module 6 Flashcards
what is the advantage of a multicellular organism ?
not every cell has to be able to perform everything in which cells can specialize to collectively benefit the entire organism
what are cell junctions
membrane proteins that facilitate cell to cell attachments that is needed for communication and to form barrier
epithelial cells and endothelial cells are used for ?
for tight networks to keep unwanted cellular material out and need cell adhesion proteins known as junction complexes
endothelial cells will line ?
blood vessels
epithelial cells will line
cavities and surfaces of organs and will rest on basement membrane
what is a junctional complex ?
tight junctions, adherens junctions and desosomes make up the complex
what is a tight junction ?
will structually and functionally divide the plasma membrane into 2 domains ( apical top and basal bottom), will regulate paracellular transport and the proteins in a tight junction will connect to the cytoskeleton
what is adherens junctions ?
found in cardiac muscle cells and synapses they use transmembrane receptor proteins called cadherins that will bind to other cadherins on neighbouring cells .Act like overlapping velcro with other cadherins
what are desmosomes ?
provides structural integrity and act like snaps , are also connected to the cytoskeleton in the cell and are found in cells that are exposed to physical stress like skin cells and cardiac muscles
what is a hemidesmosome?
half a desmosome complex which will be tethered to the base membrane of the epithelial cells where they will be strongly linked to the ECM
what are gap junctions ?
distinct because they create an open pore between 2 cells and facilitates the transfer of ions and small cellular material between them ( not part of the junctional complex )
what is the structure and function of a gap junction?
composed of 2 halves they will connect to cross the intracellular gap and cells that are connected with gap junctions can use channel gating, to move ions, nulceotide and sugars from one cell to the other . very important in cardiac muscle
what is the extracellular matrix ?
network of molecules that will fill the space inbetween cells
roles of proteins in ECM ?
provide external structural support of cells and tissues
types of proteins found in the ecm
collagen, fibronectin, elastin, laminins, proteoglycans
what is collagen ?
most prevelant protein in the body and the main structural protein in the ECM will cross link to form fibrils and then form collagen fibres
fibronectin
glycoproteins that connect cells to collagen matrices functioning in cell adhesion and are expressed as dimers that bind to integrins
what is elastin ?
will give elasticity to tissues allowing them to return to there regular shape after being under stress by external force( contains both hydrophobic and hydrophilic regions that allow for this
laminins
provide adhesive substrate for cells and strengthens the ECM and form triple helical coils . Has a cross like structure that has many binding sites for ECM proteins Can handle strength in multiple directions because of shape
proteoglycans
hydrated gel that are resistant to compressive forces - critical for cartilege in joints and has a polypeptide core with sugar residues
what is a tissue ?
group of cells that is not identical but will collectively carry out a function
what are epitthelial tissues ?
found in skin, glands and the digestive tract , play an important role as acting as a barrier- anything that comes in the body must pass through and epithelial barrier - protects inside body from outside environment
what glands can epithelial tissues be found in ?
exocrine and endocrine glands
epithelial cells in digestive tract
used for absorption secretion and protection
what are the 3 roles that epithelial cells can play in the digestive tract ?
produce and excrete proteins
form digestive glands
facilitate transportation
what is nervous tissue ?
highly specialized cells that use electrical communication to carry info over large distances in the body ( made of nerve cells, glial cells and shwann cells)
muscle tissues
can convert chemical signals into mechanical movement ( actin and myosin generate contraction ) the 3 types of muscle are smooth, cardiac and skeletal
connective tissues
provide shape and structure outside of cells , filling in space between cells and provide mechanical strength and cushioning ( big component of the ECM)
different types of connective tissues will differ how ?
each will be characterized by there ECM(lungs are high in elastin because they need to have alot of movement
what is an organ ?
where 2 or more tissue types come together to form a function
muscle cells in the stomach
outer layer of the stomach that has a layer of smooth muscle cells and rythmically contract
epithelaial cells in stomach
line the inside to protect from gastric acids
nervous tissues
found in the stomach wall , helps control and coordinate muscle contraction
connective tissues in stomach
holds everything together and provides shape to the stomach
what isa body system ?
when 2 or more organs come together to form a coordinated purpose
explain how the cardiovascular system is a body system ?
made up of the heart, blood vessels and the blood
Blood carries nutrients and removes waste, the heart acts as a pump and the blood vessels serve as transportation for blood
why can tissue types serve so many roles in different systems
tissue types can specialize for specific functions of the organ
what is homeostasis ?
ability of cell or organism to regulate its internal environment regardless of the influences of the external environment - change in physical enivronment results in the internal trying to regulate
what is the set point ?
optimal conditions to maintain homeostasis
what is the homeostatic control system ?
consists of the sensor the integrator and the effector
what is the sensor?
will detect the environmental variable
what is the integrator ?
compares the variables values to its set points
what is the effector ?
if value is different than set point then effector initiates changes to restores set point
explain how the body will regulate body temperature
set point : between 36-38 degrees
sensor: temp sensing nerve cells which will send info to the thermolregulation centre
integrator: the thermoregulation centre will compare info to set point , if there is a difference , will send info to the effector
effector : causes the blood vessels to constrict reducing heat loss and skeletal muscles will contract to generate shivering which creates heat
intrinsic control
known as local control and the sensor, effector and communicator are all in the same tissues ( tissue can regulate its own internal environment )
ex) skeletal muscle
extrinsic
when regulatory mechanisms are outside of the tissues or organ
what is a negative feedback loop ?
change in environmental parameter causes corresponding effector to start a response in opposite direction , restoring parameter to set point
