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
Where is oestradiol produced?
In the granulosa cells of growing follicles
Which Oestrogen is the weakest?
OEstrone
Which oestrogen is present after menopause?
Only oestrone
Where is oestrone produced?
Adipose tissue
What are the 4x main features of oestrone?
- The Weaker oestrogen
- Important for males and post-menopausal woman
- The only source of oestrogen post/after menopause. Also produced pre-menopause
- Located in Adipose (fat) tissue
What are the 4x main features of oestriol?
- The hormone of pregnancy
- Produced in the placenta
- Large amount produced just prior to birth
- As it softens and widens the cervix during labour
What is the hormone of pregnancy?
oestriol
- produced by the placenta, especially just prior to birth, as softens and widens the cervix
also
Progesterone
-exclusive to woman, produced by placenta and corpus luteum, as prepares for and maintains pregnancy
Where is oestriol produced?
In the placenta
-large amount produced just prior to birth
What regulates the menstrual cycle in woman?
Oestradiol
Which sex steroid is associated with bone growth?
oestrogen
-in both males and females
What are the roles of Oestrogen in males?
Spermatogenesis
Bone growth
What are the role of Androgens in females?
Sexual behaviour (Libido- sex drive)
What are the 5x Key properties of Oestrogens?
- Female sexual development (oestrogens more important during puberty, than in early development)
- Endometrium Growth
- Regulation of the Menstrual cycle
- Bone growth (males and females)
- Males: spermatogenesis and bone growth
What is Key to the growth of the endometrium?
Oestrogens
What is the coherent difference between genders and sex steroids?
Males NEVER have any progestogens
-is a dimorphic steroid hormone only for females after ovulation
What are the key features of Progestogens?
A Progestogen = progesterone
Progestogens are the Major Steroid Hormone of the Corpus Luteum and Placenta
Most dimorphic steroid hormone - only in females. Occurs After ovulation. Hormone of pregnancy as it is associated with the preparation for and maintenance of pregnancy.
Where is the steroidal hormone progestogen located?
Progestogens are the major steroidal hormone of:
- Corpus Luteum
- Placenta
What is the most dimorphic steroid hormone?
The Progestogen Progesterone
-only in female after ovulation
What does progesterone occur?
after ovulation
How is progesterone also a hormone of pregnancy?
Progesterone is associated with 1. the Preparation of Pregnancy
2. and the Maintenance of Pregnancy
What are the 4x main endocrine glands associated to reproduction?
- Hypothalamus H
- Pituitary Glands P
- Adrenal Glands
- Gonads (testes and ovaries) G
HPG axis
What are most of the hormones produced in the pituitary gland likely to be?
Circulating hromones
When is the HPG axis activated?
during puberty
Essentially what is cholesterol?
backbone of all sex steroids
Concisely how to water soluble hormones act?
Peptides and proteins
Phosphorylation of enzymes to change cell activity
Concisely how to lipid soluble hormones act?
Steroid hormones
v important in reproduction
Act by changing gene expression
What is the Effects of Reproductive Water Soluble hormones?
Fast effect (sec-mins) Level of change is enzyme phosphorylation Causes a lesser change
What are the Effects of Reproductive Lipid Soluble hormones?
Slow effect (hours - days)
Level of change/action is at changing gene expression, at the level of making new proteins
Causes a greater change
Triggers events which are harder to turn on than too turn off
Does need a soluble carrier protein
Only 2-3% of lipid soluble hormones are Free at any one time- too high or too low conc. of hormones free can be damaging
What is hormone action like?
Complex
- can have more than one affect
- often many/multiple hormones used
What is the size of the hypothalamus?
Hypothalamus is the size of a nut
What is the size of the pituitary gland?
Pituitary gland is the size of a pea
What is the arrangement of the HPG axis like?
Heirarchical arrangement of the endocrine glands
What does the hierarchical arrangement of the endocrine glands allow for?
Signal amplification
(Pecagram amount of products produced in the Hypothalamus) –> (Microgram amount of products produced in the Pituitary gland) –> (Milligram amount of products produced in the Gonads)
What amount of products is produced in the Hypothalamus?
Pecagram quantities of products
-smallest in the hierarchical arrangement of endocrine glands which allows for signal amplification
What amount of products is produced in the Pituitary gland?
Microgram quantities of products
-middle in the hierarchical arrangement of endocrine glands which allows for signal amplification
What amount of products is produced in the gonads?
Milligram quantities of products
-largest in the hierarchical arrangement of endocrine glands which allows for signal amplification
What is the main function of the hypothalamus?
Homeostatic regulator for: 1. Reproduction 2. stress 3. body temperature 4. hunger and thirst 5. sleep - is a neuroendocrine organ as it processes both Neural and Hormonal information
How is homeostasis regulated?
Homeostasis is regulated by the Hypothalamus in 1. reproduction 2. stress 3. body temperature 4. hunger and thirst 5. sleep
What 5x things is the hypothalamus a homeostatic regulator of?
- Reproduction
- Stress
- Body Temp
- Hunger and Thirst
- Sleep
What type of organ is the hypothalamus?
hypothalamus is called a Neuroendocrine organ, as it Processes both Neural information and Endocrine information, integrating it all together
What are some key features of the Pituitary gland?
Pear shaped
about 1.5cm
IS attached to the hypothalamus by a stalk called the infundibulum
Consists of 2x anatomically and functionally separate lobes (anterior (adenohypophysis) and posterior (neurohypophysis))
Both are required - if there is one missing there is no hormones produced. If overactive (e.g. tumour) results in adverse effects also
How big is the Pituitary gland?
about 1.5 cm
2x lobes. Posterior lobe is the smallest, 1/2 the size of the anterior lobe
2x anatomically and functionally separate lobes (anterior and posterior)
Are both lobes of the pituitary gland required?
BOTH lobes of the pituitary gland are required
- if one is missing there are no hormones produced
- if one is Overactive (e..g tumour) results in adverse effects also
What is another name for the posterior pituitary?
Neurohypophysis
What is the Neurohypophysis?
Posterior pituitary
Where does the posterior pituitary originate from?
Neural origin
drops down/is a down growth of the brain
Which pituitary gland is a down growth from the brain/is of neural origin?
Posterior pituitary
What sort of neurons enter into the posterior pituitary?
Neurosecretory neurons
- which
1. conduct nerve impulses
2. Synthesize neurosecretory hormones
3. Carry and release neurosecretory peptide hormones
What types of hormones to neurosecretory hormones synthesize, carry and release?
Neurosecretory peptide hormones
What produces neurosecretory peptide hormones?
Neurosecretory neurons located in the Hypothalamus
Neurosecretory peptide hormones are carried too, stored and released from the posterior pituitary
What are neurosecretory hormones aggregated into?
Nuclei/cell bodies
What is the function/abilities of normal neurons?
can conduct nerve impulses
Release neurotransmitters
Where are neurotransmitters secreted from?
Normal neurons
-neurosecretory peptide hormones are released by neurosecretory neurons
What is the function/abilities of neurosecretory neurons?
conduct nerve impulses
Synthesize neurosecretory peptide hormones
Carry and release Neurosecretory peptide hormones
Long axon tracts which pass into the Posterior pituitary
What are some important facts about neurosecretory hormones?
- Neurosecretory hormones are Synthesized in the hypothalamus
- are Travel bound to Carrier proteins down axon to the axon terminals
- Stored in secretory vessels (located in posterior pituitary)
- as nerve impulses travels along the axon it Triggers EXOCYTOSIS of the neurosecretory vesicles. These neurosecretory vessels then Release their neurosecretory peptide hormones from the posterior pituitary
Where is the storage of neurosecretory hormones ?
Secretory vessels
- in posterior pituitary
What is the transport of neurosecretory hormones like?
travel bound to carrier proteins down the axon to axon terminals
How are neurosecretory peptide hormones secreted?
as Nerve impulse travels down axon it reaches axon terminals and triggers the EXOCYTOSIS of the secretory Vesicles, which releases the neurosecretory Peptide hormones at the posterior pituitary
what are the 2x types of neurosecretory peptide hormones made in the hypothalamus and released via exocytosis but the posterior pituitary?
- Oxytocin
2. ADH (anti-diuretic hormone) . Vasopressin
What is Oxytocin?
Neurosecretory peptide hormone
made in hypothalamus
Secreted via exocytosis from posterior pituitary
What is Anti-diuretic Hormone (ADH)?
also called Vasopressin
Neurosecretory peptide hormone
made in hypothalamus
Secreted via exocytosis from posterior pituitary
What is another name for ADH?
vasopressin
Anti-diuretic hormone
What is another name for Vasopressin?
ADH
Anti-diuretic hormone
What is the comparison between ADH/vasopressin and Oxytocin?
Similar structure
Very different specificities of action
What are the 3x main roles of oxytocin?
Major effects on:
- Milk Ejection
- the secretion of Oxytocin is stimulated in response to the stimulation of the nipples (lactation) - even just seeing or hearing baby - Contraction of smooth muscle at childbirth
- -the secretion of oxytocin is stimulate in response to uterine distension (uterine enlarging ballooning) - Oxytocin is used to INDUCE LABOUR
- Love hormone important for bonding
- love, lust, orgasm
What are the main roles of ADH/antidiuretic hormone/Vasopressin?
Acts on kidneys to retain water
How does ADH/Anti-diuretic hormone/Vasopressin effect the kidneys?
“Anti”-“diuretic”
Against peeing
Acts on the kidneys to RETAIN WATER
What effect does the neurosecretory peptide hormones oxytocin have on milk ejection?
- Oxytocin has a major effect on milk ejection
- release of oxytocin is stimulated by the stimulation of Nipples (lactation) - even just seeing or hearing baby
How are nipples stimulated?
via lactation (just seeing/hearing baby) causes the release of the neurosecretory peptide hormone oxytocin
What effect does the neurosecretory peptide hormones oxytocin have on contraction of smooth muscle in childbirth?
Oxytocin has a major effect on contraction of smooth muscle in child birth
-release of oxytocin is stimulated by uterine distention (uterine enlarging ballooning)
Oxytocin is used to INDUCE LABOUR
What does uterine distension cause?
Release of oxytocin for smooth muscle contraction
Which hormone is called a Love hormone?
Neurosecretory hormone OXYTOCIN
love hormone - love, lust Orgasm
Which hormone is used to induce labour?
Oxytocin
What role does oxytocin have in child birth?
Upon uterine distension (expansion or enlargement) causes contraction of smooth muscle for childbirth
Oxytocin is used to INDUCE labour
