W1 - Cells and Basic Tissues Flashcards
LO1: Describe the general function of human cells
In total the human body is made up of ~75 trillion cells and ~200 different cell types.
Cell functions include communication, covering/lining, connection, movement, storage, defence and reproduction.
LO2: Describe the structure and basic functions of the main components of a typical cell - nucleus
Acts as the control centre of the cell. Most cells have one nucleus, but some such as red blood cells have none and others such as skeletal muscle cells have several.
Contains three basic structures: nuclear envelope, nucleolus and chromatin.
Fluid or semifluid medium filling the nucleus is nucleoplasm and contains dissolved nucleotides and proteins.
LO2: Nucleus (nuclear envelope)
Double-layered membrane surrounding the nucleus, separating the nucleoplasm from the cytoplasm of the cell. It controls the movement of materials between the nucleus and the cytoplasm via small openings called nuclear pores.
LO2: Nucleus (nucleolus)
This is a dense, spherical body that produces the subunits forming ribosomes, which are involved in protein synthesis. The presence and number of nucleoli indicates the protein synthetic activity of the cell.
LO2: Nucleus (chromatin)
This is the fine, uncoiled strands of DNA in the nucleus.
LO2: Describe the structure and basic functions of the main components of a typical cell - cytoplasm
Consists of all cellular components between the nucleus and the plasma membrane. It includes three main elements, which are the cytosol, organelles and inclusions.
LO2: Cytoplasm (cytosol)
This is the viscous fluid medium in which the other cytoplasmic elements are suspended. It contains a variety of dissolved solutes such as proteins, carbohydrates, lipids and other small molecules. It also contains a network of protein filaments or rods called the cytoskeleton, which supports cell structure and movement.
LO2: Cytoplasm (organelles)
Specialised structures that form the metabolic machinery of the cell, with each carrying out a specific metabolic activity within the cell. E.g., mitochondria
LO2: Cytoplasm (inclusions)
Small substances found in some cells such as lipid droplets in fat cells and the pigment melanin in some skin cells.
LO2: Describe the structure and basic functions of the main components of a typical cell - plasma membrane
Separates the internal cellular components from the external environment.
It is composed of a double or bi-layer of lipid molecules with protein molecules dispersed in it that form a constantly changing mosaic pattern.
Structure allows it to play a dynamic role in many cellular activities e.g. movement of substances into and out of the cell.
LO3: Cell surface specialisations
microvilli, stereocilia, cilia, flagella
LO3: Microvilli
Small, immotile projections on the surface of some cells that form what is known as a brush border.
They increase the surface area for absorption and secretion. - e.g. on the surface of the cells lining the small intestine, where the absorption of nutrients and water occurs.
LO3: Stereocilia
Stereocilia are elongated microvilli (immotile, finger-like projections) that can be found on the surface of the cells lining the epididymis and vas deferens, as well as the sensory cells of the inner ear.
LO3: Cilia
Cilia are elongated, hair-like, motile projections on the surface of some cells that function to move substances along a passage. For example, they can be found on the surface of the cells lining the respiratory tract, where they support the self-cleaning mechanism (mucociliary transport) of the airways. Each respiratory epithelial cell has around 200 cilia.
LO3: Flagella
Flagella (singular = flagellum) - similar but longer than cilia - found on sperm cells to support motility.
LO4: The four basic tissue types and provide examples of where each can be found in the body
Nervous, muscle, epithelial, connective
LO4: Epithelial tissue
Epithelial tissue (a.k.a. epithelium) forms sheets of cells lining body cavities and covering body surfaces. In addition, the glands of the body have glandular epithelium. The overall function of epithelium is to form boundaries between different environments, protect, secrete, absorb and filter.
LO4: Connective tissue
Connective tissue supports, protects and binds other tissues together. There are five subtypes of connective tissue, which are dense and loose connective tissue (collectively termed connective tissue proper), blood, bone and cartilage.
LO4: Muscle tissue
Muscle tissue is responsible for body movement. There are three subtypes of muscle tissue, which are skeletal, cardiac and smooth muscle.
LO4: Nervous tissue
Nervous tissue is the main component of the nervous system (the brain, spinal cord and nerves) which controls and regulates body functions via the transmission of nervous impulses. It contains two main cell types, which are neurons (a.k.a. nerve cells) and glial cells (a.k.a. supporting cells).
