Where do we think the integration centre responsible for regulation of core body temperature is located?
Usually no more than a mark allocated to questions like this, best answer would be "hypothalamus". If you misspell hypothalamus so it resembles something else you may not get the mark, could clarify with "in the brain" if you are unsure of your spelling.
Outline the homeostatic responses that would occur following detection of a decrease in core temperature.
A complete answer would describe this as a homeostatic negative feedback control mechanism. It would include description of signals being sent via nerves to skeletal muscles to increase heat generation by shivering, other signals sent via nerves to the sm
State two important functions of the plasma membrane.
-To enclose the cell's organelles, solutes, substrates, enzymes, genetic material etc.
-To regulate the movement of substances between intra- and extracellular environments.
-To provide a site for anchorage to other cells and extracellular components.
-Pr
Define the term hypotonic
Hypotonic" refers to solutions that have a non-penetrating solute concentration lower than that of the intracellular fluid (i.e. water concentration is higher) and if bathing cells would cause those cells to swell.
Define the term hypertonic
Hypertonic" refers to solutions that have a non-penetrating solute concentration higher than that of the intracellular fluid (i.e. water concentration is lower) and if bathing cells would cause those cells to shrink. Human RBCs would shrink if placed in
Define the term isotonic
Isotonic" refers to solutions whose non-penetrating solute concentration is the same as that of intracellular fluid and results in no change in cell volume when used to bathe cells.
What is the osmolarity of a 150mM NaCl solution?
300mOsm
What is the osmolarity of a 300mM urea solution?
300mOsm
Would red blood cells placed in each of the above solutions (150mM NaCl & 300mM urea) behave in the same way? Explain.
No, they wouldn't behave the same in each solution. The resting cell membrane is relatively impermeable to Na and Cl, so 150mM NaCl is isotonic with ICF and cells placed in this solution would neither shrink nor swell.
Urea is a penetrating solute, that i
Some substances may cross the cell membrane without expenditure of energy, whilst other substances cannot. Explain.
Electrical and chemical gradients exist across most cell membranes; these provide driving forces for ion and solute movements. Substances will move across membranes down their electrical and/or chemical gradients with a tendency towards electrochemical eq
How is it possible for a substance to enter or leave the cell without crossing the plasma membrane? Give an example of an important substance that can enter the cell without crossing the membrane, and another example of one that can leave without crossing
Some substances can be taken into the cell by becoming enclosed in a membrane-bound vesicle, and process known as endocytosis. A membrane vesicle is pinched off on the inside of the cell and some of the substance that was sitting in the ECF outside the ce
what is exocytosis
Exocytosis is the process by which substances may leave the cell without crossing a membrane. Here, a membrane-bound vesicle inside the cell may fuse with the plasma membrane, effectively dissolving in the surface membrane and then discharging its content
what is diffusion
Movement of particles through the phospholipid bilayer or through channels from an area of high concentration to an area of low concentration (down the concentration gradient)
example of diffusion
Movement of CO2 out of all cells,
Na+ moving into nerve cells during impulse conduction
what is osmosis
Diffusion of water through selectively permeable membrane from an area of high water concentration to an area of low water concentration (down the concentration gradient)
example of osmosis
Diffusion of water molecules into and out of cells to maintain water concentration
what is facilitated diffusion - channel mediated
Diffusion of particles through a membrane by means of channel structures (down conc. gradient)
examples of channel mediated facilitated diffusion
Diffusion of sodium ions into nerves cells during a nerve impulse
what is Facilitated Diffusion -Carrier Mediated
Diffusion of particles through a membrane by means of carrier structures (down conc. gradient)
examples of Facilitated Diffusion -Carrier Mediated
diffusion of glucose
What is Primary active transport
Movement of solute particles from an area of low conc. to high conc. by means of an energy-consuming pup structure in the membrane
Examples of primary active transport
Na/K ATPase
What is secondary active transport
Secondary active transport does not use ATP directly but takes advantage of a previously existing concentration gradient.
The net direction of movement is dependent on the concentration gradient.
Secondary active transport can move materials against the c
Examples of secondary active transport
Sodium-Glucose co transporters
What is endocytosis
results in the formation of an intracellular vesicle by virtue of the invagination of the plasma membrane and membrane fusion.
Examples of endocytosis
Cholesterol intake
Examples of exocytosis
Many cellular processes involve exocytosis.
Secretion of proteins like enzymes, peptide hormones and antibodies from cells.
Release of neurotransmitter from presynaptic neurons
What is exocytosis
Many cellular processes involve exocytosis.
Secretion of proteins like enzymes, peptide hormones and antibodies from cells.
Release of neurotransmitter from presynaptic neurons
T/F: The composition of the fluid bathing the cells of the body is essentially the same as that within the cells
False
T/F: In general, polar molecules diffuse more rapidly across cell membranes than do nonpolar molecules
False
T/F: The component of the plasma membrane that acts as the selective barrier for diffusion is the integral proteins.
False
T/F:The concentration of calcium in the cytosol of cells is very much lower than the concentration of extracellular calcium
True
T/F: Active transport, facilitated diffusion and osmosis all require the expenditure of metabolic energy
False
T/F: The higher the osmolarity of a solution, the higher the concentration of water in it.
False
A portion of a cell's plasma membrane is removed during endocytosis.
True
Homeostasis refers to:
. Refers to dynamic constancy of the internal environment.
A positive feedback mechanism is an effective way to:
bring about a rapid change in the body
Diffusion depends upon
depends upon the random motion of molecules
The net flux of a penetrating solute into a cell will increase if the:
- permeability constant for that solute increases
- temperature increases
- concentration of that solute in the ECF increases.
- both permeability constant for that solute increases and concentration of that solute in the ECF increases are correct
A cell is placed into a 1-millimolar solution of substance X and over time you witness the concentration of X inside the cell increase to 5 millimolar. The best explanation for this is:
X is moving into the cell by primary active transport.
If a cell is placed in a hypotonic solution, it will:
Swell
Which form of endocytosis is nonspecific, in that it occurs by the formation of an invagination of the plasma membrane, which then fills, with interstitial fluid of the immediate area?
Pinocytosis
Assertion: Cells normally swell in hypotonic solution BECAUSE the water concentration outside the cell initially exceeds that inside the cell
both true
Diffusion is very fast over short distances (cellular dimensions) but slow over large distances (cm) BECAUSE diffusion times increase in proportion to the cube of the distance over which diffusion occurs
first true, second false
What is the % of body fluids in males?
60%
What is the % of body fluids in females?
55%
Distribution of body fluids in ICF and ECF
ICF : 2/3
ECF: 1/3 ... 4/5 interstitial fluid
1/5 plasma
blood is 50-60% plasma >> blood colume is 4-6 litres