PSL300 Term test 2 COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS WITH RATIONALES (VERIFIED
ANSWERS) |ALREADY GRADED A+
T3 vs T4
both circulate in blood while bound to plasma proteins
T3 is more potent than T4
T4 is converted to T3 in target tissue
both bind to nuclear thyroid receptors - lipophilic (form homodimers or
heterodimers with retinoic acid receptor)
alter gene transcription
functions of thyroid hormones
metabolism (metabolic rate, oxygen consumption, heat production,
protein degradation, lipolysis), nervous system (brain development,
enhanced speech, thinking, reflexes), growth and development (esp in
children, works with GH), CV (increased heart rate and contractility,
peripheral blood flow, increased number of beta adrenergic receptors),
too much causes muscle weakness (too much protein degradation)
,hyperthyroidism
- thyroid hormone excess
- caused by tumours of anterior pit or thyroid, or thyroid-stimulating
immunoglobulins (Graves' disease)
- symptoms: goiter (increased metabolism, high energy demand),
nervousness, insomnia, anxiety, high heart rate, bulging eyes
(exophthalmos), weight loss
- treatment: removal of part of thyroid gland, drugs blocking synthesis of
T3 and T4 or conversion to T3 and T4
Graves disease
- common cause of hyperthyroidism
- abnormal antibodies against TSH receptor produced (autoimmune
disease)
- most common cause of general thyroid enlargement (goiter) in
developed countries
,hypothyroidism
- thyroid hormone deficiency
- causes: underactive thyroid gland, lack of iodine
- symptoms: goiter (normal parts of thyroid grow bigger to compensate
for decreased thyroid hormone), decreased metabolism, slowed heart
rate, slowed speech, fatigue, cold-intolerance, CRETINISM (infants -
abnormal development of nervous system), stunted growth, WEIGHT
GAIN
- treatment: exogenous T4
iodine deficiency
- thyroid gland unable to produce t4 and T3
- lack of negative feedback leads to excess TSH secretion
- TSH stimulates growth of thyroid gland
meiosis vs mitosis
- meiosis: DNA replicated once, but 2 divisions, nonhomologous
recombination, independent assortment, haploid gametes
mitosis: normal cell division, DNA replicated once, and 1 division
, GnRH pulses
- regulated by hormonal feedback (androgens and estrogens) and higher
brain centres
- frequency/amplitude changes during development (low freq - FSH
release, high freq - LH release)
production of sperm in testes
- produced in testes
- optimal at 2-3 degrees lower than body temp (scrotum is external to
body)
- takes around 64 days
- further mature in epididymis
spermatogenesis
- spermatogonia (2n) formed during fetal development
- following mitosis, one spermatogonium stays to produce more
- the other cells begin to undergo meiosis forming spermatocytes
- primary (4n) and secondary (2n) spermatocytes, spermatids (n)
- 4 spermatids from one starting cell
- spermatids mature into spermatozoa
DETAILED ANSWERS WITH RATIONALES (VERIFIED
ANSWERS) |ALREADY GRADED A+
T3 vs T4
both circulate in blood while bound to plasma proteins
T3 is more potent than T4
T4 is converted to T3 in target tissue
both bind to nuclear thyroid receptors - lipophilic (form homodimers or
heterodimers with retinoic acid receptor)
alter gene transcription
functions of thyroid hormones
metabolism (metabolic rate, oxygen consumption, heat production,
protein degradation, lipolysis), nervous system (brain development,
enhanced speech, thinking, reflexes), growth and development (esp in
children, works with GH), CV (increased heart rate and contractility,
peripheral blood flow, increased number of beta adrenergic receptors),
too much causes muscle weakness (too much protein degradation)
,hyperthyroidism
- thyroid hormone excess
- caused by tumours of anterior pit or thyroid, or thyroid-stimulating
immunoglobulins (Graves' disease)
- symptoms: goiter (increased metabolism, high energy demand),
nervousness, insomnia, anxiety, high heart rate, bulging eyes
(exophthalmos), weight loss
- treatment: removal of part of thyroid gland, drugs blocking synthesis of
T3 and T4 or conversion to T3 and T4
Graves disease
- common cause of hyperthyroidism
- abnormal antibodies against TSH receptor produced (autoimmune
disease)
- most common cause of general thyroid enlargement (goiter) in
developed countries
,hypothyroidism
- thyroid hormone deficiency
- causes: underactive thyroid gland, lack of iodine
- symptoms: goiter (normal parts of thyroid grow bigger to compensate
for decreased thyroid hormone), decreased metabolism, slowed heart
rate, slowed speech, fatigue, cold-intolerance, CRETINISM (infants -
abnormal development of nervous system), stunted growth, WEIGHT
GAIN
- treatment: exogenous T4
iodine deficiency
- thyroid gland unable to produce t4 and T3
- lack of negative feedback leads to excess TSH secretion
- TSH stimulates growth of thyroid gland
meiosis vs mitosis
- meiosis: DNA replicated once, but 2 divisions, nonhomologous
recombination, independent assortment, haploid gametes
mitosis: normal cell division, DNA replicated once, and 1 division
, GnRH pulses
- regulated by hormonal feedback (androgens and estrogens) and higher
brain centres
- frequency/amplitude changes during development (low freq - FSH
release, high freq - LH release)
production of sperm in testes
- produced in testes
- optimal at 2-3 degrees lower than body temp (scrotum is external to
body)
- takes around 64 days
- further mature in epididymis
spermatogenesis
- spermatogonia (2n) formed during fetal development
- following mitosis, one spermatogonium stays to produce more
- the other cells begin to undergo meiosis forming spermatocytes
- primary (4n) and secondary (2n) spermatocytes, spermatids (n)
- 4 spermatids from one starting cell
- spermatids mature into spermatozoa
