ANP 1106 Lecture Notes - Lecture 8: Ketone Bodies, Respiratory Center, Aldosterone
6 Jun 2018
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Department
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Professor
Anatomy and Physiology 1107
Notes: Lecture 13
Prof: J. Carnegie
➢ Fluid compartments
o Intracellular fluid compartment (ICF) accounts for 60% of the total body fluid
o Extracellular fluid compartment (ECF) accounts for 40% of the total body fluid,
there are two sub-compartments
▪ Plasma (20% ECF)
▪ Interstitial space (80% of ECF, it includes cerebrospinal fluid, lymph,
syovial seretios…)
o Electrolytes have a greater osmotic power than non-electrolytes because each
electrolyte molecule dissociates into at least 2 ions
▪ In ICF the chief cation is K and the chief anion is Phosphate
▪ In ECF the chief cation is Na and the chief anion is Cl
▪ Na+ and K+ are opposite when comparing ECF and ICF because of the ATP
dependent Na/K pumps that keep in the intracellular Na low and
maintain a high intracellular K, renal mechanisms can reinforce these ion
distributions by secreting K as Na is being reabsorbed from the filtrate
➢ Water balance
o Water intake must equal water output
▪ Intake: liquids, foods, cellular metabolism
▪ Output: 60% of water is lost via the kidneys, also through the lungs, skin,
sweat and feces
o Increased plasma osmolality
▪ Thirst: increases water intake
▪ ADH: stimulates renal water reabsorption
o Decreased plasma osmolality
▪ Thirst is not stimulated
▪ ADH secretion is not stimulated
o Thirst mechanism
▪ There is a decreased in the plasma volume of ≥ % or a irease i
plasma osmolarity of 1-2% which leads to dry mouth
▪ Osmoreceptors of the hypothalamic thirst center lose water to
hypertonic ECF and become irritable and depolarize
▪ Dampening of thirst begins once the mucosa of the mouth and throat
become moistened, it prevents overdrinking while water moves to ECF
o Obligatory water losses
▪ Insensible water loss via the lungs and skin
▪ Occurs via the feces
▪ Minimum sensible urinary loss is 500ml/day
o Disorders of water balances
▪ Dehydration
find more resources at oneclass.com
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• It is fluid loss either by the loss of water or the loss of water and
solutes together
• Occurs after hemorrhage, severe burns, prolonged vomiting or
diarrhea
▪ Hypotonic hydration
• It is over-hydration when a large amount of water is consumed at
one
• When a person is dehydrated in the desert they must be
rehydrated slowly in order to avoid hypotonic hydration
▪ Edema
• It is fluid accumulation in the surrounding interstitial space
leading to tissues
• The extra fluid can impair the tissue functions by increasing the
distance across which oxygen and nutrients must diffused
between the blood and cells
➢ Sodium balance
o Salt content of the body can vary due to diet, loss via sweating, vomiting, etc
o Sodium
▪ 90-95% of ECF solute (sodium and anions), NaCl and NaHCO3 contribute
to 280 or the 300 mOsm solute concentration
▪ Regulating the Na balance is one of the most important functions of the
kidneys
▪ The sodium content of the body may change but its concentration in ECF
remains stable due to immediate adjustments in water volume
o Factors influencing Na
▪ Aldosterone
• It is the most the influential agent with respect to the kidney, it
acts slowly
• Even without aldosterone, 65% of Na in the filtrate is reabsorbed
in the proximal convoluted tubule and 25% in the loop of Henle,
aldosterone secretion is essential to life
• High aldosterone is when virtually all of the remaining Na (Cl is co-
transported) is actively reabsorbed by the distal convoluted
tubule and collecting ducts
• 2 pathways of secretion
o Renin-angiotensin system
o Direct effect of high K or low Na
• Renin secretion in response to
o Sympathetic nervous system
o Decreased filtrate osmolarity
o Decreased stretch (blood pressure)
• Addiso’s disease
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Intracellular fluid compartment (icf) accounts for 60% of the total body fluid: extracellular fluid compartment (ecf) accounts for 40% of the total body fluid, there are two sub-compartments, plasma (20% ecf) Interstitial space (80% of ecf, it includes cerebrospinal fluid, lymph, sy(cid:374)ovial se(cid:272)retio(cid:374)s : electrolytes have a greater osmotic power than non-electrolytes because each electrolyte molecule dissociates into at least 2 ions. In icf the chief cation is k and the chief anion is phosphate. Water balance: water intake must equal water output. Intake: liquids, foods, cellular metabolism: output: 60% of water is lost via the kidneys, also through the lungs, skin, sweat and feces. Insensible water loss via the lungs and skin: occurs via the feces, minimum sensible urinary loss is 500ml/day, disorders of water balances, dehydration. It is fluid loss either by the loss of water or the loss of water and solutes together: occurs after hemorrhage, severe burns, prolonged vomiting or diarrhea, hypotonic hydration.
