General Revision Q's Flashcards
Concerning fertilisation of the human ovum:
(i) spermatozoan penetration of the corona radiata causes cortical granules to release their contents within the ovum to prevent further entry from additional spermatozoa.
(ii) fertilisation is complete once the male and female pronuclei have fused.
(iii) the ovum contains 21 chromosomes in total.
(iv) the cytoplasm of the spermatozoan does not contribute to the formation of the embryo proper or supporting tissues
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
B
Concerning implantation of the embryo:
(i) the blastocyst ‘hatches’ from the zona pellucida on day 3-4
(ii) embryoblast cells penetrate the endometrium of the uterus and initiate proliferation of blood vessels and glands.
(iii) Luteinising hormone promotes continued production of progesterone from the corpus luteum to maintain endometrial thickness following implantation.
(iv) ectopic pregnancies are defined by implantation occurring in any location other than the body of the uterus.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
D
Concerning the formation of the primitive streak:
(i) it forms as a thickening of the hypoblast.
(ii) it elongates towards the prechordal plate of the embryo.
(iii) epiblast cells migrate through the primitive groove to displace hypoblast cells and form the definitive ectoderm.
(iv) the invagination of cells through the primitive pit forms the notochordal process.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
B
Concerning the process of ossification:
(i) formation of bone tissue directly from a condensed mesenchyme is called endochondral ossification.
(ii) irregular-shaped bones such as the vertebra and os coxa form from a single primary ossification centre.
(iii) all secondary ossification centres form after birth.
(iv) the epiphyseal plate is the site of endochondral ossification during longitudinal bone growth.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
D
Concerning the development of the musculoskeletal system:
(i) the sclerotome contributes to the formation of the vertebrae and ribs.
(ii) the hypomere forms the skeletal muscles of the thoracic and abdominal walls, and limbs.
(iii) sacralisation is characterised when L5 vertebra fuses with S1 to contribute to the formation of the sacrum.
(iv) in the case where only one chondrification centre develops in the body of the vertebra, a hemivertebra may form resulting in congenital scoliosis.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
E
Concerning spina bifida:
(i) spina bifida occulta is more common in neonates than adults, suggesting that it may represent delayed fusion of the vertebral arch rather than failed fusion in some patients.
(ii) spina bifida may result from a failure of the neural tube to close.
(iii) in spina bifida cystica, if the cyst contains only meninges and cerebrospinal fluid it is classified as a meningocele.
(iv) spina bifida myeloschisis is fatal.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
E
Concerning cell fate, organisers and gene signalling:
(i) the right/left axis is established by Nodal secreted by the primitive node being pushed to the left side of the embryo by the directional beating of cilia.
(ii) the severity of upper limb defects in infants was higher in women taking Thalidomide earlier in their pregnancy.
(iii) expression of Runx2 is required for mesenchyme or cartilaginous tissue to differentiate into bone tissue.
(iv) the anterior/posterior axis is established by a thickening of the epiblast cells called the prechordal plate
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
C
Concerning bone tissues:
(i) bones are unable to use interstitial growth to expand due to the hardness of the tissue bestowed by its inorganic/mineral phase.
(ii) osteoblasts are multinucleated cells that resorb bone tissue.
(iii) the periosteum is a source of blood vessels and mesenchymal stem cells for tissue growth and repair.
(iv) osteons are formed from multiple concentric lamellae surrounding a perforating canal in trabecular bone tissue.
KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct
A
Explain the purpose of the periosteal callus during fracture healing and describe the event that signals consolidation of the callus
Concerning the foetal circulation:
(i) The fossa ovalis directs blood flow from the right atrium to the left atrium
(ii) Avoids the pulmonary system
(iii) The closure of the fossa ovalis is made from the septum secundum and septum primum
(iv) The ductus arteriosus directs blood flow from the aorta to the pulmonary artery
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct
Concerning the foetal circulation:
(i) the ductus arteriosus carries blood to the inferior vena cava.
(ii) the oxygenated blood is carried from the placenta of the embryo/foetus to the umbilical vein.
(iii) the umbilical vein regresses to form the medial umbilical ligaments.
(iv) the ductus arteriosus allows the blood to bypass the pulmonary circuit in the foetus
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct
Concerning the effect of oestrogen deficiency on bone remodeling:
(i) osteoclastic resorption is relatively rapid, osteoblastic replacement of bone may take up to 3 months in adult humans, creating a temporary bone deficit called the remodelling space.
(ii) oestrogen deficiency also stimulates osteoclast apoptosis.
(iii) both osteoblast and osteoclast numbers increase with oestrogen deficiency.
(iv) the average lifespan of an osteoblast is 12 days, while the osteoclast lifespan varies from a few days to 100 days.
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct
Concerning ageing of the muscular system:
(i) an increased sedentary lifestyle with age results in a decrease in muscle mass, known as sarcopenia.
(ii) with reduced diameters, the muscle fibres have a decreased ability to produce ATP and therefore have reduced ability to produce force and fatigue quickly.
(iii) the rate of sarcopenic muscle loss can be controlled by the level of activity and exercise of the individual.
(iv) motoneuron number and calcium ion release from the sarcoplasmic reticulum increases with age resulting in less fine control of movements and diminished muscle force production
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct
Concerning the development of the axial skeleton:
(i) cells of the sclerotome migrate to surround the neural tube and form the spinal chord.
(ii) the epimere differentiates into the myotome and hypomere.
(iii) the notochord persists in the intervertebral disks as the nucleus pulposus, but degenerates in the bodies of the vertebrae.
(iv) the epimere forms the superficial muscles of the back
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct
Concerning spina bifida:
(i) myeloschisis is classified as a neural tube defect
(ii) occulta is the most severe form of Spina Bifida
(iii) meningocele contains nervous tissue, cerebrospinal fluid and meninges
(iv) it is a result from failed fusion of the chondrification centres of the right and left hemiarches of vertebral column
KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct