Human Development Flashcards
Male vs female pelvis
Female = larger and wide Female = more flared iliac crests Male = sharper pubic arch Females = wider more oval pelvic inlet Males = coccyx angled more forwards Males = ischial bones closer giving narrower pelvic outlet
Sacrotuberous ligament
Sacrum –> ischial tuberosity
Sacrospinous ligament
Sacrum –> ischial spine
Sacroiliac ligament
sacrum –> ilium
Greater sciatic foramen
Formed by sacrotuberous and sacrospinous ligaments
Piriformis, sciatic nerves, superior and inferior gluteal vessels and nerves, internal pudendal nerve and vessels
Lesser sciatic foramen
Former by sacrospinous ligaement superiorly and sacrotuberous inferiorly
Obturator internus, internal pudendal nerve (re-entering the pelvis)
Parts of levator ani from anterior to posterior
Levator prostate/sphincter vaginalis
Puborectalis - pubic bone around rectum
Pubococcygeus - pubis –> anococcygeal body
Iliococcygeus - ilium –> sanococcygeal body and coccyx
Coccygeus
Ischial spines –> lateral sacrum and coccyx
Function of pelvic floor
Support and maintain pelvic viscera is position
Maintain continence
Resisting abdominal and intra-pelvic pressure
Folic acid in preventing birth defects
400mg per day
Could prevent around 75% of neural tube defects
Embryonic vs foetal period
Embryonic = 3-8 weeks Foetal = 8 weeks --> term
Major vs minor congenital defects
Major = require medical or surgical intervention or causes significant handicap
Anencephaly
Malformed head and brain
Failure of anterior neuropore to close
Spina bfida
Herniation of spine and contents in the lower back
Failure of posterior neuropore to close
Hypospadias
Male urethra opens out in unusual place
Cleft lip
Failure of maxillary and medial nasal prominences to fuse
Cleft palate
Failure of palatine shelves to fuse
Holoprosencephaly
Loss of midline structures
Omphalocele
Abdominal contents do not correctly return from umbilical cord
Gastrochisis
Abdominal contents herniate through defect in anterior abdominal wall
Phocemelia
Limb abnormalities
Syndactylyl
Digits fused together
Polydactyly
Extra digits
Ankyloglossia
Tongue tie
Unusually thick and short frenulum
Hydatiform male
Diploid cells but genetic material purely from father
Sirenomelia
Lower body parts fused
Epiblast cells stop invaginating too early
Situs invterus
Reversal of left and right axis of the body
Atrial septal defect
Blood can flow between two atria
Ventricular septal defect
Blood can flow between two ventricles
AV canal
Lack of AV septum
Coarctation of aorta
Aortic narrowing where ductus arteriosus inserts
Transposition of the great vessels
Vessels connect to incorrect heart chamber
Truncus arteriosus
Aorta and pulmonary trunk fail to fully separate
Tetralogy of Fallot
Overriding aorta that can take blood from left heart
Pelvic kidney
Kidney that failed to migrate up to posterior abdominal wall
Horseshoe kidney
Kidneys fused inferiorly
Vitelline duct abnormality
Meckel’s diverticulum
Small pocket of vitelline duct remains in the ileum
Tracheo-oesophageal fistula
Failure of trachea and oesophagus to fully divide
Hirschprung’s disease
Loss of enteric nervous system ganglion cells in the gut
Female vs male primitive genital tubes
Female = Mullerian ducts
Male = Wolffian ducts
Mullerian ducts more lateral
When do gonadal ridges begin to form?
5th week of gestation
Where does the gubernaculum attach?
To the gonadal ridge and the labioscrotal swellings (future scrotum or labia majora)
Contents of spermatic cord
Gubernaculum, vas deferens, testicular vessels, nerves and lymphatics
What is the tunica vaginalis?
Portion of peritoneum that was pulled down into the scrotum with the descent of the testicles
When does testicular descent occur?
Around the 26th week
Inguinal canal structure
4cm long
2mm above inguinal ligament
Starts at deep inguinal ring
Ends at superficial inguinal ring
What passes through the inguinal canal
Ilioinguinal nerve
Round ligament in females
Spermatic cord in males
Testicular blood supply
Bia testicular arteries from L2 of AA
Venous drainage via testicular veins to the IVC on the right and left renal vein on the left
Vas deferens length
45cm
Vas deferens course
From the epididymis in the scrotum
Up into the pelvis through the spermatic cord
Crosses external iliac vessels
Passes around the lateral walls of the pelvis
Crosses ureter posterior to the bladder
Joined by seminal vesicle to empty into the ejaculator duct in the prostate
Indirect inguinal hernia
Herniation of abdominal contents through the deep inguinal ring
Processes vaginalis fails to close
Hydrocele
Accumulation of peritoneal fluid in the scrotum
Processes vaginalis still slightly open
Ovarian ligament
Cranial gubernaculum remains
Ovary –> uterus
Round ligament
Caudal gubernaulum remains
Uterus –> labia majora
Broad ligament
Double fold of peritoneum overlying uterus
Suspensory ligament
Peritoneum overlying ovarian vessels
Ovarian blood supply
From AA
Venous drainage to AA on the right and left renal vein on the left
Peritoneal pouches
Vesicouterine = between bladder and uterus
Rectouterine (pouch of Douglas) = between uterus and rectum
Fluid can accumulate here
Support of the uterus
Levator ani
Transverse cervical ligaments
Pubocervical ligaments
Sacrocervical ligaments
Vagina fornices
Anterior
Posterior
2 lateral
Ureter course in females
Pass over pelvic prim at common iliac bifurcation
Pass under ovarian arteries
Run of lateral pelvic walls and pass anterior to reach the bladder passing either side of the cervix
Ectoderm
Skin, hair, nails, nervous system
Mesoderm
Muscles, skeleton, heart, connective tissue
Endoderm
GI system, lungs, liver, pancreas, GU system
Foregut
Pharynx –> superior duodenum
Midgut
Superior duodenum –> 2/3 of transverse colon
Hindgut
1/3 of transverse colon –> rectum
Urogenital triangle borders
Pubic symphysis anteriorly
Inferior pubic rami laterally
Line between ischial tuberosities posteriorly
Anal triangle borders
Line between ischial tuberosities anteriorly
Sacrotuberous ligaments laterally
Coccyx posteriorly
Pudendal canal
Contains pudendal vessels and nerve
Lies within the fascia of the obturator internus in the lateral walls of the ischioanal fossa
Branches of internal pudendal artery
Dorsal artery of the clitoris/penis
Perineal artery
Inferior rectal artery
Pudendal nerve
S2-4
Leaves pelvis through greater sciatic foramen
Re-enters pelvis to reach the perineum through lesser sciatic foramen
Branches to give the dorsal nerve of penis/clitoris, perineal and inferior rectal
Deep perineal pouch contents
External urethral sphincter Deep transverse perineal Vagina Proximal female urethra Membranous male urethra Male bulbourethral gland
Superficial perineal pouch contents
Crura of penis/clitoris Bulb of penis/clitoris Bulbospongiosus Ischiocavernosus Superficial transverse perineal Bartholin's gland in females
Superficial perineal fascia layers
Membranous (Colles’) - thin, strong layer binding muscles of the root of the penis
Fatty (Camper’s) - continuous with fascia of the thigh
Erection
Parasympathetic outflow via inferior hypogastric plexus
Nitric oxide release
Vasodilation and engorgement
Ejaculation
Sympathetic fibres cause contraction of the epididymis, vas deferens, seminal vesicles and prostate
Bladder sphincter contracts to prevent retrograde ejaculate flow
Bulb of vestibule
Divided by vagina
Superficially covered by bulbospongiosus
Crura of clitoris
Attaches to pubic arch and rami and pubis and ischium
Superficially covered by ischiocavernosus
Bartholin’s gland
Found posterior to the bulbs of vestibule
Secrete lubricating mucous into the vaginal orifice
Blockage of ducts can lead to Bartholin’s cyst
Muscles attaching to perineal body
Levator ani
External anal sphincter
Bulbospongiosus
Superficial transverse perineal
Genitofemoral nerve
L1-2
Skin of scrotum/labia majora
Cremaster muscle
Lumbosacral trunk
L4-5
Emerges medial from psoas major
Joins sacral plexus
Anatomical orientation of the uterus
Anteverted with respect to the vagina
Anteflexed with respect to the cervix
Process of gastrulation
Formation of primitive streak in epiblast
Epiblast cells invaginate to displace the hypoblast to become endoderm
Cells that do not invaginate become the ectoderm
Cells between the layers become mesoderm
What do neural crest cells form?
Cranial –> bones of the skull, pia and arachnoid mater, cranial nerves components
Trunk –> melanocytes, Schwann cells, dorsal root ganlia, parasympathetic nerves
Oligohydramnios
Lack of amniotic fluid
Due to kidney defects
Poluhydramnios
Excessive amniotic fluid
Due to GI atresia
AFP
= foetal albumin
High levels = neural tube defects, GI atresia
Low levels = Down’s syndrome
Haemopoiesis sources in gestation
Initially = yolk sac Secondly = liver, thymus and spleen Finally = bone marrow
Sinus venosus becomes…
Coronary sinus and smooth part of right atrium
Primitive atrium becomes…
Trabeculated atrial parts
Primitive ventricle becomes…
Trabeculated ventricular parts
Bulbus cordis becomes…
Smooth ventricular parts
Truncus arteriosus becomes…
Aorta and pulmonary trunk
1st pharyngeal arch
CN V
Muscles of mastication, mylohyoid, anterior belly of digastric
Maxilla, mandible, incus, malleus, zygomatic, temporal, palatine, vomer
2nd pharyngeal arch
CN VII
Muscles of facial expression, posterior belly of digastric, stylohyoid, stapedius
Stapes, styloid process, lesser horn of hyoid
3rd pharyngeal arch
CN IX
Stylopharyngeus
Greater horn of hyoid
4th pharyngeal arch
CN X (superior laryngeal) Muscles of soft palate and pharynx, cricothyroid
5th pharyngeal arch
CN X (recurrent laryngeal) Muscles of the larynx, upper oesophageal muscle
1st pharyngeal pouch
Epithelial lining of auditory tube and middle ear
2nd pharyngeal pouch
Palatine tonsil
3rd pharyngeal pouch
Inferior parathyroid gland and thymus
4th pharyngeal pouch
Superior parathyroid gland
1st pharyngeal groove
External auditory meatus
1st pharyngeal membrane
Tympanic membrane
Origins of the tongue
Anterior 2/3 from 1st pharyngeal arch
Posterior 1/3 from arches 2-4
Skull fontanelles
Anterior
Sphenoid
Mastoid
Posterior
Testosterone secretion
From Leydig cells by LH
Sertoli cell function
Support and nourishment of spermatogenic cells
Secretion of androgen binding protein
Secretion of inhibin for negative feedback
Epididymis function
Accumulation, storage and maturation of spermatozoa
Epididymis epithelium
Pseudostratified columnar with sterocilia
Vas deferens epithelium
Pseudostratified columnar with sterocilia
Seminal vesicles secretions
Secretion rich in fructose, vitamin C and prostaglandins
Prostate divisions
Anterior fibromuscular zone with CT and muscle fibres
Central zone around ejaculatory ducts
Transitional zone around urethra
Peripheral zones where the majority of glands are found
Where does BPH occurs?
Transitional zone
Where does carcinoma of the prostate occur?
Peripheral zones
Prostate gland secretions
Rich in citric acid and hydrolytic enzymes such as fibrinolysin
Endo vs ectocervix
Endocervix closer to uterus
Ectocervix closer to vagina
Endocervix = simple columnar epithelium
Ectocervix - stratified squamous epithelium
Layers of villi at the start
Capillary endothelium
Loose CT of the villus core
Cytotrophoblast
Syncytiotrophoblast
Layers of villi after maturation
Capillary endothelium
Syncytiotrophoblast
When do erthyrocytes lose their nuclei?
9th week of gestation
Telomere sequence
TTA GGG
Diseases where shortened telomeres are found
Atherosclerosis
Heart disease
Hepatitis
Cirrhosis
Pearl index formula
= number of unintended pregnancies per 100 women years of use
COCP mechanisms of action
Oestrogens inhibits FSH secretion resulting in anovulation
Progesterone inhibits LH secretion resulting in anovulation, thickens cervical mucous and causes endometrial atrophy
COCP contraindications
Heart disease, stroke, hyperlipidaemia, liver disease, pregnancy, oestrogen dependant tumours
COCP advantages
Protection from ovarian and endometrial cancer
Reduced incidence of benign breast lumps, ovarian cysts and endometriosis
COCP disadvantages
Increased chance of clots
Impaired liver function
Weight gain
POP mechanism of action
Progesterone inhibits LH secretion resulting in anovulation, thickens cervical mucous and causes endometrial atrophy
POP advantages
No increase in thromboembolic events
Can be used by those with contraindications of COCP use
POP disadvantages
Irregular bleeding
Headache
Acne
Fertilisation steps
Sperm finds and recognises egg via ZP3 glycoprotein
Acrosome reaction to penetrate extracellular layer
Fusion of cell membranes
Calcium wave to block polyspermy
Fertilisation cone formation
Movement and fusion of pronuclei
Acrosomal enzymes
Hyaluronidase
Acrosin
When does hatching occur?
Day 5
When does the blastocyst attach to the uterine wall?
Day 7-9
When does first differentiation take place?
Day 6
Diseases associated with proportionate short stature
Turner syndrome Renal insufficiency GI disease Nutritional deficiency Hypothyroidism Hypercortisolism
Diseases associated with disproportionate short stature
Achondroplasia
Hypochondroplasia
Rickets
Onset of puberty is defined as…
Tanner stage B2 for girls - breast budding
Tanner stage G3 for boys - testes volume >3ml
Mean age of puberty onset
11 for girls
12 for boys
When do the primordial germ cells leave the ectoderm and move to the yolk sac wall?
3rd week
When do the PGCs move to the gonadal ridges?
6th week
When do oogonia undergo intensive mitosis?
2nd-5th months of pregnancy
Stages of meiosis
Meiosis I = reduction division - diploid –> haploid
Meiosis II = equatorial division - independant reassortment of maternal and paternal chromosomes
When does crossing over occur?
Prophase I
What stimulates completion of meiosis I in primary oocytes
LH
Where does meiosis II arrest?
Metaphase
What triggers completion of meiosis II?
Fertilisation
Follicular antrum contents
Enzymes for digestion of follicular wall
Proteoglycans to attract water
Define primary spermacyte
Type B spermatogonia as they enter meiosis I
Define secondary spermacyte
Spermacyte that has completed meiosis I
How long does sperm meiosis I take?
24 days
Define spermatid
Sperm that has completed meiosis II
Why is the foetus not rejected by the mother’s immune system?
IgM antibodies to fathers MHC molecules
Placenta sequesters foetus from maternal T cells
Protective features of the trophoblast including HLA-G expression, IDO production (depletes tryptophan to inhibit T cell activation) and lack of classic MHC molecules
Which antibody can pass through the placenta?
IgG
Which antibody can pass through breast milk?
IgA
How is IgG transported across the placenta?
Neonatal FcR
Structure of IgA
Dimer
Two antibodies connected by J chain
Secretory component to prevent degradation
Contraindication for immunisation
Anaphylaxis to previous dose
Immunosuppression
Acute illness
Inactivated vs attenuated vaccines
Virus can replicate in attenuated and not in inactivated
Inactivated vaccines general humoral immunity whereas attenuated develop humoral and cell-mediated
Labour associated prostaglandins
E2 and F2a
Signs of labour
The show
Rupturing of membranes
regular painful contractions accompanied by cervical dilatation
What is cut in an episiotomy?
Vaginal epithelium and perineal skin
Bulbocavernosus
Superficial and deep perineal muscles
Someones external anal sphincter
Define menopause
The last menstrual period
Average age of menopause
52
When are women said to have gone through the menopause?
After 1 year of no periods
Perimenopausal symptoms
Changes in menstrual cycle length
Hot flushes and night sweats
Short term menopause symptoms
Hot flushes Night sweats Palpitations Depression Mood swings Increased urinary frequency Urge incontinence Vaginal dryness Pain during urination and intercourse Dry inelastic skin Hair loss Joint pain
Long term menopause symptoms
Ischaemic heart disease Osteoporosis Inelastic thin skin Prolapse Incontinence Depressed libido Atrophic changes to GU organs Pain during intercourse
Combinations of HRT
Oestrogen and progesterone if uterus present
Oestrogen only if no uterus present
Side effects of HRT
Heavy cyclical bleeding Bloating and fluid retention Weight gain Mastalgia Headaches Depression
Complications of HRT
Increased breast cancer risk
Increased risk of thrombo-embolic events
Contraindications for HRT
Breast cancer Endometrial cancer Endometriosis Fibroids Ischaemic heart disease
Non-hormonal treatments for menopause
Biphosphonates and calcitonin - reduce osteoclast activity
Selective oestrogen receptor modulators
Venlafaxine - reduce vasomotor symptoms
Follicular phase
Days 1-10
5-12 follicles stimulated to grow
One will become a Graafian follicle
GnRH stimulates FSH and LH which stimulates the growth of the follicle and oestrogen secretion
Ovulatory phase
Days 11-14
Graafian follicle bulges from ovary wall
Ovulation occurs
Surge of LH and FSH
Luteal phase
Days 15-28
Formation of corpus luteum
Progesterone secretion maintains endometrium
Menstrual phase
Days 1-5
Collapse of endometrium
Withdrawal of oestrogen and progesterone
Proliferative phase
Days 6-14
Thickening of endometrium and formation of glands and spiral arteries
Synthesis of progesterone receptors on endometrial cells
All stimulated by oestrogen from the mature follicle
Secretory phase
Days 15-28
Enlargement of glands and secretion of mucous and glycogen
Stimulated by progesterone from the corpus luteum
Structure of surfactant
Monolayer of phospholipids
Mainly consists of DPPC and PG
Stabilised by surfactant protein B
Foetal metabolic stores
34g of glycogen
560g of fat
Newborn metabolic fuels
Free fatty acids
Glucose and ketone bodies for the brain
Immune protection from breastmilk
IgA
Lactoferrin
Lysozyme
Complement
Blood changes in pregnancy
Increase in plasma volume by up to 45%
Increase in RBC volume
RBC increase less so physiological anaemia of pregnancy possible
Why does plasma volume increase during pregnancy?
Vasodilation Decreased TPR Decreased renal perfusion Activation of RAAS Sodium and water retention
Cardiac output in pregnancy
Increases by 35-40% in first trimester and 50% by term
Increase in stroke volume by 25%
Increase in heart rate by 25%
When is blood pressure at a low point
17-24 weeks
Mediators involved in TPR decrease
Progesterone, oestrogen, NO, relaxin
Haemostasis in pregnancy
Hyper coagulable state
Increase in fibrinogen and all clotting factors (except XI and TF)
Decrease in coagulation inhibitors
Increased platelet production
Respiratory changes in pregnancy
Increased oxygen consumption
Increased alveolar and minute ventilation
Increased tidal volume
Mechanisms of increase in ventilation
Progesterone-mediated hypersensitivity to CO2
Acid base changes in pregnancy
Increased ventilation means more CO2 expelled
Respiratory alkalosis
Some renal compensation
Foetal vs maternal placenta surfaces
Foetal = smooth with umbilical cord centrally with vessels radiating outwards Maternal = dull and grey with 15-20 segments
Umbilical artery vs vein
2 umbilical arteries carrying waste and carbon dioxide from the foetus to the placenta
1 umbilical vein carrying oxygen and nutrients from the placenta to the foetus
Human placental lactogen function
Increases FFA by lipolysis
Promotes mammary duct proliferation
Inhibits gluconeogenesis
Human placental growth hormone function
Regulation of maternal blood glucose levels
Types of locia
Lochia rubra - red - 0-3 days
Lochia serosa - pink - 4-10 days
Lochia alba - yellowish white - up to 6 weeks
Hormones responsible for mamogenesis
Oestrogen, progesterone, prolactin, human placental lactogen
Action of prolactin
Secreted from anterior pituitary gland
Causes lactogenesis
Action of oxytocin
Secreted from posterior pituitary
Release stimulated by suckling
Causes contraction of myoepithelial cells in ducts and alveoli to empty milk from the breast
Steroid structure
27 carbon skeleton with 4 fused rings
Core formed by cholesterol
Testosterone –> DHT
By 5a reductase enzymes in Sertoli cells
Androgen potencies
DHT = 100% Testosterone = 50% Androstenedione = 8% DHEA = 4%
Oestrogen potencies
17b oestradiol = 100%
Oestriol = 10%
Oestrone = 1%
LH vs hCG
Same alpha subunits (and for FSH)
Same beta subunits but hCG contains additional 24 amino acids
Sites of inhibin secretion
Males = Sertoli cells Females = granulosa cells
Prostaglandin synthesis
Essential fatty acids –> arachidonic acid
Arachidonic acids are then oxidised by COX enzymes to produce prostaglandins
Characteristics of stem cells
Undifferentiated
Can divide indefinitely
Order of stem cell potencies
Totipotent Pluripotent Multipotent Oligopotent Unipotent
Visual acuity at birth
6/60
Piaget’s sensorimotor stage
0-2
Integration of perception and motor actions
Cause and effect understanding
Object permanence
Piaget’s pre-operational stage
2-7
Egocentric
Animism
Only considers one feature of a problem at a time
Piaget’s concrete operational stage
7-12
Can apply logic
Can classify objects according to several features
Piaget’s formal operational stage
12-19
Abstract reasoning
Becomes concerned with hypothetical and future scenarios
Freud’s psychosexual stages
Oral = 0-2 Anal = 2-4 Phallic = 4-5 Latency = 6-puberty Genital = puberty onwards