Fibres — collagen, elastic, reticular
- Ground substance — matrix
Types
- Loose (areolar) — packing tissue
- Dense — regular (tendon), irregular (dermis)
- Special — cartilage, bone, blood, adipose
Cells, fibres and matrix combine in loose, dense and special forms. Fibre Feature Collagen Strength (type I) Elastic Stretch / recoil Reticular Framework (type III) Applied
- Scurvy — defective collagen
- Marfan syndrome — elastic (fibrillin)
🔑KEY POINTS TO REMEMBER- Connective tissue = cells + fibres + ground substance.
- Fibres: collagen (strength), elastic (recoil), reticular (framework).
- Types: loose, dense, special.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Muscle tissue is a contractile tissue producing movement; there are three histological types — skeletal, cardiac and smooth.
Skeletal
- Long cylindrical, multinucleated
- Striated, voluntary
- Nuclei at the periphery
Cardiac
- Branched, single central nucleus
- Striated, involuntary
- Intercalated discs
Smooth
- Spindle-shaped, single central nucleus
- Non-striated, involuntary
Three histological types differ in nuclei, striations and control. Type Nucleus Striations Control Skeletal Multiple, peripheral Yes Voluntary Cardiac Single, central Yes Involuntary Smooth Single, central No Involuntary Applied
- Intercalated discs (cardiac — gap junctions)
- Limited regeneration
🔑KEY POINTS TO REMEMBER- Skeletal: striated, multinucleated (peripheral), voluntary.
- Cardiac: striated, central nucleus, intercalated discs.
- Smooth: non-striated, central nucleus, involuntary.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Nervous tissue consists of neurons (conducting cells) and neuroglia (supporting cells).
Neuron
- Cell body (soma) with Nissl bodies
- Dendrites (receive)
- Axon (transmit)
- Myelin sheath (in some)
Neuroglia (support)
- CNS — astrocytes, oligodendrocytes, microglia, ependyma
- PNS — Schwann cells, satellite cells
Neurons conduct impulses; glia support and myelinate them. Glia Function Astrocyte Support, blood–brain barrier Oligodendrocyte Myelin (CNS) Schwann cell Myelin (PNS) Microglia Phagocytosis Applied
- Demyelination (multiple sclerosis)
- Nissl bodies — protein synthesis
🔑KEY POINTS TO REMEMBER- Nervous tissue = neurons + neuroglia.
- Neuron: soma (Nissl), dendrites, axon.
- Myelin: oligodendrocyte (CNS), Schwann (PNS).
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
The cell is the basic structural unit of the body; cell junctions connect adjacent cells and coordinate their functions.
Cell Organelles
- Nucleus — DNA
- Mitochondria — ATP
- Endoplasmic reticulum (rough/smooth), Golgi
- Lysosomes, ribosomes
Cell Junctions
- Tight junction — seals (barrier)
- Adherens / desmosome — adhesion
- Gap junction — communication
Organelles run the cell; junctions bind cells into functioning tissues. Junction Function Tight Barrier / seal Desmosome Strong adhesion Gap Communication Applied
- Pemphigus (desmosome autoantibodies)
- Gap junctions in cardiac muscle
🔑KEY POINTS TO REMEMBER- Cell: nucleus, mitochondria, ER, Golgi, lysosomes.
- Junctions: tight (seal), desmosome (adhesion), gap (communication).
- Pemphigus targets desmosomes.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Epithelium is classified by the number of cell layers and the shape of the surface cells.
By Layers
- Simple (single layer)
- Stratified (multiple layers)
- Pseudostratified
By Shape
- Squamous (flat)
- Cuboidal
- Columnar
Special
- Transitional (urothelium) — stretchable
Layer number and cell shape together name each epithelium. Type Location Simple squamous Alveoli, endothelium Simple cuboidal Kidney tubules Simple columnar GIT Stratified squamous Skin, oesophagus Transitional Bladder Applied
- Wet vs keratinised stratified squamous
🔑KEY POINTS TO REMEMBER- By layers: simple, stratified, pseudostratified.
- By shape: squamous, cuboidal, columnar.
- Transitional = stretchable (bladder).
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Exocrine glands secrete their products through ducts onto a surface; they are classified by structure and by mode of secretion.
By Structure
- Simple vs compound (branched duct)
- Tubular, acinar (alveolar), tubuloacinar
By Mode of Secretion
- Merocrine — exocytosis (salivary)
- Apocrine — apical cytoplasm lost (mammary)
- Holocrine — whole cell shed (sebaceous)
Glands are grouped by duct shape and how they release secretion. Mode Example Merocrine Salivary, pancreas Apocrine Mammary, sweat Holocrine Sebaceous Applied
- Contrast with endocrine (ductless)
🔑KEY POINTS TO REMEMBER- Exocrine glands secrete via ducts.
- Structure: tubular/acinar; secretion: merocrine, apocrine, holocrine.
- Sebaceous = holocrine.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Collagen is the most abundant protein in the body, providing tensile strength to connective tissues.
Features
- Triple helix of polypeptide chains
- Rich in glycine, proline, hydroxyproline
- Synthesised by fibroblasts
- Requires vitamin C (hydroxylation)
Types
- Type I — skin, bone, tendon
- Type II — cartilage
- Type III — reticular fibres
- Type IV — basement membrane
Fibroblasts build collagen; vitamin C is essential for its cross-linking. Type Location I Skin, bone, tendon II Cartilage IV Basement membrane Applied
- Scurvy (vitamin C deficiency)
- Ehlers–Danlos, osteogenesis imperfecta
🔑KEY POINTS TO REMEMBER- Collagen: triple helix, most abundant protein.
- Types I (skin/bone), II (cartilage), IV (BM).
- Needs vitamin C → scurvy if deficient.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Cell junctions are specialised contacts connecting adjacent cells for sealing, adhesion or communication.
Types
- Tight (occluding) — barrier / seal
- Adherens junction — adhesion belt
- Desmosome — strong spot adhesion
- Gap junction — direct communication
- Hemidesmosome — anchors to basement membrane
Different junctions seal, anchor or connect neighbouring cells. Junction Function Tight Seal (barrier) Desmosome Adhesion Gap Communication Hemidesmosome Anchor to BM Applied
- Pemphigus (desmosome autoantibody)
- Gap junction — cardiac conduction
🔑KEY POINTS TO REMEMBER- Tight (seal), adherens/desmosome (adhesion), gap (communication).
- Hemidesmosome anchors to basement membrane.
- Pemphigus = desmosome; gap junctions in heart.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
The three muscle types — skeletal, cardiac and smooth — differ in histological structure and function.
Key Differences
- Skeletal — striated, multinucleated (peripheral), voluntary
- Cardiac — striated, single central nucleus, intercalated discs, involuntary
- Smooth — non-striated, single central nucleus, involuntary
The three types split by striations, nuclei and control. Feature Skeletal Cardiac Smooth Striations Yes Yes No Nuclei Many, peripheral Single, central Single, central Discs No Yes No Control Voluntary Involuntary Involuntary Applied
- Intercalated discs are unique to cardiac muscle
🔑KEY POINTS TO REMEMBER- Skeletal: striated, peripheral nuclei, voluntary.
- Cardiac: striated, central nucleus, intercalated discs.
- Smooth: non-striated, central nucleus.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
The neuron is the structural and functional unit of the nervous system, specialised for conduction of impulses.
Parts
- Cell body (soma) — nucleus + Nissl bodies
- Dendrites — receive impulses
- Axon — conducts impulses away
- Myelin sheath (in some)
Types
- Multipolar (commonest)
- Bipolar (retina)
- Unipolar / pseudounipolar (sensory)
A neuron receives at dendrites, integrates in the soma, and conducts along the axon. Part Function Dendrite Receive Soma Integrate Axon Conduct Applied
- Nissl bodies — protein synthesis
- Chromatolysis after injury
🔑KEY POINTS TO REMEMBER- Neuron: soma (Nissl), dendrites, axon.
- Types: multipolar, bipolar, unipolar.
- Chromatolysis after axon injury.
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.Definition
Cartilage is an avascular connective tissue with chondrocytes in lacunae, embedded in a firm matrix.
Features
- Chondrocytes housed in lacunae
- Firm matrix (chondroitin sulphate)
- Avascular — nutrition by diffusion
- Covered by perichondrium (mostly)
Types
- Hyaline (type II collagen)
- Elastic (elastic fibres)
- Fibrocartilage (type I collagen)
Chondrocytes sit in lacunae within a firm, avascular matrix. Type Location Hyaline Joints, airway Elastic Ear, epiglottis Fibrocartilage Intervertebral disc Applied
- Avascular → poor healing
- Osteoarthritis
🔑KEY POINTS TO REMEMBER- Chondrocytes in lacunae; firm avascular matrix.
- Types: hyaline, elastic, fibrocartilage.
- Poor healing (avascular).
📚SOURCES: Inderbir Singh’s Textbook of Human Histology; di Fiore’s Atlas of Histology; Gray’s Anatomy.