Tissue Preparation and Cell Structure

A tissue preparation method using liquid nitrogen to rapidly freeze tissues, allowing for quick cutting and microscopic observation.

The fundamental unit of life, varying in size and shape based on its function.

The cell's control center, containing genetic information.

The jelly-like substance filling the cell, containing organelles and inclusions.

Essential cell components enclosed by membranes, like the cell membrane, mitochondria, and endoplasmic reticulum.

Essential cell components not enclosed by membranes, like ribosomes, microtubules, and filaments.

The outer boundary of the cell, separating the cytoplasm from the surrounding environment.

Non-essential components within the cell, such as stored food, pigments, and crystals.

The cell membrane is a thin, flexible barrier surrounding the internal parts of a cell. It's made mainly of a lipid bilayer with embedded proteins.

Two layers of phospholipids arranged with their hydrophilic heads facing outward and hydrophobic tails facing inward.

A type of lipid molecule with a phosphate group head and two fatty acid tails.

A lipid that strengthens and stabilizes the cell membrane, preventing it from becoming too fluid or rigid.

The carbohydrate-rich layer on the outer surface of the cell membrane, formed by glycoproteins and glycolipids.

Proteins with attached carbohydrate chains on the cell surface.

Lipids with attached carbohydrate chains on the cell surface.

The cell coat provides protection, allows cell adhesion, and contains cell-specific antigens.

The glycocalyx, a layer of carbohydrates on the cell surface, is predominantly negatively charged. This creates a repulsive force between adjacent cells, maintaining a space of about 20 nm between them.

The passive movement of molecules across a cell membrane from a region of high concentration to a region of low concentration, without requiring energy.

The passive movement of molecules across a cell membrane with the assistance of membrane proteins (channels or carriers), following the concentration gradient.

The movement of molecules across a cell membrane against the concentration gradient, requiring energy (ATP).

A vital active transport system that pumps 3 sodium ions out of the cell for every 2 potassium ions pumped in, against their concentration gradients.

The process by which cells take in substances from their surroundings by engulfing them in a membrane-bound vesicle.

The process by which cells release substances from their interior to the outside by fusing a vesicle containing the substance with the cell membrane.

Mitochondria are responsible for converting organic materials (food) into cellular energy in the form of ATP.

Mitochondria help regulate the concentration of calcium ions within different compartments of the cell.

A disorder caused by dysfunction in mitochondria, leading to insufficient energy production for life and growth. It often affects cells in the brain, heart, liver, muscles, and kidneys.

Mitochondria play a role in programmed cell death (apoptosis), contributing to the controlled dismantling of a cell.

A network of interconnected flattened tubules (cisternae) with ribosomes attached. Involved in protein synthesis.

A network of interconnected tubules or vesicles with smooth walls (no ribosomes). Involved in lipid metabolism, calcium storage, and detoxification.

Synthesizes proteins, packages them into vesicles for transport to the Golgi apparatus, and produces lysosomal enzymes.

Involved in lipid metabolism, steroid hormone synthesis, calcium storage, and detoxification of drugs and toxins.

A specialized type of smooth endoplasmic reticulum found in muscle cells, involved in calcium regulation for muscle contraction.

The smooth endoplasmic reticulum (SER) plays a key role in the production of lipids, especially in cells that specialize in producing steroids, like those found in the adrenal cortex.

The SER membrane is involved in the regulation of glycogen metabolism, a process that breaks down and builds up glycogen, a form of stored glucose. This is especially important in the liver, where glucose levels are controlled.

The SER contributes to mineral metabolism, including processes like the production of hydrochloric acid (HCl) in the stomach, which is essential for digestion.

The SER stores calcium in skeletal and cardiac muscle cells, playing a crucial role in regulating muscle contraction. This controlled release of calcium initiates the process of muscle movement.

The SER is responsible for detoxifying harmful substances by breaking them down. This is due to the presence of cytochrome P450 enzymes within the SER membrane, especially in the liver cells.

The Golgi apparatus, a collection of flattened sacs, processes, packages, and sorts newly synthesized proteins and lipids, ensuring they are delivered to the correct destinations within the cell or outside.

Lysosomes are small, membrane-bound sacs containing powerful enzymes that break down various materials within the cell. These 'cellular garbage disposals' are crucial for destroying waste products and cellular debris.

Primary lysosomes appear as spherical, homogenous, electron-dense vesicles under an electron microscope. As they digest material, they become secondary lysosomes, characterized as spherical, heterogeneous, electron-dense vesicles due to their varied contents.

Lysosomes are membrane-bound organelles that act as the cell's recycling center, breaking down waste products and engulfing foreign invaders. They are essentially the 'garbage disposals' of cells.

Lysosomes are formed in a two-step process. First, enzymes are made in the RER and packaged into vesicles. Then, these vesicles travel to the Golgi apparatus, where they are further modified and packaged into lysosomes.

Primary lysosomes are newly formed and haven't been involved in digestion yet. Secondary lysosomes are actively digesting material, and their subtypes include heterophagosomes, multi-vesicular bodies, and autophagosomes, each digesting different types of materials.

After digestion, nutrients are released back into the cytoplasm for reuse. Undigested material is packaged into residual bodies and removed from the cell by exocytosis.

Lysosomes play crucial roles in digesting a variety of materials, including old organelles (autophagy), engulfed bacteria (phagocytosis), and even the entire cell in programmed cell death (autolysis).