Biology : Chapter 12
Why does semen contain fructose?
To nourish the sperm
What is the advantages of breast-feeding over formula milk?
- breast milk free of pathogens - breast milk carries antibodies - breast milk naturally produced for free - process provides emotional and psychological support to mom and baby Bottle feeding only good when mom can't breastfeed and to strengthen relationship between baby and other fam members
Describe puberty : Males
- sperm production begins (declines with age) - secondary sexual characteristics: o Pubic + Facial hair o Deepening of voice o Muscular development
Give an indicator for the time of ovulation
-Rise in female body's temperature by about 0.5°C and remains elevated till end of cycle - texture and color of mucus and vagina becomes more transparent, slippery, and liquid
When is an embryo called a fetus?
After the eighth week following fertilization
What is the Caesarean section ( C- section)?
An operation in which the mother is anesthetized and baby is surgically removed from uterus
Give the natural methods of contraception
Avoidance of sexual intercourse (abstinence) at all times or only during the days of the females menstrual cycle when probability that fertilization will occur is high (around time of ovulation)
What is ovulation?
The release of an egg from an ovary
What are sperm ducts?
They carry the sperm from each epididymis and eventually join the urethra
Why does fertilization increase variation in the population?
This process brings together chromosomes from two different sources (paternal and maternal)
Define acrosome
Vesicle containing enzymes that are released to dissolve the layer of jelly around the egg allowing the sperm to reach the egg during fertilization
When does the formation of the placenta begin?
When the implantation process of the embryo is complete. Continues to grow throughout pregnancy
Is there more sperm compared to eggs?
Yes
Describe puberty : Females
- The first ovulation occurs -> Start of menstrual cycle - secondary sexual characteristics: o Breast development o pubic hair o increase in size of pelvis
How does the placenta act as an endocrine organ?
By producing hormones, such as progesterone, but I need it for a healthy pregnancy. (Progesterone sustains the lining of the uterus, preventing menstruation during pregnancy)
What is antenatal care?
Care and medical support a woman should receive while she is pregnant
Pathway of sperm
Convoluted tubules (testes) -> Epididymis (mature here) -> Sperm ducts -> Urethra -> Penis
Define umbilical cord
Cord that connects the embryo or fetus to the placenta. It contains two arteries and one vein (umbilical arteries and the umbilical vein).
What controls the events that occur during each menstrual cycle?
Cynical changes in the levels of the ovarian hormones estrogen and progesterone and two pituitary hormones, FSH and LH
Describe the placenta
Dark red in color and has many villi
Where does the embryo move to as it divides?
Down the oviduct to the uterus, facilitated by the beating of Cilia lining the oviduct
Why do babies lose heat quickly?
Due to a small small size, a newborn has a large surface area to volume ratio
What does corpus luteum mean? Give its function
A structure formed by a mature empty follicle after ovulation. It releases progesterone, which maintains the developed lining of the uterus and keeps it richly vascularized and ready to receive an embryo
What is a fetus?
A unborn organism in the later stages of development
What is the placenta derived from?
Both embryonic and maternal tissues
What happens to the corpus luteum if fertilization does not occur?
Degenerates, resulting in a drop of progesterone levels in the blood, (already low estrogen in blood), causes the disintegration of the uterine lining and menstruation
What type of blood do the umbilical arteries hold?
Deoxygenated blood and waste from baby -> to the placenta At placental villie -> CO2+WASTES diffuse from embryonic capillaries thru walls of placental villi TO MATERNAL BLOOD in spaces of uterine wall
Why does successful fertilization occur usually at the top of the oviduct (close to ovary)?
Eggs move slowly through the oviduct, it can only cross a small portion of the oviduct before it dies. A live egg will most likely be found in that area.
What is released from acrosomes to digest holes in the jelly layer of the egg?
Enzymes
What do follicles secrete as they develop?
Estrogen, causing estrogen levels to increase gradually in the blood
What is semen?
Fluid containing sperm mixed with secretions from specific glands (seminal vesicles + prostate gland)
What is the name and purpose of FSH?
Follicle stimulating hormone; it stimulates several follicles to develop
What is the epididymis?
Highly convoluted tube behind the testes where the sperm mature (become capable of fertilization) and are stored temporarily
What mineral requirements are needed for a pregnant woman?
Iron + Calcium + Higher E requirements
What is the placenta's role in immunity?
It allows antibodies to cross from maternal to fetal blood during fetal development
Describe an egg/ovum cell
Large, immotile cell with haploid nucleus - cytoplasm rich in nutrients to nourish egg once fertilized - layer of jelly that is important for fertilization (hardens when single sperm enters egg)
What is the name and purpose of LH?
Luteinizing hormone; triggers ovulation, in which the mature follicle bursts, releasing the eggs to the oviduct
For fertilization to work, when must sperm cells be deposited in the female body?
Near the time of ovulation; at a point in the females menstrual cycle when a life egg is or will soon be present in the oviduct
Why is semen slightly basic?
Neutralize the acidity of the female reproductive tract (acidity good for female, bad for sperm)
What toxic substances can cross the placenta?
Nicotine, carbon monoxide, alcohol
Does embryonic and maternal blood mix?
No, embryonic blood is kept inside the capillaries of the placental villi, which are separated from maternal blood. (If baby and mom diff blood groups -> mixing of blood deadly)
Are the ovaries and oviducts directly connected?
No, oviducts have a funnel shaped opening to receive the egg released from the ovaries which are a small distance away
In females, are the excretory organs also the reproductive organs?
No. (Males yes, but not anus)
What does an increase in the levels of testosterone do?
Normal sperm production, appearance of male secondary sexual characteristics
What is the placenta?
Organ that connects the embryo, and later the fetus, with the walls of the uterus to allow the exchange of material (nutrients, gases, wastes,) between maternal and embryonic/fetal blood
Pathway of eggs
Ovaries -> Oviduct -> Uterus
Get the function of villi in the placenta
Provides a large surface area for contact with the uterine lining. Large spaces in the lining of the uterus bathe the villi of the placenta with maternal blood.
What is adolescence?
Puberty marks the beginning of it; it is the period of life between childhood and adulthood
Which disease can cross the placenta?
Rubella disease, caused by a virus. It can cause serious harm to the developing baby; deaf, blind, stillbirth (some cases). Vaccine taken prior to pregnancy
What is the scrotum?
Sac of skin that holds the testes outside the body
What are follicles?
Sacs in which eggs mature. A group of supporting cells are present inside each follicle.
Define lactation
Secretion of milk by mammary glands (only mammals)
What brings the changes that occur in males and females at puberty?
Sex hormones
Describe a sperm cell
Small, motile with haploid nucleus - divided into three parts : Head, middle piece, tail Head : haploid nucleus + acrosome Middle piece : contains mitochondria (for energy) Tail : flagellum to reach egg
What does extra iron for pregnant women do?
So that the mothers body can produce more red blood cells to keep up with the increasing demand for oxygen and supply the developing baby with the oxygen it needs
What is ejaculation?
Sperm cells in semen are released from the penis
What does estrogen do?
Stimulates the growth of the uterine lining after menstruation and causes the endometrium to become thick and spongy
List the organs and structures of the male reproductive system
Testes, scrotum, epididymis, sperm ducts, seminal vesicles, prostate gland, urethra, penis.
What facilitates the movement of sperm through the oviduct?
The beating action of the cilia present in the walls of the ducts, and by muscle contractions
What is menstruation?
The discharge of endometrial fragments and some blood from the vagina about once per month
What happens if fertilization does not occur?
The egg that was released into the oviduct will die, continue its path to the uterus, and then moved out of the body through the vagina. Hormone levels will change, causing the thick and spongy layers of the endometrium to disintegrate into fragments and leave the body through the vagina (they are no longer needed)
What is implantation?
The embedding of the embryo into the uterine lining and subsequent attachment to the uterine wall
Right after menstruation, what happens?
The endometrium begins to prepare again to receive an embryo in case the next egg released is fertilized
Define amniotic fluid
The fluid in the amnion, which cushions and supports the developing embryo or fetus
What part of the sperm actually enters the egg?
The head, while the tail remains outside the egg
What is the endometrium?
The inner mucous lining of the uterus
Define penis
The male genital/reproductive organ through which urine and semen leave the body
What is the cervix? State it's function.
The neck like structure at the base of uterus that projects into the vagina. It connects the uterine cavity and the vagina cavity, and dilates during childbirth.
Define uterus
The organ in which the embroyo develops in the female body
Define vagina
The organ that extends from the cervix to the outside of the body. It receives the semen and is the passageway for delivery.
What are testes?
The organs that produce gametes (sperm) and testosterone
What are oviducts/Fallopian tubes?
The pair of ducts that receive eggs from the two ovaries
What is puberty?
The period of development during which humans become sexually mature + appearance of secondary sexual characteristics
What happens when estrogen reaches a certain level?
The pituitary gland secretes a surge of LH and FSH
What is contraception?
The prevention of unplanned pregnancies
Define reproduction
The processes by which organisms give rise to offspring
What happens after fertilization?
The resulting zygote will divide as it continues its journey down the oviduct to the uterus. Implantation occurs.
After ovulation, what happens to estrogen levels?
The secretion drops
Define menstrual cycle
The sequence of events that occur in a female from the first day of menstruation to the first day of the following menstruation
What is the myometrium?
The thick layer of smooth muscle in the uterus
Define menopause
The time in a females life when the ovaries stop ovulating, menstruation ceases to occur, and the menstrual cycle stops
What happened prior to each ovulation?
The uterine wall begins to prepare for the possibility of receiving an embryo. Endometrial wall becomes thick, spongy, and more vascularized in preparation for receiving an embryo and nourishing it with nutrients and oxygen.
How are the estrogen and progesterone levels in the beginning of the cycle (during menstruation)?
They are low; The pituitary gland starts to secrete FSH
What happens to sperm as they travel along sperm duct?
They mix with fluids secreted by specific glands, mainly the seminal vesicles and the prostate gland => makes semen
What is the testes made of?
Tiny coiled tubules in which the sperm are made; the cells in the walls of these tubules undergo meiosis to produce sperm
What does extra calcium for pregnant women do?
To ensure that the mothers bones are not weakened while her body provides the calcium necessary for fetal bone formation
Why must pregnant women take folic acid?
To help prevent spinal cord and brain defects in the baby
Define amnion
Transparent membrane that encloses the embryo or fetus during pregnancy
What does an increase in estrogen do?
Triggers the first ovulation to occur, associated with secondary sexual characteristics
What are the parts of the female reproductive system?
Two ovaries, two oviducts, uterus, vagina
After being deposited on the vagina, where do sperm cells go?
Vagina -> UTERUS -> oviduct
What is fertilization?
Fusion of the nucleus of a sperm cell and egg cell producing a diploid cell (zygote)
What is the function of the scrotum?
Helps maintain the testes at an optimum temperature for sperm production; for healthy viable sperm temp -> lower than body
What causes the penis to become erect?
Increased blood flow to special tissues; this enables the penis into the vagina and release the semen close to the cervix
What type of blood does the umbilical vein hold?
Oxygenated blood, oxygen and nutrients diffuse from the maternal blood across the walls of placental villi to the embryonic blood in the embryonic capillaries and then into the umbilical vein
What helps the egg move to the uterus?
Peristalsis of the muscles in the oviduct walls
Define ovaries
The female reproductive organs that produce the female gametes (eggs) and estrogen and progesterone
STEPS OF BIRTH
1) Fetus rotates in mother's uterus so head is down resting above cervix 2) LABOR: - rhythmic contractions of the uterine muscles (become more intensive) that push the fetus's head against cervix -> cervix dilates - amnion breaks -> releasing amniotic fluid - cervix keeps dilating -> once completely dilated , strong muscle contractions push baby out mothers body thru vagina 3) Cut umbilical cord (not painful as no nerves) 4) Placenta breaks away from uterus and pushed out of body (AFTERBIRTH)
