chapter 9: water Flashcards
how much water can be found in an adult human body?
about 40 L of water
–> 2/3 are inside cells
proportion of muscle and epithelial cells that is made up of water?
about 70 to 80%
proportion of fat and bone cells that is made up of water?
less than 20%
if the 2/3 of water in the body is in cells, where is the remaining 1/3?
in the extracellular fluid compartment
what does the extracellular fluid compartment include
the cardiovascular system
the interstitial system
the lymphatic system
sweat
tears
gastric juices
spinal fluid
fluid between joints
chemistry golden rule #3
where Ions go, water follows
–> water molecules move towards compartments with the highest concentration of solutes
controlling the amount of solutes in each compartment will do what?
the body can control the water inside and outside of cells
osmosis
the third chemistry golden rule
where Ions go, water follows
the diffusion of water through a selectively permeable membrane
the movement of water across a membrane toward the side where solutes are more concentrated
how does the body maintain a the balance of compartmental fluids?
by controlling the concentration of ions in each department
what do the cells do to control the movement of water?
they direct a movement of major minerals:
sodium
potassium
magnesium
chloride (sometimes)
phosphate (sometimes)
sulfur (sometimes)
these minerals, called salts, dissociate when place in water into ions (electrolytes)
–> water molecules are immediately draw to them
electrolytes
salts that dissolve in water and dissociate into charged particles called ions
positively charged ions
cations
negatively charged ions
anions
the most important function water does
the transport of nutrients and waste
what is plasma
plasma is 92% water
there are nutrients that are delivered to cells
there is waste that is delivered to kidneys for elimination
water functions in the body
the transport of nutrients and waste
water participates in chemical reactions
–> some of the water in our cells is made with chemical reactions (metabolic water)
water regulates body temeprature
metabolic water
water generated during metabolism
the amount of metabolic water produced per day depends on what?
on our physical activity level
how much metabolic water do physically inactive people produce?
about 300 mL per day
how much metabolic water do very physically active people produce?
about 550 mL per day
during exercise, why does our body heat up (body temperature regulation)?
blood rushes to the surface of the skin carrying the heat generated from the metabolic reactions made in our cells
this increase in blood flow allows more heat to dissipate, which cools down our core
role of sweat in body temperature regulation
it is what allows our body to cool during exercise
–> this only works when the sweat is allowed to evaporate
how can we ensure our sweat evaporates when exercising?
we have to ensure we do not work out in an environment that is too humid
–> if we do, the heated body water remains trapped in the body
–> can cause heat stroke
human body is composed of how much water?
50 to 70% of the body is water
which two factors affect how much our body is made up of water
age
sex
a newborn is how much water weight?
75%
an elder is how much water weight?
45%
who has more body water between men and women?
why?
men
because muscle tissue is 75% water and fat tissue is 20% water
men have generally more lean muscle
what is metabolic water produced from?
from the chemical breakdown of macronutrients
all the ways water can be consumed
metabolic water
food
beverages
all the ways water can be excreted
expired air
insensible respiration
sweat
urine
feces
every time that the heat contracts, how much of the blood forced out of the head goes to the kidneys?
21%
each minute, how much blood to kidneys receive?
how much urine will they make out of it per minute?
5 cups
1 mL per minute
from which artery do kidneys receive blood from the heart?
the renal artery
the blood that is clean (removed waste) leaves the kidneys through which vein?=
the renal vein
through what does the urine leave the kidneys to go to the bladder?
via the ureter
roles of kidneys
eliminating waste
controlling blood pressure
controlling blood volume
controlling the solute concentration of body fluids
the greater the amount of fluid, the greater or lower the amount of pressure on the walls of blood vessels?
the greater the amount of pressure
the kidneys are controlled by what?
by secretions from the Posterior Pituitary Gland (located in the brain)
by the Adrenal Glands (sitting on top of the kidneys)
The Posterior Pituitary Gland secretes which hormone?
what does this hormone do?
Antidiuretic Hormone (ADH)
controls the volume of urine and its solute concentration
–> makes less urine when blood levels are low to conserve water
promotes the elimination of potassium
The Adrenal Glands secrete which hormone?
what does this hormone do?
Aldosterone
controls the volume of urine and its solute concentration
–> reduces the excretion of sodium when blood levels are low
–> water follows ions, so since sodium stays more, so does water
promotes the elimination of potassium
when does the Posterior Pituitary Gland secrete Antidiuretic Hormone (ADH)?
when blood volume is low
or
when concentration of sodium in blood plasma is high
natural ways to lower blood pressure
increase potassium intake
increase magnesium intake
reducing sodium intake
how can cells that are more richly populated with electrolytes lower blood volume?
(when we increase potassium and magnesium intake, and maybe lower sodium intake)
by drawing water out of the extracellular fluid compartments and into the intracellular fluid compartments
–> Dietary Approaches to Stop Hypertension (DASH)
what can water deficiency and toxicity cause?
fluid and electrolyte imbalance
overwhelms the capacity of our kidneys to maintain fluid and electrolyte homeostasis
how to treat mild dehydration?
simple water intake
for ex: vomiting and diarrhea
how to treat more severe cases of dehydration?
requires electrolytes to be replenished
hyponatremia symptoms
severe headache
confusion
seizures
hyponatremia at the cellular level
water leaves the intravascular and interstitial compartments and migrates into cells
hyponatremia treatment
immediate medicla attention
hyponatremia
a decreased concentration of sodium in the blood
water intoxication
the rare condition in which body water contents are too high in all body fluid compartments
can cause hyponatremia
when does water intoxication occur?
when excessive amounts of plain water is consumed in short time period
or
when the kidneys have difficulty filtering water from blood
how is energy from the food spent?
spent on the chemical reactions running inside our cells
metabolism
the sum of all the chemical reactions that go on in living cells
includes all reactions by which the body obtains and expends the energy from food
high or low metabolism
the rate at which the chemical reactions that go on in living cells occur
anabolic chemical reactions
build stuff
require energy output
reactions in which molecules are put together to build larger ones
how much energy per day does the liver require to function?
380 Kcal per day
a very demanding organ
what are the roles of the liver that we have seen so far
build glycogen
synthesize cholesterol
Make VLDLs
Synthesize 11 non essential amino acids
convert ammonia to urea
convert retinol into other Vitamin A
Convert vitamin d3 into an intermediate form
how much energy per day do Kidneys require to function?
140 Kcal per day
why do kidneys require so much energy?
converts inactive vitamin D into active form
process 5 cups of blood per minute to make urine
the two main chemical reactions in the metabolism?
anabolic and catabolic chemical reactions
catabolic chemical reactions
release stored chemical energy
reactions in which large molecules are broken down to smaller ones
they release energy
–> released as heat or as Adenosine Triphosphate (ATP)
energy currency of the cell
Adenosine Triphosphate (ATP)
The Adenosine Triphosphate (ATP) facotry of every cell
the mitochondria
what do the mitochondria do?
they transfer the energy from macronutrients into the ATP
they also create Metabolic Water and CO2 out of this
Adenosine Triphosphate (ATP)
a highly reactive molecule ready to perform work
–> liked a compressed spring
contains about 40% of the chemical energy that was stored in the carbon hydrogen bonds of glucose
–> the rest is lost as heat
cells that have the most mitochondria
muscle cells
liver cells
cells that have the least mitochondria
fat cells
why is ATP the energy currency of the cell?
it releases kinetic energy
they phsopshorylate muscle fibers, allowing us to move
–> with the last phospate group released from the ATP
how does ATP work?
it is loaded with negative hydrogen bonds which make it highly reactive
the last phosphate bond of the ATP is released
–> released as kinetic energy
–> phsopshorylating
what changes an enzyme’s configuration and causes them to work?
phsopshorylatisation
when happens to ATP when it loses it’s last phosphate bond?
it turns into ADP
what ATP synthesized from?
Adenosine Diphosphate (ADP)
Phosphate
the reaction is made possible by the break down of macronutrients
what uses more of the energy we consume?
our basal metabolism
basal metabolism (or basal metabolic rate)
the energy needed to maintain life when the body is at rest
the rate of energy use for metabolism when at a 12-hour fast and respectful sleep, no physical activity or emotional excitement, and in a comfortable setting
calculates energy spent on breathing, circulating blood, and maintaining organ functions
usually expressed as kilocalories per kilogram body weight per hour
basal metabolism (or basal metabolic rate)
the energy needed to maintain life when the body is at rest
the rate of energy use for metabolism when at a 12-hour fast and respectful sleep, no physical activity or emotional excitement, and in a comfortable setting
usually expressed as kilocalories per kilogram body weight per hour
our organ with the biggest BMR?
the liver
why is BMR measured only after 12 hours of fasting?
energy must be spent to make chemical digestion of food possible
–> enzymes allow this to happen
mechanical digestion is also energy costly
–> this is why we feel tired after big meals
Thermic Effect of Food (TEF)
the estimated energy required to process food
consumes about 10% of total caloric intake
some people can eat a lot and not gain weight
others can be way more sensitive
what influences our Basal Metabolic Rate?
body composition
sex
body surface area
age
height
environment
quality of our diet
some people can eat a lot and not gain weight
others can be way more sensitive
what influences our Basal Metabolic Rate?
body composition
sex
body surface area
age
height
the more muscle tissue we have, the more or less our BMR?
the more
why does a taller person of the same weight have a higher BMR than another person that is shorter and of same weight?
because the taller one has more surface area from which heat can escape
–> to maintain body temperature, the taller body needs more energy
why does a taller person of the same weight have a higher BMR than another person that is shorter and of same weight?
because the taller one has more surface area from which heat can escape
–> to maintain body temperature,
environment as a factor influencing BMR includes what?
us in the womb
us as infants and growing up
us as adults
role of the environment as a factor influencing BMR
explain how the development of sweat glands in babies work in a hot and cold environment
babies in hot environment will develop more functional sweat glands in a hotter environment
the colder the environment, the fewer the number of adult sweat glands
why do people with more functional sweat glands have less chance of dying from heat stress?
because they can cool the body more effectively
the thrifty gene theory
fetuses deprived of calories lower their BMR because they predict and environment of food scarcity
role of our diets in influencing our BMRs
our nutrients can change our gene expression
epigenetics
in which two ways do the relationship between diets and genes go?
nutrigenomics
nutrigenetics
in which two ways do the relationship between diets and genes go?
nutrigenomics
nutrigenics
nutrigenomics
studies how food can affect gene expression
nutrigenetics
studies how genes influence how nutrients are metabolized
