Human Bio - Tissues

• What is the "dynamic cell" concept?

A: A cell as an active system—organelles, transport, and cytoskeleton work together to adapt, move, and function

Name the three main cytoskeleton components and their roles.

A: Microfilaments (actin, motility), microtubules (tubulin, transport), intermediate filaments (support).

Q: How does Botox affect protein transport?

A: Cleaves SNARE proteins, preventing vesicle fusion and acetylcholine release, causing muscle relaxation.

What are the four main tissue types?

A: Epithelial (covers surfaces), Connective (supports), Muscle (movement), Nervous (communication)

Q: What are the key characteristics of epithelial tissue?

A: Highly cellular, avascular, regenerative, polar, derived from all germ layers

Q: Compare simple vs. stratified epithelium.

A: Simple: Single layer, fragile, for absorption/secretion (e.g., simple squamous in alveoli). Stratified: Multiple layers, protective (e.g., stratified squamous in skin).

Q: What is the function of transitional epithelium?

A: Accommodates stretching (e.g., in urinary bladder), protects against urine’s caustic effects.

What are the three main classes of connective tissue?

Connective Tissue Proper, Supporting Connective Tissue, Fluid Connective Tissue.

Name the three types of protein fibres in the ECM.

Collagen (strength), Elastic (stretch), Reticular (network support).

What is the difference between loose and dense connective tissue proper?

Loose: Fewer fibres, more ground substance (e.g., areolar, adipose). Dense: More fibres, less ground substance (e.g., regular collagenous in tendons).

What causes scurvy, and what are its symptoms?

Cause: Vitamin C deficiency (unstable collagen). Symptoms: Bleeding gums, loosened teeth.

How does smoking contribute to pulmonary emphysema?

Stimulates excess elastase, destroying elastic fibres in lungs, causing alveoli to enlarge and bronchioles to collapse.

What are the two main divisions of the nervous system?

Central Nervous System (CNS): Brain and spinal cord. Peripheral Nervous System (PNS): Cranial and spinal nerves.

What are the key properties of neurons?

Irritability (respond to stimuli), conductivity (transmit impulses), longevity, high metabolic rate (need oxygen/glucose).

Why can’t neurons divide?

Lack centrioles, making them post-mitotic.

Compare the roles of oligodendrocytes (CNS) and Schwann cells (PNS).

Oligodendrocytes: Myelinate multiple axons in CNS. Schwann cells: Myelinate one axonal segment in PNS, form Nodes of Ranvier, aid repair.

What is the role of ependymal cells in the CNS?

Line ventricles, form/circulate CSF, monitor CSF composition, act as a barrier.

What are the three types of muscle tissue?

Cardiac (heart), Smooth (hollow organs), Skeletal (attached to bones).

What are the key properties of muscle tissue?

Excitability, contractility, extensibility, elasticity, well-vascularized, packed with connective tissue.

How is skeletal muscle stimulated to contract?

Via neuromuscular junction (NMJ)—motor neuron releases acetylcholine, binds to sarcolemma, triggers contraction.

What are the connective tissue layers in skeletal muscle?

Epimysium (entire muscle), Perimysium (fascicles), Endomysium (individual fibres).

What is Duchenne Muscular Dystrophy?

A muscle-destroying disease (dystrophy), genetic, caused by lack of dystrophin, leads to progressive degeneration.