SLE211 Study Guide - Midterm Guide: Ion, Myoglobin, Osmoregulation
5 Jun 2018
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Homeostasis - Maintenance of constant internal environment in the face of external change.
Components:
• Sensor
• Control
• Effector
Positive feedback: Amplifies an initial change.
Eg. Oxytocin release during childbirth -
• Oxytocin causes contraction of the uterus
• Contractions push baby's head against the cervix
• Pressure on the cervix causes the release of MORE oxytocin
Negative Feedback: Is a process in which the body senses a change and activate mechanisms to
reverse and oppose the change.
Eg. Maintaining body temperature, O2 levels, blood levels
Internal Environment -
Body Fluid Distribution:
• Two main fluid compartments water occupies in
the body.
ICF - Intracellular Fluid
• Within cells
• Approx 2/3 water content
ECF - Extracellular Fluid
• Outside cells
• Approx 1/3 water content
• Comprises of IF and plasma
Composition of body
fluids:
• Plasma and ICF are
very similar due to
having a leaky
capillary wall
between them.
Plasma Membrane
• Separates the
interstitial fluid and
intracellular
• Semi-permeable
barrier
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Transport
Passive:
• Down a concentration gradient
• Along an electrical gradient
• Unassisted
• Lipid soluble
Diffusion:
• High to low concentration
Facilitated diffusion:
• Diffusion with transport proteins
providing pathways or channels
for water-soluble molecules
• Same rate as simple diffusion
• Limited
Active:
Active transport:
• Requires energy
• Against concentration gradient (Low to
High)
• Nerve cells (Na pumped out, Ka pumped
in)
Primary – Carrier protein gets energy directly
from ATP through hydrolysis
Secondary – Energy is stored in the
concentration gradients of ions
Uniport – Single substance, single direction
Symport – Two substances, same direction
Antiport – Two substances, opposite direction
Osmosis- Diffusion of water
• Water with regard to water concentration gradient = High to low conc.
• Water with regard to solute concentration gradient = Low to high
Osmoregulation - Control solute and water content
Osmolarity - Measure of the concentration of the dissolved particles in that solution (Solutes per
litre) Eg. Osmolarity of ECF and ICF is 300 mOsmol/L
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Tonicity - Refers to the effects the concentration of non-penetrating solutes in a solution has on cell
volume
• No set unit
Animal:
Hypotonic - Lysed
Isotonic - Normal
Hypertonic - Shrivelled
Plant:
Hypotonic - Turgid
Isotonic - Flaccid
Hypertonic - Plasmolysed
Fick's Law of Diffusion - Factors on rate of
diffusion
• Concentration gradient
• Surface area of membrane
• Lipid solubility (Lipid soluble and gases
pass easily!)
• Molecular weight of substance
• Distance
Solution: A homogenous mixture of 2 or more pure substances
Solvent: Substance in which the solute is dissolved
Solute: Dissolving medium. Soluble in the solvent.
Iso-Osmotic VS. Isotonic
Iso-osmotic - Solution has the same number of dissolved solutes
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Document Summary
Homeostasis - maintenance of constant internal environment in the face of external change. Oxytocin release during childbirth : oxytocin causes contraction of the uterus, contractions push baby"s head against the cervix, pressure on the cervix causes the release of more oxytocin. Negative feedback: is a process in which the body senses a change and activate mechanisms to reverse and oppose the change. Body fluid distribution: two main fluid compartments water occupies in the body. Icf - intracellular fluid: within cells, approx 2/3 water content. Ecf - extracellular fluid: outside cells, approx 1/3 water content, comprises of if and plasma. Composition of body fluids: plasma and icf are very similar due to having a leaky capillary wall between them. Passive: down a concentration gradient, along an electrical gradient, unassisted. Facilitated diffusion: diffusion with transport proteins providing pathways or channels for water-soluble molecules. Active transport: requires energy, against concentration gradient (low to. High: nerve cells (na pumped out, ka pumped in)
