Lecture 3 - Introduction to Cellular Pathology

Question 1

Multicellular organisation / Histology / Histopathology (3)

Answer 1

• Histopathology - The study of tissues affected by disease. Useful in making a diagnosis and in determining the severity and progression of a disease.
• Histology is used to understand pathology. Understanding the normal structure and function of different tissues is essential for interpreting the changes that occur during disease.
• HISTOLOGY– Histology is the study of tissues and their structure. Study of the “more complex structures”.

Question 2

Organisation at 4 levels (4)

Answer 2

o Tissue structure - how cells combine together with extracellular material and each other to form a tissue
o Cellular structure - how a cell is shaped, and how the components inside cells are organized to support that cells specific function
o Sub-cellular structure - detailed analysis of organelles and inclusions
o Histochemical structure - molecular analysis of cellular structure

Question 3

Epithelial cells (3)

Answer 3

• Is made of cells arranged in a continuous sheet with one or more layers; has apical and basal surfaces.
o A basement membrane separates the epithelial layer from the underlying connective tissue.
o Two types of epithelial tissues: 1) Covering & lining epithelia; 2) Glandular epithelium (endocrine and exocrine).

Question 4

Epithelial cells - Classification (4)

Answer 4

o Number and distribution of cell layers
 Simple Epithelium - one cell layer.
 Stratified Epithelium - two or more cell layers.
 Pseudostratified Epithelium - cells are all anchored to the basement membrane (i.e. one cell layer) but not all cells reach the apical surface (nuclei do not align, does not look like one cell layer).
o Shape of the top layer of cells
 Cuboidal, columnar, squamous

Question 5

Connective tissue (3)

Answer 5

• There are two main groups: 1) Connective tissue proper; 2) Specialised connective tissue.
• Contains:
o Many different cell types including: fibroblasts, macrophages, mast cells, and adipocytes.
o Connective Tissue Matrix made of two materials: 1) ground substance - proteins and polysaccharides; 2) fibres – reticular, collagen and elastic.

Question 6

Connective tissue - Classification (4)

Answer 6

o Loose Connective – fibres and cells in gelatinous matrix, found in skin & surrounding blood vessels, nerves and organs.
o Dense Connective – bundles of parallel collagen
fibres & fibroblasts, found in tendons and ligaments.

Question 7

Connective tissue - specialised (4)

Answer 7

• Cartilage is made of two main components: 1) collagen & elastin fibres embedded in a matrix of glycoproteins; 2) Chondrocytes. There are 3 types:
• Hyaline cartilage – Weakest, most abundant type.
-Found at end of long bones, & structures like the ear and nose.
• Elastic cartilage - maintains shape, branching elastic fibers distinguish it from hyaline.
• Fibrous cartilage - Strongest type, has dense collagen & little matrix, found in pelvis, skull & vertebral discs.

Question 8

Connective tissue - bone (3)

Answer 8

• Bone is composed of bone cells - osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts – suspended in a matrix consisting of collagen fibres and minerals.
o Bone development can be 1) Membranous – as in flat bones, clavicle or mandible; 2) Endochondral – as in limb and vertebral column bones.
o Mature bone may be 1) Compact – concentric circular layers (lamellae) organised in lacunae and a central canal (Harvesian system); 2) Trabecular – slender interlacing parallel lamellae with marrow within the spaces.

Question 9

Muscle tissue (3)

Answer 9

• Skeletal Muscle – voluntary, striated, striations perpendicular to the muscle fibers and it is mainly found attached to bones. Organised in myofibres with nuclei peripherally located. Forms a lined up banding pattern from one cell to another when observed longitudinally.
• Cardiac Muscle – involuntary, striated, branched and has intercalated discs. Cells smaller than skeletal muscle with nuclei centrally located.
• Smooth Muscle – involuntary, non-striated, spindle shaped and is found in blood vessels & the GI tract. Cells vary in size and have a fusiform shape. Nuclei observed in different positions.

Question 10

Nerve tissue (7)

Answer 10

• Constitutes the Central Nervous system (CNS) & the Peripheral Nervous System (PNS). Consists of two main functional cell types: 1) Neurons - cells that convert stimuli into electrical impulses to the brain.
2) Neuroglia – collection of different cell types with supportive role.
• Neurons – are made up of cell body, axon and dendrites. There are 3 types of neurons:
o Motor Neuron – carry impulses from CNS to muscles and glands.
o Interneuron - interpret input from sensory neurons and end responses to motor neurons.
o Sensory Neuron – receive information from environment and transmit to CNS.
• Neuroglia – is made up of astrocytes, oligodendrocytes, ependymal cells and microglia in the CNS, and Schwann cells and satellite cells in the PNS.

Question 11

Development (4)

Answer 11

• All tissues of the body develop from the three primary cell layers that form the embryo:
• Ectoderm - develops into nervous tissue and epithelial tissue.
• Mesoderm – develops into epithelial tissue, connective tissue and muscle tissue.
• Endoderm – develops into epithelial tissue.