bible notes part 2

Question 1

what causes the penis to become erect

Answer 1

arterioles entering penis dilates and venules leaving constrict
build up of blood causes the errection

Question 2

what causes penis to ejaculate

Answer 2

movement results in contraction of smooth muscle in the walls of the epididymis, vas deferens and penis

Question 3

capacitation defenition

Answer 3

changes in sperm cell membrane that increases its fluidity and allow acrosome reaction to occur

Question 4

acrosome reaction defenition

Answer 4

acrosome enzymes digest corona radiata and zona pellucida alloweing sperm and oocyte membranes to fuse

Question 5

cortical reaction defenition

Answer 5

fusion of cortical granule membranes with the oocyte cell membrane, releasing their contents which convert the zona pellucida into a fertilisation membrane

Question 6

how long does released secondary oocyte remain fertile

Answer 6

24 hours

Question 7

how long do sperm stay viable

Answer 7

2-5 days

Question 8

when is peak fertility of sperm

Answer 8

12-24 hours after ejaculation

Question 9

how long does it take for the sperm to swim to the oviduct

Answer 9

5 mins to respond to oocytes chemoattractants

Question 10

what is the significance of the capacitation process in fertilisation

Answer 10

sperm can only fertilise a secondary oocyte after this process compelted

Question 11

what is capacitation process

Answer 11

removal of cholesterol and glycoproteins from cell membrane over the acrosome in the sperm head

Question 12

what is the end effect of the capacitation process

Answer 12

membrane becomes more fluid and more permeable to calcium ions

Question 13

what actually is the acrosome reaction

Answer 13

releases proteases which digest the cells of the corona radiata

Question 14

what happens when zona pellucida and sperm meet after acrosome reaction?

Answer 14

acrosome membrane ruptures and releases another protease (acrosin) which hydrolyses zona pellucida around secondary oocyte

Question 15

when is it called an ovum

Answer 15

after entry of sperm head in the secondary oocyte

Question 16

where does the acrosome reaction actually happen

Answer 16

in sperm

Question 17

where does the cortical reaction happen

Answer 17

in oocyte

Question 18

very simply what is the cortical reaction

Answer 18

reaction of oocyte that produces the fertilisation membrane, preventing polyspermy

Question 19

what is the trigger for the cortical reaction

Answer 19

sperm attatches to secondary oocyte, oocytes smooth ER releases calcium ions into the cytoplasm

Question 20

what do the calcium ions released by smooth ER of oocyte in cortical reaction do

Answer 20

make cortical granules fuse with cell membrane and release their contents of enzymes by exocytosis

zona pellucida is chemically modified so expands and hardens forming a fertilisation membrane

Question 21

what is the end effect of the cortical reaction

Answer 21

zona pellucida is chemically modified so expands and hardens forming a fertilisation membrane

Question 22

what does entry of sperm trigger

Answer 22

fertilisation membrane
meiosis II

Question 23

what happens within 24 hours of fertilisation

Answer 23

first mitosis combines genetic material of parents to make diploid cells of embryo

sperm chromosome join ovum chromosome on cell equator
cell is now known as a zygote

Question 23

when does meiosis II happen

Answer 23

when sperm head enteres secondary oocyte

Question 24

what happens during meisosis 2 after sperm entry

Answer 24

goes through anaphase 2 and telophase 2, divides and expels the second polar body

Question 25

when is it known as a zygot

Answer 25

when first mitosis combines genetic material of parents with sperm chromosomes joining ovum chromosomes on cell equator

Question 26

how does a zygot turn into a embryo

Answer 26

first mitotic division produces 2 cells and until organs have developed at about week 10 this collection of cells is called an embryo

Question 27

when is it classified an embryo

Answer 27

about week 10 - organs developed

Question 28

what happens as the embryo moves down the oviduct

Answer 28

divides many times by mitosis in sequence called clevage

Question 29

when does a morula form

Answer 29

within 3 days

Question 30

what is a morula

Answer 30

solid ball of 16 cells

Question 31

what process gets it from a morula to a blastocyst

Answer 31

clevage continuing

Question 32

what happens by 7 days

Answer 32

medula becomes hollow and is called a blastocyst

Question 33

when is it a blastocyst

Answer 33

7 days - when ball of cells becomes hollow

Question 34

what are the cells around the blastocyst

Answer 34

trophoblasts

Question 35

whats the function of the trophoblasts

Answer 35

divide to make an innner cell mass on one side

Question 36

what happens to endometrium after ovulation

Answer 36

thickens and gets an increased blood supply to prepare it to recieve an embryo

Question 37

when is the implantation window

Answer 37

between 6 and 10 days after ovulation

Question 38

what happens about 9 days after ovulation

Answer 38

trophoblastic villi penetrate the endometrium to increase surface area for absorption of nutrients

Question 39

what are trophoblastic villi actually

Answer 39

protusions from trophoblast cells of the blastocyst

Question 40

what actually is implantation

Answer 40

embedding of blastocyst into the endometrium

Question 41

when does implantation happen

Answer 41

within 8-10 days usually

Question 42

what does the placenta connect

Answer 42

embryo and foetus to the uterus wall

Question 43

what is the placenta made of

Answer 43

tissues derived from the embryo and from the mother

Question 44

what does the trophoblast develop into

Answer 44

chorion

Question 45

what happens between the chorion and vili

Answer 45

chorion move into the trophoblastic vili and form much larger chrionic villi

Question 46

whats the chorion

Answer 46

outer membrane surrounding the embryo

Question 47

whats unique about chorionic villi

Answer 47

develop blood cappilliaries which are connected to the umbilicial artery and vein

Question 48

projections from endometrium between chronic villi will have whos tissue

Answer 48

maternal tissue

Question 49

how can the placenta be described as

Answer 49

endocrine organ

Question 50

how many major roles of the placenta are there

Answer 50

5

Question 51

what are the main roles of the placenta (5)

Answer 51

- produces hormones - exchange between mother and foetus blood including nutrients, waste products and respiratory gases - physical barrier between foetal and maternal circulation - providing passive immunity - protection from mothers immune system

Question 52

why is the placenta called a endocrine organ

Answer 52

produces hormones to support the pregnancy

Question 53

why is it beneficial that the placenta is a physical barrier between foetal and maternal circulation

Answer 53

protects the fragile foetal capillaries from damage from higher blood pressure from mother protects from changes in maternal blood pressure

Question 54

how does passive immunity work (to do with placenta)

Answer 54

mothers antibodies cross the placenta and attack pathogens but do not attack foetal cells

Question 55

whats the inter-villous spaces called

Answer 55

lacunae

Question 56

whats the lacunae

Answer 56

inter-villous spaces containing the mother blood

Question 57

whats good about the chorionic villus to do with the lacunae

Answer 57

microvilli, gibing a large area of contact with mothers blood

Question 58

do foetus and maternal blood mix

Answer 58

NO

Question 59

distance between maternal and foetal blood in placenta (walls of chorionic villli)

Answer 59

5um

Question 60

where does gas exchange happen in placenta

Answer 60

walls of chorionic villi

Question 61

what type of flow is there in the chorionic villi

Answer 61

counter current flow

Question 62

why can't the mothers immune system make a immune response against the foetus / placenta

Answer 62

wall cells of chorionic villi fuse so theres no spaces between them making a syncitum immune cells cannot get through to foetal blood

Question 63

whats the syncitium

Answer 63

when cells of the wall of the chorionic villi fuse so theres no spaces between them

Question 64

what are some of the things placenta cannot protect against (4)

Answer 64

spontaneous abortions rhesus disease pre-eclampsia microorganisms such as rubella

Question 65

whats the significance of a flaw of the placenta and micro-organisms

Answer 65

such as rubella virus can cross the placenta from mothers blood into fetus blood as can some drugs including nitotine and heroin

Question 66

whats the significance of a flaw of the placenta and pre-eclampsia

Answer 66

develop when they have very high blood pressure one cause is abnormal immune response towards placenta

Question 67

when would pre-eclampsia happen

Answer 67

2nd / 3rd trimester

Question 68

what is rhesus diseases (as a flaw of the placenta)

Answer 68

destruction of foetus blood cells by antibodies produced by rhesus neg mother and blood cells of pos foetus gets worse for each successive rhesus pos foetus

Question 69

between what blood types would rhesus disease happen

Answer 69

rhesus neg mother rhesus pos foetus

Question 70

spontaneous abortions as a factor of placentas being flawed

Answer 70

equivalent to rejection of a transplanted organ

Question 71

where does the umbilical cord develop from

Answer 71

from the placenta

Question 72

whats the point of the umbilical cord

Answer 72

transfers blood between the foetus and the mother

Question 73

how does the blood of foetus reach the placenta

Answer 73

through 2 umbilical arteries

Question 74

why are the umbilical artieries called artieries even though its deoxygenated

Answer 74

as the blood is coming away from the foetus heart

Question 75

what the feature of the blood in the umbilical artieres

Answer 75

blood is low in nutrients and is deoxygenated

Question 76

where does nutrient exchange between mother and foetal blood happen

Answer 76

at the chorionic vili and returns through a single umbilical vein

Question 77

how many umbilical veins are there

Answer 77

1

Question 78

how many umbilical arteries are there

Answer 78

2

Question 79

whats the compesition of the blood in the umbilical vein

Answer 79

oxygenated high in nutrients