MCB 135E
Please print this out; it'll help with your studying!
Lecture #2 Male Reproductive System
Key Words to Know
1. What is gametogenesis?
a. What are the male and female gametes?
b. What is the product of fertilization?
2. Anatomy of Male Reproductive System
a. What is the PRINCIPAL reproductive organ? The Brain
b. Primary male sex organs?
c. Secondary male sex organs?
d. What are the three type of cells in male repro system and what do they do?
e. what is spermatogenesis?
i. Where is the site of spermatogenesis in the testis?
ii. What is spermatocytogenesis?
iii. What is spermiogenesis?
f. What are the parts of the mature spermatozoa?
i. What is the threshold when a man is considered sterile?
g. How many spermatids are formed from one spermatogonium? How long does it take?
h. What can harm the development of sperms?
Lecture #2 Study Guide Answers
1. development of male and female sex cells or gametes
a. Sperm and Ovum
b. Zygote
2. a. The Brain
b. The testis
c. epididymic, vas deferens, ejaculatory ducts, seminal vesiscles, prostrate and bulbourethral glands, penis with urertha
d. i. Germ Cells fertilization ii. Interstitial Cells of Leydig secrete testosterone iii. Sertoli Cells secretory and repro
e. process of formation of male gametes
i. seminefeirous tubules
ii. first stage of meiosis spermatogonium (N = 46) to spermatocytes (N=23) to spermatids
iii. second stage of maturation, spermatids become spermatozoa
f. head with acrosome, midpiece, long tail or flagellum, 23 chromos, and LARGE number 80-100 million per ejaculation.
i. less than 20 million
g. 500-600 and 70 days
h. HEAT!!
Lecture #3 Female Reproductive System
1. What is the primary female sex organ?
2. What are the secondary sex organs?
3. What are the two function functions of the ovaries?
4. what is N=46 chromosome germ cell in the female called?
5. what is the hormone that stimulates the release of estrogen from the follicular cells?
6. Describe the succession of hormones that promote ovulation.
7. what is this system of hormonal regulation between these three organs called?
8. what type of hormones are GnRH, LH and FSH?
9. what type are estrogen and progesterone?
10. Describe the relative hormonal levels during the menstrual cycle?
Lecture #3 Answers
1. Ovaries
2. oviducts, vagina and external genitalia
3. a. Produce the ova
b. Secretion of estrogen and progesterone (from what type of cell?) and protein hormones relaxin and inhibitin
Notes/Extra Stuff on Inhibin and Relaxin
Relaxin encourages relaxation of cervical muscles (one of strongest muscles in the body) thus assisting in labor and delivery.
Inhibin is the hormone which stop the pituitary hormones from being released. It actually opposes activin (follicle-stimulating hormone-releasing protein). In studies, the addition of activin increased gonadotropin-releasing hormone (GnRH). Inhibin by itself did not modify placental immunoreactive GnRH, hCG, and progesterone secretion but reversed the activin-induced changes.
4. oogonium
5. FSH
6. a. GnRH from hypothalamus into portal system
b. FSH and LH released by anterior pituitary
c. FSH stimulates granulose cells to produce and release estrogen
d. LH stimulates the rupute of the follicle around Day 14
7. hypothamal pituitary gondal axis
8. Peptide
9. Steroid
10. a. follicular period (1-14 days)? FSH elevated,
estrogen elevated
b. ovulation (Day 15) burst of LH, follicle ruptures
c. luteal phase (15-28 Days) follicle becomes corpus luteum which produces estrogen and progesterone IF NO FERTILIZATION CL involutes, estrogen and progesterone decrease, FSH increases, back to Day 1
Also see Granulosa Cell Handout (will be posted on-line)
Lecture #4 Fertilization
1. What are the three phases of fertilization?
2. What does the ovum do at fertilization?
3. What is the role of the sperm at fertilization?
4. True or False The sperm are mature when they leave the testis.
5. What is capacitation and what is involved?
6. Where in the oviduct does fertilization usually occur?
7. How long after ovulation usually occur?
8. Where are the specific receptors to which the spermatozoa bind and what do they promote?
9. What is the result of fertilization?
10. Place these in order of division from earliest to latest: blastocyst, zygote, morula
COVER THIS UP YOU CHEATER!! J
Answers to Lecture #4
1. a. Penetration of ovum by sperm b. Activation of sperm and ovum c. Fusion of nuclei
2. a. maternal component of chromos b. rejects all sperm but one c. provides nourishment for developing zygote
3. a. GETS THERE!! b. Activates nuclear and cytoplasmic division c. Contributes paternal chromos AND DETERMINES SEX!!!
4. False not fully motile until get through male and female tract and get all those good juices!!!
5. The way in which the sperm are able to fertilize the ovum. Involves increasing adherence of spermatozoa to ovum, promotes acrosomal reaction and penetration of the ovum.
6. medial 1/3 (closest to ovary)
7. 48 hours
8. Zona pellucida receptors bind to spermatozoa. They act as binding sites and stimulate fusion of acrosomal membrane with plasma membrane of ovum.
9. a. DIPLOID number of chromos for the zygote b. SEX, determination of, not the actc. cell division
10. zygote, morula, blastocyst
Lecture # 5 Implantation
1. What happens when fertilization does not occur 48 hours after ovulation for any number of reasons i.e. sperm got lost, stupid latex barrier, drunken date couldnıt, well you know, etc.?
2. If fertilization does occur, at what day/s does the fertilized implant in the uterus? What is this stage of cellular division called?
3. Why do you need implantation to occur at this time?
4. What is nidation and what does it involve?
5. What does estrogen and progesterone do the uterine wall?
6. Which cells of the fertilized egg are dividing faster and why?
7. Why do you need the chorion?
8. What will the inner cells become?
Note: For the sake of the trees fold your paper over. Look at you, you environmentalist/tree hugger.
Lecture #5 Answers
1. Ovum degenerates (you canıt keep a girl waiting that long). It travels down to uterus and expelled with the menses (this happens because the corpus luteum involves, estrogen and progesterone levels decrease, endometrium is no longer maintained, but you knew that right?)
2. 6-8 days, Blastocyst
3. a. the fertilized egg is OUT OF MOJO nutritional resources have been taxed and need a refill (itıs like a road trip without a pit stop, for god sakeıs you need Mountain Dew to keep going!!), b. protection where would you rather go a biggy, cushy pillow that has immune protection or a long, dark tunnel.
4. Fancy-shmacy Latin way of saying implantation use this at cocktail parties (or frat parties) and impress your friends. It involves a complex set of interactions between zygote and mother that prepares the uterus for implantation.
5. Estrogen proliferation of uterine wall (becomes hypertrophic), Progesterone vascularization of uterine wall (becomes hypervascularized)
6. Outer cells need to assure implantation and these are the cells that will becomes the chorion
7. The chorion releases hCG which maintains corpus luteum (a good hormonal enviroment) and is the first means of communication (nutrient, oxygen, etc transfer) between mother and blastocyst.
8. THE BABY!!!
Note: THIS IS THE EXACT PICTURE FROM LECTURE. I found it on UCSDıs med school website. You love me, I know.
Vocab:
Cytotrophoblast : inner layer of trophoblast
Syncytiotropoblast: outer layer of the trophoblast; site of
synthesis of human chorionic gonadotropin.
Cytokines: hormone-like proteins, secreted by many cell types, which regulate the intensity and duration of immune responses and are involved in cell-to-cell communication
Lecture #6 Early Embryonic Stages and Placenta
But firsta little sex ed:
1. How does oral contraceptive prevent pregnancy? How effective is it?
2. What are the mechanical means of contraceptive?
3. What do both IUD and "morning after" pill prevent?
4. How effective are coitus interuptus and the rhythm method?
Now for the "serious" stuff:
5. What is the placenta and VERY BASICALLY how is it formed?
6. What is its function?
7. What is hCG, where is it produced and what does it do?
8. What is a uterine sinus?
9. What are chorionic villi and what do they do?
10. What is the arrow pointing to?
11. What is the yolk sac, how long does it last and what does it do?
12. What is the allantois and what will it become?
13. What is the amnion and what its function?
14. What is the deciduas? Basalis? Capularis? Parietalis?
15. How is amniocentesis performed and when is it done? What are the risks? What can it detect?
16. What is chorionic villi sampling? When? What can it detect?
17. Why would you perform these tests?
Answers Lecture #6
1. Prevents ovulation and changes cervical mucosa to make it more acidic thus killing sperm. 95-97% if taken regularly.
2. Tubal ligation and Vasectomy.
3. Implantation
4. 75-80% effective, makes you think twice doesnıt it!!
5. The organ by which the fetus will get all its nutrients and oxygen throughout the pregnancy. (will also accept Leonardo da Vinci). It is formed by a fusion (or apposition) of fetal and maternal tissues.
6. Feed the fetus, take away itıs waste, protect it immunologically, make hormones (hCG, hCS, estrogen, progesterone)
7. HSC (Human Chorionic Somatomammotropin)) or HPL (Human Placental Lactogen) Hormone producted by plancenta and regulated by estrogen that helps develop mammary glands. Also reduces the level of glucose consumed by the mother. The levels increase steadily from 3 weeks gestation to a limit in the last month of pregnancy (remember what estrogen does?)
8. Blood filled cavity or the uterus.
9. Thread like projections that extend into the uterine sinus from the chorion through which nutrient, oxygen and waste transfer occur.
10. Ok I didnıt really expect you to know this. Itıs a cotelydon a subdivision of the uterine surface of the discoidal planceta. You can also point out villi.
11. Yolk sac lasts from 6 weeks to 6 months. It produces fetal blood and is back-up feeding for the fetus.
12. The allantois is around for a very short time 3rd-4th wk. Why? Because it becomes the umbilical cord, arteries and vein which are ESSENTIAL to fetal survival.
13. The amnion right from implantation to birth. It serves as protection for the embryo/fetus.
14. These are all maternal membranes.
a. Deciduas is the uterine mucosa shed with delivery of placenta.
b. Basalis lies in between zygote and uterine wall and forms the maternal part of the placenta, stays throughout pregnancy.
c. Capsularis lies over the chorion, thin and distended, eventually fuses with parietalis.
d. Parietalis cover the uterus but
Eventually atrophies as the pressure from the fetus increases.
15. Amniocentesis is an invasive prenatal diagnostic tool that involves inserting a hypodermic transabdmoinally (usually with ultrasound guidance) into a pregnant womanıs uterus to collect amniotic fluid. It can be performed any time after the 14th week of pregnancy; early in pregnancy (usually between 14 and 18 weeks), it is uselful in detecting birth defects, while later in pregnancy (3rd trimester) it is useful in measuring fetal lung maturity if the baby needs to be delivered early. Can be use to detect alpha-feto protein which indicate neural tube defect and karyotypes show genetic abnormalities like Downıs Syndrome.
What are the risks of amniocentesis?
A. Infection (1:1000, increases risk of premature labor)
B. Hemorrhage
C. Needle may damage fetus (rarely)
D. Fluid Leak (1:100, usually self-limiting)
E. RH+ exposure
F. Spontaneous abortion (between 1:200 and 1:450)
G. Ethical conflict re. selective termination
16. CVS samples the chorionic cells and can be done earlier than amnio at 8-10 weeks of pregnancy.
17. advanced maternal age {note 80% of Downıs Syndrome children are born to mothers under 35}, alpha feto-protein, family history of genetic abnormalities.
Lecture #7 Hormones of Pregnancy
1. One more time: what are the hormones secreted by the placenta?
2. Is the FPM unit which creates the endocrine environment?
3. What does hCG do, when does it peak and what is produced by?
4. What does hCS do? Where is it produced? Who does it affect? When does it appear?
5. When does estrogen surpass progesterone as the most abundant hormone?
6. What does estrogen do during pregnancy and where is the majority produced?
7. What does progesterone do during pregnancy and where is the majority produced?
8. Why would you want to inhibit pituitary gonadotropins?
9. What is the precursor to hormones estrogen, progesterone and hormones produced by the fetus?
10. What does the fetal adrenal cortex produce that impacts fetal development?
11. The medulla?
Answers to Lecture #7 Guide
1. Estrogen, progesterone, hCG, hCS
2. Fetal-Placental-Maternal Unit the integrated way in which these three function to create the correct balance of hormones to maintain a successful pregnancy.
3. hCG is produced by the placenta, it maintains the corpus luteum to encourage endometrial growth, suppresses maternal lymphocytes and peaks at 60-70 days of pregnancy.
4. hCS is a hormone produced by the placenta that is similar to growth hormone. It appears ONLY in the maternal blood starting at about 10 weeks and is related to increasing estrogen levels. It maintains placental sufficiency (it is proportionate to placental size) by maintaining high levels of glucose in the blood. It also serves iin the development of mammary tissue.
5. week 16 (not shown well on this chart)
6. Maintains uterine structure and function. 90% in placenta
7. Maintains uterine vascularization, mammary growth and development, and inhibits pituitary gonadotropins, 80-90% in planceta
8. Because FSH and LH are responsible for ovulation. Donıt need that!!
9. CHOLESTEROL!!
10. Cortex produces glucocorticoids (cortisol and development of surfactant in 5th fetal month), mineralcorticoids (aldesterone which acts on water and electrolyte balace hence it comes much later in pregnancy when fetus needs to prepare for self-resulation) and sex steroids
11. The medulla produces catecholamines (epinephrine and norepinephrine) which help in dealing with stress.
Lecture #8 Study Guide Diagnosis & Length of Pregnancy and the
Development of Germ Layers
1. What are some presumptive signs of pregnancy?
2. What are some probable signs of pregnancy?
3. What are the positive signs of pregnancy? And at what stage are these possible?
4. What is the normal length of pregnancy and how is this calculated?
5. When is an infant considered "premature" (duration of gestation or birth weight)?
6. When is an infant considered "small for date?"
7. When is an infant considered "post-mature?"
8. What do the inner cells divide into and what these different layers develop into?
9. What are the main functions of circulation?
10. Name the major components of the circulatory system and their functions.
11. Trace the path of blood through the (adult) types of blood vessels as it leaves the heart and returns (in general terms).
_______________________________________________________________
Lecture #8 Study Guide Answers
1. amenorrhea, nausea & vomiting (morning sickness), engorgement of breasts, frequent urination, constipation, fatigue, skin pigmentation, softening of lower uterine segment, hormonal tests
2. all of the above signs, uterine enlargement, uterine contraction, detection by ultrasound
3. Auscultation of fetal heartbeats (17-18 weeks), Palpation of fetal outline (24 weeks), imaging (sonogram, MRI variable)
4. a. 280 days (40 weeks or 10 lunar months) from beginning of last menstrual period
b. 266 days (280 days minus 14 days)
5. < 37 weeks gestation or <5.5 lbs.
6. born after 38 weeks but < 5.5 lbs
7. born 2+ weeks after expected due delivery date, weight > 9 LBS
8.
a. Ectoderm: epidermins, nervous system, chromaffin organs (adrenal gland), eye structure, neuroepithelium, some GI epithelium and teeth enamel
b. Endoderm: epithelial lining in the GI (ESP pancreas and liver), epithelium of inner ear, epithelium of larynx, trachea & smaller passages, epithelium of urinary tracts, bladder, urethra and prostate
c. Mesoderm: all connective tissue, teeth, entire body musculature (smooth and striated), blood and lymphatic vessels, adrenal cortex, lining of pericardium, pleura and peritoneum
9.
a. supply O2 to tissues
b. transport nutrients from GI tract to tissues
c. transport CO2 to lungs
d. transport metabolic and other wastes to kidneys and GI for excretion
e. regulation of body temperature
f. distribution of hormones and other agents regulating cell function through the body
10.
a. Heart pumps blood through blood vessels to cells
b. Blood & Blood vessels: carry gases, metabolic products, hormones from all tissue to heart and back
c. Brain and Peripheral Nervous centers: control of vasodilation and vasoconstriction substances, regulation of cardiovascular function
11. Left atria of heart -> large arteries (AORTA) -> arteries -> arterioles -> capillaries (site of nutrient/oxygen/waste/etc transfer between blood and other cells) -> venules -> veins -> large veins (INFERIOR AND SUPERIOR VENA CAVA) -> right atria of heart
Lecture #9 Development of Fetal Circulation
1. What does the umbilical vein do?
2. What do the two umbilical veins do?
3. Trace the pathway of fetal circulation from the umbilical vein to the umbilical artery.
4. Where is the actual anatomical site of nutrient and gas exchange within the placenta?
5. What are the three mechanisms by which the fetus avoidance a Mount Everest situation (a state of low oxygenation leading to hypoxia)?
6. Why is the liver considered the most important organ in blood distribution?
7. Why is the brain, which is first in priorities in the adult, relegated to the three spot?
8. What is the function of the ductus venosus?
9. What is the function of the foramen ovale?
10. What is the ductus arteriosus?
11. What do the maternal corkscrew arteries?
12. Describe the major differences between the adult and fetal heart.
13. What is the tubular heart?
14. At what point in development (what week) does the heart start beating?
15. At 16-18 weeks, what is the normal heart rate of the fetus?
16. When do the atria and ventricles of the embryonic heart take shape?
17. By what point will the heart have an adult EKG pattern?
18. Name three congenital defects that can occur during development.
Answers to Lecture #9
1. carries highly oxygenated and nutrient rich blood from placenta to fetus
2. carry poorly oxygenated blood and high concentrations of metabolic waste blood from fetus to placenta
3. Please See Diagram Below and UNDERSTAND!!
Step 1: Richly oxygenated blood enters umbilical vein from the placenta and travels to the liver.
Step 2: Via the ductus venosus, most of the oxygenated blood is shunted away from the liver (but still giving it first dibs on the most richly oxygenated blood) to the inferior vena cava
Step 3: Partially oxygenated blood enters the right atria, some of this still pretty well oxygenated blood travels through the foramen ovale to the left atria while the rest goes through to the right ventricle.
Step 4a: From right ventricle, blood feeds the collapsed lungs through the pulmonary trunk. However, most of the blood is shunted via the ductus arteriosus back to the aorta.
Step 4b: Partially oxygenated blood from the left atria, travels to left ventricle and into the aorta.
vStep 5: Partially deoxygenated blood in the aorta splits into the brachiocephalic trunk, which feeds the brain, and the rest of the body.
Step 6: Partially deoxygenated blood will travel around the rest of the body and eventually make its way back to the placenta via the umbilical arteries.
Sites of deoxygenated blood: 1. After the blood has left the brain, 2. after the blood has left the lungs 3. as the blood is traveling up the IVC before it meets the ductus venosus.
4. Uterine sinus embryo/fetus discharges CO2 via umbilical arteries and picks up nutrients and O2 via umbilical veins
5. A. Establishment of a preferential hierarchy for tissues (Liver, Heart, Brain, Everything Else)
B. Establishment of specific structures in maternal and placental unit
C. Fetal Hemoglobin which has a higher affinity for oxygen than HgB A (Adult Hemoglobin) and releases it more easily
6. responsible for making all new proteins without which development CANNOT occur
7. Because it is not as active as in adult stage, the brain does not require as much blood. For example, there is no need for thermoregulation because that is done by the mother.
8. The shunt between the umbilical vein and the inferior vena cava in order to provide "best" fetal circulation.
9. It is the shunt between the right from the left atria and it provides the "second best" fetal circulation to the rest of the body.
10. It is the shunt between the pulmonary artery and aorta that assures the "third best" circulation.
11. They are the arteries on the maternal side of the placenta that "spray" blood into the uterine sinuses where the chorion will absorb nutrients and gas, etc.
12. a. In the adult heart, there is a septa between the left and right side of the heart. In the fetal heart, there is communication between the right and left atria through the foramen ovale. There is also communication between the right ventricle and the aorta through the ductus arteriosus.
b. The pressure in the adult is higher on left side of the heart (because there is more pressure pumping to the systemic circulation). The pressure in the fetus is higher on the right side of the heart (because there is more pressure pumping to the collapsed lungs).
c. In the adult, deoxygenated blood and oxygenated blood are kept separate. In the fetus, oxygenated blood from the umbilical veins is mixed with the deoxygenated blood from the vena cava.
13. It is the primitive heart that is formed between 2-4 week by the development of "cell clusters." The ventral mesoderm and endoderm form two parallel lines that fuse to form a single tube. At week 3-4, the tubular heart forms three layers: the pericardium, the endocardium and myocardium.
14. 4th week of development
15. 120-140 beats per minute
16. 6th week of development
17. 16-18th week of development
18. Abnormal position of the heart, abnormalities of large blood vessels entering the heart, abnormalities of the ductus arteriosus, defect of cardiac septa, failure of the foramen ovale to close upon birth (not really developmental but important to know about)
Step 4b:
Please check out this website for a VERY good interactive display of the fetal circulation: http://www.indiana.edu/~anat550/cvanim/fetcirc/fetcirc.html
Lecture #10: Development of the Nervous System
1. What is the difference between the CNS and the PNS?
2. What are the main functions of the nervous system?
3. What are the neurons and how do they communicate with each other?
4. What are neuroglia?
5. How many neurons are there in the human brain? How many glial cells are there in the brain?
6. How many connections does each neuron have?
7. In the 5th/6th week of development, the neural groove closes to become the neural tube. At the 7th/8th week of development, the anterior portion of this tube becomes the what? What does the posterior portion of this tube becomes what?
8. An open canal persists and then forms which portion of the CNS?
9. What do the cells of the neural crest give rise to?
10. How do neurons communicate with each other?
11. What is the function of the spongioblast?
1. The Central Nervous System (CNS) is made up by the brain and the spinal cord. It serves as the main communication and control center of the nervous system. The Peripheral Nervous System (PNS) is made up of 12 cranial nerves and 31 spinal nerves. This system is further divided into the autonomic and somatic nervous system. The autonomic system controls involuntary actions (ie motor and sensory for digestion, reflexes, balance) and the somatic controls voluntary actions (motor and sensory for all actions you decide playing basketball, walking, studying yeah right).
2. a. communication between internal and external environments by regulating motor activity, sensory perception, special senses, balance and control)
b. regulation of intellect, behavior and general interpretation
c. regulation of metabolism
d. regulation of homeostasis
e. regulation of endocrine function
f. regulation of immune function
3. The neuron is the basic unit cell of the nervous system. They are responsible for relaying messages throughout the body. They communicate via neurotransmitters (ie dopamine, epinephrine) and neurohormones (ie. GnRH)
4. Neuroglia are the "support cells" which nourish and create products (ie myelin) for the neurons. These include astrocytes which are serve as the metabolism center (they feed the cells) for neurons and the oligodendrites which produce myelin.
5. There are 1012 neurons in the adult brain. There are 10 to 15 times more glial cells than neurons.
6. Each neuron has 10,000 connections.
7. The anterior portion becomes the brain and the posterior section becomes the spinal cord.
8. The open canal persists and forms the central canal of the spinal cord and the ventricles of the brain.
9. The cells of the neural crest give rise to the spinal ganglia. The spinal ganglia is responsible for sympathetic nervous system functioning ("fight or flight response).
10. Neurons communicate via neurotransmitters, for example serotonin, dopamine, Ach. A neuron will release neurotransmitters from its dendrite which will travel across the synapse to another neuronıs axon. Once the neurotransmitter is received, this will stimulate an electrical impulse in the downstream neuron. This cell will now pass on the message to other neurons.
11. Spongioblasts are cells found in developing nervous system: gives rise to astrocytes and oligodendrocytes.
Lecture #11 Development of the Nervous System Part II
1. Through the secretion of neurotransmitters and hormone, neurons communicate across synapse and regulate what function?
2. What is the function of the astrocytes?
3. What do oligodendrocytes do?
4. What percentage of oxygen consumption does the adult brain receive?
5. What is part of the brain develops first and why?
6. The forebrain and the cerebellum develop significantly after birth. Why?
7. What is the major source of fetal energy and where does it come from?
8. The fetus stores glucose as glycogen in the liver. What is the hormone responsible for facilitating this vital storage?
9. In terms of glucose levels, what state is the fetus usually in with respect to its mother, and why?
10. What is the relationship between glycolysis and respiration?
11. True or false: once neurons die, they are never replaced.
12. Levels of education have been shown to increase life expectancy and decrease rates of disability. Provide some possible explanations for this phenomenon.
13. There is evidence to show that increased levels of education has physiological effects on the CNS. Name some of these effects.
14. True of False: Versus other animals, humans have a decreased ability to learn and incorporate new information as they age.
1. Neurons regulate motor and sensory as well as mental/behavior responses.
2. Astrocytes are responsible for regulating the extraneuronal environment. For example, they are responsible for maintaining a proper concentration of neurotransmitter concentration at the synaptic cleft.
3. Oligodendrocytes are responsible for the production of myelin which facilitates electrical conduction.
4. While it is only 2% of total body weight, the brain consumes 20% of total oxygen taken in. It also hogs 15% of cardiac output through the internal carotid and vertebral arteries.
5. The brainstem (or medulla oblongata) develops first. It is virtually complete by the time the fetus is 10 weeks old because it is responsible for regulating all autonomic nervous function (ie circulation, cardiac rate, etc).
6. The cerebellum and especially forebrain are responsible for higher mental functioning. In utero, this fetus needs to concentrate resources on protein synthesis, development of vital organs, fat storage in order to be able to successfully survive. The higher mental functions are not absolutely vital to the babyıs survival in the first months of life a very critical and vulnerable periods. While crucial for later survival, the cerebellum and forebrain develop primarily after birth because it is a lower priority than other systems.
7. The fetus derives most of its energy from glucose which it gets mom via the placenta.
8. Glucocorticoids, which are produced in the adrenal glands, are responsible for converting glucose into glycogen in the liver.
9. The fetus is usally hypoglycemic (lower blood sugar) than its mother because of higher glucose utilization and greater sensitivity to insulin.
10. Glycolysis is a necessary function during gestation and postnatally in order to assure that the fetus/baby receives enough energy. After birth, when breathing begins (thus indicating a higher metabolic rate) the gycolytic enzyme increases as respiration (indicated by an increase in succinic dehydrogenasse - a respiratory enzyme) increases. This occurs because the fetus now needs to combat hypoglycemic states due to increased heat loss and increased cardiac expenditures of energy.
11. False: it was once thought that the nervous system did not have the capacity for regeneration. Current research shows that in fact the CNS does have the ability to regenerate and repair to a certain extent.
12. There is a direct correlation between increased level of education and increased income levels. The rise in income level is correlated with less risky occupations, better access to medical care, nutrition and recreational activities. Basically, think of education as potentially having a whole-body impact on health through access to resources.
13. Increasing educational level from <12th grade to >12th grade is associated with an increased mean dendrite length, increased total dendrite length and dendritic segment count.
14. False, as compared to a cat and a bird, a human can learn new information throughout its entire lifespan. While this ability lessens to a certain extent in old age, there is no doubt that with humans an :old dog can learn new tricks."
Lecture #12 Development of the Nervous System Part III
1. What is functional first the brain or the spinal cord?
2. How does a reflex work?
3. The fetus is essentially a "reflex" individual. What reflexes should you see developed at 7-8th weeks, 17-20th weeks and by the 24th week?
4. After birth, the baby increasing takes conscious control over these reflexes including the startle reflex (much to sleep-deprived parents thanks). What may be occurring if these reflexes are excessive?
5. What are the external factors that impact brain development?
6. Internal factors that influence brain development are centered around the function of what hormone?
7. Hypothyroidism (not enough thyroid hormone) is associated with what kinds of developmental problem?
8. What are the major functions of thyroid hormone?
9. Describe the negative feedback loop by which thyroid hormone is regulated.
10. What are some signs of hypothyroidism?
11. What are some signs of hyperthyroidism?
12. In the absence of thyroid hormone, what specific developments of the CNS are impaired?
1. The spinal cord is functional before the brain because it needs to serve as the relay center for reflexes.
2. A reflex is an automatic activity which bypasses the brain. It starts at the sensory organ where the afferent neuron sends a message through the spinal cord to the efferent neuron. The efferent neuron synapses with the effector organ and stimulates a reaction.
3. a. By week 7-8, the motor reflexes should be developed. These serve in order to protect the fetus from harm during impact or shock.
b. By 17-20th week, the respiratory reflex should be functional as evidenced by chest movements. The fetus will inhale and exhale amniotic fluid. If the fetus cannot do this, polyhydramnios (too much amniotic fluid) may occur.
c. By the 24th week of development, the gastrointenstinal reflex should be developed such as suckling. This is preparation for postnatal feeding.
4. If the baby exhibits excessive reflexes, this may indicate a delay in the maturation of brain centers that regulate reflex activity.
5. External factors include continuing educational stimuli.
6. Thyroid hormone.
7. Hypothyroidism is associated with a serious compromise of the CNS both motor and cognitive development is stunted. Children have characteristic vacant expressions, protruding tongues, lack of awareness and muscle control.
8. a. promotion of body growth (stimulation of bone growth)
b. development of the CNS in fetal and neonatal stages: promotes myelination, neurogenesis, brain metabolism
c. stimulates oxygen consumption in all cells
9. TRH =Thyroid Releasing Hormone
TSH = Thyroid Stimulating Hormone
T3 and T4 are iodine containing amino acids. T3 is most biologically active. At the target cells, T3 is converted into T4.
10. Signs of hypothyroidism include decreased or delayed growth, decreased metabolism, low body temperature, high levels of cholesterol and LDL, decreased mental function: cognition, memory, behavior.
11. Signs of hyperthyroidism include weight loss, hyperphagia (increased appetite and eating), heat intolerance, increased blood pressure, nervousness, tremors, profuse sweating, protrusion of the eyes.
12. Without thyroid hormone, myelination, synaptogenesis, neurotransmitter transport and metabolism, neuron survival, microtubule production are all compromised.
Lecture #13 Sex Differentiation
1. Which parent determines sex?
2. From what embryonic tissue, do the gonads develop from?
3. When does sexual differentiation occur in embryonic life? A. Describe male sexual differentiation. B. Describe female differentiation.
4. What are some factors that may be involved in testis differentiation?
5. Since the 6th week is crucial for sexual development, there is a chance that things donıt go right. What are some example of disorders of sex differentiation with normal chromosomal complement? With an abnormal complement?
6. The CNS plays an important role in sex differentiation. Please describe the effects of neonatal androgens on the CNS in males and females.
Answers to Lecture #13
1. The father through an X or Y sperm will determine sex of the fetus.
2. The primordia of the gonads and gondal ducts arise from a thickening of mesodermal tissue. Anatomically, this occurs below the kidney primordial. The tissue is undifferentiated and can give rise to either male or female genitalia depending on specific stimuli.
3. Sex Differentiation occurs at the 6th week of development.
a. In the male, the Y chromosome will code for the H-Y antigen which will stimulate the bipotential gonad to differentiate into a testis. The testis will start to secrete testosterone from the Leydig cells. The Wolferian ducts develop into the male secondary sex organs. The Mullerian ducts regress under the influence of Mullerian Inhibiting Substance (MIS) secreted by Sertoli cells. The testosterone will convert into dihydrotesterone (DIT) which will induce male external genital differentiation.
b. In the female, there is no sex responsible gene (SRY). The default for the bipotential gonad is to become an ovary. In the absence of MIS and T, the Wolffian ducts regress and the Mullerian ducts become the female secondary sex organs and external genitalia.
4. Some factors involved may include H-Y antigen, testis determining factor (TSF), the "Zinc Finger" protein on Y and several other Y chromosomal genes.
5. A. With normal complement of chromosomes, pseudohermaphroditism may occur. In the female, this may occur because of abnormal levels of androgens in the mother, a virilizing adrenal or ovarian tumor or treatment with androgens and progestins. In the male, this may occur with androgen resistance, defective testicular development, congenital steroid enzyme deficiency.
B. With an abnormal complement, we may see Ovarian dysgenesis (XO) or Turnerıs Syndrome in women or Seminiferous tubule dysgenesis or Klinefelterıs Syndrome (XXY) in men. In women may see superfemales (XXX or even XXXX) and men supermales XYY (I checked on this it does exist). Or in the rarest case, we see true hermaphrodites who are mosaics and have both functional sets of sex organs.
6. In males, androgen stimulate presence of larger (than females) nucleus of the pre-optic area (SDN-POA) in the hypothalamus, a larger spinal nucleus of the bulbocavernosus muscle and male sexual behavior.
In female, androgens are still important because they stimulate the development of smaller SDN-POA and SNB muscles. Female sex behavior will also appear including lordosis.