BIOL 380 Lecture Notes - Lecture 7: Troponin, Blood Vessel, Myosin
19 Jun 2018
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BIOL 380 – Lecture 7 – Chapter 10: Fluid and electrolyte balance
-Body fluid is the liquid portion of cells and tissues characterized by its ability to move freely and
changeably, adapting to the shape of the container that holds it
Body fluid
1. Intra-cellular fluid: within the cell, 2/3 of body fluid
2. Extra-cellular fluid: outside of the cell, 1/3 of body fluid
oInterstitial fluid (80%) flows between cells that make up a
particular tissue or organ (muscle and liver etc.)
oIntravascular fluid (20%) is the water in the blood and
lymph:
plasma
transports
blood cells
within
arteries, veins and capillaries
- Males have more lean tissue and thus a higher
percentage of body weight as fluid than females.
- The amount of body fluid as a percetnage of total
weight decreaes with age
Fluid composition
- Fluid composition of tissue varies by,
1. Tissue type: lean tissue (muscle) have higher fluid content than fat tissues (compared to
adipose tissue which is hydrophobic due to triglycerides)
2. Gender: males have more lean tissue and therefore more body fluid than females
3. Age: decrease in body water results partly from loss of lean tissue as people age
- Within the body fluids are solutes. Major minerals such as sodium, calcium, potassium, chloride,
and phosphorous
- Mineral salts = electrolytes
Functions of body fluids
1. Fluids dissolve and transport substances
oWater is an excellent solvent because it dissolves a variety of substances
oWater-soluble substances are readily transported in the bloodstream: amino acids,
glucose, vitamins, minerals and medications
1
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oFatty substance are transported attached to or surrounded by water-soluble proteins
(so fluid transports hydrophobic things too)
2. Fluids account for blood volume (high blood pressure = more fluid)
oBlood pressure increases when blood volume rises
oHigh blood pressure (hypertension) is a risk factor for heat disease and stroke
oLow blood pressure can cause people to feel tired, confused or dizzy (low amount of
fluids in our blood – hypotension)
oKidneys help to regulate blood volume and blood pressure
3. Fluids help maintain body temperature
4. Protect and lubricate tissues
Hormones and enzymes responsible to regulate the amount of body fluids
- Antidiuretic hormone (ADH) (posterior) stimulates the kidneys to reabsorb water
oCollecting tubules, just before urine is formed, when signaled the kidneys will retain
water, contributes to inc blood pressure
- Renin (kidneys) responds to decreased blood pressure by activating angiotensinogen to
angiotensin I
okidney senses high conc of solutes, so the granular cellls secrete renin, which activates
cascade of events to inc blood pressure
- Angiotensin I is cleaved to angiotensin II (vasoconstrictor) (liver) which increases blood pressure
oIf you constrict size of blood vessel, blood pressure inc
oANG II tells cortex of adrenal glands to produce aldosterone
- Aldosterone (adrenal glands) is released in response to angiotensin, and signals the kidneys to
retain sodium and chloride, thereby retaining water and increasing blood pressure
In response to the increased concentration of solutes in your blood, antidiuretic hormone (ADH) is
released from the pituitary gland. ADH stimulates the kidneys to reabsorb water and to reduce the
production of urine. This drop in blood pressure stimulates pressure receptors in kidneys, which signal
the kidney to secrete the enzyme renin. Renin then activates a blood protein called angiotensinogen,
which is produced in the liver. Angiotensin I is converted to angiotensin II, which is a powerful
vasoconstrictor. Angiotensin II also signals the release of the hormone aldosterone from the adrenal
glands. Aldosterone signal the kidneys to retain sodium and chloride, which results in water retention,
which increases blood pressure and decreases urine output.
2
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- Lower fluid intake or loss of water higher salt in blood or
high blood osmotic pressure
Regulation of blood pressure and blood volume by
the kidneys
- Reabsorb = moving back into the blood
3. Fluids help maintain body
temperature
- Body temperature must be within a safe range
- Water has a high capacity for heat, which means that only
sustained high heat can increase body temperature
- When heat needs to be released increase in the blood
flow from warm body core to the periphery evaporation
results in cooling
- Sweating releases heat as the evaporation of water from the skin cools the skin and blood
4. Protect and lubricate tissues
- Cerebrospinal fluid protects brain and spinal cord
- Amniotic fluid protects the fetus
- Synovial fluid lubricates joints
- Tears cleanse and lubricate eyes
- Saliva moistens food for swallowing
ELECTROLYTES
- Electrolytes: Dissolved substances in
solution that disassociate into electrically charged particles called ions
oPositive charge: Na+ , K+ , Ca2+
3
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Document Summary
Biol 380 lecture 7 chapter 10: fluid and electrolyte balance. Body fluid is the liquid portion of cells and tissues characterized by its ability to move freely and changeably, adapting to the shape of the container that holds it. Males have more lean tissue and thus a higher percentage of body weight as fluid than females. The amount of body fluid as a percetnage of total weight decreaes with age. Major minerals such as sodium, calcium, potassium, chloride, and phosphorous. Functions of body fluids: fluids dissolve and transport substances, water is an excellent solvent because it dissolves a variety of substances, water-soluble substances are readily transported in the bloodstream: amino acids, glucose, vitamins, minerals and medications. Hormones and enzymes responsible to regulate the amount of body fluids. Antidiuretic hormone (adh) (posterior) stimulates the kidneys to reabsorb water: collecting tubules, just before urine is formed, when signaled the kidneys will retain water, contributes to inc blood pressure.
