chap 1- homeostasis/functional organization of the human body (b1- foundation) Flashcards
define homeostasis.
maintenance of nearly constant conditions in internal environment
what is the difference between the ionic composition of ICF and ECF? (inside and outside the cell basically)
ICF: potassium, proteins, phosphate, magnesium, sulfate (think the 3 P’s)
ECF: sodium (Na), chloride (Cl), bicarbonate (HCO3)
- others (not imp) are oxygen, CO2, sugar, fatty acids, amino acid
explain total body water distribution of the body
- water consists of 60% of total body weight, which means volume of 42 L
- 2/3 total body weight is intracellular fluid, which is 28 L
- extra cellular fluid = 1/3 TBW, Volume of 14L
- extracellular fluid further divided into interstitial fluid (80% of ECF, volume= 11 L) and plasma (20% of ECF, volume= 3L)
what are the 2 main regulatory systems of the body? + further divisions
1. Nervous system which is further divided into voluntary (sensory system (sensory receptors like eye, ear, & touch receptors) → center (brain + spinal cord) → motor system (effector, usually muscles)) and autonomic (heart contractility, breathing, blood pressure)
2. Endocrine system (hormone system)
name 4 hormones controlled by the endocrine system and their functions
thyroid hormone: increases metabolic rate
insulin hormone: controls glucose metabolism
adrenocorticotropic hormone (ACTH): helps body respond to stress by stimulating adrenal glands to release cortisol
parathyroid hormone: regulates calcium levels in the body
what are the components of the homeostatic mechanism?
stimulus (from external environment) → receptors → control center (set point) → effectors (muscles or glands) → response (change is corrected)
able to detect deviations from norm, integrate relevant info, make appropriate adjustments
what are the 2 control systems of the body?
feed back and feed forward
explain the 2 types of feedback mechanisms
negative feedback: stimulus causes an opposite output in order to maintain an ideal level of balance
- opposite direction
positive feedback: amplification of a body’s response to a stimulus (product enhances the reaction)
- same direction
blood clotting example
rupture of blood vessel → clot formation begins → clotting factors are activated → further activates other clotting factors → resulting in platelet plug formation
positive feedback mechanism
labor example
uterine contraction → baby’s head moves downward → stimulates cervix receptors → further increases urine contractions
positive feedback
feedforward mechanism + example
responses made in anticipation of a change
- ex. cephalic phase of gastric secretion (food in mouth causes stomach to start releasing chemicals)
most effective regulation system of the body
temperature (thermoregulation)
what is gain and what is the formula?
gain = correction/error
gain: degree of effectiveness with which a control system initiates constant conditions
more gain value = more efficient
also think of it as improvement done/improvement not done
gain in a positive feedback mechanism
there is no gaining a positive feedback system!!
- gain sign is otherwise negative
blood loss of more than 2L example
- body cannot compensate when blood loss is more than 2L
blood loss → weakening of cardiac output → decreased coronary blood flow → organs get less too → weakening of heart → progressive shock & death
vicious cycle
adaptive control
past experience & learning can change the control system’s output
delayed negative feedback
- ex. motor skills (not touching a stove without gloves again)
“internal environment” refers to
extracellular matrix/fluid
clinical relevance: failure of homeostasis leads to…
diseases like shock, acidosis, and hypertension
sodium normal values in ECF and what happens when they drop/raise too much
range: 135-145 mmol/L
below 135 = hyponatremia
above 145 = hypernatremia
potassium normal values in ECF and what happens when they drop/raise too much
range: 3.5-5.3 mmol/L
below 3.5 = hypokalemia
above 5.3 = hyperkalemia
calcium normal values in ECF and what happens when they drop/raise too much
range: 1.0-1.4 mmol/L
below 1.0 = hypocalcemia
above 1.4 = hypercalcemia
bicarbonate acid base balance
bicarbonate is a base that helps maintain body’s acid-base balance (acts as a buffer)
which ion is in higher concentration in the ICF vs the ECF?
potassium
- makes sense b/c its values are also lower than sodium’s b/c sodium is more outside the cell in the blood
