Guided Studies Flashcards
What are juxtoglomerular cells?
The juxtaglomerular cells (JG cells, or granular cells) are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth muscle cells mainly in the walls of the afferent arterioles, and some in the efferent arterioles, that deliver blood to the glomerulus.
What proportion of a healthy young man is water?
Know what proportion of a healthy young man is water
- 60%
Know what proportion of a healthy young woman is water
- 50%
Know the fluid compartments within the body and their approximate values
- Intracellular fluid (ICF) compartment (2/3 of water)
o Consists of cells - Extracellular fluid (ECF) compartment (remaining 1/3)
o Consists of the body’s internal environment, i.e. external to cells
o 2 main sub-compartments: Plasma and interstitial fluid. (Other compartments: lymph, CSF, humors of the eye, synovial fluid, serous fluid, GIT secretions)
State the difference between electrolytes and non-electrolytes:
- Electrolytes: Electrolytesare chemical compounds thatdodissociate into ions in water. Because ions are charged particles, they can conduct an electrical current–hence the nameelectrolyte.Typically, electrolytes include inorganic salts, both inorganic and organic acids and bases, and some proteins.
- Non-electrolytes: Non-electrolyteshave bonds (usually covalent bonds) that prevent them from dissociating in solution; therefore, no electrically charged species are created when nonelectrolytes dissolve in water. Most nonelectrolytes are organic molecules–glucose, lipids, creatinine, and urea, for example
Explain why electrolytes have a greater osmotic power than non-electrolytes:
Electrolytes have much greater osmotic power than nonelectrolytes because each electrolyte molecule dissociates into at least two ions.
State the MAJOR differences in composition between ICF and ECF
ICF contains
- Less Na+ and Cl-
- More K+ and phosphate
- Substantial quantities of soluble proteins
ECF contains
- More Na and Cl-
- Less K+
Explain the mechanisms and consequences of ADH release
Mechanism via osmoreceptors: Osmoreceptors of the hypothalamus sense the ECF solute concentration and trigger or inhibit ADH release from the posterior pituitary accordingly (Figure 26.6). A decrease in ECF osmolality inhibits ADH release and allows more water to be excreted in urine, restoring normal Na+levels in the blood. An increase in ECF osmolality stimulates ADH release both directly by stimulating the hypothalamic osmoreceptors and indirectly via the renin-angiotensin mechanism.
Mechanisms via baroreceptors: ADH secretion is also influenced bylargechanges in blood volume or blood pressure. Under these conditions, baroreceptors in the atria and various blood vessels sense a decrease in BP and reflexively trigger an increase in ADH secretion from the posterior pituitary.
Consequences: When ADH levels are high, aquaporins are inserted in the principal cell luminal membranes and nearly all of the filtered water is reabsorbed; a small volume of concentrated urine is excreted.
Difference between cystitis and kidney infection?
Cystitis: Infection of the bladder. Presents as frequency, urgency, dysuria, suprapubic discomfort, cloudy/red/pink urine. Symptoms settle quickly
Kidney infection: AKA pyelonephritis, infection of the parenchyma. Similar presentation as cystitis, also pain in renal angle and/or loin. Nausea, vomiting and diarrhoea as a sign of general upset. High fever and rigors as a sign of serious infection. Neutrophilia
What is honeymoon cystitis? And can Chlamydia cause cystitis?
Honeymoon cystitis: When cystitis follows sexual intercourse
Chlamydia and Gonorrhoea can present in a similar way to infection of the urethra. Hence are important when making a differential diagnosis as (1) infection may be asymptomatic in females and (2) untreated may lead to dysfunction and infertility.
When my mother got a second urine infection, why did the pharmacist suggest drinking cranberry juice?
Cranberry products have been shown to have a beneficial effect in preventing urinary recurrent infections in adult women.
Why does my wee brother, who recently had a urinary infection, have to go to hospital for
special tests while my older sister was treated by our family doctor?
Unlike adults, urinary tract infections in children are often associated with underlying renal tract abnormalities which can be associated with recurrent infection and scarring of the kidneys. So it is good clinical practice to refer them for further investigations to clarify matters.
What does “mid- stream” mean? Sounds like salmon fishing! Why is it important?
Mid-stream samples are used as they are the most reliable portion of the urine specimen: both the first and the last part of the urine sample can be contaminated with debris and matter.
Early specimen: From the urethra or the trigone of the bladder (the floor/base of bladder)
Late sample: prostate gland
Normal serum concentration of Mg2+?
0.75-0.95mmol/l
Distribution of Mg2+ in the body?
Muscle 27%
Soft tissue 19%
Matrix of bone 53%
Functions of Mg2+
Energy metabolism
Nucleic acid syntheses
Shipping ions across cell membranes
