Animal Tissues and Organ Systems
Animal Tissues and Organ Systems tests histology as functional anatomy. You must identify a tissue from cell shape, matrix and arrangement, then link it to the organ system it serves.
Core rules
- Epithelium covers and lines; it is avascular and rests on a basement membrane. Simple squamous is thin for diffusion; cuboidal for secretion; columnar for absorption; ciliated epithelium moves substances; glandular epithelium secretes.
- Connective tissue has cells separated by matrix. Loose areolar cushions; dense regular forms tendons; cartilage is avascular; bone is vascular; blood is connective tissue with a fluid matrix.
- Skeletal muscle is striated, multinucleate and voluntary. Smooth muscle is spindle-shaped, uninucleate and involuntary. Cardiac muscle is striated, branched and has intercalated discs.
- Neural tissue conducts impulses; a neuron has dendrites, a cell body and an axon, often myelinated.
Worked example
A sample has parallel collagen bundles with fibroblasts aligned in rows and resists strong pull in one direction. Identify the tissue and the structure.
Reasoning: parallel regular collagen is dense regular connective tissue. Tendons attach muscle to bone and have this arrangement; ligaments attach bone to bone and contain more elastic fibres. Answer: dense regular connective tissue, tendon.
Traps that cost marks
- Epithelium and cartilage are avascular; bone is vascular.
- Blood is connective tissue, not epithelium.
- Cardiac muscle has intercalated discs; smooth muscle does not.
- Do not confuse tendon with ligament by attachment alone.