Blood and urine Flashcards
blood
- consists of plasma and various formed elements, including red blood cells, white blood cells, and platelets. - Plasma makes up about 55% of blood volume and contains water, electrolytes (such as sodium and potassium), proteins (including albumin and antibodies), hormones, nutrients (glucose, amino acids, lipids), waste products (urea, creatinine), and gases (oxygen, carbon dioxide).
- Red blood cells are responsible for oxygen transport, while white blood cells are part of the immune system. Platelets are involved in blood clotting.
urine
Urine is a liquid waste product that is produced by the kidneys and excreted through the urinary system.
- It primarily contains metabolic waste products, excess salts (sodium, potassium), excess water, and small amounts of urea, creatinine, uric acid, ammonia, and other substances.
1 Filtration
Blood enters the kidneys through the renal arteries and is filtered in tiny structures called nephrons.
- During filtration, small molecules and waste products, such as urea and creatinine, pass from the blood in the glomerulus (a cluster of capillaries) into the renal tubules, forming a fluid called filtrate.
2 Reabsorption
The renal tubules reabsorb essential substances, such as water, glucose, amino acids, and electrolytes, back into the bloodstream from the filtrate.
- This process ensures that vital substances are conserved and not lost in the urine
3 Secretion
The kidneys can also secrete certain substances (e.g., hydrogen ions, potassium ions) into the renal tubules from the blood.
- Secretion helps regulate the body’s acid-base balance and electrolyte concentrations
4 Selective Processes
The kidney’s selective processes determine which substances are retained in the blood and which are eliminated in the urine.
- The composition of urine is adjusted based on the body’s needs and conditions. For example, during dehydration, the kidneys conserve water, resulting in concentrated urine.
