Cells and Tissues (Q1,P2) Flashcards
Cells
the smallest living units in our bodies
Organelles
little organs” – carry on essential functions of cells
Enzymes
direct chemical reactions in cells
Metabolism
- the sum of all chemical reactions in the cell
- two types: Anabolic reactions & Catabolic reactions
Plasma Membrane
- defines the extent of the cell
- has a phospholipid bilayer
- Provides barrier against substances outside the cell
- Some plasma membranes act as receptors
- Determines which substances enter or leave the cell (semipermeable)
Nervous Tissue
- Main components of the brain, spinal cord, and nerves
- Contains two types of cells: neurons & Supporting cells (neuroglial cells)
Neurons
Conduct electrical impulses
Supporting Cells/Neuroglial Cells
nonconducting cells
What are the three types of muscle tissue?
Skeletal muscle tissue
cardiac muscle tissue
smooth muscle tissue
Skeletal muscle tissue
striations; voluntary movement; long, cylindrical cells (fibers)
cardiac muscle tissue
striations; involuntary movement; occurs in walls of heart (myocardium)
Smooth muscle tissue
lacks striations; involuntary control; propels substances along internal passageways; mostly walls of hollow organs
Integral Proteins
firmly imbedded in, or attached to lipid bilayer
Peripheral proteins
attach to membrane surface
Simple Diffusion
molecules move from a region where they are more concentrated to an area where they are less concentrated
Osmosis
the simple diffusion of water across a membrane; water moves from a higher concentration to a lower concentration
Endocytosis
- mechanism by which particles enter cells
- Two types: Phagocytosis & Pinocytosis
Phagocytosis
- Type of endocytosis
- “cell eating” – primary nonspecific defense mechanism of the host; many white blood cells carry out this function
-nonselective or nonspecific
Pinocytosis
- Type of Endocytosis
- “cell drinking” – many cells of the digestive system will use this process to sample the nutrients of the tissue fluid
- nonselective or nonspecific
Exocytosis
mechanism that moves substances out of the cell; secretory cells will use this process
Cytoplasm
- lies internal to plasma membrane
- Consists of cytosol, organelles, and inclusions
Cytosol (cytoplasmic matrix)
- Jelly-like fluid in which other cellular elements are suspended
- Consists of water, ions, and enzymes
Ribosomes
constructed of proteins and ribosomal RNA (rRNA)
ribosomal RNA (rRNA)
- Site of protein synthesis
- Assembly process is called translation and is dictated by the DNA
- Instructions are carried out by the messenger RNA (mRNA)
Endoplasmic reticulum
“network within the cytoplasm”
- two types: rough er, smooth er
Rough ER
- type of Endoplasmic reticulum
- ribosomes stud the external surfaces
- Cell’s membrane factory; produces the proteins of the the cell’s membrane, secretory proteins, digestive enzymes
- Stores ionic calcium which acts as a signal for the beginning of many cellular events
Smooth ER
- type of Endoplasmic Reticulum
- consists of tubules in a branching network
- No ribosomes are attached; therefore no protein synthesis
- Lipid metabolism
- Stores ionic calcium which acts as a signal for the beginning of many cellular events
Golgi Apparatus
- a stack of three to ten disk-shaped envelopes
- Sorts products of rough ER and sends them to the proper destination
- Often referred to as the “post office” of the cell
Mitochondria
- generate most of the cell’s energy (ATP); most complex organelle
- Often referred to as the “powerhouse” of the cell
- Energy is stored in chemical bonds of nutrient molecules to produce ATP (energy for the cell)
(ATP stands for adenosinetriphosphate)
Lysosomes
- membrane-walled sacs containing digestive enzymes
- Digest unwanted substances
- membrane-walled sacs of oxidase and catalase enzymes
- Enzymes neutralize free radicals and break down poisons
- two types: Oxidase & Catalase
- Break down long chains of fatty acids
- Are numerous in the liver and kidneys
Oxidase
an enzyme that breaks down free radicals and forms hydrogen peroxide
Catalase
an enzyme that further breaks down the hydrogen peroxide into H2O and O2
Break down long chains of fatty acids
Cytoskeleton
- “cell skeleton”
– an elaborate network of rods - Serves as the cell’s bones, muscles, and ligaments
Cytoplasmic Inclusions
- Temporary structures
- not present in all cell types
- May consist of pigments, crystals of protein, and food stores
Nucleus
- control center of cell
- DNA directs the cell’s activities
- Nucleus is approximate 5µm in diameter
- Genetic information of the cell
- Nucleus is surrounded by a nuclear membrane also called a nuclear envelope
Nucleolus
– “little nucleus” – in the center of the nucleus
- Contains parts of several chromosomes
- Site of ribosome subunit manufacture
Cellular Diversity
Specialized functions of cells relates to:
Shape of cell
Types of organelles present
Tissue
a group of closely associated cells that perform related functions and are similar in structure
Organ
a discrete structure made up of more than one tissue
Four Basic Tissue Types and Basic Functions
Epithelial tissue – covering and lining
Connective tissue – support
Muscle tissue – movement
Nervous tissue – control / communication
Epithelial Tissue
- Covers a body surface or lines a body cavity
- Forms most glands
- Functions of epithelium:Protection
Absorption, secretion, ion transport, Filtration - Forms slippery surfaces
Special Characteristics of Epithelia
Cellularity, support by connective tissue, avascular, innervated, regeneration
