1 - Reproduction II Flashcards
How does oxygen reach the placenta
Enriched blood arrives via umbilical vein
Oxygen to placenta pathway
Passes by liver via ductus venous
Inferior VC —> RA —> LA —> aorta (heart and rest of body) —> superior VC —> RA —> RV 1/3 goes to the lungs (ductus arteriosis to aorta) —> deoxygenated returns returns to placenta by umbilical cord
Difference in ductus arteriosus (foetal and newborn)
Foetal - open
Newborn - closed
Difference in foraman ovale (foetal and newborn)
Foetal - open
Newborn - closed
Stages of Birth
- Cervix dilation (induced by smooth muscle contractions stimulated by oxytocin), contractions shorten uterus and baby is pushed towards cervix
- Cardinal stages (delivery)
- Stringy uterine contractions separate placental and deliver it (blood vessels compressed to reduce bleeding
Hormonal lactation
physical stimulation —> hypothalamus stimulates posterior pituitary to release oxytocin which stimulates breast milk production
Menopause
reduction in hormone production by ovaries in repsonse to gonadotrophons
(hypothalamic —> pituriaty —> overly axis shuts down)
Eggs and reproductive strategies (birds, mammals, some invertebrates)
gamete containing eggs are fertilised by sperm internally (copulation)
Eggs and reproductive strategies (invertebrates, fish, amogibians)
release of gamete containing eggs to evironment
Different types of eggs - Microelecithal
all eutherian mammals, some marine mammals
(very little or no yolk)
Different types of eggs - Centrolecithal
Insects, arthropods, Cnidaria (yolk and haploid germ cell located centrally)
Sperm can only enter at micropyle as chorion (gas exchange via pores)
Different types of eggs - Mesolecithal
amphibians and teleost fish (moderate amount of yolk (unevenly distribute
yolk is heavy
collects at vegetal pole lower half
Different types of eggs - Macrolecital
birds, reptiles, some mammals
very large amounts of yolk, unevenly distributes, supports embryo development until yolk completely consumed
Reproductive strategies - viviparous animals
placenta (eutharian mammals) allows brith of free living young that have developed in the mother
Reproductive strategies - Marsupials
with ouch in which young grow in after delivery from uterus, development in uterus is very short
embryo within ‘shell-type egg’
underdeveloped when born
pouch provides protection and access to teats or milk
Reproductive strategies - Monotremes
egg laying - no internal connection with mother
after hatching new born take up milk via mammary glands that are openings in the skin
long parental care of young
Vertebrates with amnion
Reptiles, birds, mammals
(Amnion is membrane around embryo)
Chick embryo
entirely surrounded by amnion
yolk sac provides nutrition
chorion and allantios form vascularised membrane on inside of cell for gas exchange
Amniotes and Sperm Diagram on OneNote
Acrosome
Derived from Golgi
Contains enzymes that digest proteins and sugars, these enzymes are required to lyse outer coverings of egg
Acrosome - nucleus
Contains haploid number of chromosomes
Acrosome - midpiece
Contains mitochondria that produce the energy (ATP) required for motility
Acrosome - flagellum
Required for sperm propulsion
Motor portion of flagellum is the axoneme
Stages of fertilisation
- Attraction and activation of sperm by contents of female reproductive tract
- Binding of sperm to zone pellucida
- Release of enzymes from acrosme to lose hole in zone
- Passage of sperm through zona
- Fusion of sperm and oocyte plasma membranes
Acrosomal reaction
Triggered by initial contact between sperm and zona pellucida (jelly like coat on surface of the egg)
Hydrolysis enzymes released by acrosome generate opening of zona pellucida
Plasma membranes of sperm and egg fuse —> syngamy (meiosis)
Sperm nucleus enters egg
Protective reaction to prevent polyspermy - cortical granulates fuse with plasma membrane to make it impenetrable (cortical reaction)
Annelid reproduction
A-sexual and sexual
Any 2 earthworms can mate by joining together and fertilising each others eggs, tube of mucus secreted by citellum and forms an egg case which slips off worms body and then hatch out into soil
Insect reproduction - parthenogenesis
production of unfertilised eggs which result in female offspring (thekytoky) or male offspring (arrhenotoky - mostly haploid)
Insect Reproduction - metamorphosis
insect larva hatches from egg, then change body shape and size to develop into adult insect
3 different types of metamorphosis - incomplete / complete / no metamorphosis
Insect reproduction - overview
Mostly oviparous
Insect Reproduction - Holonetabolus
Most of larval tissue within the pupa is enzymaticaly digested
Imaginal discs arise which organise rapid cell division to form body structures of adult (eyes, legs, wings)
Fish reproduction
Fish fertilise eggs externally
Large numbers of eggs and sperm released into water (fertilisation by chance)
Amphibian Reproduction - overview
External fertilisation (eggs are mesolethical —> laid in water)
Amphibian Reproduction - Metamorphosis
Egg encases in gel like mass / hatching tadpole with external gills / metamorphosis into adult amphibian —> growing hung and front legs and resorption of tail
Amphibian Reproduction - how is metamorphosis controlled
Metamorphosis controlled by hormones generated by thyroid, which either activate or repress transcription of genes
Amphibian Reproduction - Biochemical transformations
Haemoglobin changed from tadpole to adult version
Binds to O2 more slowly and releases more rapidly
Liver enxymes change to reflect habitat (tadpoles excrete ammonia and adult urea)
Mammalian Reproduction - fertility and reproductive cycles
Uterine bleeding if no pregnancy
Seasonal or repeated reproductive cycles
Spontaneous or stimulated ovulation to release eggs
Mammalian Reproduction - Embryonic diapause
Delayed development in stages of pregnancy
Determined by environemtal factors and lifestyle
Mammalian Reproduction - Lactation
Number of young nursed at same time
Mammary gland structure and morphology
Duration of lactation
Composition of milk
Passive immunity
Plant Reproduction - Angiosperms
Flowering Plants
Flowers attractive pollinators or passive pollination / pollen grows pollen tube / 2 haploid pollen nuclei move down towards ovaries
Plant Reproduction - Key Events (meiosis)
Meiosis in both male and females
Follwed by mitosis to produce 1/2 haploid gametes and additional support cells
Plant Reproduction - Key Events
Pollen with 2 haploid sperm cells
Ovule with 1 haploid egg cell and 1 centeral cell with 2 haploid nuce (and additional support cells)
1 sperm cell fuses with haploid egg —> diploid zygote (mitosis)
1 sperm cell fuses with centeral cell
Plant Reproduction (gymnosperms)
non flowering plants (conifers, cycads)
