PBL 9 Flashcards
How big are the kidneys?
Approximately 11cm long
Where are the kidneys located?
On the posterior abdominal wall, either side of the vertebral column, approximately at level T12 to L3.
Why does the right kidney lie slightly lower than the left?
The large right lobe of the liver restricts it superiorly.
What is the shape of the kidney?
The lateral margin of each kidney is smoothly convex, while the medial margin is concave, and further indented in the middle at the hilum.
What is the function of the hilum in the kidneys?
The renal vessels and the renal pelvis enter and exit the kidney.
What are the three layers of supportive tissue that cover each kidney?
The renal capsule, the adipose capsule and the renal fascia
What is the renal capsule?
A thin fibrous sac made of dense, irregular connective tissue that adheres closely to the kidney.
What is the function of the renal capsule?
It maintains the shape of the kidney and protects it from trauma and infection
What is the adipose capsule?
a layer of fat that surrounds the renal capsule of the kidney
What is the function of the adipose capsule?
It protects and supports the kidney
What is the renal fascia?
A layer of tissue that passes in front of and behind both kidneys. It is made of dense irregular connective tissue and attaches to the renal capsule by strings of fibres.
What is the function of the renal fascia?
It provides anchorage of the kidneys to surrounding structures
What is the renal cortex?
the outer 1 cm of the kidney that contains the arcuate and interlobular arteries and veins and cortical nephrons (except for parts of the loop of henle and the collecting tubules which descend into the medulla.
What function occurs in the renal cortex?
Ultra filtration
What are the renal columns?
Extensions of the cortex that project in between the pyramids of the medulla and help anchor the cortex.
What is the renal medulla?
The inner section of the kidney that lies deep to the cortex and contains the renal pyramid. The medulla appears striated as it contains the striated as it contains the tubular systems of the juxtamedullary nephrons, as parts of the loop of Henle and collecting tubules of the cortical nephrons
What are the renal calyces?
Renal pyramids drain into minor and major calyces which in turn empty into the renal pelvis, and ultimately, the ureter
What are the renal pyramids?
Cone shaped structures that terminate medially by protruding into the minor calyces. They appear striated because they are packed with bundles of nephron loops and collecting tubules, plus associated capillaries.
What is the renal papilla?
Where the tips of the pyramids protrude into the minor calyces. Here all the urine from the collecting tubules into the minor calyces.
What are minor calyces?
Cup like projections that surround the papilla of each pyramid. Several minor calyces converge to for a major calyce.
What are major calyces?
There are two or three in each kidney. They join to form the renal pelvis
what is the renal pelvis?
A single funnel shaped structure located centrally at the hilum of the kidney. it drains into the ureter
Outline the flow of urine?
Renal pyramid—papilla—minor calyces—major calyces—renal pelvis—ureter
What supplies blood to the kidneys?
Renal arteries arising directly from the abdominal aorta .
How much of the blood pumped out of the heart do the kidneys receive?
Since the kidneys are so important in the regulation of blood composition they receive roughly 20%
Where does the renal artery go?
It passes laterally from the abdominal aorta to reach the hilum of the kidney before branching into segmental arteries
Where do the segmental arteries go?
They branch from the renal artery and split into interlobar arteries
Where do the interlobar arteries go?
Pass through the renal columns
Where do the arcuate arteries go?
Leave the interlobar arteries at right angles to branch over the outer surface of the pyramid, forming an arterial anastamosis
How many renal pyramids are there?
8-10
What is an arterial anastomosis?
A connection between two arteries
Where do the interlobular arteries go?
They branch from the arcuate arteries to supply the cortex
What are the interlobular arteries also known as?
cortical radiate arteries
Outline the flow of blood into the kidneys?
Renal artery—segmental arteries—interlobar arteries—arcuate arteries—interlobular arteries—afferent arterioles
What are the afferent arterioles?
Each nephron receives one arteriole,which then divides again to form a plexus of capillaries of capillaries around the nephron
Outline how blood leaves the kidneys?
Efferent arterioles—arcuate veins—interlobar veins—renal vein
How big is the prostate?
Roughly 3cm in diameter
Where is the prostate situated?
Underneath the bladder, and it surrounds the beginning of the urethra
What travels through the prostate?
The prostatic urethra and ejaculatory ducts and open into the prostatic urethra
What is the prostate composed of?
Tubular alveolar glands supported by stromal connective tissue containing thick sheets of smooth muscle.
What are the functions of prostatic fluid?
- to aid sperm mobility
- aiding viability of sperm
- protects sperm against the acidic vaginal secretions
How many nephrons does each kidney have?
There is about 1 million in each kidney
What are nephrons?
The functional unit of the urinary system
What do nephrons consist of?
an intricate system of tubules surrounded by blood vessels.
What are the key functions of the kidneys?
Osmoregulation and removal of waste from the blood
What part of the nephron is found in the cortex?
The renal corpuscle
What is the renal corpuscle?
A tubular capsule wrapped around a tight network of capillaries
What comes after the renal corpuscle?
the renal tubule
What is the function of the renal tubule?
It connects the tubular capsule of the renal corpuscle to the collecting ducts that are responsible for gathering up the urine from several different nephrons
what are the segments of the renal tubule?
- proximal convoluted tubule (PCT)
- Loop of Henle
- Distal convoluted tubule (DCT)
What are the two types of nephrons?
cortical and juxtamedullary. Approximately 85% are cortical and 15% are juxtamedullary
What distinguishes between the two types of nephrons?
cortical nephrons have short loops of Henle whereas juxtamedullary nephrons have long loops of Henle which extend into the medulla
What is the glomerulus?
A compact network of capillaries
What is the glomerular capsule?
Also known as bowmans capsule, it surrounds the glomerulus
What happens between the glomerulus and the glomerular capsule?
Filtration of the blood
What is produced by the filtration of blood?
Glomerular filtrate
Where does the glomerular filtrate move to after its filtered?
It then enters the renal tubules for further processing before it can be called urine
What type of cells line the glomerulus?
The wall of the glomerulus consists of one layer of specialized epithelial cells which have many holes
What are the holes in the wall of the glomerulus called?
fenestrations
What are the two layers of the glomerular capsule?
The visceral and parietal layer
What is the visceral layer?
the innermost layer composed of highly specialised cells called podocytes
What is the parietal layers?
The outermost layer which forms the outer wall of the capsule
What is the gap in between the two layers of the glomerular capsule?
The capsular space. Once fluid has exited the glomerulus, it enters this space prior to moving into the PCT
Where does the fluid go after it has left the renal corpuscle?
It enters the renal tubule, which is divided into three main sections
What are the three main sections that the renal tubule is divided into?
The PCT, the loop of Henle and the SCT
Where is the PCT located?
The renal cortex.
What happens in the PCT?
A large proportion of solute and water reabsorption
Where is the Loop of Henle located?
Begins in the renal cortex and extends into the renal medulla before turning 180 degrees and re-entering the renal cortex
What happens in the Loop of Henle?
Water and some solute reabsorption, Active and passive reabsorption of sodium and water, Passive ion reabsorption. Impermeable to water. Significant quantities of Na+, K+, and Cl- are reabsorbed.
What does the DCT do?
Links the loop of Henle with the collecting ducts
What happens in the DCT?
Reabsorption of water, Na+, Cl-, and Ca2+ (early) Reabsorption of Na+, HCO3-, urea, and the facultative reabsorption of water. The secretion of K+ and H+. (late)
Where does the fluid go after the DCT?
The Collecting ducts
What are the collecting ducts?
Continuous with the DCT and function to drain the renal tubules
What happens in glomerular filtration?
blood flows from the afferent arteriole into the glomerulus, where pressure forces fluids and specific solutes to leave the blood and enter the glomerular capsule
What type of molecules are filtered?
Only small molecules travel with the fluid into the glomerular capsule to become part of the glomerular filtrate
What happens to molecules that remain in the blood?
Cells, and larger molecules with a diameter greater than 7 nm are prevented from entering the glomerular capsule by the filtration membrane, and are thus retained within the circulatory system and subsequently enter the efferent arteriole.
What are the two main categories that kidney dysfunction can be divided into?
Acute Kidney Injury (AKI)
Chronic Kidney Disease (CKD)
What is AKI?
An abrupt loss of kidney function within a few days
What is CKD?
A progressive loss of function of more and more nephrons that gradually decrease kidney function
What are the main categories of the causes of AKI?
Prerenal AKI
Intrarenal AKI
Postrenal AKI
What is Prerenal AKI?
Results from decreased blood supply to the kidneys. Reflects an abnormality originating outside the kidneys
What is Intrarenal AKI?
Results from abnormalities within the kidney itself including those that affect the blood vessels, glomeruli, or tubules
What is postrenal AKI?
results from the obstruction of the urinary collecting system anywhere from the calyces to the outflow of the bladder
When do clinical symptoms of CKD usually start?
When the number of functioning nephrons falls below 70-75% below normal
What are some possible causes of CKD?
Metabolic disorders, Hypertension, Renal vascular disorders, Immunological disorders, Infection, Primary tubular disorders, Urinary tract obstruction and congenital disorders
What is BPH
Benign prostatic hyperplasia, or, enlargement of the prostatic gland
What symptoms can this cause?
- Frequent or urgent need to urinate
- Increased frequency f urination at night (nocturia)
- Difficulty starting urination
- Weak urine stream or a stream that stops and starts
- Inability to completely empty the bladder
What cells undergo hyperplasia in BPH?
Glandular epithelium and the stromal cells (including muscle fibres)
What are possible causes of BPH (theories)
- Hormonal causes (different proportions of oestrogen to testosterone)
- DHT (dihydrotestosterone) (a male hormone that plays a role in prostate development and growth
- Ageing
What are risk factors of BPH?
Ageing, Family history, obesity, lack of physical activity and ED
What are the conditions for a screening programme?
- The condition should be an important problem for the individual and the community
- There should be an accepted treatment for patients with the disease
- Facilities for diagnosis and treatment should be available
- There should be a recognisable latent or early symptomatic stage
- There should be a suitable test or examination
- The test should be acceptable to the population
- The natural history of the condition, including development from latent to declared disease, should be adequately understood
- There should be an agreed policy on whom to treat as patients
- The cost of the case finding programme should be economically balanced in relation to expenditure on medical care as a whole
- Case finding should be a continuing process
- There should be quality assurance, with mechanisms to minimise potential risks of screening.
- The programme should ensure informed choice, confidentiality and respect for autonomy.
- The programme should promote equity and access to screening for the entire target population.
- The overall benefits of screening should outweigh the harm.
What is screened for in pregnant women?
infectious diseases, downs syndrome, pataus syndrome and Edwards syndrome, sickle cell diseases and physical abnormalities
What is screened for in new born babies?
physical examination, hearing test, blood spot test
What are examples of other screening programmes?
Diabetic eye screening, Cervical screening, breast screening, bowel cancer screening, AAA screening
Is there screening for prostate cancer?
No because PSA tests are unreliable and can give fals positive/ false negative results.
