BIOB34H3 Lecture Notes - Lecture 8: Vehicle Emissions Control, Threshold Potential, Nephron
FEEDING REGULATION
- Feeding is regulated à animals
need to reguatle feeding to
regulate their body mass
-Adipsotiy signals send signal
for long-term energy stores of
the body (in the form of fats
and carbs)
leptin à produced by white fat
cells à more white fat cells =
more total leptin in body à
more leptin = more fat the
animal is// –ve sign means it
suppresses your appetite)
insulin à produced to tell how
much glucose is in the blood/stored in the body à insulin is also an appetite
suppressant
-Gut hormones (satiety signals) send signals to brain about the short-term energy
stores of the body (energy present in the gut)
ghrelin is produced when stomach is empty (stomach can detect presence of nutrients
in it, and can also see if the stomach is distended [more food = more stretched]) à when
stomach is nutrient empty/not distended à produces ghrelin à acts as an appetite
stimulant à person feels hungry
- Stomach regulates in accordance w/ other signals (eg. Should I eat and how much) are
regulated in by the adiposity and gut hormones together
OSMOREGULATION
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ANIMAL BODY COMPOSITION
- Body solids are mostly proteins
and lipids. Some jellyfish can be
up to 95% body fluids.
- Can sep. body into many
multicompt. Models
molecular model: 4 molecules-
fat/protein/mineral/water
fat/protein form the body
solids // water/minerals/little
bit of proteins make up the
body fluids à fluids make up
bulk of animal body
- Osmoregualtion looks at how the body fluids are regulated
BODY FLUID COMPARTMENTS
- Body fluids are compartmentalized à separated by
various barriers
1. intracellular fluids/cytosol à fluids inside cells
(cytoplasm refers to everything inside cell outside
the nucleus/cytosol is just the fluid)
cell membrane is the barrier that sep.
intracellular fluids from other ones
2. plasma à sep. by other fluids by the
endothelium (the inner layer/lining of every blood
vessel)
3. interstitial fluid/lymph à outside blood plasma,
but also outside of cells (“directly bathing the
cell”) à Lymph + Plasma are collectively called the
ECF
- This scheme only applies to animals w/ closed circulatory system (have clearly
closed vessels and thus have separation)
- Animals w/ an open system (is not continuous) à then don’t have sep. between
blood plasma and IF à are mixed together à the ECF is then called the hemolymph
- 3 aspects need regulation
> 1. volume
> 2. osmolarity (# of solutes)
> 3. ionic composition (what ions are dissolved)
VOLUME
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- Need to regulate volume b/c they lack cell walls à means
shape/size/structure of animals cells is shaped by the volume of fluids
inside of the cell
eg. If water left animal cell, it will shrink and shrivel up à eg. If nerve cell
shrivels up and shrinks à neurons need to be close to communicate à shrink
= harder to communicate = hard for brain to function
- People who are dehydrated have reduced cognitive function
eg. If water entered animal cell à they need a biconcave shape (natural) à
allows to maximize surface area/volume à make them become spherical
(low SA:V ratio) = blood cell is less effective // RBCs can also lyse
-Exoskelton = can’t expand = if too much water, there won’t be enough
space = pressure will build up = too much water in crab = can expand the
body = crush and kill cells
same problem for brain swelling
OSMOLARITY
-Osmolarity = total conc. Of solutes in a solution
- Making 1 mM of NaCl = 2mOsm (b/c NaCl dissociates into
Na+ and Cl-)
-Hypo-osmotic soln = conc. In cell is higher than water
water moves into the cell
-Hyperosmotic soln = conc. In water is higher than the cell à
water moves out of cell and to water
-Osmoregularity Is thus important for protecting cells from
shriveling up/swelling up
-Water moves through the Aquaporins à if move aquaporins
out of the cell, then in theory it should stabilize properply à
however: membranes leak across membranes à thus
whenever there is a conc. Gradient, water will leak through
these membranes regardless of tere being aquaporin’s or not
IONIC COMPOSITION
-Ionic comp. = what types of ions are present in the body
- Are plotting cations and anions à find that there is an equal amount of both à body
fluids are electrically neutral
usually when something positive moves along, there’s something negative that moves
away to compensate for the charge difference
Blood plasma
- Dominant ions are Na and Cl à BPsm is dominantly Na+ and Cl-
Interstitial Fluid
- Dominant = Na+ and Cl- à this is b/c see that the endothelium is there and is not 100%
effective à thus have relatively similar composition in these 2 fluids
- Noteworthy diff: proteins à are found in list b/c proteins under neutral physiological
condtions, proteins are –vely charged
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Document Summary
Feeding is regulated animals need to reguatle feeding to regulate their body mass. Adipsotiy signals send signal for long-term energy stores of the body (in the form of fats and carbs) Leptin produced by white fat cells more white fat cells = more total leptin in body more leptin = more fat the animal is// ve sign means it suppresses your appetite) Insulin produced to tell how much glucose is in the blood/stored in the body insulin is also an appetite suppressant. Gut hormones (satiety signals) send signals to brain about the short-term energy stores of the body (energy present in the gut) Stomach regulates in accordance w/ other signals (eg. should i eat and how much) are regulated in by the adiposity and gut hormones together. Some jellyfish can be up to 95% body fluids. Fat/protein form the body solids // water/minerals/little bit of proteins make up the body fluids fluids make up bulk of animal body.
