L14. Pt 2 Flashcards
Glomerular filtration rate (GFR)
Volume of blood filtered/ time
If Glomerular filtration rate (GFR) is too high what happens
Lose of too much water and salt ➡️ dehydration & electrolyte imbalance
If Glomerular filtration rate (GFR) is too low it causes
Accumulation of wastes - which is toxic
How much urine needed to be made/created a day?
400ml/day
What effects Glomerular Filtration rate (GFR)
Dehydration & blood loss
Intrinsic regulation of GFR goal
ensure each nephron operates optimally for waste removal
Extrinsic regulation of GFR goal
To maintain BP by conserving water
What are the 2 intrinsic regulation mechanisms of GFR
Myogenic mechanism & Tubuloglomerular feedback
Goal of Myogenic mechanism
Keep glomerular filtration rate (GFR) constant as mean arterial BP changes from 70-180mmHg and protects the glomerulus
In the Myogenic mechanism what happens if GFR is too high? What about too low?
Too high GFR = stretched smooth muscle of afferent arteriole (smooth muscle contracts) ➡️ decrease GFR
Too low GFR = relaxed (dilated) smooth muscle ➡️ increase GFR
Goal of Tubuloglomerular feedback
Decrease GFR when too much filtrate is moving through tubules
In the tubloglomerular feedback if filtrate is too high what happens/ too low?
Too high filtrate = macula densa cells release ATP ➡️ contraction of afferent arteriole smooth muscle ➡️ decrease GFR
Too low filtrate - macula densa cells decrease ATP release ➡️ dilation of afferent arteriole smooth muscle ➡️ increase GFR
What do macula densa cells sense
Increase filtrate - Nacl (salt) & H2o (water) in tubular fluid
Goal of Extrinsic regulation of GFR and why it does that
Maintain BP by conserving h2o
Reason= maintains perfusion pressure
What’s the reason for maintaining BP by conserving h2o
Maintain perfusion pressure
Extrinsic regulation of GFR mechanism (sympathetic NS)
Decrease blood pressure (stimulus) ➡️ baroreceptor reflex ➡️ increase sympathetic NS activity ➡️ increase in CO & vasoconstriction in skin/ GI tract = increase TPR
Afferent arteriole diameter greater than efferent arteriole
TRUE or FALSE
True: has greater filtration presssure
What are the two responses to decrease Blood pressure (BP)
- Baroreceptor reflex
- RAAS (Renin Angiotensin Aldosterone System)
The baroreceptor reflex
- only works w/ adequate blood volume
- an immediate response mediated by the Sympathetic NS
- increases BP
RAAS: Renin Angiotensin Aldosterone System
- corrects for inadequate blood volume
- not an immediate response (follows Baroreceptor reflex)
- initiated by kidneys/ mediated by hormones (Renin, Angiotensin 2)
- increase BP & Blood volume
RAAS: Renin Angiotensin Aldosterone System Mechanism
Stimulus = decrease blood pressure = decrease blood flow to kidneys ➡️
Regulation of sodium
If BP low - save na+ ➡️ increase BP
Sodium mechanism
Stimulus = low Na+ intake ➡️ low plasma na+ concentration (decrease osmolarity) ➡️ osmoreceptors in hypothalamus ➡️ posterior pituitary to decrease ADH ➡️ decrease aquaporins present = decrease water absorption in collecting duct ➡️ increase urine volume & decrease blood volume = decrease BP
Blood volume is regulated to control _________________
Blood pressure
How is blood volume regulated to control blood pressure
By regulating salt balance with aldosterone
What do you want to do with sodium if you have a
Low BV = ________
High BV_______
Low = save sodium b/c h2o follows
High = lose sodium b/c water follows
Blood osmolarity is regulated to prevent what
Cell shrinking and swelling
How is blood osmolarity regulated to prevent cell shrinking and swelling
By regulating water balance with ADH
High osmolarity =
Low osmolarity =
High = save water to dilute salt
Low = lose water to concentrate salt
Regulation of potassium
Increase k+ ➡️ increase k+ in plasma ➡️ increase aldosterone secretion ➡️ increase plasma aldosterone ➡️ k+ secretion in distal convoluted tubule & collecting duct ➡️ increase k+ excretion
Why is potassium (k+) important
Important for action potentials
What are the two locations calcium is regulated
Thyroid gland & parathyroid gland
Calcitonin
Decreases blood ca+
Parathyroid hormone
Increases blood ca+
What are the 2 sources of calcium?
Eating it or releasing from bone
Why do we need calcium?
- blood clotting
- muscle contraction
- neurotransmitter release
- second messengers
Regulation of calcium when too high mechanism
Stimulus =rising of blood ca+ level ➡️ thyroid gland to release calcitonin ➡️ bone to take in ca+ , decrease urine out, absorb less ca+ in intestines
Regulation of calcium when low Ca+
Stimulus = low/falling blood ca+ level ➡️ parathyroid gland to release parathyroid hormone ➡️ intestines to absorb more ca+ , kidneys uptake more ca+ & bones release ca=
Bone resorption
Parathyroid hormone stimulates osteoclasts to resorb bone
Absorb
Take into the blood (was never there before
Reabsorb
Was once in the blood, was removed and now returning back to the blood
Resorb
Removed by gradual breakdown
What are the 3 levels of ph regulation
- Buffers
- Lungs
- Kidneys
Buffers
Stabilize ph
- every fluid compartment is buffered
Blood buffers
Hco3 (bicarbonate) & HB (hemoglobin)
Intracellular buffers
Proteins
Urine buffers
Phosphate ions
Lungs
Exhale acid (co2)
Kidneys
Excrete acid
- can save hco3 & h+ too
Volatile acid
- a gas excreted by lungs
Nonvolatile acids
Not gases that are excreted by kidneys
Handling of H+ and Hco3 by the kidneys
Urine = little hco3
Acid ph = 5-7
Kidneys regulate ph by
Reabsorbing hco3 (bicarbonate) @ proximal convoluted tubule
Secreting H+ @ distal involuted Tubule
Acidosis
Secrete more H+, Reabsorbing /making more Hco3
Alkalosis
Hold onto H+, don’t make/reabsorb all Hco3
