2. Core Concepts Cell structure and Organisation Flashcards
(216 cards)
- how many mm in a m
- how many Um in a mm
- how many nm in an Um
1.1000
2.1000
3.1000
labelled light microscope
define magnification
how many times bigger the image of a specimen observed is in compared to the actual (real-life) size of the specimen.
define resolution
Resolution is the ability to distinguish between two separate points
max resolution of light and electron microscope
light 0.2 micrometers
electron 0.002 micrometers
max magnification of light and electron microscope
light x1,500
electron x500,000
function of cellulose cell wall
allows high internal pressure, WO bursting
surface cell membrane image
plasmodesmata
can animal cells have vacuoles
yes, temporary
the centrosome
-two centrioles
-involved in nuclear division of animal cells
Animal and plant cells similarities and differences
division of labour
describes specialised functions of cell organelles
-come together to ensure cell is capable of surviving + perform roll in body
define tissue
A tissue is an aggregation (group) of similar cells carrying out the same function.
For example, the layer of cells that line the alveoli in the lungs is a type of epithelial tissue.
define organ
Organs are aggregations of several tissues which carry out a function for the whole organism.
For example, the eye contains many tissues all of which are needed for the organ to function correctly.
define organ system
Organ Systems are groups of organs that work together to carry out a function.
For example, the digestive system has several parts, such as the oesophagus and stomach, and is linked to accessory organs such as the pancreas and gall bladder.
Circulatory = heart blood blood vessels
Epithelial tissues
Epithelial tissues are made from cells (at least in the bottom layer) which sit on an additional layer of membrane, the basement membrane.
Epithelial tissues are found covering surfaces and are often the sites of absorption of substances.
Columnar epithelium
These cells are taller than they are wide and are found in many organs of the body, e.g. the small intestine, where the cells are covered in microvilli to increase the surface area for absorption.
Cuboidal epithelium
These cells have approximately the same height and width. They can be found lining the proximal convoluted tubules in the kidney. They reabsorb useful substances that are filtered out of the blood.
Squamous epithelium
Squamous epithelial cells are very thin. These cells line the alveoli in the lungs. Being very thin reduces the diffusion distance for the exchange of gases.
Stratified epithelium
These tissues are made from layers of cells. The bottom layer is in contact with the basement membrane and divides to make the upper layers of the tissue. The top layers are usually dead and they can be worn away without damage being caused to the layers underneath. Examples of this type of tissue are found in skin and the oesophagus (shown below).
Ciliated epithelium
Ciliated epithelial cells have a brush border of cilia; these contain protein microtubules that can move.
This type of epithelium is found in the trachea where mucus needs to be moved out of the lungs and in the fallopian tubes where the cilia set up a current to move an embryo into the uterus.
What is epithelial tissue made of?
Cells (at least in the bottom layer) that sit on a basement membrane.
What are the general functions of epithelial tissue?
Covering surfaces and serving as sites of absorption.