Human Bio

6 stages of fertilisation?

1. Capacitation

2. sperm binding

3. acrosomal reaction

4. membrane fusion

5. cortical reaction

6. zygote formation

what happens in capacitation stage?

sperm undergoes changes in the female reproductive tract to become capable of fertilising the egg

what happens in the sperm binding stage?

the sperm binds to the zona pellucida of the egg

what happens in the acrosomal reaction stage?

the sperm releases enzymes from the acrsome to digest and penetrate the zona pellucida

what happens in the membrane fusion stage?

the sperm and egg plasma membranes fuse allowing the sperm nucleus to enter the egg

what happens in the cortical fusion stage?

the egg releases cortical granules to modify the zona pellucida, preventing other sperm from entering

what happens in the zygote formation?

the sperm and egg nuclei fuse to form a single diploid nucleus creating the zygote.

endometrium

the innermost lining layer of the uterus, main function being to prepare the optimal environment for the implantation of the embryo and support fetal development during pregnancy.

Gastrulation

process during embryonic development that changes the embryo from a blastula with a single layer of cells to a multilayered structure called the gastrula.

role of hormones during labour and delivery

prepares the body for labour and facilitating the delivery process. Hormones such as oxytocin and prostaglandins play a crucial role in initiating and regulating uterine contractions, helping to progress labor and deliver the baby.

what test do newborns get assessed with

APGAR score, evaluating heart rate, breathing, muscle tone, reflex and skin colour.

what can affect the success of breastfeeding in the early days?

The mothers and the newborns health.

what changes occur in a women’s body during pregnancy?

hormonal shifts, blood volume increases, heart rate increases, increased lung capacity, breathlessness, back and leg pain, swelling ankles, increased urination frequency, changes in skin, hair and nails thicken and grow faster and mental changes.

how does placenta support the developing baby?

delivering oxygen and nutrients, removing waste products from the babys blood and transported back to the mothers.

produces hormones

and starts to pass maternal antibodies.

common symptoms and health concerns in the first trimester

(1-12 weeks) morning sickness, nausea, breast tenderness, frequent urination

common symptoms and health concerns in the second trimester

(13-27 weeks) morning sickness, lower back pain, heart pain, constipation

common symptoms and health concerns in the third trimester

(28-40 weeks) shortness of breath, swelling, braxton hicks, back pain

what happens in the first stage of childbirth?

the cervix begins to dilate and efface under the pressure of contractions

what happens in the second stage of childbirth?

the baby descends thorugh the birth canal and is born, take from a few mins to a few hours.

what happens in the third stage of childbirth?

after the baby is born the uterus contracts to expel the placenta, the mother and placenta will be closely monitered.

organogenesis

process begins in the embryonic period (3-8 weeks) and continues until birth. involves the formation of 3 cell layers (ectoderm, mesoderm, and endoderm)

stem cells

cells that can differentiate into various other cell types, important for development, tissue repair and growth

types of stem cells

undifferentiated - cells haven’t yet become into a specific type of cell

self-renewal - can divide and create more stem cells

differentiation - have the potential to become other cell type

folic acid and the importance

the synthetic version of the vitamin B9 and plays a important role in development of the neural tube which eventually forms the brain and spinal chord.

Ectoderm germ layer in early development

the outermost layer, forms the outer layer of skin, hair, nails and parts of the nervous system

Mesoderm germ layer in early development

located between the ectoderm and endoderm, develops into various tissues and organs

Endoderm germ layer in early development

the innermost layer, gives rise to the lining of the digestive tract, lungs, live, pancreas

conditions for fertilisation to occur successfully

a healthy sperm and egg, the ability of sperm to reach the egg and the fusion of their nuclei. the egg must be viable and the embryo must be able to implant in the uterus

how does the sperm reach the egg

sperm released into vagina and propelled by their own motility through the cervix, uterus, and into the fallopian tubes, facing challenges like cervical mucus and the immune system. Once in the fallopian tube, sperm undergo changes to enhance their ability to fertilize, including capacitation and hyperactivation. Finally, a single sperm penetrates the egg's outer layer, initiating fertilization. 

changes that occur in the egg cell after its fertilised

the fusion of sperm and egg nuclei, rapid cell division (cleavage), and movement of the fertilized egg down the fallopian tube toward the uterus. 

morula

a ball of cells created by zygote division by mitosis

difference between fertilisation and plantation

fertilisation is the fusion of sperm and egg resulting in a zygote. implantation is the process where the fertilised egg burrowns into the lining of the uterus.

embryo differ from a foetus

embryo - developing human during first 8 weeks, basic body structures and organs are forming

foetus - developing human from the ninth week until birth, primary focus shifts to growth and development of those structures and organs.

vitelline membrane

cell membrane protects the cell contents and regulates substances coming in and out of the cell, sperm breaks through to fertilise the cell

IVF

where a sperm and an egg is combined outside the body

what happens when the membranes of the sperm and oocyte fuse during fertilisation

the sperm transfers its nucleus into the egg

zona pellucida

protective glycoprotein layer surrounding the oocyte

perivitelline space

space between the vitelline membrane and the zona pellucida

main function of the cortical reaction

to harden the sperm

zona pellucida

protective glycoprotein layer surrounding the oocyte

It helps protect the egg

corona radiata

a large white matter bundle that consists of ascending and descending fibers

what is the organ that first develops in foetus

the heart

nucleus in the oocyte

contains the DNA (haploid)

the outermost layer surrounding the ovum

zona pellucida

what does thinning the membrane of the sperm head during capacitation allow

the sperm to bind more easily with the egg

sperm binding occurs when

one sperm has made its way through the corona radiata cells and binds with specific proteins present on the zona pellucida called ZP3 molecules

how long is the journey of sperm from the vagina to the fallopian tube

30 mins-2 hours

acrosome part of the sperm

responsible for binding to the ZP3 molecules on the zona pellucida

pronuclei

two enlarged nuclei formed from the sperm and oocyte, visible in the center of the cell

true moment of fertilisation

two sets of chromosomes combine to produce a diploid zygote

how does the zygote change as it moves towards the uterus

it divides into more cells through mitosis, becomes a morula then forms a blastocyst, by the time it reaches the uterus its ready too implant into the lining of the uterus

organogenesis

begins in the embryonic period and continues until birth, process involves the 3 cell layers during gastrulation

changes in womens body during pregnancy

increased hormones, blood volume, lung capacity and urination frequency, body pain, heartburn, constipation and mental changes

how does placenta help developing baby

delivering oxygen and nutrients, removing waste products from babys blood and transporting back into mothers blood from elimination

what signals the body to begin labour

cervix dilation and effacement, babys descent into the pelvis

hormones in labour and delivery

work together to trigger contractions, manage pain and prepare baby for birth