ESA4

Question 1

In a patient with tonsillitis, which single palpable LN would you expect to be enlarged?

Answer 1

Jugular-digastric LN

Question 2

A pharyngeal pouch may occur, particularly in the elderly. What is its anatomical explanation?

Answer 2

A pharyngeal pouch represents a posteromedial diverticulum through Killian’s dehiscence. I.e. It is an outpocketing of the posterior wall of the pharynx above the entrance of the oesophagus. During swallowing, muscles of pharynx contract and pressure in pharynx increases. If cricopharyngeus muscle does not open at correct time, pressure builds immediately above it and the pharyngeal mucosa may herniates through a potential weakness in the posterior wall of the pharynx at Killian’s dehiscence. Patients usually present in 6th and 7th decade. Difficulty swallowing, sensation of lump in throat or food stuck in throat. Food may enter pouch rather than passing down oesophagus –> hoarseness of voice, recurrent chest infections. May become large enough to be noticed as lump in neck. Common method of dragons is barium swallow. Only treated if significant symptoms. The pouch may develop as the result of a lack of muscle tone within the cricopharyngeus muscle at the top of the oesophagus. It is a herniation between the thyropharyngeus and cricopharyngeus muscles that are both inferior constrictor muscles of the pharynx. Inferior pharyngeal constrictor muscles innervated by via pharyngeal plexus and RLN of CNX.

Question 3

Describe the physiological mechanism of a penile erection.

Answer 3

Normally erectile tissue in pens - corpora cavernosa is tonically contracted. Following physical stimulation or psychological stimulation, signals cause triggering of sacral spinal segment reflex. Activation of parasympathetic and activation non-adrenergic non-cholinergic (NANC) nerves. Release of ACh from post-ganglionic neurones causes a rise in intracellular Ca2+ –> activates eNOS and causes release of nitric oxide from endothelial cell. NO also released directly from NANC nerves. NO Diffuses into SM –> stimulates guanylyl cyclase which converts GTP –> cGMP. CGMP then acts on protein kinases to lower calcium levels in SM –> promotes cavernosa relaxation/vasodilation –> increased blood flow and increased intracavernosal pressure –> erection. Maintenance of the erection is a result of the increased arterial blood flow into the penis which fills the sinusoidal spaces therefore –> venous outflow reduced by compression between tunica albuginea and sinusoids.

Question 4

Describe the process of emission.

Answer 4

Sympathetically controlled - T10-L2
Contraction of SM in ductus deferens, seminal vesicles and prostate
Expulsion of sperm and seminal fluid into prostatic urethra. N.B. Leakage can occur here and this is why withdrawal method is not effective!
Internal and external urethral sphincters contracted

Question 5

Describe the physiological process of male ejaculation.

Answer 5

Sympathetic control S2-S4
Internal urethral sphincter remains contracted. External urethral sphincter relaxes. Filling of internal urethra stimulates pudendal nerve –> contraction of genital organs, ischiocavernosus and bulbospongiosus muscles –> expulsion of semen

Question 6

What is oligozoospermia?

Answer 6

Less than 20x10^6 sperm per ml of ejaculated semen

Less than 5 X 10^6 = severe oligozoospermia

Question 7

Describe the composition of normal semen and their origins.

Answer 7

Seminal vesicle - contribute around 60%. Fructose for ATP. Alkaline fluid - transport of sperm. Clotting factors - semenogelin. PGs
Prostate - 25% volume. PSA and pepsinogen –> break down clotting factors –> re-liquefied semen after 15-20 mins. Citric acid –> ATP.
Cowper’s glands –> alkaline fluid lines tip of penis

Question 8

Describe physiological changes that occur in the female to facilitate coitus.

Answer 8

Depending on point in menstrual cycle cervical composition will change. Day 7-14 of cycles where there is endometrial proliferation and oestrogen only = most conduicive to fertilisation. Oestrogen only = abundant cervical mucus that is clear and non-viscous.
Later in cycle when there is progesterone + oestrogen –> thick sticky mucus plug (helps limit infection and prevent polyspermy if fertilisation were to occur in first half of cycle)

Question 9

Why is cleavage of the zygote important?

Answer 9

Generation of a large number of cells that can undergo differentiation and gastrulation to form organs
Increase in nuclear: cytoplasmic ratio. One nucleus cannot transcribe tsufficient RNA to support enormous cytomasm of zygote
Cleavage is asynchronous

Question 10

What day post-fertilisation is the embryo fully embedded in the endometrial wall?

Answer 10

Day 10 approx

Question 11

Give examples of forms of natural contraception and include advantages and disadvantage.

Answer 11

1. Abstinence
2. Coitus interruptus - withdrawal method. Ineffective as sperm already in prostatic urethra pre-ejaculation and can leak out.
3. Rhythm - abstinence during 7-16 d fertile period. Requires very regular cycles to work

Question 12

Name 3 types of barrier contraception

Answer 12

Condoms
Diaphragm inserted into vagina to cover cervix
Cervical caps

Question 13

What is Sheehan’s syndrome and how could it cause secondary infertility?

Answer 13

Postpartum ischaemic necrosis of anterior pituitary. Results from extreme blood loss during birth process –> decreased blood supply to anterior pituitary (post. Pit spared due to direct blood supply) –> necrosis
Can result in deficiencies in GH, FSH, LH, TSH, ACTH, MSH
Symptoms: failure to breast feed, loss of pubic and axillary hair, hypotension, amenorrhea

Question 14

IN PCOS exposure of follicles to androgens may lead to inhibition of FSH but not LH. By what mechanism might FSH be selectively inhibited? Why might there be no LH surge in this condition?

Answer 14

Follicles may secrete inhibin. Inhibin release only selectively inhibits FSH, thus reducing FSH in relation to LH and affecting the ratio. Androgens may suppress LH surge. Because there is no negative feedback control via oestrogen as there is irregular secretion of oestrogen due to non-cyclical pulsations of GnRH.

Question 15

How does viagra work to maintain erection?

Answer 15

Viagra inhibits action of PDE-5 which normally breaks down cGMP to 5-GMP. By inhibiting PDE-5 allows levels of cGMP to remain high which can then activate protein kinases which decrease Ca2+ in the SM of corpora cavernosa –> maintaining erection

Question 16

What does haemomonochorial mean in regards to the human placenta?

Answer 16

Means one layer of trophoblast ultimately separates maternal blood from fetal capillary wall

Question 17

What are the main aims of implantation?

Answer 17

To establish basic unit of exchange - via chorionic villi
Anchor placenta - establishment of outermost cytotrophoblast shell
Establish blood flow within placenta

Question 18

Give 4 examples of implantation defects.

Answer 18

Placenta praevia
Ectopic pregnancy
Incomplete invasion - placental insufficiency
Pre-eclampsia

Question 19

Describe the structure and functional purpose of the chorion.

Answer 19

The chorion is one of four extraembryonic membranes of the developing foetus.
It is made of trophoblast and inner somatic mesoderm. Trophoblast consists of inner cytotrophoblast and syncytiotrophoblast. Trophoblast layer rapidly proliferates to give rise to chorionic villi which invade and destroy the uterine decidua (pregnant endometrium). Chorionic villi originally only composed of trophoblast but mesoderm invades villi to vascularise it as it brings uterine vessels with it.
Chorionic villi help to form placenta thus creating good network for exchange with mother

Question 20

What is the function of the amniotic fluid?

Answer 20

Protective environment
Allows development of key structures
Allows practice movements of lungs
Allows some freedom of movement for foetus in late pregnancy

Question 21

After Week 8 which part of the decidua continues to retain chorionic villi?

Answer 21

Decidua basalis - the part of the decidua that will form the maternal contribution of the placenta

Question 22

What forms the placenta?

Answer 22

Trophoblastic layer consisting of cytotrophoblast and syncytiotrophoblast layer develop into the placenta.Trophoblast layer and infiltrating mesenchyme form the chorionic villi which help create the foetal-maternal circulation within the placenta. A subset of villi cross intervillous space and attach directly to maternal uterine decidua and = anchoring villi.

Question 23

What process occurs in order to convert endometrium into decidua and what hormone plays a key role.

Answer 23

Decidualisation is the process by which uterine endometrium is primed by progesterone and undergoes changes to become the decidua of pregnancy. Changes include eosinophilic proliferation around arterioles, glandular secretion, promotes development of spiral arteries and oedema. This process primes the endometrium and allows it to become ready for implantation. Decidual cells also prevent excessive invasions. Therefore lack of decidual cells –> potentially too much invasion –> severe haemorrhage.

Question 24

Discuss the importance of remodelling of the spiral arteries and state a condition where this process is affected.

Answer 24

Spiral arteries develop during the luteal phase of menstrual cycle to help prepare endometrium for implantation - this occurs regardless of fertilisation. Following fertilisation remodelling must occur which involves infiltration of the spiral arteries by maternal leukocytes and extravillious trophoblast. This causes alteration of the SM of the artery and increases lumen of the artery allowing it to receive high BF volume. This is essential adaptation to allow high volume of BF to intervillous space at low pressure. In IUGR and pre-eclampsia it is thought that this remodelling process is compromised and some of the spiral artery remains –> placental insufficiency.

Question 25

What cells are the main source of placental hCG?

Answer 25

Syncytiotrophoblast cells

Question 26

Give 2 situations where interhaemal distance is decreased more than normal.

Answer 26

High altitude and mother who smokes

Question 27

In simple terms what does the Barker Hypothesis state?

Answer 27

Conditions and factors occuring in utero/foetal life impact risk of adult disease

Question 28

What produces hPL and what is its function?

Answer 28

Human placental lactogen produced by syncytiotrophoblast cells of placenta. It acts to decrease maternal insulin sensitivity thereby increasing maternal blood glucose –> more available for foetus. HPL also decreases utilisation of glucose by the mother and favours lipolysis –> increased production of FFAs –> can be used by mother as fuel source allowing more glucose to be avialble to foetus

Question 29

What are the 3 main roles of the placenta?

Answer 29

Metabolism - production of glycogen, cholesterol and FAs
Endocrine - protein synthesis: hPL, hCG, hCT. Steroid synthesis: progesterone and oestrogen
Transport : via facilitated diffusion, simple diffusion, active transport

Question 30

Describe the cardiovascular changes that occur in the mother during pregnancy.

Answer 30

50% blood volume increase - to account for blood loss in parturition and foetal demand
Increase CO by 40%
Increase HR by 15%
Systemic vascular resistance decreases by 30%
BP - decreases in T1 and T2 but returns to normal in T3

Question 31

WHat is responsible for the systemic drop in vascular resistance and what potential consequence can it have for the mother?

Answer 31

Progesterone causes relaxation of SM –> decreased resistance
Increased risk of haemorrhoids and varicose veins

Question 32

What is aortocaval compression syndrome?

Answer 32

Compression of abdominal aorta and IVC by gravid uterus in pregnant women when lying in supine position. Common cause of maternal hypotension and can result in loss of consciousness. Resolved by woman lying on her side.

Question 33

Why might you find glucose in the urine of a pregnant lady and not really be concerned?

Answer 33

Progesterone released by placenta causes vasodilation of afferent arterioles in kidney –> increased GFR and increased renal plasma flow –> increased clearance. Despite increased GFR, reabsorptive capacity at PCT remains the same so glucose can sometimes be found in urine in pregnant women

Question 34

Why are pregnant women more likely to develop UTIs. Think adaptations…

Answer 34

Progesterone acts on collecting ducts as well –> dilated. Causes urine speed in ureters to decrease. More static urine –> increased risk of renal calculi AND UTIs.
UTIs–> increased risk of pyelonephritis –> AKI

Question 35

What changes/adaptations occur in the respiratory system in a pregnant women. Discuss both anatomical and physiological changes.

Answer 35

Diaphragm pushed up by increased uterus size. Increased AP and transverse diameter of thorax. Increased tidal volume, same RR, decreased FRC, increased O2 consumption (20%). Pa02 increases and PaCO2 decreases.

Question 36

What is physiological hyperventilation in regards to pregnancy?

Answer 36

Increased blood CO2 due to transfer from foetus. This along with progesterone triggers respiratory centre to increase respiratory drive. Hyperventilation causes excess CO2 to be blown off –> respiratory alkalosis. But increased GFR and clearance results in increased bicarbonate excretion to balance loss of CO2. However, this compensation means there is less bicarbonate buffering system and increased risk of metabolic acidosis in pregnancy.

Question 37

How do maternal adaptations ensure a constant supply of glucose is available for foetus.

Answer 37

Maternal adaptations controlled by various placental hormones including progesterone and hPL. Increased insulin production following a meal. Upregulation of maternal beta cells in pancreas. Increased insulin resistance –> more glucose in blood available for foetus. Mother switches to gluconeogenesis and lipolysis –> FFAs and ketones which can be used as fuel sources to leave glucose available for foetus. Decreased utilisation of glucose by mother. Decreased insulin sensitivity –> hypoglycaemia in mother. Hypoglycaemia –> increased lipolysis –> FFA release. HUMAN Placental lactogen production is directly proportionate to placental size so levels rise throughout pregnancy.

Question 38

Describe blood glucose levels in pregnant women.

Answer 38

Decreased fasting blood glucose levels but increased post-prandial blood glucose due to level of hPL

Question 39

What is pre-eclampsia?

Answer 39

High blood pressure, proteinuria and oedema only seen in pregnant women. Often in 3rd trimester (after 20 weeks gestation)
Caused by inadequate remodelling of spiral arterioles of endometrium which should be invaded by chorionic villi and mesenchyme core to vascularise them and expand the lumen for increased blood volume and blood delivery. Without this happening effectively –> foetal blood supply compromised so mothers BP increases to try to meet demand.