Week 11 - Genitourinary System

Question 1

what is screening

Answer 1

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

Question 2

important requirements for a screening programme

Answer 2

1. The condition should be an important problem for the individual and the community
2. There should be an accepted treatment for patients with the disease
3. Facilities for diagnosis and treatment should be available
4. There should be a recognisable latent or early stage
5. There should be a suitable test or examination
6. The test should be acceptable to the population
7. The natural history of the condition, including development from latent to declared disease, should be adequately understood
8. There should be an agreed policy on whom to treat as patients
9. The cost of the case finding programme should be economically balanced in relation to expenditure on medical care as a whole
10. Case finding should be a continuing process

Question 3

describe a cervical smear test

Answer 3

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

Question 4

what is HPV

Answer 4

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

Question 5

risk factors for cervical cancer

Answer 5

HPV
smoking
poor immune function eg. immunosuppression
multiple sexual partners

Question 6

how does HPV invade the body

Answer 6

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

Question 7

what does HPV do once in the body

Answer 7

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

Question 8

precursor lesions for cervical cancer

Answer 8

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

Question 9

describe cervical cytology

Answer 9

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

Question 10

what is a colposcopy

Answer 10

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

Question 11

breast screening process

Answer 11

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

Question 12

bowel screening process

Answer 12

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

Question 13

problems that can occur if homeostasis is not maintained

Answer 13

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)

Question 14

recommended uk salt intake

Answer 14

should eat no more than 6g of salt/day. Many adults exceed this

Question 15

typical renal blood flow

Answer 15

625ml/100g/min

Question 16

describe the two types of nephron

Answer 16

Superficial – have short loops that dives into medulla
Juxta-medullary – longer loops
Water reabsorption is more effective in the longer juxta-medullary nephrons

Question 17

parts of a nephron

Answer 17

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)

Question 18

describe the cortex of a kidney

Answer 18

the body/supporting tissue

Contains glomeruli, bowman’s capsule and convoluted tubules

Question 19

describe the medulla of a kidney

Answer 19

where most filtering happens

organised into renal pyramids

Question 20

renal hilum components

Answer 20

renal vein
renal nerve
renal artery

Question 21

main blood supply to kidney

Answer 21

renal artery which arises from the abdominal aorta

Question 22

which renal artery is longer

Answer 22

right renal artery is longer as it has to pass behind the IVC to reach the right kidney

Question 23

normal glomerular filtration rate

Answer 23

90-140ml/min

Question 24

describe glomerulus ultrafiltration

Answer 24

force of hydrostatic pressure in glomerulus pushes out water and small molecules through slits between podocytes
filtrate is passed into bowman’s capsule

Question 25

describe reabsorption

Answer 25

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

Question 26

describe the loop of henle

Answer 26

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

Question 27

absorption and secretion in DCT

Answer 27

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

Question 28

describe secretion

Answer 28

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

Question 29

describe collecting duct function

Answer 29

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

Question 30

max and min urine output

Answer 30

max is ~20ml/min | min is ~1ml/min

Question 31

describe what happens in the collecting ducts when excess water is consumed

Answer 31

plasma osmolarity falls Hypothalamus secretes less ADH/AVP Collecting Duct walls loose permeability to water Dilute urine is produced

Question 32

describe the renin/angiotensin/aldosterone system

Answer 32

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

Question 33

function of aldosterone

Answer 33

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

Question 34

describe the structure of the bladder

Answer 34

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

Question 35

ureter function

Answer 35

transports urine from kidney to bladder | there are two - one from each kidney

Question 36

describe bladder filling

Answer 36

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

Question 37

describe how a catheter works

Answer 37

1. Place one opening in the bladder to allow direct filling and measure bladder pressure 2. Inflate balloon to close off urethra 3. Position second opening in the urethra to measure the sphincter pressure 4. Then fill the bladder and record the pressure to establish bladder compliance. 5. As bladder fills watch for signs of bladder wall contraction and sphincter contraction

Question 38

describe the difference between a sphincter urethrae in a male and female

Answer 38

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

Question 39

what is the urethra

Answer 39

a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males

Question 40

describe the pressure and volume changes in the storage phase

Answer 40

1. 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 2. No flow in urethra: urethral pressure > bladder pressure 3. Sensations develop, then sphincter contracts to maintain continence – bladder keeps filling and there is a second sensation which is the first urge to micturate

Question 41

describe the pressure and volume changes in the voiding phase

Answer 41

1. ‘Urge’ sensation then ‘Voluntary voiding’ (VV) 2. Bladder contracts, urethra and sphincters relax - bladder pressure increases - Flow in urethra: bladder pressure > urethral pressure. 3. ‘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

Question 42

describe the innervation to the bladder and sphincters

Answer 42

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)

Question 43

describe the positioning of the afferent and efferent nerves at the bladder

Answer 43

Afferents: 1. Sensory fibres sense the stretch of the bladder wall - These afferents run in the hypogastric nerve and enter cord in the upper lumbar roots. 2. Other sensors near the urethra sense flow of urine (not shown below) 3. Skeletal muscle sensors in the external sphincter Efferents: 1. Parasympathetic to detrusor 2. Sympathetic to detrusor and internal sphincter 3. Somatic to external sphincter

Question 44

describe the role of sympathetic and parasympathetic fibres at the bladder

Answer 44

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.

Question 45

compare the normal bladder pressure relationship to a neurogenic and atonic bladder

Answer 45

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

Question 46

what is the affect of a partially obstructed urethra on urine flow rates

Answer 46

If urethra is narrowed, flow rate is reduced. Time of flow is increased. Volume voided may be reduced, leading to increased frequency of voiding.

Question 47

which gender have separate urinary and reproductive tracts

Answer 47

women | males have combined tracts at the urethra

Question 48

function of vas deferens

Answer 48

takes sperm upwards from testis to the urethra | in spermatic cord

Question 49

structure of the peritoneum

Answer 49

there is a parietal and visceral layer | it is a serous membrane

Question 50

describe parietal peritoneum

Answer 50

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

Question 51

describe the visceral peritoneum

Answer 51

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

Question 52

intraperitoneal organ examples

Answer 52

intraperitoneal organs - spleen, stomach and liver

Question 53

retroperitoneal organs

Answer 53

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

Question 54

functions of the kidneys

Answer 54

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

Question 55

components of the hilum

Answer 55

renal artery, renal vein, renal nerve and ureter

Question 56

describe the medulla

Answer 56

functional tissue where main filtering happens | organised into renal pyramids

Question 57

structure of the cortex

Answer 57

body of the kidney | contains glomeruli, bowman's capsule and convoluted tubules

Question 58

what does a renal corpuscle and renal tubules make up

Answer 58

nephrons

Question 59

components of a renal corpuscle

Answer 59

glomerulus and bowmans capsule

Question 60

components of renal tubules

Answer 60

PCT, loop of henle and DCT

Question 61

where does the filtered fluid go

Answer 61

comes in through renal corpuscle and then is filtered and passed into PCT, loop of henle, DCT, collecting duct and then into ureter

Question 62

what are diuretics

Answer 62

medicines that promotion urination - increases salt and water excretion used to to treat conditions like heart failure, cirrhosis or high blood pressure (hypertension)

Question 63

what is horseshoe kidney

Answer 63

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)

Question 64

describe the structure of pyramids (in medulla)

Answer 64

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

Question 65

describe the breakdown from the renal artery

Answer 65

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

Question 66

which renal vein is longer

Answer 66

left

Question 67

where do renal veins drain to

Answer 67

IVC

Question 68

effects of polycystic kidney disease

Answer 68

high level of cysts leads to destruction of parenchymal leading to loss of nephrons raised bp headaches abdominal pain

Question 69

function of ureter

Answer 69

transports urine to bladder from kidneys

Question 70

peristalsis

Answer 70

is contraction of smooth muscle in ureter to allow urine to pass from kidney to bladder

Question 71

describe the bladder

Answer 71

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

Question 72

why are the testes external

Answer 72

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

Question 73

what is the cremaster muscle

Answer 73

it is what controls whether testes are lower or higher – when it contracts it raises testes towards body, raising temp of sperm

Question 74

describe the development of testes

Answer 74

begins in abdomen | descend into scrotum around 7th month in utero

Question 75

sperm production

Answer 75

seminiferous tubules produce spermatozoa (sperm cells) - immature sperm cells mature in epididymis

Question 76

structure of testes

Answer 76

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

Question 77

describe cryptorchidism

Answer 77

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

Question 78

describe varicocoele

Answer 78

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

Question 79

describe hydrocoele

Answer 79

accumulation of fluid within the tunica vaginalis | examination with a penlight reveals a translucent scrotum

Question 80

parts of the male urethra

Answer 80

prostatic membranous pendulous (penile)

Question 81

describe the prostatic urethra

Answer 81

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

Question 82

describe the membranous urethra

Answer 82

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

Question 83

structure of prostate

Answer 83

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

Question 84

prostate function

Answer 84

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

Question 85

gonads in males and females

Answer 85

testes and ovaries

Question 86

ligaments at uterus

Answer 86

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

Question 87

positionings of uterus

Answer 87

``` Anteverted – orientated forward Anteflexed – fundus forward relative to cervix Retroverted – orientated backward retroflexed – fundus points backward normal is anteverted, anteflexed ```

Question 88

what is the normal positioning of a baby in pregnancy

Answer 88

External cephalic version

Question 89

ectopic pregnancy

Answer 89

implantation of fertilised egg outside the uterus | mainly occurs in fallopian tube