8. Cells And Epithelia Flashcards
Describe what a somatic cell is. Give two points
- all cells except reproductive cells
- produced by mitosis (diploid)
Describe what germ cells are (2 points)
they are reproductive cells - gametes
produced by meiosis (haploid)
What are the t wo ways tissues can increase in size?
hyperplasia - increase in cell number
hypertrophy - increase in cell size
What is the process of tissue homeostasis? (balance..)
there is a constant turn over of body cells!
the process is that cell death and production is balanced - they are produced by stem cells
What are two special features of animal stem cells?
they are unspealised cells in the body - can become any type of tissue
can reproduce indefinitely
How do stem cells regenerate?
stem cell divides inot one new stem cell (progenitor) and one daughter cell
daughter cell produces new cells which differeniciate inot required cell type. These cells can regenerate
How is there a homeostasis of cells in the GI tract?
the cells are generated at the bottom and migrate to the top of the virus after 3-5 days. There is only cell division at the bottom, non at the top. Once at the top they fall off
What are the three different types of stem cells and what are each of their features?
totipotent cells - capable of generating a completly new organism (totally potent)
pluripotent cells - derived from fetal tissue, generates many different cell types
multipotent cells - adult stem cell - generates a limited number of cell types
What is an example, function and special feature of epithelial cells?
example: lining gut and blood vessels, covering the skin
function: barrier, absorbtion and secretion
special fetures: tightly bound together by cell junctions
What is an exampe, function and special eater of hormone secreting cells?
example: thyroid and adrenal
function: indirect cell communication
special features: secrete chemical messengers into the blood
What are cell junctions?
They help organise cells into sheets of epithelium and endothelium. It provides contact between cells or the extracelluar matrix
What are the three types of cell junctions and name a function of each
tight junctions- seals cells together in an epithelium
desmosomes/anchoring junctions- connect the cytoskeleton of a cell to extracelluar contacts
gap junctions- allows small molecules to pass from cell to cell
What are three functions of tight junctions?
they help regulate the movement of molecules across epithelia - only molecules that are permeable or have transport proteins
restricts free movement of membrane proteins and lipids which causes cell polarisation between the apical and basolateral cell surface
What is the function of anchoring junctions?
they connect the cytoskeleton of a cell to the cytoskeleton of its adjacent cell, this forms a strong sheet
What is the purpose of focal adhesions
They link the cytoskeleton of the cell to the extracelluar matrix
What is the purpose of gap junctions and what ion are they regulated by?
they allow small molecules to pass directly from cell to cell, which is regulated by Ca2+ ions
What are the three surfaces of epithelial and where are they attached too?
apical surface: the free top surface
lateral surface: on the sides
basal surface bottom of cells attached to basal lamina
What are the two types of movement subsatacne can do to cross the epithelium and endothelium?
transcelluar- the movement of ions across the cytoplasm via plasma membrane channels
paracellular- the movement of ions through the intercellular spaces between epithelial cells
What is the two variations in epithelium of how solutes and water are allowed to pass between the lumen and interstitial fluid?
leaky epithelia - less tight junctions
tight epithelia - very tight junctions
What is the structure and functions of epithelial cells that are specialised for transcelluar transport?
Define what a gland is and what the two different types are
a gland are single cells or groups of cells specialised for secretion
endocrine: secrete into bloodstream
exocrine: secrete externally
