Humans Flashcards
what is fertilisation
fusion of the nuclei
from a male gamete (sperm) and a female
gamete (egg cell)
Function of the testes
production of sperm cells (by meiosis) and testosterone
What is testosterone?
male hormone involved in primary: sperm production- and secondary: penis enlargement, deep voice, body hair, shoulder enlargement, “aggressiveness” (sexual male characteristics)
What is the function of the scrotum?
sac enclosing testes outside of the body - protection and to ensure a proper temperature in testicles (35-33 deg.C)
What is the function of the sperm duct?
sperm passes to urethra
What is the function of the prostate gland?
lubricating secretion for semen: releases fluid rich in sucrose, which sperm cells will use as a source of energy in aerobic respiration)
What is the function of the urethra?
releases urine from urinary bladder for excretion and during ejaculation releases semen
What is the function of the penis?
penis becomes erect and can be inserted inside the vagina
What is the function of the ovaries?
production of egg/follicle cells by meiosis and oestrogen + progesterone
What is progesterone?
female hormone involved in primary - follicle production - and secondary - breast development, hips enlargement, body hair and fat deposits develop (sexual female characteristics)
What is the function of the oviducts?
tube that moves follicle cells from the ovary towards the uterus using peristalsis and ciliated cells, usual site for fertilisation
What is the function of the uterus?
muscular organ where embryo implants, foetus grows and further contracts during birth/labour so baby is delivered
What is the function of the cervix?
muscular opening for uterus: dilates for birth, acts as a barrier against sperm cells, opens when a woman is ovulation so it increases chance of fertilisation
What is the function of the vagina?
muscular tube where blood is released out of the body during menstruation, semen is deposited during sexual intercourse, passageway of natural child birth
How are sperm adapted to their function?
flagellum: important for movement
mitochondria: important for aerobic respiration to keep flagellum moving
enzymes in acrosome: break down jelly coat present in the egg
How is an egg cell adapted to its function?
- jelly coat: changes stiffness when sperm cell penetrates, avoiding penetration of other sperm cells, avoiding polyspermy
- energy stores in cytoplasm: allows egg to survive for several days + nourishes zygote if fertilisation occurs until it can implant in the wall of the uterus
Compare male and female gametes in terms of: size, mobility and numbers
Female: large cell size, doesn’t move (is moved), one per menstrual cycle
Male: small cell size, moves using flagellum, millions per ejaculation (live for up to 5 days)
What happens to the zygote in early development?
the zygote forms an embryo which is a ball of cells that implants into the lining of the uterus
State the functions of the umbilical cord
- connects the foetus to the placenta
- contains arteries that deliver deoxygenated blood from foetus to placenta for exchange
- contains one vein, delivering oxygenated blood from placenta to foetus
State the functions of the placenta
- respiration
- excretion
- nutrition
- immunity
- hormonal
What is the placenta?
a very thin membrane that allows diffusion to take place: there is very close contact between maternal and baby blood, but they don’t mix to avoid coagulation of different blood types
Placenta: respiration
allows diffusion of oxygen from mother to foetus and CO2 from foetus to mother
Placenta: excretion
allows diffusion of waste products produced by the baby such as lactic acid, urea, and bicarbonates into mother’s blood
Placenta: nutrition
allows diffusion of glucose, vitamins, and minerals from mother to foetus
Placenta: immunity
mother’s antibodies pass to baby
Placenta: hormonal
placenta releases 3 hormones to maintain pregnancy (HCG, oestrogen and progesterone)
What is the maternal artery?
artery carrying oxygenated blood, sending O2 and nutrients towards baby
What is the maternal vein?
vein carrying deoxygenated blood, removed carbon dioxide and waste products away from the baby
What is the umbilical artery?
carries CO2 away from baby to mother
What is the umbilical vein?
carries oxygenated blood from mother’s blood towards baby
What is the intervillous space?
part of the placenta that surround the villi and contains maternal blood, has low pressure so exchange of materials is constantly done
Describe the thickening phase
corpus luteum releases progesterone causing endometrium to thicken for implantation
Describe the menstruation phase
endometrium sheds, FSH is released, stimulating growth and maturation of 1 egg
Describe the follicular phase
follicles grow and mature, oestrogen releases as response to FSH stimulus (positive feedback) causing endometrium to rebuild
Describe the ovulation phase
oestrogen stimulates release of LH from pituitary gland, causing release of eg into oviduct: empty follicle, without egg, is called corpus luteum
Where are oestrogen and progesterone released from and what do they target?
released by ovary, targets the uterus lining
What is the role of FSH?
stimulates ovulation and development of the corpus luteum
What is the role of oestrogen?
builds up endometrium after menstruation
What is the role of progesterone?
thickens endometrium after ovulation
What happens to the corpus luteum if the egg IS NOT fertilised?
corpus luteum is degenerated therefore levels of progesterone fall, leading to menstruation
What happens to the corpus luteum if the egg IS fertilised?
blastocysts releases a hormone that stimulates maintenance of corpus luteum: therefore levels of progesterone are kept high during all pregnancy so endometrium doesn’t shed
What is an STI (sexually transmitted infection)?
an infection that is transmitted through sexual contact
What is HIV?
human immunodeficiency virus- a pathogen that causes an STI
What may HIV infection lead to?
AIDS
Describe the methods of transmission of HIV
- transmitted by direct contact with certain body fluids from an infected person: like blood, semen and vaginal fluid.
- can happen through: - unprotected sex,
- cuts and sores,
- using contaminated needles for injecting drugs,
- receiving blood transfusions,
- mother to child during childbirth/pregnancy/breast-feeding
How is the spread of STIs controlled?
using condoms
