The Urinary System Flashcards
The urinary system consists of those organs that function to?
- Produce Urine
2. Eliminate it from the body
What are the organs that make up the urinary system?
- Two kidneys
- Two ureters
- One bladder
- One urethra
Also male and female genitalin
The urinary tract is the most important mechanism for maintaining what?
A constant internal environment for the body essential for life.
What is the composition of blood determined by?
Not by what the mouth ingests but by what the kidney keeps
True or false. The right kidney is usually slightly larger than the left kidney.
False - the left is slightly larger.
Where are the kidney’s located?
Either side of the spinal column just above the waist line (below diaphragm)
What normally encases each kidney and what does it do?
A heavy cushion of fat encases each kidney and holds it in position.
What anchors the kidneys to surrounding structures and helps maintain normal position?
Connective tissue
What brings blood to each kidney?
A large branch of abdominal artery called the renal artery.
What are the microscopic structures in the kidneys called?
Nephrons; about 1.25 million per kidney make up the bulk of kidney substances (this is where the kidney’s work is actually done.)
What are the three main parts of nephrons?
- Glomerulus
- Tubule
- Bowmans capsule
What are kidneys?
High vascular organs
How much blood flows through the kidney every minute?
1200 ml
Kidneys process the blood before doing what?
Returning it to general circulation.
What is a nephron shaped like?
A tiny funnel with an unusual stem.
What are the functions of the kidneys?
- To produce and secrete urine.
- Fluid and electrolyte balance
- Acid-base balance (proper P.H.)
Why is the kidney’s function of producing and secreting urine so important?
It is a life preserving function because the stability of the body’s internal environment depends on it.
How do the kidney’s maintain fluid and electrolyte balance?
By varying the amounts of water and electrolytes leaving the blood in urine.
How do kidneys maintain the bodies acid base balance?
- Acids are constantly being produced by cell metabolism.
- Nitrogenous wastes from protein metabolism (notably urea) exit via kidney.
- Certain foods can cause acids or bases to be formed in the body.
- Kidneys balance these.
When kidneys fail, what things are not held to their normal concentrations?
- Sodium
- Potassium
- Chloride
- ^ These 3 are electrolytes - Nitrogenous wastes (e.g. urea) from protein metabolism.
What happens if the body’s internal environment is not returned to normal during kidney failure?
Inevitable death results
What happens in the glomerulus?
Filtration takes place in the glomerulus.
What is the functional part of the kidney?
The nephron.
What is the bowman’s capsule?
Cup shaped part of the nephron.
How does the nephron form urine?
They form urine by means of three processes:
- Filtration
- Reabsorption
- Secretion
Explain the filtration process in the nephron?
Water, electrolytes and nutrients move from the blood in the glomerulus to bowman’s capsule and eventually move into the kidney tubules. Blood is under high pressure in the glomerulus and these substances pass through the walls of the blood vessels into tubulars. Blood cells are too large to pass through the vessel walls.
Explain reabsorption in the kidneys (nephron)
A major portion of water and electrolytes and normally all cell nutrients move from the tubules back into the blood.
Explain secretion in the kidneys (nephron)
Other substances like potassium and hydrogen move from the blood and into the distal tubules. What remains in the tubules after the 3 processes is urine and will be excreted by the other parts of the urinary system.
What are some factors that regulate the amount of urine produced?
The volume of urine produced is regulated, not by changes in the amount of water filtered from the glomerulus, but by changes in the amount reabsorbed from the distal and collecting tubules.
What factors regulate H2O reabsorption from the tubules?
- ADH (Antidiuretic hormone from posterior pituitary)
- Aldosterone - (adrenal) (Both decreases urine output, they increase water reabsorption in the distal and collecting tubules)
What is the ureter?
Ureters are tubes through which the urine flows from the kidneys to the bladder. They extend from kidneys to posterior surface of bladder.
How does urine travel through the ureter to the bladder?
As urine is secreted it drops out of collecting tubules into the urethras and eventually down to the bladder.
What is the function of the ureters?
- Ureters collect urine as it forms and drains it into the bladder.
- Waves of involuntary muscle contraction (1 - 5 per minute) force urine down to ureters and into the bladder.
What is a common disorder of the kidneys?
- Stones known as renal calculi sometimes develop within the kidney (kidney stones)
- Urine may wash them into the ureter, where they may cause extreme pain if large enough to distend its walls.
What is the bladder?
The bladder is an elastic sack that stores the urine until the quantity stimulates the nerves that signal the need to urinate.
What forms the walls of the bladder?
Smooth muscle fibres
What forms the lining of the bladder?
Mucous membrane
How many openings are in the bladder?
There are 3 openings
- 2 form ureter
- 1 into urethra
What are the functions of the bladder?
- Reservoir for urine before it leaves the body
- Aided by urethra, expels urine from the body.
Explain the mechanism for voiding urine.
a) Starts with voluntary relaxation of external sphincter muscle of bladder.
b) In rapid succession, reflex contraction of smooth muscle fibres along urethra, and then of the detrusor muscle follow.
c) This combination squeezes urine from the bladder.
Voluntary control of voiding is learned. For infants it is a reflex action.
What is responsible for alerting the body to the need to pass urine and what does it do?
The nervous system is responsible for alerting the body to the need to pass urine and activates the release of urine from the bladder when it is full.
What is the urethra?
A small tube leading from floor of bladder to exterior
How long is the urethra in males and females respectively?
Female - 1 - 1 1/2 inches
Male - Urethra follows tortuous course of approximately 8 inches - immediately below bladder, it passes through the centre of the prostate gland, then through penis.
What are the functions of the urethra?
- Passageway from the bladder to the outside of the body.
- Male urethra is terminal portion of reproductive tract (passageway for semen)
- In female, urethra serves only urinary tract.
Explain the chemical composition of urine.
Urine is 95% water - in which several kinds of substances are dissolved.
What is urine?
Urine is water/waste produced in the kidneys and released from the bladder.
What substances are dissolved in urine?
- Nitrogenous wastes from protein metabolism such as urea (most abundant) in urine and ammonia.
- Electrolytes - mainly sodium, potassium, ammonium, chloride, phosphate and sulphate
- Toxins
- Pigments - yellow from bile pigments
- Hormones - pregnancy is determined by certain hormones in urine
- Various abnormal constituents sometimes found in urine - glucose and blood most common.
Why is it important to “force fluids” on someone suffering from an infectious disease?
During disease, bacterial poisons leave the body in urine; an important reason for “forcing fluid” on patients suffering with infectious disease, so as to dilute the toxins that might damage the kidney cells.
What are the excretory systems of the body?
- Urinary system
- Intergumentary system
- Respiratory system
- Digestive System
What are the excretory organs in the body?
- Kidneys
- Skin (sweat glands)
- Lungs
- Intestine (large)
What substances do the kidneys excrete?
- Nitrogenous wastes (from protein metabolism e.g urea)
- Toxins (from bacteria)
- Hormones
- Water (from ingested and from metabolism)
- Pigments
- Electrolytes
What substances does the skin excrete?
- Water
- Electrolytes
- Small amounts of nitrogenous wastes
What substances fo the lungs excrete?
- Carbon dioxide
- Water
What substances do the large intestines excrete?
- Wastes from digestion (cellulose, connective tissue, etc)
- Some metabolic wastes (for example, bile pigments; also salts of calcium and other heavy metals)
