1 - Anatomy Flashcards

Question

What is the process of oogenesis?

Answer 1

Begins in fetus before birth * **Primordial germ cells** (from yolk sac of the embryo) move to colonise the cortex of the primordial gonad. Replication by mitosis peaks around 20 weeks. Cell death occurs after this peak to leave 2 million cells * **Meiosis I** before birth and forms **primary oocytes** * Primary oocytes in the gonads as clusters, epithelial cells surrounding them, called the **primary follicle**. * During childhood, further **atresia** occurs, leaving ~40,000 eggs at puberty. * Once **puberty** begins, a number of primary oocytes (15-20) begin to mature each month, although only one of these reaches full maturation to become an oocyte. **Preantral, antral, ovulatory** * The secondary oocyte will only complete meiosis II following **fertilisation.**

Answer 2

**_Pre Antral_** * Squamous cells become stratified cuboidal (granulosa cells) and secrete zone pellucida **_Antral_** * Fluid filled spaces form between granulosa cells, these eventually combine together to form a central fluid filled space called the **antrum** * This is now a **secondary follicle** and only one dominates and matures a month **_Pre-Ovulatory_** * LH surge induces this stage and meiosis I is now complete. Inside the follicle one polar body and one **secondary oocyte. Meiosis II starts,** two polar bodies but the **secondary oocyte arrests in metaphase of meiosis II**. This happens 3 hours prior to ovulation. **_Ovulatory_** * Now a **Graafian follicle** * LH surge occurs increases collagenase activity, weakening the follicular wall and ovulation **_Fertilisation_** * The secondary oocyte will only complete meiosis II following **fertilisation** * If fertilisation doesn’t occurs, oocyte degenerates 24 hours after ovulation, remaining arrested in meiosis II

Answer 3

**C****apacitation** ## Footnote Reorganises sperm cell membrane and results in the tail movement changing from a beat-like action to a thrashing whip-like action to help propel the sperm forward. Removal of the protein coat of sperm exposes **acrosome** enzymes so can penetrate zone pellucida

Answer 4

Calcium enters the oocyte and the sperm cell stop moving. Rise in intracellular **calcium** * The egg cell membrane depolarises in order to prevent polyspermy – this is the **primary** block. * The **cortical reaction** occurs, which is where cortical granules that lie just beneath the egg cell membrane fuse with the membrane and release their contents into the zona pellucida. This is a **secondary** block to polyspermy as it hardens the zona.

Answer 5

* Levels of progesterone (from corpus lute and then placenta) and oestrogen (from placenta) increase * Increase in oestrogen levels results in increase in hepatic production of **thyroid-binding globulin** (TBG). As a result, more free T3 and T4 bind to the TBG, this causes more TSH to be produced. *Free* T3 and T4 levels remain unchanged – but ***total*** **T3 and T4 levels rise**. Ensures that there is a **constant supply of thyroxin** to the foetus early in pregnancy as fetes cannot produce it's own until second trimester * Increase in **human placental lactogen, prolactin and cortisol levels.** These are **anti-insulin hormones** therefore, they increase **insulin resistance in the mother** and reduce peripheral uptake of glucose. This ensures that there is a continuous supply of glucose for the foetus. * The mother switches to an alternative source of energy which is provided by lipids. The breakdown of lipids can result in ketogenesis thus, pregnancy is associated with an increased risk of **ketoacidosis**.

Answer 6

Progesterone decreases systemic vascular resistance in pregnancy which leads to a **decrease in diastolic blood pressure** during the first and second trimester of pregnancy. In response **cardiac output** increases by about 30-50%. Pregnancy results in the **activation of the RAAS** leading to an **increase in sodium levels and water retention**. This means that the **total blood volume increases.**

Answer 7

* Growth of the foetus causes **upward displacement of the diaphragm** but does not decrease total lung capacity as **increase in the transverse and anterior-posterior diameters** of the thorax * In pregnancy, a woman faces an increase in their metabolic rate, which leads to an increased demand for oxygen. The **tidal volume and the minute ventilation rate increases** to help the mother meet these oxygen demands. * Hyperventilation due to increased carbon dioxide production and the increased respiratory drive caused by progesterone. Results in a **respiratory alkalosis with a compensated increase in renal bicarbonate excretion**

Answer 8

* **Reflux, nausea and vomiting** due to upward displacement of stomach causing increased gastric pressure * **Appendix may move** to right upper quadrant * **Constipatio**n due to increase in progesterone causing **smooth muscle relaxation**, which decreases gut motility * **Risk of gall stones** as increased progesterone causes relaxation of gallbladder so biliary tract stasis

Answer 9

* **Increased GFR** by about 50-60% due to increased cardiac output which causes increase in renal plasma flow. Levels of urea and creatinine will be lower as increased clearance * **Risk of UTIs** (usually pyelonephritis) due to stasis from relaxation of the ureter and muscles of the bladder due to progesterone

Answer 10

* **Risk of VTE** as **increase in fibrinogen and clotting factors** in the blood and a decrease in fibrinolysis. Additionally, due to an increase in progesterone levels stasis of blood occurs. Warfarin can not be given to counteract this as can cross the placenta is a teratogen. Use LMWH if needed * **Dilutional anaemia** as plasma volume increases significantly but red cell mass does not increase by as much

Answer 11

* Hypertrophy of the **ductular-lobular-alveolar system** * From mid-gestation alveolar cells differentiate to be capable of milk production but little milk secretion due to the **high progesterone:oestrogen ratio** which favours growth rather than secretion. Only once placenta is delivered and progesterone falls does it start to form milk

Answer 12

First milk produced after birth (24-48 hours after birth) Contains less water soluble vitamins, fat and sugar than mature milk, but contains more proteins (particularly immunoglobulins) and fat soluble vitamins 40 ml/day

Answer 13

Babies do not suck the milk out it is ejected by the **let-down reflex** In response to suckling, **oxytocin** is released from pituitary gland which stimulates **myoepithelial cells** that surround alveoli to contract thus squeezing milk out of the breast. Despite suckling being the major stimulus for milk let down, the **reflex** can be conditioned. The cry or sight of an infant and preparation of the breast for nursing may cause let-down, whereas pain, embarrassment or alcohol may inhibit it.

Answer 14

**Maintained:** Adequate suckling at a feed to stimulate prolactin for next feed **Cease:** Stop suckling, Steroids or Dopamine Agonists. Turgor induced damage to secretory cells and low prolactin levels.

Answer 15

* Begin as **genital ridges** from intermediate mesoderm and overlying epithelium. * **Germ cells migrate** in week 4-6 **from yolk sac** to ridges * Simultaneously, epithelium of genital ridges proliferates and penetrates the intermediate mesoderm to form the **primitive sex cords**. Germ cell + Sex cords = Gonads

Answer 16

**_Male_** Testosterone (produced by the Leydig cells), causes **mesonephric ducts** develop to form the primary male genital ducts. They give rise to the efferent ductules, epididymis, vas deferens and seminal vesicles. **Paramesonephric ducts** degenerate due to **anti-Mullerian hormone** – produced by sertoli cells in the testes **_Female_** **Mesonephric ducts** degenerate due to lack of testosterone. Absence of anti-Mullerian hormone allows for development of the **paramesonephric ducts** * **Cranial** – becomes the Fallopian tubes * **Horizontal** – becomes the Fallopian tubes * **Caudal** – fuses to form the uterus, cervix and upper 1/3 of the vagina. The lower 2/3 of the vagina is formed by **sinovaginal bulbs** (derived from the pelvic part of the urogenital sinus).

Answer 17

Cloacal folds form **genital tubercle, urethral folds and anal folds** **Male** * Presence of DHT causes **elongation of tubercle, closure of genital swellings** to form scrotum, **closure of urethral folds** * Can get hypospadias from this **_Female_** * Oestrogens cause genital swellings to be labia majora and urethral folds to be labia minora * Genital tubercle becomes clitoris * Urogenital groove therefore remains open, forming the **vestibule** into which the urethra and vagina open

Answer 18

Arise in the upper lumbar region, tethered to the scrotum or labia by the **gubernaculum**

Answer 19

**Females**: 8-14 **Males**: 10-16 **_Hypothalamic-Pituitary-Gonadal (HPG) axis_** * Hypothalamus release GnRH in pulsatile fashion to stimulate anterior pituitary to release LH and FSH * LH and FSH stimulate sex hormones to be produced that then negatively feedback

Answer 20

COME BACK TO AND FINISH

Answer 21

They produce anti-mullerian hormone so mullein duct degenerates

Answer 22

* Miscarriage * Premature birth * Malpresentation

Answer 23

Discovered at menses, patient has cyclical pain/cramping but no bleeding Retrograde menstruation can lead to endometriosis Need to do surgical incision

Answer 24

Septum transverse across vagina that can be perforate or imperforate If perforate will menstruate but issues with tampon use and intercourse. If imperforate then similar to imperforate hymen **Dx**: MRI, US or exam

Answer 25

* Infertility * Pregnancy complications Can have surgery to correct but risk of recurrence and vaginal stenosis

Answer 26

Failure of Mullerian Ducts to develop Pt will still have ovaries so will still produce female sex hormones Use vaginal dilator or surgery

Answer 27

**X linked recessive** inheritance in **androgen receptor gene**. Pt is **XY**, genetically male with internal testes but female external genitalia Lack of androgen receptors so body cannot respond to androgen. Androgens get converted to oestrogens so **female secondary sex characteristics** **Pt has testes and a vagina but no upper vagina, fallopian tubes, uterus, ovaries** as testes produce **anti-mullerian hormone** so they degenerate

Answer 28

In infancy with **inguinal hernias** from testes or in teenage years with **primary amenorrhea** * Lack of pubic hair * Lack of axilla hair * Lean muscles * Taller than female average * Infertile

Answer 29

TESTICULAR CANCER

Answer 30

* micropenis * clitoromegaly * bifid scrotum * hypospadias * diminished male characteristics

Answer 31

* Raised LH * Normal or raised FSH * Normal or raised testosterone levels (for a male) * Raised oestrogen levels (for a male)

Answer 32

* ***Bilateral orchidectomy*** to avoid testicular tumours * ***Oestrogen therapy*** * ***Vaginal dilators*** or ***vaginal surgery*** can be used to create an adequate vaginal length * ***Psychological support***

Answer 33

4 weeks (can feel pregnant uterus above pubic symphis at about 12 weeks)

Answer 34

POP!!! Can only fit coil 48 hours after delivery or 4 weeks after

1 - Anatomy Flashcards

(60 cards)