The Urinary System Flashcards
What is the main function of the kidney?
Kidneys filter blood and return clean blood back to the body.
Kidneys remove waste from the blood and extra fluid from your body.
Kidneys help maintain a healthy balance of water, salt and minerals in your body.
What hormones do the kidneys secrete.
The kidney secretes:
Renin-angiotensin - increases blood pressure
Erythropoietin- stimulates red blood cell production
Calcitral- keeps your bones strong can healthy, controls calcium levels
What is the overview of the kidney
Two kidneys that secrete urine
Two ureters that transport urine to the bladder
Urethra that transports urine externally
Adrenal glands that produce hormones
Describe the blood supply to the kidneys
renal arteries branch into segmental arteries
segmental arteries branch into interlobular arteries towards renal columns
The interlobular arteries arch along the border of renal pyramids and cortex as arcuate arteries
Numerous branches radiate towards the periphery (outside) of cortex - cortical radiate arteries
Numerous different afferent arterioles, one per nephron
Multiple small renal veins drain into single left and right renal veins
Where does the renal artery and renal veins deliver blood to
Renal artery - delivers blood to kidneys to be filtered
Renal veins - delivers filtered blood back to heart
What are nephrons
They are the functional unit of the kidneys
Where filtration takes place
Function of cortex
Blood enters through the cortex
What is the function of the renal medulla
The medulla also known as pyramids is where the filtration happens.
The medulla contains long nephrons
The renal medulla is composed of renal pyramids
What is the function of the calyx
The calyx (major and minor) are collecting ducts for urine that is filtered out of blood.
What is the ureter function
The two ureters are collecting ducts, they collect urine from the calyx and bring it down to the bladder.
It is retroperitoneal
What is the ureter continuous with ?
Renal pelvis
Structure of ureter
Composed of three layers
Peripheral protective fibrous tissue (Adventitia)
Middle muscle layer to propel urine
Internal longitudinal
External circular
External longitudinal (distal 1/3 only)
Inner protective mucosa
Transitional epithelium
Protects from urine
What is the ureter anterior and posterior to
Anterior to psoas muscle, over brim of pelvis
The ureter passes obliquely into posterior aspect of bladder - vesico uretic junction
(vui)
What does the peristalsis do
It helps gravity propel urine - 1-5 waves per minute
Describe the afferent and efferent arterioles in the nephrons
Efferent arterioles - takes blood away from the glomerulus
Afferent arterioles - takes blood to the glomerulus
What is the glomerulus
A bunch of arteries in the bowman’s capsule
20% of blood plasma in the glomerulus exits into the bowman’s capsule. It is now called filtrate
What is filtrate
Filtrate is filtered fluid. The 20% of blood plasma that leaves the glomerulus and enters the bowman’s capsule is called filtrate.
Talk about what blood goes into the bowman’s capsule and what stays
80% of blood plasma - white / red blood cells stay in blood vessels as they are too big.
Bigger proteins are too big to get filtered as well.
What happens in the proximal convoluted tubule?
H20 and nutrients (sugar and vitamins) get reabsorbed back into the blood stream and are diffused out of the pct.
What are the two parts of the nephron loop
The nephron loops consists of the descening limb ascending limb - it is also known as loop of Henley.
What happens in the descending limb of the nephron loop.
H2O diffuses out of the descending limb via osmosis
As the loop of Henley descends into the medulla, it becomes extremely salty.
Two reasons why
- Salt attracts water
- more sodium and chloride ions
Describe which parts of the nephron are in the cortex or medulla
The glomerulus, bowman’s capsule, pct, dct and start of collecting duct - minor calyx is in the cortex
The descending limb descends into the medulla
The ascending limb ascends into the cortex. The calyx descends into the medulla as it brings the urine down into the ureter.
What happens in the ascending limb of the nephron loop.
Active transport
Sodium ions and chlorine ions get pumped out via active transport making the medulla salty.
Na + and Cl-
Active transport takes up a lot of energy so a lot of energy is needed in the kidneys.
Which part of the nephron has an area that is impearmable to water.
The ascending limb has an area that is impearmable to water. Water cant leave or enter the ascending part of the loop of henle.
What happens in the distal convoluted tubule
Water can diffuse out - if your dehydrated, the dct and collecting duct will leak water into the salty medulla ( remember salt attracts water ) back into the blood stream.
This will only happpen if ADH is produced by pituitary gland.
What is anti diuretic hormone
Anti diuretic hormone makes you pee less and causes water leakage.
It is produced by pituitary gland.
If we are hydrated, the brain will stop the pituitary gland from producing adh - contents will leave the body via collecting duct.
What is function of the collecting duct
Lots of branches of collecting duct as as there are lots of nephrons filtering blood.
Collecting ducts contain urine and form the calyx which then connects to the ureter and then down to the bottom of the bladder.
What is the renal sinus?
The renal sinus contains the renal hilum
The opening of the renal sinus is called the renal hilus
It is the entrance of the kidney
What is the function of the hilum in the kidney
The hilum is a small depression in the middle part of the kidney. The renal artery and nerves enter the hilum and pass through the renal sinus.
The renal vein, lymphatic vessels and the ureter pass through renal sinus before leaving the kidney at the hilum
What is the Renal pelvis
It is subdivided into the major and minor calyces - small renal papillae project into minor calyces
Explain how the kidney is protected by structures surrounding it.
The kidneys are surrounded by the renal capsule
The renal capsule is an outer layer of connective tissue
The renal capsule is surrounded by adipose tissue - fat. This cushions and protects the kidneys.
A layer of connective tissue is called the renal fascia. This surrounds the adipose tissue and anchors the kidneys at the hilum and pass through the renal sinus.
Describe the structure of the urinary bladder
It is a hollow, muscular organ that lies in the pelvic cavity posterior to the symphysis pubis.
What is difference of males and females urinary bladder in terms of position
Males - anterior to the rectum
Females - anterior to the cervix and vagina and anterior and inferior to the uterus.
How does the urinary bladder volume increase?
Increases depending ion the amount of urine stored
Describe the wall of the urinary bladder
The wall is made up of 4 coats
- Inner mucous coat of transitional epithelium
- Submucosa coat
- Detrusor muscle - Thicker muscular cat made up of smooth muscle
- outer serous coat
What forces the urine out of the urinary bladder?
The contraction of the detractor muscle forces urine out of the urinary bladder.
The bit of the detrusor muscle that surrounds the neck of the bladder forms a internal urethral sphincter muscle
Describe the role of the raa system in regulating blood pressure
The raa system is a negative feedback loop so there are four stages.
The first stage is the stimulus. This is the change
There may be a sodium deficiency
There may be reduced blood pressure due to a haemorrhage
There may be reduced blood volume due to dehydration in the body - blood is made out of mostly water.
The second stage is the sensors - this is what decent the change
Chemoreceptors detect that there is a sodium deficiency, they can check how much dosing is passing by. Chemorecetos are found in the macula densa which is located in the distal convoluted tubule.
These chemreceptors send a signal to the baro receptors.
These baroreceptors are stretch receptors which are located in the juxtaglomerular cells in the afferent arterioles.
These cells can stretch to see how much blood there is and how much pressure there is.
The 3rd stage is the integration
This is where we produce something called angiotensin2
There are 3 organs involved in this
So first we the liver. The liver produces angiotensiogen and releases it. Angiotensiongen is an inactive hormone and has no effect. The word gen in angiotensoigen means that it isnt active but it will be active soon.
Then we have the kidneys which produce renin. This is an enzyme. This renin is produced by the juxtaglomerular cells in afferent arterioles. The enzyme renin reacts with angiotensinogen to produced angiotensin1. This is also an inactive hormone and has no effect. Then the lungs produce something called an angiotensin converting enzyme (ace). This enzyme reacts with angiotensin1 to produce angiotensin2 . This is an active hormone
This hormone does many things to regulate the blood and sodium levels.
- Angiotensin 2 enters the adrenal glands to produce aldosterone
- Angiotensin 2 enters the kidneys directly - works on pct
- Vasoconstriction
- Pituitary - ADH - dct and collecting duct.
