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Biology🧬 > Sexual reproduction in humans (C2) > Flashcards

Sexual reproduction in humans (C2) Flashcards

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1
Q

Name what the male reproductive systems include

A

Male:

  • scrotum (external sac protecting testes)
  • testes ( x2 contains seminiferous tubules and epididymis)
  • epididymis (spermatozoa mature here and stored)
  • vas deferens (tube; sperm pass along here from epididymis to urethra)
  • seminal vesicle (x2 sponge; produces mucus secretion aiding sperm mobility)
  • prostate gland (round bubble; alkaline secretion neutralises urine and for sperm mobility)
  • urethra (passage between bladder and external)
  • penis (organ introduces sperm to female uterus)
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2
Q

Name what the female reproductive systems include (6)

A

Female:

  1. OVARY ( x2 produce ova/ovarian cycle)
  2. FALLOPIAN TUBES/OVIDUCTS (lined with ciliated epithelial cells)
  3. UTERUS (aka womb, muscular walls and lined by endometrium)
  4. ENDOMETRIUM (mucus membrane well supplied with blood, embryo implants itself here during pregnancy, shed during menstruation)
  5. CERVIX (ring of muscle and connective tissue, entrance to uterus)
  6. VAGINA (passageway for blood and mucosal tissue from uterus, passage for child birth, receives penis during copulation)
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3
Q

Processes of spermatogenesis to produce spermatozoa; location, cells produced

A
  • takes place in the seminiferous tubules within the testes
  • germinal epithelium (the origin cell) undergoes mitosis forming spermatogonia; spermatogonia 2n divide many time by mitosis to produce primary spermatocytes n; primary spermatocytes undergo meiosis I forming secondary spermatocytes n; secondary spermatocytes undergo meiosis II forming spermatids n which mature and differentiate into spermatozoa (our haploid gametes)
  • spermatozoa are protected and nourished by Sertoli cells
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4
Q

What is spermatogenesis and gonads?

A

the formation of sperm in the testes

gonads are sexual organs i.e. testes or ovary

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5
Q

What is the role of the interstitial cells?

A

interstitial cells in testes (cells of Leydig) secrete testosterone

testosterone is involved in stimulating the process of spermatogenesis

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6
Q

Name the structures and functions found in a

mature sperm cell?

A

3 man structure: head, mid piece, tail
HEAD - contains haploid NUCLEUS and covered at the end by a lysosome, ACROSOME containing digestive enzymes used in fertilisation
CENTRIOLE - between head and mid piece
MID PEICE - packed with mitochondrion, one large spiral shaped providing ATP for movement
TAIL - aka FLAGELLUM, lashing movements allowing sperm mobility

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7
Q

Processes of oogenesis to produce secondary oocytes; location, stages of cells produced? pre birth to fertilization?

A
  • oogenesis up to the secondary oocyte stage takes place in the ovary
  • pre birth: GERMINAL epithelium (origin cell in embryo) divide by MITOSIS making DIPLOID OOGONIA; oogonia undergo MITOSIS many times to form DIPLOID PRIMARY OOCYTES; primary oocytes start MEIOSIS I arresting during PROPHASE I - birth on baby girl

• puberty to menopause: primary oocytes MATURE before each ovulation completing first MEIOTIC division forming HAPLOID SECONDARY OOCYTES and a POLAR BODY (less cytoplasm, often degenerates)
OVULATION occurs releasing the secondary oocyte which begins MEIOSIS II arresting a MATAPHASE II until fertilisation

• fertilization: on FERTILISATION the entry of sperm triggers completion of MEIOSIS II and a large OVUM and SECOND POLAR BODY are formed

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8
Q

What is the process of fertilization?

A
  1. following sexual intercourse/copulation spermatozoa move into the FALLOPIAN tubes
  2. CAPACITATION increases the permeability of the membrane in front of the acrosome
  3. on contact with the zona pellucida the ACROSOME REACTION releases hydrolase enzymes which digest the zona pellucida
  4. the membranes of the sperm and secondary oocyte fuse and the genetic material of the sperm cell enters the secondary oocyte
  5. this triggers the CORTICAL REACTION in which CORTICAL GRANULES fuse with the cell membrane, their contents modify the zona pellucida to form the hardened fertilisation membrane - preventing POLYSPERMY
  6. entry of the genetic material also triggers MEIOSIS II to continue - forming the ovum and the second polar body
  7. the nuclei of the sperm and ovum fuse to form a ZYGOTIC nucleus
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9
Q

What is capacitation?

A

involves changes in the membrane covering the acrosome;

  • where CHOLESTEROL and GLYCOPROTIENS are removed
  • increasing PERMEABILTY of acrosome membrane to CALCIUM ions and improves sperm MOBILITY
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10
Q

What is the acrosome reaction?

A
  1. spermatozoa push way through to cells of CORONA RADIATA
  2. on contact with ZONA PELLUCIDA the acrosome membrane ruptures and releases hydrolytic enzymes digesting a path through the zona pellucida
  3. MEMBRANES of sperm and secondary oocyte FUSE and genetic material of the sperm (n -haploid nucleus) enters the secondary oocyte
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11
Q

Name the three reactions that occur during fertilization?

A
  1. capacitation - permeability of acrosome membrane
  2. acrosome reaction - release of hydrolytic enzymes from acrosome on contact with zona pellucida
  3. cortical reaction - cortical granules fuse with membrane forming fertilisation membrane
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12
Q

What is the process of implantation?

A

• the zygote undergoes repeated MITOTIC divisions, called cleavage, to form a ball of cells called
the BLASTOCYST
• the blastocyst is moved into the uterus where it attaches and sinks into the endometrium –
IMPLANTATION
• a PLACENTA forms between the tissues of the mother and the foetus

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13
Q

What secretes FSH? what does the hormone stand for and stimulate?

A

FSH (follicle stimulating hormone):
• secreted by the ANTERIOR PITUITARY GLAND
• stimulates the DEVELOPMENT/MATURATION of a FOLLICLE in the ovary
• AND stimulates the production of OESTROGEN
• oestrogen, which is secreted by developing follicles, increases in blood

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14
Q

Levels of oestrogen post menstruation? triggers?

A

following menstruation (shedding of endometrium) the level of oestrogen INCREASES in the blood, due to secretion by developing follicle. The oestrogen levels triggers:

  1. the REPAIR of the endometrium
  2. this INHIBITS FSH production
  3. STIMULATES LH production (luteinising hormone) by anterior pituitary gland
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15
Q

What is LH secreted by? high level initiate? causing development of?

A

a HIGH level of LH, secreted by the anterior pituitary, initiates OVULATION (the mature graafian follicle migrates to surface of ovary bursting and the secondary oocyte is released)
then causing the Graafian follicle to develop into a CORPUS LUTEUM (which, if fertilisation occurs, secretes hormones for pregnancy)

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16
Q

What does the corpus luteum secrete? what does this cause? secretion inhibits production of? and increases?

A

the corpus luteum secretes PROGESTERONE -progesterone, secreted by the corpus luteum, causes • further DEVELOPMENT of the ENDOMETRIUM
before menstruation
• progesterone also INHIBITS further production and release of LH (no additional ovulation) and INCREASES level of MUCUS in cervix to block entry of sperm

17
Q

What happens if implantation does not occur? x4

A

if implantation does not occur,:
• FALLING FSH and LH levels cause the corpus luteum to DEGENERTAE into the CORPUS ALBICANS
• progesterone levels fall (corpus luteum not secreting it)
• the endometrium BREAKS DOWN down and is LOST during menstruation
• FSH secretion is NO LONGER INHIBITED and another menstrual cycle is initiated where follicles develop

18
Q

What are the hormones during pregnancy? first 16 weeks? placenta secretes? inhibited? causes of hormones?

A

• just before and following implantation, the developing EMBRYO secretes HCG (human chorionic
gonadotrophin) - this MAINTAINS the corpus luteum for the first 16 WEEKS of pregnancy

  • the PLACENTA then secretes PROGESTERONE and OESTROGEN which rise to HIGH levels in the plasma
  • FSH and LH secretion are inhibited
  • PROGESTERONE SUPRESSES the UTERINE wall’s ability to CONTRACT and maintains endometrium
  • OESTROGEN stimulates the GROWTH of the uterus to accommodate the GROWING FOETUS foetus and stimulates the growth and development of the MAAMMARY GLANDS (responsible for lactation) during pregnancy
19
Q

What are the hormones during births?

A

• just before birth OESTROGEN levels INCREASE and PROGESTRONE levels DECREASE – the uterine wall
can now contract
• OXYTOCIN secreted by the POSTERIOR PITUITARY GLAND stimulates CONTRACTION of the UTERINE wall which stimulates the secretion of MORE oxytocin – this is an example of POSITIVE feedback
• prolactin is also released from the anterior lobe of the pituitary gland during and after birth to
stimulate the production of milk by the mammary glands

20
Q

What stimulates milk production during and after birth? released by? hormone? gland? where?

A

• the ANTERIOR lobe of the PITUITARY gland releases PROLACTIN during and after birth to
stimulate the production of milk by the MAMMARY GLANDS in the breasts

21
Q

What are the roles of the placenta? x5

A
  1. EXCHANGE of GASES and NUTRIENTS across a thin barrier separating maternal and foetal blood (INTO foetal blood: glucose, oxygen, amino acids, salts; OUT OF foetal blood: carbon dioxide and nitrogenous waste)
  2. providing a BARRIER between the maternal and foetal blood
  3. protection in difference in maternal and foetal BLOOD PRESSURES (mothers too high for foetus)
  4. protection from the IMMUNE SYSTEM of MOTHER but passage of maternal ANTIBODIES for short term immunity
  5. secretion of HORMONES
22
Q

What are the roles of the amniotic fluid? x2

A
  1. acting as a SHOCK ABSORBER and in protecting the foetus during development from injury outside
  2. maintains foetal TEMPERATURE
23
Q

What is the placenta? connects to foetus by? blood vessels?

A

• forms between the tissues of the mother and the foetus and is connected to the foetus by the UMBILICAL CORD - the umbilical cord contains TWO blood vessels

  1. umbilical ARTERY - carries deoxygenated blood containing co2 AWAY from foetus
  2. umbilical VEIN - carries blood containing o2 and glucose TO the foetus
24
Q

Type of blood flow in the placenta?

A

blood flow in OPPOSITE directions:
COUNTER CURRENT flow between maternal and foetal blood supplies - maintaining CONCENTRATION GRADIENT across whole placenta

25
Q

What are found on foetal capillaries and role?

A

CHORIONIC VILLI found on foetal capillaries forming a BOUNDARY between maternal and foetal blood

26
Q

What is the intervillous space found in the placenta?

A

where BLOOD from maternal ARTERIOLES EMPTIES into - oxygen and nutrients enter and can diffuse into foetal blood and co2 and waste can be removed by maternal VENULES - foetal capillaries BATHE into this intervillous space for EXCHANGE of materials

there are NO maternal capillaries between the maternal arteriole and the maternal venule thus providing a SHORTER DIFFUSION PATHWAY for materials

27
Q

How can hormones be used as a contraceptive? oestrogen? progesterone? ivf?

A
  • O: inhibits FSH - follicles cannot develop and mature - no graafian follicle - no ovulation thus no fertilization
  • P: inhibits LH - no initiation of ovulation - also increases mucus in cervix blocking entry of sperm - no ovulation/no sperm thus no fertilization
  • IVF: FSH - primary follicles develop to graafian follicles
28
Q

Process of ovarian cycle? development of follicle?

A
  1. germinal epithelial cells divide forming FOLLICLE CELLS which surround the primary oocyte forming PRIMARY FOLLICLE
  2. FSH - stimulates the maturation of follicles (secreting oestrogen inhibiting further FSH) developing into a GRAAFIAN FOLLICLE containing the secondary oocyte
  3. stimulated by oestrogen levels in blood, LH initiates ovulation, graafian follicle migrates to surface of ovary bursting and releasing the secondary oocyte
  4. the graafian follicle becomes the CORPUS LUTEUM (secretes progesterone inhibiting further LH)
  5. if no fertilisation occurs corpus luteum degenerates into CORPUS ALBICANS

Biology🧬 (18 decks)

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