Urinary System Flashcards
List the 4 key anatomical components in the urinary system
2 kidneys, 2 ureters, bladder, urethra
Which body cavity are the kidneys situated in?
The abdominal cavity, below the diaphragm and behind the stomach.
Which fluid do the kidneys filter?
The blood
The urinary system (and kidneys) are one of our main systems of elimination. True or false?
True
Where is urine formed?
In the kidneys
Describe the ureters
Muscular tubes that extend from the kidneys, down the back of the abdomen. They enter the posterior part of the bladder.
Which part of the bladder do the ureters enter?
The posterior (back) part of the bladder
Describe the bladder
A muscular chamber that acts as a reservoir to contain urine, before it is expelled via muscular contraction down the urethra.
Describe the differences between the ureters and the urethra
We have 2 ureters and 1 urethra
What is the difference between the male and female urethra?
The urethra is significantly shorter (around 5 x shorter) in women than in men.
Why are women far more susceptible to urinary tract infections than men?
Because their urethra is significantly shorter than in males. The urethra connects the bladder with the outside world, so if the urethra is very short, bacteria from the outside have a very short distance to travel to get in to the bladder and cause an infection.
List some functions of the urinary system
- Excretion of unwanted substances (waste)
- Maintainance of water & electrolyte balance
- pH regulation of body fluids (especially blood)
- Regulation of blood glucose levels
- Regulation of blood pressure, volume and osmolarity
- Production of hormones (erythropoietin & calcitriol)
- Regulation of erythrocyte production
Name 2 hormones produced in the kidneys
Erythropoietin (production of red blood cells) and calcitriol (the active form of vitamin D)
What does ‘osmolarity’ mean?
The concentration of a solution
What is calcitriol?
The active form of vitamin D
What is the role of calcitriol?
It helps to absorb calcium from our foods and move it into the blood.
What role do the kidneys play in the production of red blood cells?
They detect hypoxia (lack of oxygen in the blood) and release erythropoietin, a hormone which instructs the bone marrow to start creating more red blood cells.
(The more erythrocytes you have, the more capacity you have to transport oxygen around your body).
How do the kidneys help to regulate blood pressure?
- They help to excrete excess water from the blood.
2. They help to conserve water when we’re dehydrated
What happens to blood volume when we excrete excess water in our urine? What effect does this have on blood pressure?
Blood volume lowers, therefore blood pressure lowers.
List the 3 main types of metabolic wastes excreted by the kidneys.
What do they all have in common?
- Urea
- Uric acid
- Creatinine
They all contain Nitrogen and they all have some relationship to proteins
What is urea?
A metabolite / by-product of protein metabolism
What is Uric acid?
A metabolite / by-product of purine metabolism
What is creatinine?
An end/by-product of muscle metabolism of creatine phosphate
What do urea, uric acid and creatinine all have in common?
They are all metabolic wastes, they all contain nitrogen, they all have some relationship to proteins.
What are purines? What do they create when metabolised?
A type of protein found in shellfish, game, red meats, etc. They create uric acid.
In gout, which type of metabolic waste accumulates in joints, causing pain and inflammation?
Uric acid
Why can gout sometimes be traced back to kidney disease?
Because kidney disease often means that the kidneys are not removing/excreting uric acid (the main cause of gout) from the body as effectively as they should be.
List 4 things that the kidneys excrete in urine.
- Metabolic wastes (urea, uric acid, creatinine)
- Ions (particularly hydrogen)
- Toxins (including medications)
- Hormones
Why are the kidneys relevant when it comes to removing excess acid from the body?
They excrete excess hydrogen, which is acid forming.
How do the liver and kidneys work together to excrete toxins from the body?
The liver detoxifies the toxins and then the kidneys excrete them.
The body’s water balance is mainly controlled by which organs?
The kidneys
What is the minimum quantity of urine required to clear body waste each day?
500ml per day
What happens to waste products that are not excreted through the urine efficiently?
We start to reabsorb them (not good!)
Name a condition / pathology that disrupts blood volume and causes the patient to drink lots of water / be thirsty.
Diabetes Mellitus
What are electrolytes?
Charged atoms that are in solution
List the 3 most important electrolytes regulated by the kidneys
Sodium, Potassium, Hydrogen
Na+, K+, H+
When might the taking of electrolytes be useful?
When exercising / doing sport, or for recovery from diarrhoea.
Sodium always travels with….
where one goes, the other will follow
Water
What is a buffer?
A substance that helps to neutralise any acidity / regulate changes in pH.
Which buffer do the kidneys predominately produce?
Bicarbonate
What 2 steps can the kidneys take to reduce excess acidity in the blood?
- Excrete excess hydrogen ions (acid forming) in the urine.
2. Produce bicarbonate as an acidity buffer
Blood pH level must remain fairly constant between…
7.35 - 7.45 pH
Which 2 body organs primarily manage blood pH control, and how?
Lungs - excrete CO2
Kidneys - excrete H+ (hydrogen) into urine and produce the buffer HCO3- (bicarbonate)
Which 2 body fluids can reliably measure blood pH?
Urine and saliva
What is the effect of excess CO2 on the blood?
It makes it acidic
What activates the vitamin D precursor in the skin?
UV rays
Which organ converts inactive vitamin D into its active form?
The kidneys
Why do we need calcitriol?
To make sure we’re absorbing all of the calcium from our foods.
Calcitriol stimulates calcium and magnesium uptake from the GIT, and reduces calcium loss in the kidneys (stops them excreting calcium).
Name 2 pathologies that a deficiency in calcitriol can cause.
Osteomalacia & rickets
What is erythropoietin (EPO)?
A protein hormone, produces in the kidneys, that stimulates erythropoiesis in the red bone marrow.
In kidney failure, erythropoietin production can be inadequate. Which pathology could this lead to?
Anaemia
Erythropoietin is released by the _____ in response to _____
Kidneys, hypoxia
How are erythropoietin levels measured?
Via blood test (EPO test)
What is the renal threshold for glucose?
9 mmol/L
What is a normal blood glucose level?
4-7 mol/L
What is the problem with high blood glucose?
It is damaging to blood vessels
Which pathology might be indicated by hyperglycaemia / glucose in the urine?
Diabetes Mellitus
How can the kidneys help us if we’re in a state of hypoglycaemia?
They are able to make glucose from the amino acid glutamine to help elevate blood sugar levels when needed.
From which amino acid can the kidneys make glucose?
Glutamine
What is gluconeogenesis?
The formation / production of glucose.
Which enzyme do the kidneys secrete to help regulate blood pressure?
Renin
An increase in the enzyme renin, has what effect on blood pressure?
Increased renin = increased blood pressure
What does retro-peritoneal mean?
Behind the peritoneum
What shape are the kidneys?
Bean-shaped
Which ribs partially protect the kidneys?
T11, T12
Why is the right kidney lower than the left?
Because the liver occupies considerable space on the right, superior to the kidney.
Name the 2 layers within the kidney
Outer cortex, inner medulla
Each kidney sits in the posterior abdomen and is surrounded by 3 layers (deep, middle and superficial layers). Name these layers.
- Renal capsule
- Adipose tissue
- Renal fascia
What is the renal capsule?
A smooth, transparent sheet of connective tissue, which maintains the kidney shape.
What is the role of the adipose capsule around the kidney?
Fatty tissue, providing physical protection and support.
What is renal fascia?
A thin layer of connective tissue that anchors the kidneys to surrounding structures, against the abdominal wall.
Where would you find the renal pyramids? What shape are they?
Within the renal medulla in the kidney.
Cone-shaped
The apex of each renal pyramid is called ______?
Renal papilla
What is the significance of the renal papilla?
It is the location in the kidney where the urine passed through into the minor and major calyces
What are the functional units of the kidney called?
Nephrons
Urine formed by the kidney nephron drains into the ________ and ________ ___________
Minor and major calyces
How many nephrons do we have per kidney?
Around 1 million
What is significant about the kidney nephrons?
The nephrons are where urine is created