Before Midterm Flashcards
What is comparative animal physiology?
Animal physiology is the study of how animals function at all levels of organization.
What is the August Krogh principle?
There is an optimally suited animal to study most biological problems.
What is homeostasis?
Homeostasis is a tendency for an animal to maintain relative internal stability in the face of external fluctuation
How is homeostasis possible?
Regulatory systems
What are the benefits of conformity?
No cost associated
How does negative feedback work?
Negative feedback control systems regulate a variable by opposing its deviation from a set point thereby keeping that variable within its homeostatic range.
What do beta cells do?
The beta cells monitor blood glucose and release a hormone called insulin into circulation
What do alpha cells do?
The alpha cells produce a hormone called glucagon
What are most physiological variables regulated by?
Negative feedback
How does positive feedback work?
Positive feedback control systems regulate a non-homeostatic change and that create a rapid change away from that set point and as a result of this promoting an explosive response that is unidirectional.
What are efferent sensory neurons?
neurons that project towards the central nervous system
What is acclimation?
a process of change in response to a controlling variable in the lab
What is acclimatization?
a process of change in response to a change in a natural environmental variation
What is adaption?
a chronic response to change in environmental variables through natural selection
What does the bilayer of phospholipids in cells do?
bilayer of phospholipids separates the intracellular from the extracellular fluid
Describe Peripheral proteins
- The peripheral proteins are only associated with the outer or the inner surface of the plasma membrane.
- They can be removed without destroying the membrane.
What are proteins that are anchored to the outside of cells involved in?
Cell-to-cell recognition.
Where are integral membrane proteins found?
across the plasma membrane
What do integral membranes provide the mechanism for?
transmembrane transport
What does the percentage of lipid to protein ratio and the protein composition vary according to?
The function of the cell
Why do we call the plasma membrane a fluid mosaic?
- it is composed of a mixture of proteins and lipids
- both the proteins and the lipids can readily move around in the membrane
What is the composition of cell membranes related to?
Their permeability
What must molecules following the transcellular path cross?
both the apical layer and the basal lateral side of the cell membrane
what must molecules passing through the paracellular path be able to move through?
tight junctions between cells.
What are cells in epithelium membranes attached to one another via?
tight junctions
What pathway of movement do large particles use?
transcellular
What kind of composition do cell membranes have?
Heterogeneous
What must the outer layers of cell membranes be capable of?
recognizing endocrine paracrine autocrine signals or neurotransmitters.
what is the inner layer of the cell membrane specialized for?
intracellular signaling
and attachment of the cell membrane to the cytoskeleton of the cell.
What are lipid rafts?
regions of the plasma membrane that accumulate cholesterol and glycolipids
Why are lipid rafts thicker than surrounding regions in the plasma membrane?
the phospholipid tails of the membrane are composed of more saturated fats and therefore they are more symmetrically organized and compact
What is the primary element of plasma membranes?
Phospholipids
what is the normal state for phospholipids at physiological temperature?
liquid crystalline
What type of molecules are phospholipids?
amphipathic
What is the most common class of phospholipids in plasma membranes?
Phosphatidylcholine
what does cholesterol do in the plasma membrane?
either increase or decrease fluidity
when does cholesterol decrease membrane fluidity?
when interacting with the polar head
when does cholesterol increase membrane fluidity?
when interacting with the nonpolar tail
what can alter membrane fluidity?
- fatty acid chain length
- saturation
- polar head group
- cholesterol
What will you see in terms of fat composition in the Arctic?
- lower percentage of saturated fats
- high percentages of monounsaturated and polyunsaturated fats.
How can materials move across a membrane?
through active or passive mechanisms.
where is concentration of sodium higher?
outside the cell
where is concentration of potassium higher?
inside the cell
where is concentration of calcium higher?
outside the cell
where is concentration of chloride higher?
outside the cell
where is concentration of anionic solutes higher?
outside the cell
What does Fick’s law of diffusion tell us?
what the rate of diffusion is for any given solute across a membrane
What happens to the the rate of diffusion of a substance across a membrane if you increase concentration gradient?
it increases
What happens to the the rate of diffusion of a substance across a membrane if you increase permeability?
it increases
What happens to the the rate of diffusion of a substance across a membrane if you increase molecular weight?
it decreases
What happens to the the rate of diffusion of a substance across a membrane if you increase membrane thickness?
it decreases
What happens to the the rate of diffusion of a substance across a membrane if you increase temperature?
it increases
What is the charge in the bulk solution?
Neutral
What is the charge on the inside of the cell very close to the membrane?
negative
What is the charge of the extracellular fluid very close to the membrane?
positive
What determines the movement of ions?
electrochemical gradient
What is osmosis?
he diffusion of water through a semipermeable membrane from a region of low solute concentration to a region of high solid concentration
In osmosis, when do you no longer have any water movement?
when hydrostatic pressure equals osmotic pressure.
what do the effects of tonicity depend on?
differences in osmolarity but also on the permeability of the membrane to the solutes
When is a solution called isotonic?
when the solution has no effect on cell volume
what does osmolarity take into account?
total concentration of penetrating and non-penetrating solutes
what does tonicity take into account?
total concentration of penetrating solutes only
what happens if you put a red blood cell in a hypertonic solution?
the red blood cells will shrink
what happens if a red blood cell is in an isotonic solution?
no net movement of water
what happens if a red blood cell in is a hypotonic solution?
it will grow until it bursts
