BIOSCI107 · Biology for Biomedical Science: Cellular Processes and Development
Cells, Tissues & Body Organisation
Topic 1 of University of Auckland BIOSCI 107 lays the structural groundwork: the six levels of organisation, the eleven body systems, and the four primary tissue types — epithelial, connective, muscle and nerve. It drills the detail the test rewards: which cell junction uses which linker protein, what the basement membrane is made of, and how the connective-tissue extracellular matrix (ground substance + three fibre types) is built. This material is examined only in the 30% mid-semester test (Topics 1–3, paper Teleform MCQ), not the final, and reappears in applied tissue-identification items.
What this chapter covers
- 01Six levels of organisation (chemical → cellular → tissue → organ → system → organismal) and the 11 body systems
- 02The four primary tissue types: epithelial (cover/line/glands), connective (cells in matrix), muscle (contractile), nervous (conducting)
- 03Epithelial classification: arrangement (simple/stratified/pseudostratified) × shape (squamous/cuboidal/columnar/transitional); the outer layer names a stratified epithelium
- 04Cell junctions and their linker proteins: tight (occludin/claudin), adherens (cadherin→actin), desmosome (cadherin→keratin), hemidesmosome (integrin→laminin), gap (connexins)
- 05The basement membrane = basal lamina (from epithelium) + reticular lamina (from fibroblasts); epithelia are avascular
- 06Connective tissue = ECM (ground substance + fibres) + cells; three fibre types (collagen, reticular, elastic)
- 07Ground substance: GAGs and proteoglycans; hyaluronic acid as the non-sulphated GAG
- 08Connective-tissue cell and matrix specialisations (fibroblasts, macrophages, mast cells; bone osteons and hydroxyapatite; blood as liquid CT)
Matching cell junctions to their linker proteins and jobs
- +1Desmosome — transmembrane cadherin anchored to a desmoplakin plaque, linked to keratin intermediate filaments. It resists shearing, which is why it is abundant in skin (and cardiac muscle). [+1]
- +1Hemidesmosome — the odd one out: it uses integrin (NOT cadherin), which binds laminin in the basement membrane on the outside and keratin in the cytoplasm. It anchors the whole epithelial sheet to the basement membrane. [+1]
- +1Adherens junction — transmembrane cadherin linked through catenins to actin microfilaments. It resists tension and helps hold cells in a continuous sheet. [+1]
- +1Tight junction — occludin and claudin proteins seal the paracellular space, control what leaks between cells, and maintain apical–basal cell polarity (it links to actin via ZO-1). [+1]
Key terms
- Tissue
- A group of similar cells (plus their extracellular material) performing a shared function. The four primary types are epithelial, connective, muscle and nervous — the whole of Topic 1's histology.
- Basement membrane
- The thin sheet beneath an epithelium: a basal lamina (secreted by the epithelial cells — collagen, laminin, proteoglycans) plus a reticular lamina (made by connective-tissue fibroblasts). It supports the epithelium, guides wound-healing migration and, in the kidney, filters.
- Extracellular matrix (ECM)
- The non-cellular material of connective tissue: ground substance (water + proteoglycans + GAGs) plus fibres (collagen, reticular, elastic). Its composition sets a connective tissue's mechanical properties.
- Glycosaminoglycan (GAG)
- Long unbranched repeating-disaccharide chains in ground substance. Sulphated GAGs (e.g. chondroitin, keratan sulphate) bind a core protein to form proteoglycans; hyaluronic acid is the single non-sulphated GAG and binds large amounts of water.
- Pseudostratified epithelium
- An epithelium that looks layered but is one layer — every cell touches the basement membrane, though not all reach the apical surface. Typical of the upper airways (ciliated with goblet cells).
- Osteon (Haversian system)
- The structural unit of compact bone: concentric lamellae around a central canal, with osteocytes sitting in lacunae connected by canaliculi. Spongy (cancellous) bone lacks osteons. Bone matrix = hydroxyapatite (calcium phosphate) on a collagen scaffold.
Cells, Tissues & Body Organisation FAQ
How do I keep the cell junctions straight for the test?
Anchor each junction to its linker protein and its job. Tight junction = occludin/claudin, seals and controls the paracellular gap. Adherens = cadherin to actin, resists tension. Desmosome = cadherin to keratin, resists shear (skin, heart). Hemidesmosome = integrin to laminin, anchors the sheet to the basement membrane. Gap junction = connexins forming a connexon, passes small molecules between cells. The high-yield distinction is that only the hemidesmosome uses integrin (cell-to-matrix); the others that link cells use cadherin.
What is the difference between the basal lamina and the basement membrane?
The basement membrane is the whole two-layer sheet under an epithelium. Its upper part, the basal lamina, is secreted by the epithelial cells themselves (collagen, laminin, proteoglycans); its lower part, the reticular lamina, is made by connective-tissue fibroblasts. Epithelia sit on it, are avascular (nutrients diffuse up from capillaries in the connective tissue below), but do contain nerves.
Is this topic on the final exam?
No — Topic 1 (Cells & Tissues) is tested only in the 30% mid-semester test, which covers Topics 1–3. The 40% final exam covers the second half of the course (Topics 4–7). Both are on-paper Teleform multiple-choice. Confirm the exact dates on Canvas and your course outline.
Can AI help me with Cells & Tissues in BIOSCI 107?
Yes, as a study aid. Sia can drill junction-to-protein pairs, quiz you on the 11 body systems and four tissue types, and explain why a given tissue suits its location (simple squamous for diffusion, stratified squamous for wear). Use it to prepare before the test — it does not sit the test for you, and the mid-semester test is an AI-free lane under the course's academic-integrity policy. Confirm the rules on Canvas.
Exam move
Turn Topic 1 into recall tables, because the test rewards precise pairing, not prose. Build one table for the four tissue types (function + example locations), one for epithelial classification (arrangement × shape → where it's found + why), and one for the five junctions (linker protein + job). Learn the connective-tissue hierarchy as ECM = ground substance (GAGs/proteoglycans, plus hyaluronic acid) + three fibre types (collagen strongest/most abundant, reticular for networks, elastic for stretch) + resident cells. Memorise the odd-ones-out the examiners love: hemidesmosome uses integrin (not cadherin); hyaluronic acid is the non-sulphated GAG; blood is a liquid connective tissue. Practise applied 'identify the tissue' items from histology descriptions. This is test-only material (Topics 1–3), so front-load it before the mid-semester test; confirm the date and Teleform format on Canvas.
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