Session 5 Flashcards
Q. What is oligozoospermia?
semen with a low concentration of sperm
Q. 1. Where does spermatogenesis occur?
- What is it controlled by?
- How many sperm are produced per day
- Which cell of the testes respond to LH and which respond to FSH?
A. 1. Testis: seminiferous epithelium
2. HPT axis
3. 100 million per day
4. Leydig – LH
Sertoli – FSH (environment for maturation)
Why is there negative feedback from the leydig cells to the pituitary and hypothalamus
Q. What occurs in the menstraul cycle?
A. Uterine cycle (endometrium develops) and Ovarian cycle (follicles develop)
- Why are male germ cell produced continuously?
- Waiting phase after ovulation is built into ?
- Because females only have intermittent fertility one oocyte per cycle
- Lifespan of the corpus luteum 14 days
Describe the source of semen LO
Q. Where do semen mature?
A. Epididymis
Q. What is the difference between the sperm at the head of epididymis to the sperm at the tail of epididymis?
A. Head: spermatozoa not capable of movement
No secretory product to surface of sperm
Tail: Capable of movement (potential to fertilise)
Secretory products to surface of sperm
Maturation occurs in the epididymis
– Dependent on ?
support of the epididymis by androgens
Q. What properties of the sperm changes?
Concentration, completion of sperm modelling, metabolism, mobility, membrane
Cannabis causes micro cavities in the lungs
TB bacteria in very small sacs no vascularisation no blood supply
passes it onto brother
extensive lung disease removal of one lung can’t get drug in holes of the lung
cannabis usage feuling TB
Further describe the changes above
Concentration: increases
Describe the constituents of semen LO
Q. What are the 2 main constituents of semen?
A. • Spermatozoa
• Seminal plasma
Q. What is the function of semen? (4)
A. – Transport medium
– Nutrition
– Buffering capacity
– ? Role for prostaglandins in stimulating muscular activity in the female tract
Q. What is seminal plasma derived from?
A. Seminal plasma derived from accessory glands of the male reproductive tract
Q. State the accessory glands of the male reproductive tract. Plus percentage of volume of semen they produce.
A. Bulbourethral glands (Cowper’s glands) small amount (shouldn’t it then be 15%)
Prostate gland 25 %
Seminal vesicles 60%
Gland:
Seminal vesicles
Prostate gland
Bulbourethral glands
State:
Volume of seminal plasma they produce as a percentage
Type of fluid (e.g. pH)
Function/ contents
Explain the autonomic control of sexual function/ Explain the physiological processes involved in erection, emission and ejaculation LO
Q. What are the four phases of the human sexual response
A. • Excitement phase
– Psychogenic and / or somatogenic stimuli
• Plateau phase
• Orgasm phase (ejaculation in males)
• Resolution phase
– Return to haemodynamic norm followed by a refractory period in males
Q. Excitement phase/ erection:
- What are the stimulants for an erection?
- Efferents what nerves send signals back from the afferent to effector?
- What does this result in?
A. 1. Psychogenic
Tactile (sensory afferents of penis and perineum)
2. Somatic & autonomic efferents
•Pelvic nerve (PNS)
•Pudendal nerve (somatic)
3. Haemodynamic changes
Q. • Tunica albuginea
• Erection requires:
A. – Sinusoidal relaxation
– Arterial dilation
– Venous compression
Increase blood flow to corpus spongiosum
Compression of venous drainage
Do not want to compress the urethra
Q. What nerves facilitate penile erection? And where do they arise from?
A. Parasympathetic innervation
• Pelvic nerve and pelvic plexus
• Cavernous nerve to corpora and vasculature
• Fibres
– Lumbar and sacral spinal levels
Q. The cavernous nerves are post-ganglionic parasympathetic nerves that facilitate penile erection. They arise from cell bodies in the inferior hypogastric plexus where they receive the pre-ganglionic pelvic splanchnic nerves (S2-S4).
There are both lesser cavernous nerves and a greater cavernous nerve.
Q. (Neurophysiology of erection) How does arterial dilation take place?
A. • Inhibition of sympathetic arterial vasoconstrictor nerves
• Activation of PNS
• Activation of non-adrenergic, non-cholinergic, autonomic nerves to arteries, releasing Nitric Oxide (NO)
Q. Role of NO in erection
A. • Post-ganglionic fibres release ACh
• ACh bonds to M3 receptor on endothelial cells
• A rise in [Ca2+]i, activation of NOS and formation of NO
• NO diffuses into vascular smooth muscle and causes relaxation (vasodilation)
• NO also released directly from nerves
Q. How is the concentration of calcium in the cytoplasm increased? Draw an image.
A. The ligand (acetylcholine) binds to the GPCR.
The G protein (alpha, beta-gamma (heterotrimeric protein)) is a Gq type.
Alpha subunit activates PLC
PIP2-> IP3 + DAG (cleaved)
Inositol triphosphate binds to IP3 sensitive channel/ ligated gated calcium channel on the ER
Release of calcium down its concentration gradient into cytoplasm
Q. There are four main families of G proteins:
A. Gi/Go, Gq, Gs, and G12
Q. Erectile dysfunction causes (4)
A. • Psychological (descending inhibition of spinal reflexes)
• Tears in fibrous tissue of corpora cavernosa
• Vascular (arterial and venous)
• Drugs (anti depressants & anti hypertensives, Though depression itself can lead to erectile dysfunction)
How does Viagra work?
slows rate at which cGMP is degraded
Q. Male sexual response II: Emission & Ejaculation
- What ANS control is this under?
- What is emission?
- What assists emission?
- What is ejaculation?
A. 1. Under sympathetic control
2. Emission – Movement of semen into prostatic urethra (Contraction of ducts comes put of spermatic urethra)
3. – Contraction of SM in prostate, vas deferens and seminal vesicles (Without contraction leads to a dry orgasm)
• Ejaculation
– Expulsion of semen
Q. Male sexual response III: Ejaculation
- What causes semen to come out
- Bladder internal sphincter contracts, why?
A. 1. Contraction of glands & ducts (smooth muscle)
2. Preventing retrograde ejaculation
• Rhythmic striatal muscle contractions (pelvic floor, and perineal muscles ischiocavernosus, bulbospongiosus)
Describe the physiological changes in the female which facilitate coitus LO
How does the character of cervical mucus change over the course of the menstrual cycle?
A. • Oestrogen
– Thin, stretchy
• Oestrogen and progesterone
– Thick, sticky; forms a plug
Q. What is the fern test?
A. Provide evidence of the presence of amniotic fluid and is used in obstetrics to detect the rupture of membranes and the onset of labor. It also may provide indirect evidence of ovulation and fertility, although it does not predict the time of ovulation.
Q. What is Spinnbarkeit mucus.
A. stringy or stretchy property of mucus cervical mucus at the time just prior to or during ovulation
Under the influence of estrogens, cervical mucus becomes abundant, clear, and stretchable, somewhat like egg white. The stretchability of the mucus is described by its spinnbarkeit, from the German word for the ability to be spun. Only such mucus appears to be able to be penetrated by sperm. After ovulation, the character of cervical mucus changes, and under the influence of progesterone it becomes thick, scant, and tacky. Sperm typically cannot penetrate it.
Describe the process involved in sperm transport through the cervix and uterus LO
Describe the processes of capacitation of sperm and the acrosome reaction LO
destabilisation of the acrosomal sperm head membrane which allows it to penetrate the outer layer of the egg, and chemical changes in the tail that allow a greater mobility in the sperm.[3] The changes are facilitated by the removal of sterols (e.g. cholesterol) and non-covalently bound epididymal/seminal glycoproteins. The result is a more fluid membrane with an increased permeability to Ca2+.
An influx of Ca2+ produces increased intracellular cAMP levels and thus, an increase in motility. Hyperactivation coincides with the onset of capacitation and is the result of the increased Ca2+ levels. It has a synergistic stimulatory effect with adenosine that increases adenylyl cyclase activity in the sperm.
The tripeptide, fertilization promoting peptide (FPP), is essential for controlling capacitation. FPP is produced in prostate gland of the man, as a component of the seminal fluid. FPP comes into contact with the spermatozoa during ejaculation, as the sperm and seminal fluid mix. High levels of active FPP prevent capacitation. After ejaculation, the concentration of FPP drops in the female reproductive tract. The vaginal secretions dilute it, and make it less active due to the pH of the vagina, which differs from that of semen.[citation needed]
Q. Acrosome reaction
A. - ampulla
- before corona radiata -> hyaluronidase
zona pellucida -> Acrosine,
plasmatic membrane of the oocyte. This is followed by the fusion of the sperm’s cell membrane with the oocyte cell’s membrane so the contents of the sperm cell head can transfuse into the oocyte.
Describe the process of spermatogenesis
• Spermatogonia (male germ cells) are ‘raw
material’ for spermatogenesis • Available for up to 70 years • Divide by mitosis giving rise to:
• Ad spermatogonium (“Resting”: reserve
stock) • Ap spermatogonium (“Active”: Maintain
stock & from puberty onwards produce
type B spermatogonia which give rise to
primary spermatocytes)
• Primary spermatocytes divide by meiosis
giving rise to secondary spermatocytes
and then to spermatids • Each primary spermatocyte forms 4
haploid spermatids which differentiate
(spermiogenesis) into spermatozoa
Distinguish spermatogenic cycle and wave LO
• Not all stages in spermatogenesis are
visible in a single cross-section of
seminiferous tubule
• Cells tend to appear in groups with
same maturation stages.
• Spermatogenic cycle defined as time
taken for reappearance of the same
stage within a given segment of tubule
(~16 days in human).
• Different stages in spermatogenesis
are also ordered in space as well as
time
• Each stage follows in an orderly
sequence along the length of the
tubule.
• The distance between the same stage
is called the spermatogenic wave.
How is the zona pellucida formed?
Granulosa cells secrete layer of glycoprotein on oocyte forming the zona pellucida
- Describe the common methods of contraception
- Be able to explain the physiological basis for each method
- Describe the advantages and disadvantages of each method
- Consider and explain the most common reasons for infertility
- List the initial tests you would perform in a couple experiencing problems with fertility
- Consider briefly some of the common treatment options available for treatment of infertility
What is contraception?
Any method to prevent pregnancy
- Blocking transport of sperm to avoid fertilisation of oocyte
- Disrupting the HPG axis to interfere with ovulation
- Inhibiting implantation of the conceptus into endometrium
Methods of contraception
Can be broadly split into:
- Natural
- Barrier
- Hormonal Control
- Prevention of implantation
- Sterilisation
- Emergency contraception
Describe the common methods of contraception, be able to explain the physiological basis for each method & describe the advantages and disadvantages of each method LO\
What are the natural methods?
- Abstinence
- Withdrawal method
- Fertility Awareness Methods
- Lactational amenorrhoea method
Advantages & disadvantages of
- Abstinence
- Withdrawing before ejaculation
- Adv:
- 100% reliable method of contraception
Disadv:
- no coitus
- higher risk of ovarian cancer?
2. Adv: - No devices/hormones
Disadv:
- Not reliable
- will-power to withdraw on time
- Some sperm may be released in the pre-ejaculate
- No protection for STIs
- Fertility Awareness Methods
Use of fertility indicators to identify fertile and infertile points of the menstrual cycle:
- Advantages and disadvantages?
- • Cervical secretions
- Basal body temperatures
- Length of menstrual cycle
- Advantages:
- No hormones/contraindications
Disadvantages:
- Unreliable
- No protection form STIs
- Explain what lactational amenorrhoea method
- Advantage and disadvantages
- Requirements for it to work?
- Breastfeeding delays the return of ovulation after childbirth
- Suckling stimulus disrupts release of GnRH
- Affects feedback cycle of HPG axis
- Advantages:
• No hormones/contraindications
Disadvantages:
- Unreliable
- No STI prevention
- Relies on exclusive breast feeding
Only effective up to 6 months after giving birth
Barrier
- Examples
- Mechanism
- Can also used with
- Advantages:
- Disadvantages:
- Male/Female condoms
Diaphragm/Caps
- Physical barriers- preventing entrance of sperm into the cervix
- spermicide so additional chemical barrier
- • Reliable – 98% effective (if used correctly)
- Protection from STIs
- Male condom is widely available
- • Disrupt romantic nature of sexual intercourse
- Reduce sexual pleasure
- Expiring!
- Allergy/sensitivity to latex/ spermicide
Hormonal Control
- Forms of hormonal control (4)
Combined Oestrogen and Progestogen
- COCP
- Vaginal ring
- Patches
Progesterone Depot (LARC- Long acting reversible contraception reduce user failure
• High dose progestogen
Progesterone Implant (LARC
• High dose progestogen
Low dose progestogen
• POP (progesterone only pill)
How does progesterone effect the HPG axis
Combined Oral Contraceptive Pill
- Pill containing combination of synthetic oestrogen and progestogen
Lots of types available - strength of each hormone varies
Principal action:
• Prevents ovulation
Secondary action:
- Reduces endometrial receptivity to inhibit implantation
- Thickens cervical mucus to inhibit penetration of sperm 98% effective if taken correctly
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