Homeostasis and Passive Transport

What is homeostasis?

Maintenance of certain key physiological variables within narrow limits despite changing conditions.

What state to describe homeostasis?

dynamic steady state

Stimulus in temperature regulation in homeostasis

low body temperature/ being cold

control variable in temperature regulation in homeostasis

Normal body temperature 36.5-37.5 C

Receptor in temperature regulation in homeostasis

Temperature receptors in skin

Control Center in temperature regulation in homeostasis

hypothalamus will stimulate a response

effector in temperature regulation in homeostasis

Superficial arteries constrict to reduce heat loss

Muscles shiver increases aerobic respiration to release heat

thyroid stimulates cells to increase metabolic heat production

Negative Feedback Control

response to a physiology perturbation and it'‘s role is to decrease the effect of the perturbation

Positive Feedback control

Response to physiological perturbation, job is to increase the effect of the perturbation

% of water in women

50% of body water

% of water in men

60% of water

As you age, what happens to our body fluid?

decreases

If you have more adipose tissues, what happens to your body fluid

decreases

What makes up our Extracellular fluid (ECF)?

plasma and interstitial fluid

Which one contains more fluid? ICF or ECF

ICF

What cannot cross the interstital tissues?

blood proteins like albumin

Factors in passive transport

requires no energy

goes down concentration gradient

non-membrane soluble substances require proteins to facilitate e diffusion

factors in active transport

required energy (ATP!)

goes against concentration gradient

Has primary active pumps and secondary active

Define diffusion

movement of molecules from one location to another due to random thermal motion

Which types of diffusion requires osmosis?

simple and channel mediated

types of diffusion

simple diffusion

channel mediated: ligand, voltage, mechanically gated, covalent mod and aquaporins

carrier mediated

factors that influence diffusion

steepness of gradient

temperature

mass/size of the diffusing substance

surface area of membrane

diffusion distance

viscosity of membrane

pH

Role of Aquaporins Channel

Important in tissues moving large volumes of water.

They increase water permeability and help cells adapt to changes in osmotic pressure without damaging their structure

Factors of the carrier mediated channel

Saturation

specificity

competition

affinity

Osmolarity Definition

molarity x the # of particles per molecule dissolved

Tonicity Definition

refers to the solution surrounding the cells. How a solution would affect a cell if placed in that solution

What does not contribute to tonicity?

non-penetrating solutes

How do cells behave in a 0.9% NaCl solution (0.9g of NaCl dissolved in 100mL of solution)?

Osmolarity: ECF and ICF are the same

Tonicity: has no net movement - isotonic

Hematocrit: RBC decrease due to expanded plasma volume.

How do cells behave in a 0.4% NaCl solution (0.9g of NaCl dissolved in 100mL of solution)?

Osmolarity: ECF is lower, ICF is higher - hypoosmotic

Tonicity: hypotonic, ECF moves into ICF

Hematocrit: no change (ECF increases but increase in RBC)

How do cells behave in a 7.5% NaCl solution (0.9g of NaCl dissolved in 100mL of solution)?

Osmolarity: ECF higher than ICF - hyperosmotic

Tonicity: ICF moves out to ECF - cell shrinks, hypertonic

Hematocrit: RBCs shrink and decrease

How does active transport get energy?

comes directly from ATP hydrolysis or indirectly by movement of a second ion down its own concentration gradient.