Fundamentals of Anatomy & Physiology - Chapter 3: The Cellular Level of Organization

Flashcards covering the topics from the Anatomy & Physiology lecture notes.

Cell

The smallest living unit in the human body.

Cell theory

Cells are the building blocks of all organisms. All cells come from the division of preexisting cells. Cells are the smallest units that carry out life’s essential physiological functions. Each cell maintains homeostasis at the cellular level.

Cytology

Studies the structure (anatomy) of cells and is a branch of cell biology (the study of cells).

Sex cells (germ cells or reproductive cells)

Male sperm and Female oocyte which allow for reproduction.

Somatic cells

All body cells except sex cells.

Plasma membrane (cell membrane)

Forms the outer boundary of the cell and allows for selective transport of substances; the main components are lipids and proteins.

Physical isolation

Separates the inside of the cell (or cytoplasm) from the surrounding extracellular fluid.

Regulation of exchange with the environment

Controls the entry of ions and nutrients, the elimination of wastes, and the release of secretions.

Sensitivity to the environment

Sensitive to changes in the environment and contains receptors that allow the cell to respond to chemical signals.

Structural support

Anchors cells to each other and to extracellular materials and provides stability to tissues.

Hydrophilic heads

Face outward to the watery environments of the extracellular fluid and the intracellular fluid (cytosol).

Hydrophobic tails

Form the inside core of the membrane and act as a barrier to ions and water-soluble compounds.

Cholesterol

Makes the plasma membrane less fluid and less permeable.

Integral proteins

Within the membrane.

Transmembrane proteins

Integral proteins that span the entire width of the membrane

Peripheral proteins

Bound to inner or outer surface of the membrane

Anchoring proteins

Attach to inside or outside structures and stabilize membrane position.

Recognition proteins (identifiers)

Label cells as normal or abnormal.

Enzymes

Catalyze reactions.

Receptor proteins

Bind and respond to ligands (ions, hormones).

Carrier proteins

Bind and transport specific solutes through the membrane.

Channels

Integral proteins with a central pore which permits water and small solutes to flow through.

Gated channels

Open or close to regulate the passage of substances.

Proteoglycans, glycoproteins, and glycolipids

Extend beyond the outer surface of the membrane and form sticky “sugar coat”.

Glycocalyx

Sticky “sugar coat” formed from Proteoglycans, glycoproteins, and glycolipids that extend beyond the outer surface of the membrane.

Cytoplasm

All materials between the plasma membrane and the membrane of the nucleus.

Cytosol (intracellular fluid)

A colloid which contains water and dissolved nutrients, ions, proteins, and waste products.

Organelles

Internal structures with specific functions.

Membranous organelles

Isolated from the cytosol by a plasma membrane; include the endoplasmic reticulum (E R), the Golgi apparatus, lysosomes, peroxisomes, and mitochondria.

Nonmembranous organelles

Not completely enclosed by membrane; Include the cytoskeleton, centrioles, ribosomes, proteasomes, microvilli, cilia, and flagella.

Cytoskeleton

Framework of proteins in the cytoplasm for shape, strength, and flexibility.

Microfilaments

Smallest filaments composed of the protein actin that provide mechanical strength, attach the plasma membrane to the cytoplasm, and interact with other proteins.

Intermediate filaments

Mid-sized insoluble filaments that strengthen the cell, maintain its shape, and stabilize position of organelles.

Microtubules

Large, hollow tubes of tubulin proteins that strengthen cell, anchor organelles, change cell shape and assist in cell movement, move vesicles and organelles within the cell, form the spindle apparatus to distribute chromosomes during cell division, and form structural components of organelles such as the centrioles and cilia.

Microvilli

Small finger-shaped projections of the plasma membrane on the exposed surface of a cell that increase the surface area for absorption.

Centrioles

A pair of cylindrical structures that form spindle apparatus during cell division.

Centrosome

A region of the cytoplasm next to the nucleus that serves as a microtubule-organizing center.

Cilia (singular, cilium)

Long, slender extensions of the plasma membrane.

Primary cilium

Nonmotile cilium which senses environmental stimuli.

Motile cilia

Beat rhythmically to move fluids or secretions across the cell surface in places like the respiratory and reproductive tracts.

Flagellum

A long, whip-like extension of the plasma membrane that beats in a wavelike motions and allows sperm cells to move.

Ribosomes

Organelles that synthesize proteins and are composed of small and large ribosomal subunits (Contain ribosomal R N A (r R N A) and proteins).

Free ribosomes

Manufacture proteins that enter the cytosol directly.

Fixed ribosomes

Manufacture proteins that enter the E R for packaging.

Proteasomes

Organelles that contain enzymes (proteases) which break down proteins for recycling.

Endoplasmic reticulum (E R)

A network of interconnected intracellular membranes continuous with the nuclear envelope, containing hollow tubes, flattened sheets, and storage chambers known as cisternae

Smooth endoplasmic reticulum (S E R)

No attached ribosomes, and is responsible for the synthesis of phospholipids and cholesterol (for membranes), steroid hormones (for reproductive system), glycerides, especially triglycerides (in liver and fat cells), and glycogen (in skeletal muscle and liver cells).

Rough endoplasmic reticulum (R E R)

Ribosomes attached to surface, and synthesizes proteins and glycoproteins, modifies them, and packages them in transport vesicles for export to the Golgi apparatus.

Golgi apparatus (Golgi complex)

Stacks of flattened membranous discs called cisternae.

Lysosomes

Vesicles containing enzymes which serve as digestive organelles and are produced by the Golgi apparatus.

Lysosomes

Function to destroy bacteria and debris break down molecules, and recycle damaged organelles and cellular components.

Primary lysosomes

Contain inactive enzymes.

Secondary lysosomes

Formed when primary lysosomes fuse with damaged organelles or endosomes and their enzymes are activated.

Autolysis

Self-destruction of damaged cells where Lysosomes disintegrate and release digestive enzymes which destroy the cell.

Peroxisomes

Small vesicles which contain enzymes that break down organic compounds such as fatty acids.

Mitochondria

Organelles that take chemical energy from food and produce energy in the form of A T P.

Glycolysis

Breaks down glucose into 2 pyruvates and takes place in the cytosol.

Citric acid cycle (Krebs cycle, tricarboxylic acid cycle, or T C A cycle)

Breaks down pyruvate into carbon dioxide and occurs in the mitochondrial matrix.

Electron transport chain

Happens on cristae and uses energy from electrons and hydrogen ions to produce A T P.

Membrane flow (membrane trafficking)

A continuous exchange of membrane segments by vesicles that involves all membranous organelles (except mitochondria).

Nucleus

Largest organelle which serves as the control center for cellular operations

Nuclear envelope

Double membrane around the nucleus that is connected to the endoplasmic reticulum

Perinuclear space

The space between the two layers of the nuclear envelope.

Nuclear pores

Opening in the nuclear envelope which allow for chemical communication.

Nucleoplasm

The fluid portion inside the nucleus.

Nuclear matrix

Network of filaments for structural support in the nucleoplasm.

Nucleoli

Transient nuclear organelles made of R N A, enzymes, and proteins called histones that synthesize r R N A and assemble ribosomal subunits.

Nucleosomes

Complexes made of D N A coiled around histones that are loosely coiled into chromatin in non-dividing cells, and tightly coiled into chromosomes before cell division.

Genetic code

Sequence of bases (A, T, C, G). Chemical language of D N A instructions of how to build proteins.

Triplet code

Three bases that represent one amino acid.

Gene

Functional unit of heredity, a D N A sequence that carries the instructions for one protein.

Protein synthesis

The assembling of functional polypeptides in the cytoplasm.

Gene activation

Involves uncoiling D N A and temporarily removing histones.

Promoter

Specific region of D N A at the beginning of each gene used in regulation.

Transcription

Synthesis of R N A from a D N A template.

Messenger R N A (m R N A)

Carries the transcribed information for the sequence of amino acids in a protein and takes the instructions from the nucleus to the cytoplasm where protein synthesis occurs.

RNA polymerase binding

The two D N A strands separate, and the enzyme R N A polymerase binds to the promoter on the template strand.

R N A polymerase nucleotide linking

Begins at “start” signal in promoter region, reads D N A code and builds a complementary m R N A by binding nucleotides (contain U instead of T).

Codon

Each three bases on m R N A.

Detachment of m R N A

The enzyme and the m R N A strand detach from D N A at the “stop” signal

RNA processing

m R N A is “edited” before leaving the nucleus; Noncoding sequences (introns) are removed and coding segments (exons) are attached (spliced) together.

Mutations

Permanent changes in a cell’s D N A that affect the nucleotide sequence of one or more genes and can result in changes in the structure of the resulting proteins.

Permeability

Determines what moves in and out of a cell.

Impermeable membranes

Membranes that let nothing pass.

Freely permeable membranes

Membranes that let everything pass.

Selectively permeable membranes

Membranes that allow certain substances to pass but not others based on size, electrical charge, molecular shape, lipid solubility, and other factors.

Passive transport

No energy required.

Active transport

Requiring energy.

Diffusion

The net movement of a substance from an area of higher concentration to an area of lower concentration.

Concentration gradient

The difference between the high and low concentrations of a substance.

Simple diffusion

Allows substances to cross the lipid portion of the membrane.

Channel-mediated diffusion

Allows substances to pass through a membrane channel (protein).

Osmosis

Net diffusion of water across a membrane that is permeable to water.

Osmotic pressure

The force with which pure water moves into a solution as a result of its solute concentration.

Hydrostatic pressure

The pressure that opposes the osmotic pressure and prevents osmosis.

Tonicity

Describes how the concentration of solutes in a solution affects cells

Isotonic solution

solution that has equal concentration of solute as the cell and does not cause osmosis in or out of the cell.

Hypotonic solution

Solution that has a lower solute concentration than the cell, and causes water to enter the cell by osmosis.

Hemolysis

The rupturing of a cell.

Hypertonic solution

Solution that has a higher solute concentration than the cell, and causes water to leave the cell by osmosis.