Block 5 Preview Beckworth Cartington and Tomelious Grantham.

Block 5 PreviewBeckworth Cartington and Tomelious Grantham

To cover

• Childhood milestones• Milk letdown + posterior pituitary• HPO axis• Pre-eclampsia• Spermatogenesis• Contraception• Neural tube + folic acid• Becky’s chin stubble• Tom’s infertility

Childhood milestones

When can a baby roll over?• Front to back (prone to supine) 5-6 months• Back to front (supine to prone) 6-7 months

When can a baby sit without support?• Independent sitting 5-9 months

When can a baby crawl?• Attempts to crawl at 9 months

When does a baby begin to walk?• 12 months

When can a baby pass objects from hand to hand?• 6 months

VERY HIGH YIELD - Extremely easy MCQ questions for them to ask. If anything like previous exams, learning the 11 dates below could be worth 4-5 marks in your summatives

What is an inferior pincer grip and when would we expect it to develop by?• An inferior pincer grip is when a baby can pick up a small object between finger

and thumb. • 9 months

When do babies develop object permanence? • 5 months

When does a baby distinguish strangers from familiars?• 9 months

When does a baby begin to understand “no” and “bye-bye”?• 9 months

When does a baby speak 2-6 recognizable words?• 15 months

Inguinal canal

In males testicle has descended through processus vaginalis – so this is a weak spot – hence increased chance for indirect inguinal hernias.

2 muscles – internal oblique muscle

transversus abdominus

muscle

2 ligaments – inguinal ligamentlacunar ligament

M

A

L

T

2 T’s – transversalis fascia

conjoint tendon

2 aponeuroses – aponeurosis of external obliqueaponeurosis of internal oblique

What are the borders of the inguinal canal?

Remember MALT

What is the location of the deep inguinal ring?

What are the borders of Hesselbachs triangle?

Which type of hernia is most likely present?

A 55 year old man presents with a reducible swelling in his groin. On auscultation over the area you can hear bowel sounds. You press on the deep inguinal ring and ask the patient to cough, you

feel pressure against your finger but the swelling doesn’t return.

Indirect inguinal hernia

Rectus abdominus mediallyInguinal ligament inferiorlyInferior epigastric artery superiorly

Between the midinguinal (half way between the pubic symphysis and the ASIS) point and themid point of the inguinal ligament (between the pubic tubercle and the ASIS)

Which of the structures below is likely to be found in particular abundance in Leydig cells in the testes?

*hint – testosterone is a steroid hormone produced in the Leydig cell

a) Rough endoplasmic reticulum

b) Smooth endoplasmic reticulum

c) Mitochondria

d) Ribosomes

e) Golgi apparatus

It is important to remember the following associations:

Metabolically active cells (e.g. PCT in kidneys, myocytes) have a lot of mitochondria

Cells that produce steroid hormones (e.g. leydig cells, granulosa cells) have an abundance of smooth endoplasmic reticulum (site of lipid synthesis)

Cells that produce many proteins (e.g. chief cells of stomach, acinar cells of pancreas) have a high number of ribosomes, golgi apparatus and rough endoplasmic reticulum

Which of the following hormones is produced by the posterior pituitary?a) Follicle stimulating hormone

b) Leutinizing hormone

c) Thyroid stimulating hormone

d) Oxytocin

e) Prolactin

MNEMONIC to remember the hormones of the anterior pituitary: FLAT GP

Follicle stimulating hormoneLeutinizing hormoneACTH (adrenocorticotropic hormone)Thyroid stimulating hormoneGrowth hormoneProlactin

To remember that FLAT GP tells you about the anterior pituitary, remember that GPs are on the frontline (anterior) of the NHS!

More high yield stuff…

• Baby sucking (mechanoreceptors) stimulates posterior pituitary 1

• Higher centres (hearing baby cry) stimulates posterior pituitary 1

• Oxytocin released from posterior pituitary 1

• Oxytocin causes contraction of myoepithelial cells 1

• Milk is ejected-not sucked out 1

(note that oxytocin also aids further contraction of uterus)

What position should a baby be placed in to encourage latching onto the nipple? (1)Nipple to nose

Describe the milk letdown reflex? (3)

HPG axisWhat does HPG stand for?Hypothalamus – Pituitary – GonadalLogically, depending on whether male or female, we are dealing with different axes…

What is the male gonad?Testicle. Therefore we are dealing with the HPT axis:Hypothalamus – Pituitary - Testicle

What is the female gonad?Ovary. Therefore we are dealing with the HPO axis:Hypothalamus – Pituitary - Ovary

What hormone is produced by the hypothalamus regarding the HPG axis?GnRH (Gonadotropin releasing hormone)

What hormone is produced by the anterior pituitary regarding the HPG axis? (2)FSH (follicle stimulating hormone)LH (leutinizing hormone)

HPG axis

Back to block 1… Before block 5, review the embryology lecture. Lots of the new material in block 5 assumes a knowledge of this material

For example. The trophoblast forms the cytotrophoblast and syncytiotrophoblast. The syncytiotrophoblast grows into the endometrium if the embryo implants… and secretes hCG (human chorionic gonadotrophin) – which is the basis of a pregnancy test!

Knowing and interpreting these two graphs is high yield!

Spermatogenesis Key: Diploid Haploid

Spermatogonia are present before birth and are latent untilpuberty.At puberty the seminiferous tubules hollow out andspermatogenesis begins.

Spermatogenesis: a group of spermatogonia divides a fixed number of times by mitosis to form a clone of cells ( about 64)These new cells are called primary spermatocytes.The clone of primary spermatocytes are all linked by cytoplasm. The spermatocytes undergo meiosis - each spermatocyte forms 4 haploid spermatids.

As the spermatids travel through the rete testis, ducti efferentes and epididymis they undergo remodelling and maturation to form mature sperm.The spermatogonia are replaced by mitosis and so theoreticallymales have an unlimited supply of sperm – This is useful as femaleshave a very narrow window of fertility (approx 36hrs)

Immunoglobulins – need to know

• G – Majority of antibody-based immunity. Transfer in placenta to give fetus passive immunity

• A – Mucus membranes, transfer in breast milk

• M – Isotope of this (RhF) complexes with IgG in RA

• E – allergies, triggers mast cell degranulation

• D – Signals B cell activation

More or less guaranteed exam question. Learn this table.

Disease Positive

Disease Negative

Screening Test Positive

True Positive (TP)

False Positive (FP)

PPV = TP/(TP+FP)

Screening Test negative

False Negative (FN)

True Negative (TN)

NPV=TN/(TN+FN)

Sensitivity = TP/(TP+FN)

Specificity = TN/(TN+FP)

Sensitivity is the probability that a test will indicate 'disease' among those with the disease.

Specificity is the fraction of those without disease who will have a negative test result.

The positive predictive value is the likelihood that someone with a positive test result actually had the disease (this gives us information about false positives).

The negative predictive value is the likelihood that someone with a negative test results does not have the disease (this gives us information about false negatives).

Disease Positive

Disease Negative

Screening Test Positive

True Positive (TP)

False Positive (FP)

PPV = TP/(TP+FP)

Screening Test negative

False Negative (FN)

True Negative (TN)

NPV=TN/(TN+FN)

Sensitivity = TP/(TP+FN)

Specificity = TN/(TN+FP)

Based on these data, the sensitivity of the test is:(Assume the only possible outcomes of the test are positive or negative)

The specificity of the test is:

The positive predictive value is:

If a patient receives a negative test result, what is the probability that they actually have the disease?

False negatives make up:

To evaluate the performance of a new diagnostic test, the developer checks it out on 100 known cases of the disease for which the test was designed, and on 200 controls known to be free of the disease. Ninety of the cases yield positive tests, as do 30 of the controls.

90 30

10 170

90%

85%

75%

94% 6%

NPV =

When is it important to avoid false positives?

When in is important to avoid false negatives?

When the subsequent investigations are very invasive, costly or risky and the disease isn’t life threatening.

When the disease had a rapid progression, has much better prognosis when caught early etc. Infective diseases.

Contraception

Barrier – blocks gamete fusion

Progesterone infusion (mini pill/implants) – mucus effects

Oestrogen (pill) – suppresses HPO axis

Normal fetal heartrate

• Baseline 110-160 (bpm)

• Variability (bpm) = >5

• Decelerations : none

• Accelerations : present