Unit 2: Tissues
Essential Biology notes · PTU syllabus (BMLS101-18)
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Unit summary
Tissues are groups of similar cells working together. This unit covers the structure and functions of epithelial, connective, muscular and nervous tissue.
After this unit you can
- Classify epithelial tissue and give its locations
- Describe types of connective tissue
- Compare skeletal, smooth and cardiac muscle
- Describe the structure of nervous tissue
PTU syllabus topics
- Structure and function of epithelial
- connective
- muscular and nervous tissue
Epithelial
Covers surfaces and lines cavities
Connective
Supports and binds: bone, blood, cartilage
Muscular
Contraction: skeletal, smooth, cardiac
Nervous
Carries electrical signals
Topic 1
Epithelial tissue
- Covers body surfaces and lines cavities; cells are tightly packed on a basement membrane, with no blood vessels. Functions: protection, absorption, secretion, filtration.
Simple squamous
Single layer of flat cells
Alveoli, blood vessel lining (endothelium)
Simple cuboidal
Single layer of cube-shaped cells
Kidney tubules, glands
Simple columnar
Tall cells, may have microvilli or cilia
Stomach, intestine
Pseudostratified ciliated columnar
Appears layered; cilia and goblet cells
Trachea
Stratified squamous
Many layers; keratinised or not
Skin; mouth and oesophagus
Transitional
Stretchable layers
Urinary bladder
- Glandular epithelium: exocrine glands (with ducts — sweat, salivary) and endocrine glands (ductless — thyroid).
Topic 2
Connective tissue
- Most abundant tissue; cells scattered in a matrix of fibres (collagen, elastic, reticular) and ground substance. Functions: binding, support, protection, transport, storage.
Loose (areolar)
Under skin; binds organs
Adipose
Fat storage, insulation
Dense fibrous
Tendons (muscle to bone) and ligaments (bone to bone)
Cartilage
Hyaline (joints), elastic (ear), fibrocartilage (intervertebral discs)
Bone
Calcified matrix; osteocytes in lacunae; Haversian systems
Blood and lymph
Fluid matrix (plasma) with cells
Topic 3
Muscular tissue
Shape
Long, cylindrical, multinucleate, striated
Spindle-shaped, one nucleus, non-striated
Control
Voluntary
Involuntary
Location
Attached to bones
Walls of gut, blood vessels, uterus
Note
Cardiac muscle: branched, striated, one nucleus, intercalated discs, involuntary, never fatigues
Cardiac muscle is found only in the heart
Topic 4
Nervous tissue
- Made of neurons (conduct impulses) and neuroglia (support, nourish and protect neurons).
- Cell body (soma)
- Nucleus and Nissl granules
- Dendrites
- Receive impulses
- Axon
- Carries impulses away; may have a myelin sheath with nodes of Ranvier
- Synapse
- Junction where neurotransmitters pass the signal
- Types: sensory (afferent), motor (efferent) and interneurons; multipolar, bipolar and unipolar by structure.
Key terms
- Tissue
- Group of similar cells performing a function
- Basement membrane
- Thin layer on which epithelium rests
- Matrix
- Material between connective tissue cells
- Intercalated disc
- Junction between cardiac muscle cells
- Neuroglia
- Supporting cells of nervous tissue
Quick revision
- Four basic tissues: epithelial, connective, muscular, nervous.
- Epithelium: squamous, cuboidal, columnar, pseudostratified, stratified, transitional.
- Connective: areolar, adipose, dense, cartilage, bone, blood.
- Skeletal, smooth, cardiac muscle.
- Neuron parts; neuroglia.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.Where is transitional epithelium found?
- Q2.Distinguish tendons and ligaments.
- Q3.Name the three types of cartilage.
- Q4.Give two features of cardiac muscle.
- Q5.What is the function of the myelin sheath?
- Q6.What are neuroglia?
Long-answer questions
- Q1.Classify epithelial tissue with examples.
- Q2.Describe the types of connective tissue.
- Q3.Compare the three types of muscle tissue.
- Q4.Describe the structure of a neuron.
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