Week 11 - Genitourinary System Flashcards
what is screening
A test offered to an asymptomatic person to detect those who have a high probability of having a disease
Not a diagnostic procedure (screening does not diagnose) – those with a positive test need further investigation
important requirements 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 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
describe a cervical smear test
Carried out at the GP surgery/sexual health centre
A brush is used to remove cells from the cervix
these are transferred to a pot of preservative
this is then tested for HPV - also cytology test if positive
designed to check cells from cervix for any changes
what is HPV
human papilloma virus
very common and is normally asymptomatic - most people clear the infection themselves
high risk HPV can cause changes in cells which can progress to cancer in some people
risk factors for cervical cancer
HPV
smoking
poor immune function eg. immunosuppression
multiple sexual partners
how does HPV invade the body
enters cervical epithelia at the transformation zone
Micro abrasions or epithelial trauma exposes basement membrane of cervix allowing virus to enter into replicating cells
HPV replicates in maturing squamous cells producing koilocytes
what does HPV do once in the body
low risk HPV tend to result in free viral DNA within the cell
high risk subtypes incorporate their DNA into that of the host cell
viral E6 and E7 proteins reactivate the cell cycle in cells that are not normally proliferating - they:
Bind to RB, which results in promoting the cell cycle
Bind to p53 disrupting cell death and prolonging the life of the cell
Induce centrosome duplication and genomic instability
Upregulate telomerase preventing replicative senescence
precursor lesions for cervical cancer
CIN and CGIN
CIN is divided into CIN1, CIN2 and CIN3
main purpose of cervical screening is to detect 2 & 3
CIN1 can resolve without treatment
describe cervical cytology
Cells from pot are dispersed and put on a slide in a thin layer – looked at through microscope
The cells from the transformation zone are spread out
Abnormal cells have enlarged, irregularly shaped nuclei - This is called dyskaryosis and is graded as mild (CIN1), moderate (CIN2) or severe (CIN3) depending on the size of the nucleus
These roughly equate to CIN1, CIN2 and CIN3 on histology specimens, but a biopsy is needed to confirm the degree of abnormality eg mild might not actually be CIN1
what is a colposcopy
place that does the diagnostic work on treatment required
outpatient clinic usually in a hospital
Examination of the cervix using a specialist microscope
Acetic acid is applied to highlight any abnormalities
Patients can have biopsies taken and treatments for abnormalities detected
breast screening process
Women 50-70 are invited for mammogram every 3 years - 2 x-rays taken of each breast
Those with abnormal or unsatisfactory results are seen at specialist clinic for triple assessment:
Examination
Radiology – repeated mammogram or ultrasound
Biopsy
bowel screening process
Aim is to detect precancerous changes and early cancers
Men and women aged 50-74 are invited to participate every 2 years
A faecal immunochemical test (FIT) is sent in the post for completing at home
One sample of stool is collected and returned in a pre-paid envelope - This is tested for haemoglobin – most bowel cancers cause bleeding which is visible in stool
Results are sent to the patient within 2 weeks
If the level of haemoglobin is above 80ugHb/g faeces, patients are referred for colonoscopy
Bowel polyps can be detected
problems that can occur if homeostasis is not maintained
haemorrhage
Unusual eating or drinking behaviour.
Severe dehydration, rapid fluid loss from gut (cholera etc) or after burns etc.
Unintended consequences of drug actions
(eg diuretics like Lasix can cause potassium depletion)
recommended uk salt intake
should eat no more than 6g of salt/day. Many adults exceed this
typical renal blood flow
625ml/100g/min
describe the two types of nephron
Superficial – have short loops that dives into medulla
Juxta-medullary – longer loops
Water reabsorption is more effective in the longer juxta-medullary nephrons
parts of a nephron
renal corpuscle (glomerulus and bowman's capsule) renal tubules (proximal convoluted tubule, loop of henle and distal convoluted tube) collecting duct (different origin so sometimes is said it is not part of nephron)
describe the cortex of a kidney
the body/supporting tissue
Contains glomeruli, bowman’s capsule and convoluted tubules
describe the medulla of a kidney
where most filtering happens
organised into renal pyramids
renal hilum components
renal vein
renal nerve
renal artery
main blood supply to kidney
renal artery which arises from the abdominal aorta
which renal artery is longer
right renal artery is longer as it has to pass behind the IVC to reach the right kidney
normal glomerular filtration rate
90-140ml/min
describe glomerulus ultrafiltration
force of hydrostatic pressure in glomerulus pushes out water and small molecules through slits between podocytes
filtrate is passed into bowman’s capsule
describe reabsorption
reabsorbtion mainly in PCT
complete reabsorption of glucose and amino acids
water and solutes driven through epithelial cells of tubule wall and are taken up by peritubular capillaries
Na+ reabsorption is important as it creates osmotic pressure that drives water and an electrical gradient that drives negative ions out into capillaries
describe the loop of henle
main function is to create and maintain an osmolarity gradient in the medulla that enables the collecting duct to concentrate urine
descending limb is thinner - highly permeable to water so water leaves by osmosis making filtrate more concentrated - some Na+ loss
thicker ascending limb actively pumps out Na+ making medulla salty - no water loss here
absorption and secretion in DCT
absorbs ions including sodium, chloride and calcium but is impermeable to water
aldosterone and parathyroid hormone control the process - PH causes more calcium channels to be inserted, increasing Ca absorption
similar structure and function to PCT but it does less
describe secretion
active pumping into tubules
secretes molecules out of the blood and into the urine
pumping rates controlled by hormones – aldosterone can adjust rate of N+ and K+ secretion
describe collecting duct function
Main function is to concentrate urine and preserve water – this is made possible by the osmolarity gradient generated by loop of henle
As collecting duct descends deeper into the medulla it gets saltier and the filtrate loses water
Antidiuretic hormone (ADH) controls amount of water that is reabsorbed by controlling amount of aquaporin channels (duct permeability)
When dehydrated – more water is reabsorbed back to blood and excreted urine is more concentrated
Collecting duct cells are permeable to water, then water moves out of the duct to concentrate filtrate to form urine
max and min urine output
max is ~20ml/min
min is ~1ml/min
describe what happens in the collecting ducts when excess water is consumed
plasma osmolarity falls
Hypothalamus secretes less ADH/AVP
Collecting Duct walls loose permeability to water
Dilute urine is produced
describe the renin/angiotensin/aldosterone system
if formation of glomerular filtrate is reduced, the renin/angiotensin/aldosterone system reads the reduction in filtration as a reduction in bp
If juxtaglomerular apparatus detects low Na+ in distal tubule it reads this as hypo-filtration and so low bp
Hypo-filtration initiates secretion of Renin by the Juxtaglomerular apparatus
Renin splits Angiotensinogen to make Angiotensin I which is converted to Angiotensin II, a powerful vasoconstrictor.
This system regulates renal blood flow and glomerular filtration rate
function of aldosterone
aldosterone increases when electrolyte concentrations fall
aldosterone increases reabsorption of Na+ and Cl- ions from Loop, Distal Tubule and Duct cells. It also ↑ K+ secretion
when electrolyte reabsorption increases, water reabsorption also increases
describe the structure of the bladder
bladder wall is smooth muscle called detrusor - SM allows large volume changes
bladder neck is a triangular region of smooth muscle - internal urinary sphincter is here
ureter function
transports urine from kidney to bladder
there are two - one from each kidney
describe bladder filling
the bladder fills when sphincter pressures or urethra pressures > vesicle pressures - No flow out
Bladder empties when vesicle pressures > sphincter pressures or urethra pressures - Fluid pushes past sphincter to escape
describe how a catheter works
- Place one opening in the bladder to allow direct filling and measure bladder pressure
- Inflate balloon to close off urethra
- Position second opening in the urethra to measure the sphincter pressure
- Then fill the bladder and record the pressure to establish bladder compliance.
- As bladder fills watch for signs of bladder wall contraction and sphincter contraction
describe the difference between a sphincter urethrae in a male and female
in males - very strong band of skeletal muscle sitting around the urethra that is able to deliver high pressures
females have a weaker external sphincter with less skeletal muscle and it has the potential for damage during natural childbirth
what is the urethra
a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males
describe the pressure and volume changes in the storage phase
- Early filling phase, low pressure in bladder, bladder wall and ext sphincter relaxed, both sphincters have low pressure but higher than in bladder – smooth muscle stretches to accommodate extra volume
- No flow in urethra: urethral pressure > bladder pressure
- Sensations develop, then sphincter contracts to maintain continence – bladder keeps filling and there is a second sensation which is the first urge to micturate
describe the pressure and volume changes in the voiding phase
- ‘Urge’ sensation then ‘Voluntary voiding’ (VV)
- Bladder contracts,
urethra and sphincters relax - bladder pressure increases - Flow in urethra: bladder pressure > urethral pressure. - ‘Voluntary’ stop flow - sphincters can stop the flow, bladder wall continues to contract so pressure keeps rising - then a 2nd voiding phase which is accompanied by a drop in sphincter activities and a later rise in bladder pressure
describe the innervation to the bladder and sphincters
Sympathetic: from L1, L2 – go through autonomic ganglia and fibres continue to bladder wall and internal sphincter - hypogastric nerve
Parasympathetic: from S2, S3 and S4 – fibres go through a different route but still go to Bladder wall - pelvic nerve
Somatic: from S2, S3 and S4 - Sensory and motor fibres to external sphincter - pudendal nerve
- Sympathetic NS responsible for urine retention
- Parasympathetic NS is responsible for voiding phase (peeing)
describe the positioning of the afferent and efferent nerves at the bladder
Afferents:
- Sensory fibres sense the stretch of the bladder wall - These afferents run in the hypogastric nerve and enter cord in the upper lumbar roots.
- Other sensors near the urethra sense flow of urine (not shown below)
- Skeletal muscle sensors in the external sphincter
Efferents:
- Parasympathetic to detrusor
- Sympathetic to detrusor and internal sphincter
- Somatic to external sphincter
describe the role of sympathetic and parasympathetic fibres at the bladder
Storage Phase -
Sympathetic effects dominate during bladder filling.
Fibres in the hypogastric nerve suppress contraction of the detrusor.
Somatic fibres in the pudendal nerve control the external sphincter
Voiding Phase
Parasympathetic actions dominate during emptying.
Fibres in the pelvic splanchnic nerve cause the detrusor to contract.
compare the normal bladder pressure relationship to a neurogenic and atonic bladder
Normal pressure–volume relationship, fills slowly to ~375 ml, then reflex contractions start, then stop
Neurogenic bladder, contraction starts at lower volume – increased reflex activity – can be result of disease
Atonic bladder: pressure rises slowly as bladder fills – no active reflexes – may have to use catheter to empty bladder
what is the affect of a partially obstructed urethra on urine flow rates
If urethra is narrowed, flow rate is reduced.
Time of flow is increased.
Volume voided may be reduced, leading to increased frequency of voiding.
which gender have separate urinary and reproductive tracts
women
males have combined tracts at the urethra
function of vas deferens
takes sperm upwards from testis to the urethra
in spermatic cord
structure of the peritoneum
there is a parietal and visceral layer
it is a serous membrane
describe parietal peritoneum
lines the internal surface of abdominopelvic wall
derived from the somatic mesoderm in the embryo
It receives the same somatic nerve supply as the region of the abdominal wall that it lines; therefore, pain from the parietal peritoneum is well localised. Parietal peritoneum is sensitive to pressure, pain, laceration and temperature
describe the visceral peritoneum
derived from the splanchnic mesoderm and invaginates to cover the majority of the abdominal viscera
same autonomic nerve supply as the viscera it covers
pain from the visceral peritoneum is poorly localised and the visceral peritoneum is only sensitive to stretch and chemical irritation
intraperitoneal organ examples
intraperitoneal organs - spleen, stomach and liver
retroperitoneal organs
oesophagus, rectum and kidneys - initially were in peritoneum in embryo
part of duodenum, descending colon, middle third rectum, pancreas, adrenal glands, proximal ureters, renal vasculature
functions of the kidneys
filter waste – produces urine
regulates blood - pressure, ions, pH, osmolarity, volume, glucose level
hormone production - calcitriol (active vitamin D) - raises blood calcium levels by increasing absorption from the gut, kidney and stimulation of release from bones - also produces Erythropoietin – secreted in response to hypoxia or low blood glucose
components of the hilum
renal artery, renal vein, renal nerve and ureter
describe the medulla
functional tissue where main filtering happens
organised into renal pyramids
structure of the cortex
body of the kidney
contains glomeruli, bowman’s capsule and convoluted tubules
what does a renal corpuscle and renal tubules make up
nephrons
components of a renal corpuscle
glomerulus and bowmans capsule
components of renal tubules
PCT, loop of henle and DCT
where does the filtered fluid go
comes in through renal corpuscle and then is filtered and passed into PCT, loop of henle, DCT, collecting duct and then into ureter
what are diuretics
medicines that promotion urination - increases salt and water excretion
used to to treat conditions like heart failure, cirrhosis or high blood pressure (hypertension)
what is horseshoe kidney
Condition where the 2 kidneys fuse at the lower end of the abdomen/upper pelvis and occurs in utero
1 in 500 people
Most cases are asymptomatic
More common in boys, and most cases are asymptomatic but sometimes it can lead to urinary tract infections (UTIs)
describe the structure of pyramids (in medulla)
Papilla are at the top of the pyramids and these link to form a minor calyx which drains the pyramids – minor calyx join to form major calyx
Renal pelvis is where major calyx come together – RP takes urine down through ureter
describe the breakdown from the renal artery
breaks down into arteries that supply the lobes
Interlobar artery – supply the renal lobes – goes into cortical blood vessels
Cortical blood vessels – supplying the cortex
Arcuate blood vessels - found at the border with the cortex and medulla and are shaped in arcs and come from the interlobar arteries
which renal vein is longer
left
where do renal veins drain to
IVC
effects of polycystic kidney disease
high level of cysts leads to destruction of parenchymal leading to loss of nephrons
raised bp
headaches
abdominal pain
function of ureter
transports urine to bladder from kidneys
peristalsis
is contraction of smooth muscle in ureter to allow urine to pass from kidney to bladder
describe the bladder
The urinary bladder is a muscular organ comprised of specialised smooth muscle called the detrusor. This organ helps store the urine and also helps in its removal from the body. This muscle is oriented in many directions to help in its contraction and relaxation in expanding and shrinking dependent on the amount of urine present
why are the testes external
External due to being temperature sensitive - The testes help maintain the temperature of the sperm a couple of degrees centigrade less than the rest of the body
what is the cremaster muscle
it is what controls whether testes are lower or higher – when it contracts it raises testes towards body, raising temp of sperm
describe the development of testes
begins in abdomen
descend into scrotum around 7th month in utero
sperm production
seminiferous tubules produce spermatozoa (sperm cells) - immature sperm cells
mature in epididymis
structure of testes
covered by tough fibrous layer called tunica - tunica vaginalis is the outer layer and tunica albuginea is the inner layer
tunica albuginea forms 200-200 lobules which contain 1-4 seminuferius tubules
describe cryptorchidism
maldescent of testis/testes 0 improper or incomplete descent of testis into scrotum
bilaterally (both sides) can result in infertility
spontaneous descent occurs in most cases in first year
describe varicocoele
dilation of pampiniform venous in testicle which may be due to obstruction of the testicular vein
pampiniform venous plexus usually drains the testes so it can look like a bag of worms
describe hydrocoele
accumulation of fluid within the tunica vaginalis
examination with a penlight reveals a translucent scrotum
parts of the male urethra
prostatic
membranous
pendulous (penile)
describe the prostatic urethra
contains:
urethral crest - long fold in the posterior wall of urethra - can stop passage of sperm into bladder when distended
prostatic utricle – blind ended structure and represents the origin of where the vagina and uterus would have developed in a female
Sphincter urethrae is an external sphincter - controls urine expulsion and is a second sphincter as well as the internal urethral sphincter - internal one is under involuntary control whereas the external one is under voluntary control
describe the membranous urethra
Contains Cowper glands – secrete glycoproteins in mucous during sexual arousal - This fluid produced by these glands lubricates the urethra and penis, helps remove debris and dead cells and neutralizes acidity within the urethra
structure of prostate
biggest accessory gland
Two thirds are glandular and remaining third is fibromuscular in structure
central zone - surrounds the ejaculatory ducts - the ducts here indirectly empty into prostatic urethra
transitional zone - surrounds urethra
peripheral zone - main body - ducts here vertically empty into prostatic urethra
prostate function
Secretes proteolytic enzymes into the semen which break down clotting factors in the ejaculate – allows semen to remain in a fluid state
Muscles of the prostate also ensure that semen is forcefully pressed into urethra during ejaculation
gonads in males and females
testes and ovaries
ligaments at uterus
Round ligament – maintains anteflexion of uterus i.e. fundus pointing forward
Broad ligament – acts as a mesentery and has a minor role in keeping the uterus forward
positionings of uterus
Anteverted – orientated forward Anteflexed – fundus forward relative to cervix Retroverted – orientated backward retroflexed – fundus points backward normal is anteverted, anteflexed
what is the normal positioning of a baby in pregnancy
External cephalic version
ectopic pregnancy
implantation of fertilised egg outside the uterus
mainly occurs in fallopian tube
