Chapter Two Flashcards
Cells make up the human body
What is a cell
- The smallest structure that can perform life’s functions
The cell theory
Cells are the basic structural and functional units of all living organisms
Cell structure
- Cell membrane
- Cytoplasm
- Organelles
- Cytosol
- Cytoskeleton
- Inclusions
Cytoplasm
The jelly or watery material in the cell that suspends organelles
Cytosol
- The liquid part of the cytoplasm
- Where metabolic reactions occur
Organelles
The structures within a cell that carry out a particular function
Nucleus (S.L.F)
S- Ovoid, spherical shape surrounded by porous double nuclear membrane and contains nucleolus
L- Cytoplasm
F- Stores DNA which is the blueprints for making proteins. It controls the structure of the cell and how it functions
Ribosomes (S.L.F)
S- Small, spherical
L- Free in cytoplasm or attached to membrane and rough ER
F- Involved in protein production
Endoplasmic Reticulum (S.L.F)
S- Parts of parallel membranes
L- Extends through the cytoplasm and connects the cell membrane with the nuclear membrane
F- Provides a surface in which chemical reactions can occur + is used for storage and transport of materials
Golgi Apparatus/ Body (S.L.F)
S- Flattened, membranous bags stacked on top of each other
L- Cytoplasm
F- Modifies proteins and packages them in vesicles for secretion from the cell
Mitochondria (S.L.F)
S- Spherical, sausage shaped structure
L- Spread through the cytoplasm
F- Site of chemical reactions of cellular respiration
Centrioles (S.L.F)
S- A pair of cylindrical structures
L- Usually near the nucleus
F- Involved in the reproduction of the cell
Lysosomes (S.L.F)
S- Small spheres
L- Through the cytoplasm
F- Contains enzymes that break down proteins, lipids, nucleus acids and some carbohydrates. They break down materials that are taken into the cell and worn out organelles
Inclusions
Chemical substances that are not part of the cell structure but are found in the cytoplasm of specific cells
Cilia (S.L.F)
S- Short and numerous projections that look like tiny hairs
L- Lining of the windpipe
F- Move mucous and trapped particles
Flagella
Like cilia but longer and only one (Flagellum) or two
Cytoskeleton
A framework of protein fibres that assist with cell movements and gives the cell shape
Microtubules
- Part of the cytoskeleton
- Hollow rods that keep organelles in place or move them around the cell
Microfilaments
- Part of the cytoskeleton
- Help moves materials around the cytoplasm and move the whole cell
Cell specification
Each cell is designed to perform a specific function
Cell differentiation
The process by which specialised cells develop special characteristics to suit particular functions
Cell size
10-15 micrometers (1X10^-6)
SA
- A small cell with have a larger SA to volume ratio than a larger one
- Need to be small as they rely on diffusion to get things in/out of the cell
Fluid Mosaic Model
Fluid -> constantly moving
Mosaic -> made of many different types of molecules
Cell membrane structure
- Phospholipid bilayer (lipid molecules with a phosphate group) each of which have a hydrophobic tail and a hydrophilic head that constantly move
Functions of the cell membrane
- Physical barrier
- Regulates the passage of materials
- Sense changes in the outside environment as it has receptions that are sensitive to particular molecules
- Supports the structure of the cell
Channel proteins
Form a channel through the membrane and have a central pore that allows ions, water and other small molecules to pass through
Cell requirements
- Continual supply of the materials they need to survive and a continual removal of any of these materials they produce
- Oxygen and glucose for respiration
- Produce hormones and enzymes which need to be removed from the cell as well as products such as CO2 and water
What is transport across the cell membrane
- The cell membrane is differentially permeable (allow certain molecules to pass through but restrict others)
- Can be an active or passive process
Passive transport
- With concentration gradient (high->low concentration)
- No energy required
- only small molecules or ions may pass between the lipid molecules of the membrane
Active transport
- Against the concentration gradient (low->high concentration)
- Requires energy
- Energy is supplied by ATP
Concentration (def)
The amount of a given substance contained within a solution or in a particular volume of space
Concentration Gradient
A difference in concentration of a solution, often between the inside and outside of a cell
Diffusion
The spreading of particles so they are equally distributed across the space available
Osmosis
Water or a solvent passing across a membrane
Tonicity
The concentration of solutes within a solvent. The comparison of tonicity is in reference to the substance against another substance (this controls the concentration gradient)
Hypertonic
The solution has a greater solute to solvent ratio than the substance it is being compared to (higher osmotic pressure)
Hypotonic
The solution has a lower solute to solvent ratio than the substance it is being compared to (lower osmotic pressure)
Isotonic
The solution had the same solute to solvent ratio as the substance it’s being compared to
Facilitated diffusion
- Passive process
- Moves with the concentration gradient (H->L)
- The molecule transported attached to the binding site on the carrier protein. The channel changes shape and the molecule is in the other side of the membrane
Active transport
- Requires energy
- Against the concentration gradient (L->H)
Vesicular transport
- The movement of substances across the cell membrane in membranous bound sacs (vesicles)
- Active processes
- Endocytosis (enter the cell)
- Exocytosis (exit the cell)
- If involved with solids = Phagocytosis
- If involved with liquids = Pinocytosis
Extracellular fluid
The fluid surrounding the cell
Intercellular fluid
The fluid inside the cell
Tissues
A group of similar cells working together to perform certain common functions
4 major types of tissues
- Epithelial
- Connective
- Muscle
- Nervous
Epithelial tissue
- Lining/covering tissue, covers all body surfaces inside and out
- Cells = packed together
- Also known as epithelium
Connective tissues
- Most abundant tissue in the body
- Support for the body, holds body parts together
- Cells = not as close together as epithelial, separated but a non cellular material called matrix
Muscular tissue
- Respond to stimulus by contracting and becoming shorter
- Cells = long and thin called muscle fibres
3 Different types of muscular tissue
- Skeletal
- Cardiac
- Smooth
Skeletal muscle
- Voluntary
- Striated
- muscles attatched to bones
Ligament
Connective tissue connecting bone to bone
Tendon
Connective tissue connecting muscle to bone
Smooth muscle
- Involuntary
- No striations- smoother
Cardiac muscle
- Involuntary
- Heart is made mostly out of cardiac muscle
- Striated
Nervous tissue
- Made up of nerve cells called neurons
- Long projections from the body of the cell
- A part of the neuron can be stimulated and messages are carried along the projections from one part of the body to another
- Found in bran, spinal cord and nerves
Neuron structure
- Cell body, the central body contains the neurons nucleus associated cytoplasm and other organelles
- Axons, carry signals away from the cell towards another dendrite
- Dendrite, Carry signals towards the cell body
Organs
- Body structures made of two or more types of tissue
- Some larger organs have smaller ones within the
System
- A group of organs that work together to carry out a particular task
- In addition to having a major function most body systems have a secondary function
Life processes
The series of actions such as movements, respiration, sensitivity, growth, reproduction, excretion and nutrition that are essential for life to be sustained
Blood
The red liquid that circulates in the arteries and veins of living things (animals and people) carrying oxygen to and carbon dioxide from the tissues of the body
Bone
Hard, whitish material making up the skeleton
Cartilage
Firm, flexible connective tissue
Duct
A vessel for conveying lymph or glandular secretions such as tears or bile
Gland
An organ that secretes particular chemical substances for use in the body or discharge into the surroundings
Net diffusion
The movement of liquid or gas molecules from a place of higher concentration to a place of lower concentration along a concentration gradient
Oxygen concentration in cells
- Lower inside the cell than outside as it is continuously used up for respiration
- Net diffusion of oxygen into the cell
Carbon dioxide concentration in cells
- Higher concentration inside than outside the cells as it is continuously produced through respiration
- Net diffusion of carbon dioxide out of the cell
