cells and tissues Flashcards
what are the organisation levels?
- cells
- tissues
- organs
- organ system
- organism
what does MRS GREN stand for?
Metabolism, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
what are cells?
the fundamental unit of the body, the building blocks of life, each cell has a different functions (respiration, ingestion, excretion, response, growth, reproduction, movement), the smallest structure that can perform life’s functions
what is cell theory?
- all living things are made up of cells
- cells are the basic unit of structure and function in an organism (basic unit of life)
- cells come from the reproduction of existing cells (cell division)
structure: cytoplasm
structure: thick fluid within the cell membrane but outside the nucleus and all the structures suspended in it
structure and function: cell membrane
structure: the outer boundary of the cell that separates it from neighbouring cells and from external environment, made up of a double layer of lipid molecules and associated proteins
function: determines which substances get into or out of the cell
structure and function: cytosol
structure: the liquid part of the cytoplasm, 75% - 90% water with a complex mixture of dissolved substances such as salts and carbohydrates
function: where most of the metabolic reactions occur, plays a role in controlling the osmotic pressure of the cell and the flow of chemicals in and out the cell
what are organelles?
specialised structures suspended in the cytoplasm which perform different functions.
structure and function: nucleus
structure: largest organelle in the cell and is usually oval or spherical in shape.
- nuclear membrane: the nuclear membrane separates the nucleus from the cytoplasm.
- nucleolus: inside nucleus, manufacturing proteins, made up of mostly RNA
- nucleoplasm: DNA and nucleolus are suspended in a jelly like nucleoplasm
function: controls cell, contains genetic material mostly DNA.
structure and function: ribosomes
structure: very small and spherical, free or attached to membrane
function: amino acids are joined together at ribosomes to form protein
structure and function: endoplasmic reticulum
provide a surface for chemical reactions, connects nucleus to cell membrane
- rough ER: with ribosomes, protein synthesis
- smooth ER: without ribosomes, lipid synthesis
ER transports substances within the cell specifically proteins made by the cell
structure and function: golgi. apparatus
structure: flattened membranous bags stacked on top of each other
function: modify proteins and package them in vesicles for secretion
structure and function: vesicles
structure: a membrane bound sac
function: transports materials into, out or within the cell
structure and function: centrioles
structure: a pair of cylindrical structures usually located near the nucleus
function: involved in the reproduction of the cell
structure and function: lysosomes
structure: small spheres that contains enzymes able to break down proteins, lipids, nucleic acids and some carbohydrates
function: “cell’s demolition crew”, breakdown materials that are taken into the cell or break down worn out organelles
structure and function: mitochondria
structure: structures spread through cytoplasm that have a double membrane, the outer is smooth and the inner folded in towards the centre of mitochondrion
function: mitochondria release energy for the cell through the process of respiration
structure and function: cilia
S: cell’s fine projections which are short and numerous (like hair)
F: it beats back and forth to move either the whole cell or substances over the surface of the cell e.g. mucus in the throat
structure and function: flagella
S: cell’s fine projections which are longer but have only a few on the cell
F: it beats back and forth to move either the whole cell or substances over the surface of the cell e.g. sperm swimming to the egg
structure and function: cytoskeleton
framework of protein fibres that gives the cell its shape and assists cell movements
- microtubules: hollow rods that keep organelles in place or move them around the cell
- microfilaments: which move materials around the cytoplasm or move the whole cell
what are inclusions in cytoplasm?
chemical substance found in the cytoplasm of the cell e.g haemoglobin, the red pigment of blood
what are tissues
tissues are made up of cells, similar in structure but have different functions
types of tissues
- epithelial
- connective
- muscular
- nervous
epithelial tissue: types, function and location
covers and lines body surfaces
squamous
- function: diffusion & filtration
- location: lungs, capillaries, inside mouth
columnar
- function: protection, secretion and absorption
- location: digestive tract, uterus
cuboidal:
- function: secretion and absorption
- location: ducts of salivary glands and kidneys
stratified:
- more than one layer
simple:
- one layer
pseudo stratified:
- one layer but looks like multiple layers
transitional:
- changes shape
connective tissue: types, function and location
- functions: supporting framework, help bind body structures together, repairs, stores fat and produces blood cells, binds and supports the other tissues of the body including
adipose, cartilage, bone, tendons/ligaments and blood - examples: bone, cartilage, ligaments, tendons, fat storage (adipose tissue), blood
- structure: scattered cells, separated large inter cellular material (matrix: fibres and ground substance ) → mechanical property
muscular tissue: types and function
- are long and thin and can contract to become shorter
- voluntary/involuntary movement
smooth muscle tissue:
- structure: thin and elongated, layered, non- striated
- slow and involuntary contractions
cardiac muscle tissue:
- structure: striated, short, inter-collated discs → separation
- quicker involuntary movement: heart beats
skeletal muscle tissue:
- structure: layered, long, striated
- covers larger parts of body and voluntary movement
nervous tissue: structure and function
- structure: neurons plus glial cells, thin, long projections with multiple extensions
- function: receives and transmits messages around the body
- structure allows quicker transfer of messages
what is the cell membrane?
the plasma membrane is a gateway to the cell, it is flexible and is vital in homeostasis (keeping the cellular environment constant) by controlling what enters and leaves the cell
functions of cell membrane
- protective/physical barrier (separating cytoplasm from extracellular fluid)
- regulate transport of materials in and out the cell (selectively permeable/semi-permeable) (e.g. entry of ions and nutrients)
- allow cell recognition
- provide anchoring sites for filaments of cytoskeleton
- provide binding site for enzyme
- sensitive to changes (any changes in the extracellular fluid affects the cell membrane first)
- helps support the cell (attached to the microfilaments of the cytoskeleton)
other names for cell membrane + reasoning
phospholipid bilayer, semi-permeable membrane, fluid mosaic model
The plasma membrane is called the fluid mosaic model as it is a phospholipid bilayer with embedded proteins, fluid as the molecules of which it is made of is constantly changing position, mosaic as it is composed of many different kinds of molecules
structure of cell membrane
- phospholipid bilayer
- carrier proteins
- protein channels
- receptors
- marker proteins
inputs and outputs for cell membrane
INPUTS: oxygen, water and nutrients
OUTPUTS: carbon dioxide, metabolic wastes, water, heat energy
types of cell transport
passive: no energy is required, along the concentration gradient (high to low)
active: energy is required, against the concentration gradient (low to high)
simple diffusion
molecules move from area of high concentration to low concentration.
e.g. water, oxygen, carbon dioxide, alcohol, fatty acids, steroids, ions such as sodium, potassium, calcium, lipids, soluble drugs
osmosis
- diffusion of solvent mainly water as it is the most significant solvent in the human body, across the membrane through aquaporins
- moves from high water potential (less solute) to low water potential (higher solute)
facilitated diffusion
uses transport (channel) proteins to move large molecules that can’t diffuse through lipids, from high to low concentration
e.g. glucose and amino acids
channel proteins
have a pore for materials to cross
carrier proteins (active)
change shape to move from one side to another against concentration gradient
e.g for certain ions, glucose and amino acids
vesicular transport
moving things through a vesicle
exocytosis
moving things out (contents of a vehicle are passed outside
e.g secretions, such as mucus or digestive juices
a vesicle that is formed within the cell migrates to the cell membrane and fuses with the membrane, the contents of the vesicle are then pushed out into the extracellular fluid
endocytosis
moving things in (liquids and solids)
e.g cholesterol, iron ions, micro-organisms and cell debris but only by specialised cells
the cell membrane folds around a droplet of liquid or a solid particle until the droplet or particles is completely enclosed, the vesicle formed then pinches off and is suspended in the cell’s cytoplasm
types of endocytosis
- pinocytosis
- receptor mediated endocytosis
- phagocytosis
pinocytosis
takes in dissolved molecules as a vesicle (liquids)
receptor mediated endocytosis
targets particular molecules with its receptors, take in hormones, cholesterol, etc.
phagocytosis
engulf large particles such as food, bacteria (solids)
isotonic solution
cell is at equilibrium
no net movement
same amount of solute in and outside the cell
“external solution is isotonic to cytosol”
hypotonic solution
more solute in cell, moves in causing cell to swell and eventually burst/lyse (CYTOLYSIS)
net movement into cell
“external solution is hypotonic to cytosol”
hypertonic solution
less solute, moves out of cell causing cell to shrivel up, shrink (PLASMOLYSIS)
net movement out of cell
“external solution is hypertonic to cytosol”
