Unit 5: Week 4 Flashcards
What tissue contributes to water percentage?
Fat less water than muscle so therefore infants and men have a higher water percentage than women and the elderly who tend to have more fat
What are some functions of water?
• Temperature regulation -sweat
• Cushioning t lubrication - Joints
• Reactant-provides a medium for chemical reactions
• Solvent - electrolytes/nutrients k+ Na+ Cl- Glucose lipids
-Transport - blood
What are the component of body fluid?
intercellular fluid - fluid within cell -Cytosol makes up 62% of bodies fluid and 60% of mass
Interstitial fluid- fluid around cells which contains nutrients diffused from capillaries and waste products from cells. Makes up 30% of bodies fluid and 16% of mass.
Plasma - the fluid component of blood (used to transport substances RBC, WBC
around the body. makes up 8% of bodies fluid and 4% of mass
What are the major water sources and water excretion?
Majorly from drink 60% then food 30% and then metabolic reactions where water is a product eg glucose breakdown to get CO2 and H2O 10%
Excretion kidneys (urine) 60%, intangible losses 28% sweat 8% feces 4%
What are symptoms of dehydration?
Dehydration os when you loose more water than you gain.
• Thirst - hypothalamus + Osmoreceptors
• Dry mouth- water conserved to important functions
• low bp high HR - due to low blood volume → need to prioritise brain tissue
• Headache- blood vessels dial ate in the brain to get more nutrients
Increasing pressure
• nausea
• fatigue - muscle weakness
• low volume dark urine.
What are severe symptoms of dehydration?
Sunken eyes Wrinkled skin Lack of sweating Irritable Decreased alertness
What are electrolytes and what are they used in?
They are dissolved ions that enter the body through food and drink and leave through urine sweat feces.
They have a strong effect osmolarity- providing gradients for water transport
-Cofactors for Chemical reactions
-Nerve + muscle function- produce excitability wat let
• Acid-base balance- maintain pH
-Transport - Na+/Cl-/k+ involved in moving fluids
and membrane secreation/permeability
How is sodium used in the body?
Na+ is major cation in the extracellular fluid and has the main
role in fluid/electrolyte balance-effecting homeostasis. This is because it effects BP.
Sodium can also effect ICF levels. The cell membrane is relatively impermeable
to Na+ but the active Na+/k+ pump and voltage gated Na+ channels are used to change Na+ levels
Hyponatremia - Na+ needed for AP and muscle contraction could lead to lethargy weakness confusion.
if BV is low then BP is also low, HR is high and there is low urine output (dark)
Hypernatremia - aldosterone oversecreation/water loss - thirst, dry mouth.
If high BV then - oedema+increased BP and urine production
How is potassium used in the body?
K+ is the main ICF cation. This concentration of K+ is important in membrane excitability- nerve transmitting muscle contraction
K+ levels in the heart need to be carting regulated to coordinate electrical activity- arrytnmeia
Hypokalemia- hyper polerise membrane, bradycardia - delayed ventricular depolarisation.
hyperkalemia- cramping, rapid cardiac repolarisation.
potassium is also part of the bodies buffering System. - it moves in/out of
cell (as cells are permeable to potassium) to butter the amount of H+ ions to
control PH levels. Changes to these levels can interfere with excitability and
denature proteins
What are the 3 stimuli for aldosterone?
- low BP BV - the enzyme renin is produced by Juxtaglomerular cells in
responce to low renal perfusion.
Liver produces a plasma protein called angiotensin and Renin cleaves this into angiotensin 1
As AT1 circulates through the lungs ACE converts AT1 → AT2.
AT2 is water soluble so acts through the second messenger system to produce Aldosterone from cholesterol. (AT2 is good for also acts as a vasoconstrictor for smooth muscles in arterioles)
• Another stimulus is ACTH (weak stimulus of Zone glomerulosa)
• decreasedNa+/increased K+ humoral stimulus in the production of aldosterone.
How does aldosterone work?
Aldosterone is a steroid hormone so is lipid Solvable. It binds to
intercellular receptor to form a complex. This complex binds to receptor sites on chromatin activating mRNA and altering gene expression.
This produces proteins that increase permiability of Na+ out of the distal
convoluted tubual increasing blood Na+ levels. This provides a osmolarity gradient
for water to flow into BV. Increase in BV → increase in BP.
K+ leaves the blood and is moved into the D. C. T and excreted in urine).
Atria respond to increased BV by stretching and releasing ANP which inhibits
Aldosterone production by hyper polarising cells.
The other stimuli are acted on via -ve feedback loops increase BV, BP, Na+ decreasing k+
Angiotensin 2 also acts as a vasoconstrictor of arterioles increasing Peripheral R
and BP
What is oedema?
It is when extra fluid leaks into the interstitial space this could be from the kidneys not adequately getting rid of fluid. Hormonal disorder -AHD aldosterone oversecreation heat failure- not pumping adequately causing blood to leak from BV
What is lyphodema?
lymphatic disorders-Close relation to circulatory system where extra fluid in extra vascular space is transported back to blood.
lymphoedema - tend to not be pitting and has a ‘woody’ feeling.
enlargement of a limb is elephant it is caused by obstruction in the lymphatic system (usually a parasitic from a mosquito). Cracking skin, bacterial infections, pain, reduced mobility
What is kwashiorkor?
kwashiorkor - lack of osmotic pressure from protines in blood which causes fluid to pool around eyes and belly.
It is possible to have enough caloric intake but minimal protine
