Introduction to Reproduction L16 Flashcards
What is Reproduction?
Reproduction is the process by which new individuals of a species are produced, and genetic material is passed on through generations
What is the reproductive process mediated by?
Reproductive process is mediated by a Heirachical arrangement of Endocrine Glands. These endocrine glands are ultimately under the control of the CN, but have Complex Regulatory Mechanisms operating Between the various Levels of the Heirachy
What are the 3x reasons humans have sex?
- New Individuals of a species can be produced
- Genetic material is passed on from generation to generation
- A genetically novel (unique) individual is formed as a result of Mixing genes from 2x individuals
What are the main features of Reproduction in males?
- Constant production of spermatozoon (constantly fertile)
- around 300million sperm produced per day
(1500 sperm produced per second, per testicle) - Sperm is the Smallest cell in the body
- Gradual decline of fertility with age
-but are still fertile for the most of life - further Risk of infertility only really if smoke or overweight
What is the rate of sperm production in males?
1500 sperm, produced per second, per testicle
about 300 million sperm produced per day
What is gamete production in males like?
Constant production
Constantly fertile
about 300 million sperm per day
1500 sperm, per testicle, per second
What are the main features of Reproduction in females?
- Cyclical fertility From puberty (about from age of 14-15 to 40years)
Limited span of fertility
Only fertile for 3-5 days per month - Utero (prior to birth) have about 7 million follicles
- Follicular number decreases to near 0 at menopause (50yrs)
-this decline is due to not making any more follicles - about 400 million follicles will be ovulated - normally only the best
- about 2 follicles fertilised
What is gamete production in Females like?
No production over lifespan, Born with total amount
Cyclical fertility
Fertility Limited time span: Puberty 14-15 –> 40 yrs old
Only fertile for 3-5 days per age
Born with set number of follicles, which declines with age until near 0 at menopause
How many follicles do you have as a female utero?
about 7 million
What is the number of follicles as a woman with menopause (at age of 50)?
near 0
decline due to not making any more follicles
How many follicles on average are ovulated in a female’s life?
about 400 million -normally only the best
How many follicles on average are fertilised in a female’s life?
2
What are some comparisons between a sperm and an egg?
- Sperm constant production and fertility(with only slight decrease with age) vs egg born with set amount and cyclical fertility
- Sperm is the Smallest cell in the body vs Egg is the largest cell in the body
(175,000 sperm : 1 egg) - Sperm have about a 15cm difficult swim to reach the woman’s egg. this is proportional in human terms to about a 16km swim. Only the best sperm make it to the egg
- Optimum quality of sperm is best between the ages of 20-45 years in men vs optimum egg quality is in a narrower range in woman. Woman above the age of 30 are at risk of more complications with the quality of their eggs
What is the sizing comparison between a sperm and an egg?
Sperm is the smallest cell in the body vs the egg which is the largest cell in the body
175,000 sperm : 1 egg
What are some key features of the Sperm’s travel to the ovary ?
Sperm have about a 15cm difficult swim to reach the woman’s egg
-Proportionatley in human terms is about a 16km swim
What is the optimum gamete quality span comparison between a sperm in males and an egg in females?
Optimum male sperm quality = between 20-45 years
Optimum female egg quality = smaller range = above age of 30 = at risk of more complications with the quality of their eggs
What is the function of endocrine glands?
Endocrine glands control reproductive processes by releasing hormones
Where is the hypothalamus and pituitary gland located?
In the base of the brain
What types of hormones are released hormones?
Hormones which are released are circulating hormones, which travel through the blood and bind to specific receptors
-Note: No receptor = No effect
What are the 2x main functions of the Gonads?
- To produce Gametes (sperm and eggs)
- To produce reproductive hormones (function in puberty and adulthood)
- early development of genetalia
- changes occurring in puberty - leading to 2 secondary sexual characteristics
- adulthood function is the ongoing maintenance of reproductive function
What are the 3x main functions of Reproductive hormones produced by the gonads, during 1. Puberty and 2. Adulthood?
Puberty:
1. Early development of genitalia
2. changes occurring in puberty leading to 2 secondary sexual characteristics
Adulthood:
3. adulthood function of reproductive hormones is the ongoing maintenance of reproductive function
What is the major class of Water soluble hormones?
Peptides and proteins
Free circulating proteins
What are peptides?
Water soluble hormones
Free circulating proteins
What are proteins?
Water soluble hormones
Free circulating proteins
What are the 4x main Water soluble hormones in reproduction?
- Gonadotrophin Releasing Hormones (GnRH or LHRH) -secreted from hypothalamus
- Follicle Stimulating Hormone FSH - secreted from anterior pituitary
- Lutenising Hormone LH -secreted from anterior pituitary
- Oxytocin - secreted by posterior pituitary, produced in hypothalamus
What is another name for GnRH?
LHRH = Lutenising Hormones Releasing Hormone
Where is GnRH secreted from?
Hypothalamus
Where is FSH secreted from?
Anterior pituitary
Where is LH secreted from?
Anterior Pituitary
Where is Oxytocin secreted from?
secreted from Posterior pituitary
Produced in the hypothalamus
What are all water soluble hormones (GnRH/LHRH, FSH, LH and Oxytocin)?
Water soluble hormones which are Free Circulating
What is the major class of Lipid soluble hormones?
steroid hormones
-based of 4x component cholesterol structure
What are steroid hormones?
Lipid soluble hormones
-based of 4x component cholesterol structure
What are the 3x main Lipid soluble hormones in reproduction?
- 2x Androgens (Testosterone and 5aDiHydroTestosterone) secreted from the testes 10-100x more
- 3x Oestrogen’s (Oestradiol, Oestrone, Oestriol) secreted from the ovaries 10-100x more
- 1x Progestogens (progesterone)secreted ONLY in the ovaries
Which Lipid soluble hormone is exclusive to the ovaries?
the Progestogen called Progesterone
secreted Exclusively from the ovaries
What are some main features of sex steroids?
- Androgens (2x), Oestrogen (3x), Progestogens (1x)
- After Puberty, there is a Regular production of Sex hormones
- Produced by gonads
- In general have a negative feedback
- Made from a stroid made from cholestrol. Made from the body through cholesterol (diet and made endogenously in the body). They are cholesterol converted into different forms of humans inside/conversion based on the STRUCTURE
- structure is similar to cholesterol
- -there are Different groups around the 4x rings (minor changes in structure can have big differences)
- functions, actions (also on target tissue) and specificity are very different
What is the feedback of Sex steroids like ?
Sex steroids have a negative feed back in general
What is the relationship between Cholesterol and Sex steroids?
Made from a steroid made from cholesterol
Important to our body
Backbone of all sex hormones/steroids
Sex steroids are made from the body through cholesterol
Made through cholesterol from the diet or made endogenously in the body
Cholesterol is converted into different forms inside human’s cells
Conversion is based on STRUCTURE
1. structure of sex steroid hormones is similar to cholesterol
2. there are Different groups around the 4 major rings (minor changes in structure can have big differences - i.e. between being a boy or a girl)
3. Functions, actions (on target tissues) and specificity are very different
What are the 2 main androgens?
Testosterone
5 a DiHyrdoTestosterone
What are the main features of Androgens?
Mostly associated with males, but female also produce androgens, but Little compared to males (10-100x difference)
5 a DiHydroTestosterone: More potent/ active. More important effect on target tissue.
Testosterone: the main secretary production of the testes. From Puberty to –> adulthood, testosterone is associated with the development and maintenance of Male characteristics and fertility
Key Properties of Androgens:
1. Male sex development : early in utero and during puberty
2. Spermatogenesis
3. Sexual behaviour
4. Muscle development
5. Female Libido and Sexual behaviour
What are the 2x main features of 5 Alpha DiHydroTestosterone?
- More potent/active androgen
2. Has a More Important effect on Target Tissue
What are the 2x main features of Testosterone?
- the Main secretory product of the testes
- From Puberty to Adulthood, testosterone is associated with the development and maintenance of a. Male characteristics and b. fertility
What are the 5x Key properties of Androgens?
- Male sex development (early - in utero and during puberty)
- Spermatogenesis
- Sexual Behaviour
- Muscle Development
- Female Libido and Sexual Behaviour
What are the 3x main Oestogens?
- Oestradiol
- Oestrone
- Ostriol
What are the main features of Oestrogens?
Main reproductive hormone in females
Oestrogen’s main role is the development and maintenance of female Characteristics and Fertility
Mostly in females, but is also males, even through females produce 10-100x more difference
Oestrogens Don’t play a major role in Early sexual development (instead is especially important at Puberty)
The main site of Oestrogen production is in the Granulosa cells of the Growing Follicles
Oestradiol: Produced by the granulosa cells of growing follicles. IS the main and Most potent oestrogen. Very vast amounts produced during puberty through to –> menopause (fluctuating levels). Regulates the menstrual cycle
Oestrone: Weaker, important after menopause. Important for Males and PostMenopausal woman. The only source of oestrogen after menopause. Also produced pre-menopause. Located in adipose (fat) tissue.
Oestriol: Hormone of pregnancy. Produced by the Placenta. Large amount if produced just prior to birth. As it Softens and Widens the cervix During Labour
Key properties of Oestrogens:
1. Female sexual development (mainly during puberty, not so much early on)
2. Endometrial Growth
3. Regulation of the menstrual cycle
4. Bone growth (men and women)
5. Males (spermatogenesis and bone growth)
What are the 4x main features of Oestradiol?
- Produced by the Granulosa cells of growing follicles
- is the Main and Most potent oestrogen
- Large/Vast amounts of oestradiol are produced from puberty –> until menopause
- Regulates the menstrual cycle
Which oestrogen in the main oestrogen?
Oestradiol
Which oestrogen regulates the menstrual cycle?
Oestradiol