Mitochondria Structure and Function

Cell Biology

• The cell has various organelles, including mitochondria, peroxisomes, lysosomes, and proteasomes.
• Mitochondria have inner and outer membranes, with the inner membrane forming cristae to increase surface area for ATP production.
• Peroxisomes contain oxidative enzymes and are involved in beta-oxidation, H2O2 production, and detoxification.
• Lysosomes have a membrane-bound acidic compartment for intracellular digestion and contain hydrolytic enzymes.
• Proteasomes are cylinder-shaped with no membrane and degrade denatured, non-functional, or unneeded proteins.

Tissue Types

• There are four basic tissue types: epithelial, connective, muscle, and nervous.
• Epithelial tissue covers organs and forms glands, while connective tissue provides support and connects organs.
• Muscle tissue is responsible for movement, and nervous tissue is responsible for transmission and integration of signals.

Embryonic Germ Layers

• There are three embryonic germ layers: ectoderm, mesoderm, and endoderm.
• Ectoderm gives rise to the nervous system, skin, and sensory organs.
• Mesoderm forms muscle, bone, connective tissue, blood vessels, and the dermis.
• Endoderm develops into the gut tube epithelium and luminal epithelial derivatives.

Germ Layer Derivatives

• A comprehensive list of germ layer derivatives can be found in the appendix.

Compound Glands

• Compound glands have multiple secretory units that converge to form larger ducts.
• Examples include the pancreas, salivary glands, and mucous glands in the duodenum.

Cell Structure and Function

• Cells have different structures and functions, such as fibroblasts, adipocytes, macrophages, and mast cells.
• Fibroblasts produce ground substance and extracellular fibers, while adipocytes store neutral fats and have a single huge lipid droplet.
• Macrophages are involved in phagocytosis and immune functions, and mast cells release heparin, histamine, and cytokines.

Cartilage

• Cartilage growth involves interstitial and appositional growth, with chondroblasts differentiating from mesenchymal cells.
• Cartilage degeneration involves calcification, age-related changes, and poor capacity for repair.

Bone Matrix

• Bone matrix consists of inorganic components (calcium hydroxyapatite, non-crystalline calcium phosphate, and ions) and organic components (type I collagen, proteoglycans, and glycoproteins).

Lymphoid and Immune System

• The immune system has two functional divisions: innate immunity (non-specific, mediated by granulocytes) and adaptive immunity (specific, mediated by lymphocytes and antigen-presenting cells).
• Leukocytes are divided into granulocytes and agranulocytes, with granulocytes having polymorphic nuclei and cytoplasmic granules.
• Agranulocytes lack specific granules but have some lysosomes, with spherical, non-lobulated nuclei.

Thymus

• The thymus is a bilobed mediastinal structure where T cells are produced, originating from the 3rd pharyngeal pouches (endoderm).
• The thymus has a cortex (outer darkly basophilic portion with T lymphoblasts, macrophages, and thymic epithelial cells) and medulla (lightly-stained inner portion with mature lymphocytes and TECs).
• Thymic epithelial cells (TECs) are diverse and important for the development and activity of regulatory T cells.