Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 2 Medicine > The Short but Happy Life of a Sperm > Flashcards

The Short but Happy Life of a Sperm Flashcards

1
Q

The Testis

  • Testis sits inside the … cavity lined by tunica …
  • Testis surrounded by thick … capsule - short septa project into the substance of testis - called the tunica …
  • Divides testis into lobules - within these lobules - … tubules
  • These loops - join to make … testis
  • Up to head and tail of epididymis - into ductus … - into ductus …
A
  • Testis sits inside the scrotal cavity lined by tunica vaginalis
  • Testis surrounded by thick fibrous capsule - short septa project into the substance of testis - called the tunica albuginea
  • Divides testis into lobules - within these lobules - seminiferous tubules
  • These loops - join to make rete testis
  • Up to head and tail of epididymis - into ductus epididymis - into ductus differens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Functions of the testis

  • The testis has two main products: … and …
  • Manufacture of these products occurs in discrete compartments
  • Production of … is … and highly orchestrated process
  • A number of measurable … may correlate with the function of …
A
  • The testis has two main products: spermatozoa and hormones
  • Manufacture of these products occurs in discrete compartments
  • Production of spermatozoa is complex and highly orchestrated process
  • A number of measurable parameters may correlate with the function of spermatozoa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Compartments of the Testis

  • Seminiferous tubules within which … occurs
  • Vascularised stroma containing … cells
A
  • Seminiferous tubules within which spermatogenesis occurs
  • Vascularised stroma containing Leydig cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Hormones from the testis

  • Most important hormones are … in maintaining reproductive and sexual function
  • Testosterone synthesised from … and cholesterol by … cells
  • …-… mg testosterone secreted daily
    • Principally into blood vessels but also … (and … transport to other structures probably important)
  • Some testosterone passes through to … tubules (lipid soluble)
  • Converted to dihydrotestosterone by 5a-reductase in … cells
  • Androgens are required for …
  • The testis does not function in isolation…
A
  • Most important hormones are androgens in maintaining reproductive and sexual function
  • Testosterone synthesised from acetate and cholesterol by Leydig cells
  • 4 – 10 mg testosterone secreted daily
  • Principally into blood vessels but also lymph (and lymphatic transport to other structures probably important)
  • Some testosterone passes through to seminiferous tubules (lipid soluble)
  • Converted to dihydrotestosterone by 5a-reductase in Sertoli cells
  • Androgens are required for spermatogenesis
  • The testis does not function in isolation…
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

…-… mg testosterone secreted daily

A

4 – 10 mg testosterone secreted daily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

… are required for spermatogenesis

A

Androgens are required for spermatogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pituitary Control - Testis

  • Production of … and … related functionally
    • At puberty, … rise and … commences
  • Removal of pituitary (hypophysectomy) causes testes to … and … to arrest
  • … stimulates Leydig cells to produce androgens (which are required for spermatogenesis)
  • … stimulates Sertoli cells and is required for spermatogenesis
A
  • Production of androgens and spermatozoa related functionally
    • At puberty, androgens rise and spermatogenesis commences
  • Removal of pituitary (hypophysectomy) causes testes to shrink and spermatogenesis to arrest
  • LH stimulates Leydig cells to produce androgens (which are required for spermatogenesis)
  • FSH stimulates Sertoli cells and is required for spermatogenesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

LH and FSH - Testis

  • LH stimulates … to produce … (which are required for spermatogenesis)
  • FSH stimulates … and is required for …
A
  • LH stimulates Leydig cells to produce androgens (which are required for spermatogenesis)
  • FSH stimulates Sertoli cells and is required for spermatogenesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Organisation of seminiferous tubules

  • …-… cm long
  • Total length c …m
  • Peripheral … cells
  • Then … membrane
  • … cells and … cells within the tubules
A
  • 30-80 cm long
  • Total length c 540m
  • Peripheral myoid cells
  • Then basement membrane
  • Sertoli cells and spermatogenic cells within the tubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Organisation of seminiferous tubules

  • Physiological barrier formed by …- and …-junctioned complexes between … cells
    • Creates a … compartment and a separate … compartment
A
  • Physiological barrier formed by gap- and tight-junctioned complexes between Sertoli cells
  • Creates a basal compartment and a separate adluminal compartment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Spermatogenesis in three acts

  • Three elements
    • … proliferation to produce lots of cells
    • … division to generate genetic …
    • Cell … to package chromosomes for delivery to the …
  • … numbers of spermatozoa are produced
  • … to … per gram of testis per second
A
  • Three elements
    • Mitotic proliferation to produce lots of cells
    • Meiotic division to generate genetic diversity
    • Cell modelling to package chromosomes for delivery to the oocyte
  • Large numbers of spermatozoa are produced
  • 300 to 600 per gram of testis per second
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Spermatogenesis: 1 – mitosis

  • … cells of immature testis (…) are reactivated at … to undergo rounds of mitosis in the basal compartment of the tubule
  • From this self regenerating population, emerge groups of cells called … … which undergo a series of divisions to form a clone of cells
  • Finally after the last round of division, the clone divide to form … … spermatocytes which inhabit cavities formed in … cell cytoplasm
A
  • Germ cells of immature testis (prospermatogonia) are reactivated at puberty to undergo rounds of mitosis in the basal compartment of the tubule
  • From this self regenerating population, emerge groups of cells called A Spermatogonia which undergo a series of divisions to form a clone of cells
  • Finally after the last round of division, the clone divide to form resting primary spermatocytes which inhabit cavities formed in Sertoli cell cytoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Spermatogenesis: 2 - meiosis

  • Resting primary spermatocytes push through sertoli cell junctions into … compartment
  • Enter meiotic …
  • Paired homologous chromosomes form contacts at …, break, swap segments and rejoin
    • Very sensitive to … at this time
  • First division ends with separation of homologous chromosomes to opposites ends of the meiotic spindle, cytoplasm divides forming short-lived secondary …
  • These quickly divide to form … …
A
  • Resting primary spermatocytes push through sertoli cell junctions into adluminal compartment
  • Enter meiotic prophase
  • Paired homologous chromosomes form contacts at pachytene, break, swap segments and rejoin
    • Very sensitive to damage at this time
  • First division ends with separation of homologous chromosomes to opposites ends of the meiotic spindle, cytoplasm divides forming short-lived secondary spermatocytes
  • These quickly divide to form haploid spematids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Spermatogenesis: 3 - packaging

  • Cytoplasmic … of spermatid
    • 5: … for forward propulsion
    • 4: Midpiece with … for energy
    • 3: Nucleus with packaged …
    • 2: … region forms for sperm-oocyte …
    • 1: … forms to penetrate oocyte
      • A small residual body is the dustbin for unwanted cytoplasm, later eaten by … cell
A
  • Cytoplasmic remodelling of spermatid
    • 5: Tail for forward propulsion
    • 4: Midpiece with mitochondria for energy
    • 3: Nucleus with packaged chromosomes
    • 2: Cap region forms for sperm-oocyte fusion
    • 1: Acrosome forms to penetrate oocyte
      • A small residual body is the dustbin for unwanted cytoplasm, later eaten by sertoli cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Organisation of Spermatogenesis

  • Unlike …, which is a regular but infrequent event, spermatogenesis is …
  • How is this complex process organised in space and time?
A
  • Unlike ovulation, which is a regular but infrequent event, spermatogenesis is continuous.
  • How is this complex process organised in space and time?
    • Spermatogenic cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The Spermatogenic Cycle

  • We considered generation of sperm from a single spermatogonium
  • Once this process has started, new stem cells at the same location don’t start generation of clones again for a few days
  • The interval is constant at around … days, the process by which the stem cell population controls, or is controlled is …
  • The time for completion of spermatogenesis is … days, so there are … successive sets of clonal development (at … separate stages of the process) in one place at one time – and that’s what we see when we look down the microscope
A
  • We considered generation of sperm from a single spermatogonium
  • Once this process has started, new stem cells at the same location don’t start generation of clones again for a few days
  • The interval is constant at around 16 days, the process by which the stem cell population controls, or is controlled is unknown
  • The time for completion of spermatogenesis is 64 days, so there are four successive sets of clonal development (at four separate stages of the process) in one place at one time – and that’s what we see when we look down the microscope
17
Q

Cycle control

  • If all spermatogonia were activated on 11th birthday, mature spermatozoa would be produced every … days.
  • Result: episodic …
  • If the spermatogonia were activated randomly then … production could occur
  • Infact, small regions seem to be activated …, in wedges and helices around the tubule
A
  • If all spermatogonia were activated on 11th birthday, mature spermatozoa would be produced every 16 days.
  • Result: episodic fertility
  • If the spermatogonia were activated randomly then continuous production could occur
  • Infact, small regions seem to be activated together, in wedges and helices around the tubule
18
Q

The spermatogenic wave

  • If the … tubules are dissected longitudinally, adjacent synchronised clones of … are seen
A

If the seminiferous tubules are dissected longitudinally, adjacent synchronised clones of spermatogenesis are seen

19
Q

Later events in maturation​

  • So far:
    • Starting with …
    • … to increase numbers
    • … to generate genetic diversity
    • … to form spermatozoa
    • Spacial and temporal organization in testis with … and …
    • Stimulated by … and under control of the …
A
  • So far:
    • Starting with spermatogonia
    • Mitosis to increase numbers
    • Meiosis to generate genetic diversity
    • Maturation to form spermatozoa
    • Spacial and temporal organization in testis with cycles and waves
    • Stimulated by androgens and under control of the pituitary
20
Q

The final stages of maturation of spermatozoa occur elsewhere

  • Spermatozoa wash into the …
  • Through the vasa …
  • Into the … where fluid is absorbed and sperm …
  • In the … they can twitch: by the cauda … they can swim
  • The process is dependent on … stimulation
A
  • Spermatozoa wash into the rete
  • Through the vasa efferentia
  • Into the epididymis where fluid is absorbed and sperm concentrated
  • In the rete they can twitch: by the cauda epididymis they can swim
  • The process is dependent on androgen stimulation
21
Q

The components of semen

  • Spermatozoa mixed with secretions from … tubules, epididymis etc.
  • Addition of secretions from …, … vesicles and … glands at time of ejaculation
    • About … ml human
A
  • Spermatozoa mixed with secretions from seminiferous tubules, epididymis etc.
  • Addition of secretions from prostate, seminal vesicles and bulbourethral glands at time of ejaculation
    • About 3 ml human
22
Q

Cellular components of Semen

  • S…
  • … cells from tract
  • … cells
  • … – risk of HIV etc
A
  • Spermatozoa
  • Epithelial cells from tract
  • Spermatogenic cells
  • Leucocytes – risk of HIV etc
23
Q

Fluid Components of Semen

  • Can’t be essential for …
  • Provide a fluid vehicle for …
    • N… (fructose, sorbitol)
    • B… (to protect against vaginal acidity)
    • A.. (ascorbic acid, hypotaurine)
A
  • Can’t be essential for fertilisation
  • Provide a fluid vehicle for spermatozoa
    • Nutrition (fructose, sorbitol)
    • Buffer (to protect against vaginal acidity)
    • Antioxidants (ascorbic acid, hypotaurine)
24
Q

What does the endocervix do?

  • Secretes … with cyclical variation
  • Macromolecular network of mucin fibrils ?guiding spermatozoa
  • … stimulates watery mucus
  • … inhibits secretory activity
  • Sperm can penetrate from …, peak at time of ovulation
A
  • Secretes mucus with cyclical variation
  • Macromolecular network of mucin fibrils ?guiding spermatozoa
  • Oestrogen stimulates watery mucus
  • Progesterone inhibits secretory activity
  • Sperm can penetrate from day 9, peak at time of ovulation
25
Q

What does the endocervix offer sperm?

  • Receptive to sperm at time of …, interference at other times
  • Protection from hostile vagina, and from being …
  • Supplementation of energy …
  • Sperm selection by differential M.. and M…
  • Short term … within endocervical crypts
  • Initiation of the next stage in sperm maturation: ‘…’
A
  • Receptive to sperm at time of ovulation, interference at other times
  • Protection from hostile vagina, and from being phagocytosed
  • Supplementation of energy requirements
  • Sperm selection by differential motility and morphology
  • Short term reservoir within endocervical crypts
  • Initiation of the next stage in sperm maturation: ‘capacitiation’
26
Q

Cervical mucus

  • Three properties
    • Consistency (… or …)
    • … (means elasticity, stickiness)
    • … (crystalisation on a glass surface)
A
  • Three properties
    • Consistency (watery or viscous)
    • Spinnbarkeit (means elasticity, stickiness)
    • Ferning (crystalisation on a glass surface)
27
Q

Testing cervical mucus

  • These are crude assessments of a complex … situation
  • … testing can follow
    • Eg Looking at spermatozoa penetrating mucus and assessing their motility
A
  • These are crude assessments of a complex physiological situation
  • Detailed testing can follow
    • Eg Looking at spermatozoa penetrating mucus and assessing their motility
28
Q

Capacitation

  • Sperm recovered at … don’t fertilise ova in vitro …
    • Those from the … will
  • Have undergone capacitation
  • Stripping of … from sperm surface which accumulates in the …
  • Causes hyperactive … – ‘whiplash’
  • And make sperm responsive to signals from …
A
  • Sperm recovered at ejaculation don’t fertilise ova in vitro immediately
  • Those from the uterus will
  • Have undergone capacitiation
  • Stripping of glycoprotein from sperm surface which accumulates in the epididymis
  • Causes hyperactive motility – ‘whiplash’
  • And make sperm responsive to signals from oocyte

Year 2 Medicine (162 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions