Transcript MCB 135E Exam I Review

MCB 135E
Exam I Review
Jason Lowry
Fall 2005
General Information
• Exam I – Wednesday 10/5/04
– In-class exam (50 minutes, 100 points)
– You will need a pencil and a pen
– If you write short answers in pencil, they are not
eligible for regrade
– We will provide a scantron
– You will need to place everything except pen/pencil at
the front of room or in the aisle (NOT UNDER THE
CHAIR)
– The exam will not begin until everyone has complied
General Information
• Exam I
– Material for exam will cover everything
through the lecture on Monday (10/3/05)
– Exam breakdown
– Exam questions are based on lecture material
(not website nor discussion)
Review Material
•
•
•
•
•
•
•
Reproductive Systems
Fertilization and Implantation
Embryonic Development
The placenta and hormones of pregnancy
Nervous System Development
Sexual Differentiation
Metabolism and Growth
Gametogenesis
• Spermatogenesis
–
–
–
–
–
What is it
Where does it occur
What are the hormones involved
What is the progression of sperm maturation
What are the major characteristics of sperm
Spermatogenesis
• Formation of Spermatozoa (Sperm)
• Occurs in seminiferous tubules
• Involves two distinct maturational processes
– Spermatocytogenesis
• 1st Stage of sperm formation
• Spermatogonium  Spermatids
• Involves mitosis(46 Chromosomes) initially and then meiosis
(23 Chromosomes)
– Spermiogenesis
• Spermatids  Spermatozoa
Male Reproductive
Endocrinology
Gametogenesis
• Oogenesis
–
–
–
–
What is the function of the ovaries
What is the process of oogenesis
What are the hormones involved
How are these hormones regulated
The Ovaries
• Gamete producers
• 3 cm long solid mass of cells
• Suspended in the abdomen by ligaments
and mesenteries
• Oocytes found on outside surface of ovaries
Oogenesis
•
•
•
•
Primary Oocytes form at 3 months
during fetal development
2 million primary oocytes by birth
in prophase of first meiotic division
Maturation
– Increased size and Meiosis
First meiotic division resumes a few
hrs before ovulation due to LH
Surge
• Second meiosis after fertilization
•
•
•
•
•
Division produces unequal mass of
cells most food goes to ovum and
none to polar body.
All polar bodies die eventually.
Oocyte+specialized cells=follicle:
Nourish ovum and secrete estrogens
Mature follicle bursts releasing
ovum.
Many follicles enlarge but only one
bursts.
Gamete Comparison
• Male
–
–
–
–
–
–
–
–
–
–
–
Sperm
Small Size
Elongated Shape
Millions in #
Vigorous Motility
No protecting envelope
Minimal Cytoplasm
Lacks yolk
Centrosome Retained
Mitochondria in body
Golgi Apparatus in
acrosome
– Nucleus condensed in head
– XY
• Female
–
–
–
–
–
–
–
–
–
–
–
–
–
Ovum
Large size
Spheroidal shape
Few in #
Lack motility
Egg envelopes for
protection
Bulky Cytoplasm
Little Yolk
Centrosome Disappears
Diffuse mitochondria
Diffuse golgi apparatus
Open structured nucleus
XX
Fertilization and Implantation
– Fertilization
•
•
•
•
•
•
Sperm Morphology
Organization of ovum after ovulation
Role of ovum in fertilization
Role of sperm in fertilization
Stages of fertilization
What is capacitation, acrosomal reaction, zona pelucida
– Implantation
• Pre-implantation events
• Act of implantation
Morphology
Fertilization
• Role of Ovum
– Contribute the maternal
complement of genes
– Reject all sperms but one
– Provide food reserve until the
embryo begins to feed upon
exogenous material
• Role of Sperm
– Reach and penetrate the egg
– Activate the egg to nuclear and
cytoplasmic division necessary
to embryonic development
– Contribute the paternal
complement of genes
Stages of Fertilization
• Penetration
– Random contact between sperm and egg
– Sperm propel past corona cells and attach to zona pelucida
– One sperm-One Egg
• Activation
– Completion of Meiosis of ovum – forms female pronucleus
– Sperm Changes – Sperm travels toward center of egg, head swells,
becomes male pronucleus
– Rearrangement in egg – biochemical changes necessary prior to
nuclear fusion
• Nuclear Fusion
– Union of two pronuclei
– Loss of nuclear envelope, contribution of chromosomes to first
mitotic cleavage
Uterine Preparation
• Estrogen
– Involved in proliferation of uterus (hypertrophy)
– 3-5 Days post-ovulation E dominates and is thought to
play a role in transport of ovum
• Progesterone
– Increased Vascularization (hypervascularization)
– 5-7 days post-ovulation, P increases and counters the
effect of E thus relaxing uterine contractions
Implantation
•
Days 1-8
– Fertilized egg begins to divide
by cleavage into smaller
blastomeres
– Blastomere increase follows a
double synchronous sequence
initially, but later becomes
asynchronous
– Later stage cleavage forms a
ball of cells or morula
– Fluid begins accumulating in
morula and a conversion occurs
to the blastula (blastocyst)
– Blastocyst attaches to uterine
stroma
– Outer layer of cells begin to
proliferate and invade stroma of
uterus
Implantation
•
Days 8-16
– Blastocyst lodged in uterine
stroma
– Trophoblast (outer cells)
invades uterine stroma and
begins to form placenta
– Blastocele becomes chorionic
cavity
– Inner cell mass begins to
proliferate and form germ disc
and primitive entoderm
– Complex sequence of chemical
and physical interactions occur
between ovum and mother
• Only about 50% of
fertilized eggs successfully
implant
Embryonal Development
• Germ Layer Theory
• Gastrulation
• Tissues generated
Germ Layer Theory
• Embryo’s Method of sorting out its parts
– Ectoderm – Outer covering of embryo
– Entoderm (Endoderm) – Lies under the ectoderm and
forms lining of the primitive gut cavity
– Mesoderm – Develops between ectoderm and entoderm
• Gastrulation – The process by which germ layers come
to occupy their characteristic positions
Germ Layers and Their Systems
• Ectoderm
–
–
–
–
–
–
–
Epidermis and lining cells of glands
Appendages of skin
Nervous system
Posterior Pituitary
Chromafin organs - adrenal medulla
Anterior Pituitary
Some Epithelium
• Entoderm
–
–
–
–
Epithelial lining of alimentary canal
Lining cells of glands that open to alimentary canal
Epithelium of most of the urinary bladder and urethra
Epithelium of prostate
• Mesoderm
–
–
–
–
–
–
Remaining organs and tissues not made by Ectoderm or Entoderm
Connective tissue
Teeth
Musculature
Blood
Adrenal Cortex
Placenta and Hormones of Pregnancy
• Structure of placenta
– Include
• Fetal membranes
• Maternal membranes
• Functions of placenta
– Hormones
• Role of hormones
• Hormone Biosynthesis
– Respiration
– Protection
– Excretion
• Fetal circulation
– Trace blood flow
– Know obstacles
– Know modifications
Placenta
•
Fetal
1.
2.
3.
Yolk Sac
– Center of blood formation
in early embryonal life
– Facilitates transfer of
nutrients from developing
trophoblast to embryo
Allantois
– Blood vessels develop
around allantoic tube
– Tube eventually fuses with
chorion
– By 6th week – 1 umbilical
vein and 2 umbilical arteries
Amnion
– Membranous sac that
surrounds embryo
– Fluid fills amnion that has
protective role throughout
pregnancy
•
Maternal
Deciduas
–
Highly modified uterine
endometrium
a) Basalis
•
Portion between ovum
and uterine wall
b) Capsularis
•
Region of decidua
where ovum is
embedded
c) Parietalis
•
Lines remainder of
uterus
Placenta Functions
•
•
•
•
•
•
Gas Exchange
Nutrient Delivery
Antibody Delivery
Removal of Waste
Secretion of hormones
Protection
Hormones of Pregnancy
•
•
•
•
•
Estrogen
Progesterone
hCG
Placental Lactogen (hCS)
Placental Growth Hormone
Steroid Hormone Synthesis
Challenges and Adaptations
• Challenge
– Oxygen and Nutrients are less in umbilical vein
than in adult arteries
• Adaptations
– Establish priorities
– Establish specific structures to supply priorities
– Embryonal Hemoglobin
Specific Structures
1. Ductus Venosus
•
Shunts Umbilical Vein to Inferior Vena Cava
2. Foramen Ovale
•
Shunts between atria
3. Ductus Arteriosus
•
Shunts pulmonary artery to aorta
Nervous System
• Major Functions
– Communication with external/internal environment
– Regulation of…
• Major Components
–
–
–
–
–
–
Neurons
Neuroglia
Mylenated nerve fibers
Microglia
Ground Substance
Blood Vessels and CSF
Development of the Nervous
System
•
•
•
•
Morphological Development
Biochemical Development
Functional Development
Sexual Differentiation
Neurulation
• N.S. – Arises from ectoderm on dorsal portion of
embryo
• 3-4 Weeks – Cells proliferate along middle plate
• 5-6 Weeks – Plate folds to form neural groove
• 6-7 Weeks – Groove closes into neural tube
– Brain develops from anterior portion
– Spinal cord develops from the posterior portion
Neural Epithelium
• Neuroblast
– Neuron
• Spongioblast
– Migratory Spongioblast
• Oligodendria
• Astrocytes
– Astrocytes
– Ependyma
Energy Sources
• Carbohydrates
– Primarily maternal
glucose
– Stored as glycogen
• Under influence of
glucocorticoids
• In fetus
– Insulin levels high
– Insulin sensitivity high
– Hypoglycemic
• Anaerobic Glycolysis
– Glyceraldehyde-PDehydrogenase
• Glycolitic enzyme
• High in postnatal brain
• During same period
the oxidative enzyme
– Succinic Dehydrogenase
– Much lower
Thyroid Hormone
• Functions
– Promotion of body growth
– Development of CNS through:
• Promotion of neorogenesis
• Promotion of myelination
• Promotion of brain metabolism
– Stimulates oxygen consumption in all cells
• Abnormalities
– Hypothyroidism
• Cretinism
• Short stature, low metabolic rate, skin changes
• Treatable if given Thyroxine at an early age
Functional Development
• Differential Development of N.S.
– Neurotransmitter activity in different brain regions
• Perinatal Behavior
– Reflexes – Refer to table in reader
• Motor
• Respiratory (17-24 weeks)
• Gastrointestinal (24th week)
– Suckling
• Startle (Presence of excessive activity after birth is an indicator
of delayed development of certain brain centers)
• Education
– Better educated appear to live longer with less disability
– Several pieces of evidence discussed for this in class
Sexual Differentiation
Sexual Differentiation
• Steroid hormone action on brain
development
– Androgen action on sexually dimorphic nucleus
of the preoptic area (SDN-POA)
• Male Rats – After puberty responsible for male
behavior, large SDN-POA present
• Female Rats (low androgen levels) – After puberty Small SDN-POA (reversible with androgen
treatment)
– Lordosis (arching of back when sexually receptive)
Metabolism and Growth
• Metabolism and Growth information:
– Reader / Handout
– Class Today
– Discussion Today