Cells and Tissues

Question 1

What is a tissue and the 4 primary types

Answer 1

• Tissue: A group of similar cells and their intercellular substance specialised to perform a specific function
• Types: Epithelial, muscle, connective and nervous

Question 2

What are the characteristics, function and classification of epithelial tissue

Answer 2

• Outer surface of skin, covers open cavities / walls of internal organs, have polarity
• Avascular, nourished by connective tissue, highly innervated / regenerative capacity
• Basement Membrane: Made of collagen / glycoproteins, anchors epithelium, organised scaffold, stains pink (H&E)
• Secretion, barrier, absorption, protection, transcellular transport, sensing and cover
• Layers (simple, pseudo stratified, stratified)
• Shape (squamous, cuboidal, columnar)
• Specialisations (cilia, microvilli, keratin), location of nucleus / basement membrane

Question 3

What is the difference between cilia and microvilli

Answer 3

• Cilia: 10um long, 0.2um diameter, microtubules, 9 + 2 structure, basal body anchors microtubules, movement of substances along surface, mucous cells near
• Microvilli: About 1um length, 90nm diameter, projections of plasma membrane, bundles of parallel actin filaments, increase SA for absorption

Question 4

What is keratin

Answer 4

• Main protein on apical surface of your skin and makes hair and nails
• Extremely insoluble in water, protection and barrier, desmosomes

Question 5

What are the characteristics of muscle tissue

Answer 5

• Movement by contraction, myo-filaments (actin and myosin)

- Highly vascularised / cellular, many mitochondria, specialised cells, long thin cells

Question 6

What are the 3 types of muscle tissue

Answer 6

• Skeletal: Voluntary, attached to bones, long cylindrical, stripes, striated, multi nucleated near membrane
• Smooth: Involuntary, fusiform, central nucleus, walls of hollow organs, long tapered cells
• Cardiac: Involuntary, composes walls of heart, striated / branched cells, uninucleate, intercalated discs

Question 7

What are the characteristics of connective tissue and ECM

Answer 7

• Most abundant, support / communication, insulation, protection, nutrient storage
• Connective tissue (loose or dense regular / irregular)
• Cartilage (hyaline, elastic and fibrocartilage)
• Bone and blood
• ECM: Fibres embedded in ground substance (tissue fluid), scaffold between cells, biochemical support to the surrounding cells

Question 8

Briefly describe how to identify types of connective tissue

Answer 8

• Dense regular: Parallel collagen fibres, fibroblasts
• Dense irregular: Irregularly arranged collagen fibres, fibroblasts
• Loose: Gel like matrix, multiple cells, mesh like structure, branching
• Hyaline Cartilage: Bubbles in glass (chondrocytes), surrounded by matrix
• Elastic Cartilage: Butterfly wings, irregular, multiple cell types
• Bone: Thin layers, concentric / circumferential
• Spongy Bone: Irregular osteons, white spaces surrounded by ECM
• Blood: RBC / WBC
• Adipose: White bubbles, sparse, adipocytes, peripheral nucleus

Question 9

What are the characteristics of nervous tissue

Answer 9

• Function: Highly specialised to carry electrical signals (waves of membrane depolarisation), generate and conduct nerve impulses, important for communication and control, highly cellular
• Classification: CNS (brain and spinal cord) and PNS (ganglia)
• Neurons: Excitable cells that transmit electrical signals
• Glial: Supporting cells (oligodendrocytes and astrocytes)

Question 10

Describe the structure and function of veins

Answer 10

• Vein walls thinner than walls of arteries
• Have valves, diameter is larger than of arteries
• Layering in the wall of veins is not very distinct compared to arteries

Question 11

Describe the structure and function of arteries

Answer 11

• Walls of arteries thick and compact
• Smooth muscle cell nuclei are frequent in the tunica media
• Collagen fibres and a few connective tissue cell nuclei are visible in tunica adventitia

Question 12

Describe the structure and function of capillaries

Answer 12

• Very small vessels (diameter 4-15 µm)
• Low BF and large SA, provide nutrients and oxygen to surrounding tissue
• Absorption of nutrients, waste products, CO2 and excretion of waste products

Question 13

Describe the structure of specialised structures (arteries / veins)

Answer 13

• Tunica adventitia (outer connective tissue with collagen fibres)
• Tunica media (middle circularly arranged smooth muscle / elastic fibres)
• Tunica intima (inner specialised simple squamous epithelium)

Question 14

What are the two types of cuts possible in a specimen

Answer 14

• Transverse: Inner layer of smooth muscle tissue (shape of cells, nuclei location)
• Longitudinal: Outer layer of smooth muscle tissue (striations / intercalated discs, nuclei location)