Lecture 1 Flashcards
Normal blood pH?
Arteries 7.45
Veins 7.35
Overall 7.4
Outside what blood pH range for a significant period of time is death likely?
Below 6.8 or above 8
What is homeostasis?
The ability of an organism to maintain a constant internal and external environment despite intrinsic and extrinsic factors that may impinge on the system.
What is negative feedback?
Results of an action inhibit further performance of that action e.g temperature control
Feedback loop components and example
Variable- temperature
Sensor- nerve cells in skin
Control centre- hypothalamus
Effector- sweat glands in body
Controlling high temperature?
Vasodilation
Sweating
Pilorelaxation
Stretching out
Controlling being cold?
Vasoconstriction
Piloerection
Curling up
Shivering
Positive and negative feedback examples?
Insulin for negative
Blood clotting for positive
Core body temperature?
36.5 to 37.5
Is a patient below 28 degrees with no vital signs dead?
No, not dead until warm and dead
2 main organs for acid base balance?
Lungs- respiratory balance
Kidneys- metabolic balance
What do kidneys do if blood acidotic?
Secrete h+ and retain hco3- (bicarbonate)
Can you do the ph h+ calculation.
Yes or no
What is normal H+ concentration at ph 7.4
What is it from 7.35 to 7.45
40 nmoles/L
36-44
Ph 7= 100
Change in ph of 0.3 gives a change in H+ concentration of a factor of 2
Body ph buffer systems?
Phosphate icf
Protein icf and ecf
Carbonic acid and bicarbonat ecf
Body water volumes?
70kg male
60% water
42L
One third extracellular 14L two thirds intracellular 28L
Blood plasma 25% 3L of which 40% is haematocrit
Interstitial 75% 11L
Body water distribution for ages and body weights?
Infant highest water percentage
Then male
Then female
Obese and elderly lower water percentage
What does increased ADH lead to?
Oliguria= less than 400-500 ml of urine produced in an adult daily
What is osmolality?
Concentration of solution expressed as total number of solute particles per kg. Unlike osmolarity it does not depend on temperature and pressure
What is the cause of increased serum osmolality but decreased urine osmolality?
Diabetes insipidous
How does excess ADH affect serum and urine osmolality?
Decrease serum osmolality but increase urine osmolality.
What is normal serum osmolality range?
280-300 moms/Kg
What is oedema?
Fluid retention in the body
What are fenestrations?
Holes in capillaries
Cause of Oedema?
Liver failure- albumin not produced
Lymphatic system failure
Capillary damage e.g water in a blister
Over hydration of drinking too quickly- osmotic gradient and water into cells
What is rigor?
Sudden feeling of cold accompanied by shivering, a rise in temperature and often sweating. Indicates the onset of fever.
What is a febrile seizure.
Seizure in kids 6 months to 5 years old caused by an increased body temperature without any underlying conditions.
What is the term for being over hydrated?
Hyponatremia
