The Renal System Flashcards
Renal system functions? (5)
- Regulation of water, inorganic ion balance, acid balance
- Removes metabolic waste from blood eg urea, creatinine
- Removes foreign chemicals
- Gluconeogenesis
- Production of hormones/enzymes eg EPO, Renin
Structure of the Kidney?
Renal Pelvis
Ureter
Renal cortex and medulla
Nephron
Structure of Nephron?
Renal corpuscle which contains glomerulus
Renal tubule which forms a cup around the glomerulus called the Bowman’s Capsule
What are Juxtaglomerular cells?
Mechanoreceptors - detect blood pressure in the afferent arterioles
What are Macula densa cells?
Chemoreceptros - which detect a change in NaCl
3 Main renal processes?
Glomerular filtration
Tubular secretion
Tubular reabsorption
What is GFR and the factors effecting it?
Amount of blood filtered by glomeruli each minute
- Capillary permeability
- Surface area - size of capillary bed
- Hydrostatic pressure driving fluid out of capillaries
- Osmotic forces within the capillaries which oppose exit
What is Tubular secretion?
Substances such as hydrogen ions, potassium, organic anions moving from peritubular capillaries into tubular lumen
What is tubular secretion important for?
- Disposing of drugs and drugs metabolites
- Eliminating substances or end products that have been reabsorbed by passive processes eg urea
- Removing excess K+
- Controlling blood pH
What is Renal clearance ?
The amount of a substance filtered per minute, divided
by its plasma concentration
What is filtration fraction?
The proportion of the plasma that enters the
kidneys that is subsequently filtered at the glomerulus and passes into
the renal tubules
Process of Sodium reabsorption?
- Active transport out of cells into interstitial fluid.
- Transport achieved by Na+/K+-ATPase pump
- Keeps intracellular conc. of Na+ low to allow
‘downhill’ movement of Na+ from lumen - Mechanism of Na+ movement across luminal
membrane varies between tubule segments,
whereas always via Na+/K+-ATPase pump for
basolateral membrane - Proximal tubule (a): co-transport / counter-
transport of organic molecules (glucose, aa) - Cortical collecting ducts (b): via Na+ channels
Three factors determining the rate of tubular Na+ reabsorption?
1) Aldosterone (most major)
2) Atrial Natriuretic Peptide (ANP)
3) Local effect of blood pressure on the tubules
Renal function during exercise?
Renal blood flow decreases as soon as exercise starts, as intensity increases blood flow decreases.
What is the role of baroreceptors ?
Detect blood pressure
Factors affecting steady state exercise?
The delivery of adequate oxygen to the exercising muscles
The ability of the cells to utilise this oxygen in the aerobic process of
energy metabolism
The ability to eliminate heat.
Why are humans endotherms?
They generate their own body heat and do not rely on the energy of sunlight etc.
How much energy is lost and kept?
75-80% lost through heat and the remainder is kept for external work
Why are humans known as homeotherms?
They maintain their body temperature within a narrow limit, eventhough the temperature fluctuates throughout the day
What are the mechanisms for heat conservation?
Shivering
Vasoconstriction
Muscular activity
non-shivering thermogenesis
What is the mechanisms for heat loss?
Vasodilation
Sweating
What is hyperthermia and what are signs?
When core body temperature becomes dangerously high, signs being dizziness, disorientation, dry skin etc
Effects of acclimatization?
Sweat more and sooner
Increased blood flow to skin
Have more dilute sweat (conserve electrolytes)
Increased blood volume and stroke volume
Have a lower body core temperature, heart rate, glycogen use and, thus, fatigue
overall improvement of thermoregulation of body temp
