Reproductive Physiology

1
Reproductive Physiology
2
Topics

• Introduction
• Types of reproduction
• Reproductive cycle
• Sexual behaviour/sexual act (Read Notes)
• Components of sexual act in males (Read Notes)
• Puberty

3
Introduction

• Why do we need to reproduce?
• Important for the propagation of species
• Allows hereditary traits from both parents to be
  inherited by offspring

4
Types of Reproduction
5
Reproductive Cycle
Puberty/
Weaning

• Puberty
• Coitus
• Pregnancy
• Parturition
• Lactation
• Weaning

Coitus
Lactation
Pregnancy
Parturition
6
Sexual Behaviour/Sexual Act

• EPOR
• E Excitement Phase (somatogenic or psychogenic
  stimulus)
• P Plateau Phase (maximum sexual excitement)
• Orgasmic Phase (ejaculation and climax of sexual
  excitement with involuntary rhythmic pelvic
  muscle contractions lasting a few secs
• Resolution phase (resting/refractory phase) in
  males, they have to rest before another erection
  occurs. In women, this phase will only occur
  after multiple orgasms

7
Components of sexual act in males

• Erection
• Ejaculation (Two phases emission and expulsion)

8
Erection

• Engorgement of penis with blood
• Erection reflex - a spinal reflex triggered by
  mechanoreceptors on glans penis
• Tactile stimulation on glans triggers
  parasymphatetic activity
• Vasodilation is rapid and full erection achieved
  in 5 10 seconds
• Bulbourethral gland secretes mucus for
  lubrication
• Reflex can be stimulated/inhibited by nervous
  centre that have the final nervous pathway in the
  autonomic nerves (innervates the penile arteriole
  e.g., erection can occur due to sight or a
  seductive memory without stimulation of glans
  penis)
• Reflex can also be inhibited even though glans
  penis is stimulated e.g., impotence. This
  condition is usually more influenced by
  psychology rather than physical impairment
  (damage to nerve supply that disturbs the
  autonomic function and circulation problems to
  the penis)

9
  Erection reflex Stimulation of
mechanoreceptors in glans penis     Parasymphateti
c supply Parasymphatetic supply Symphatetic
to bulbo-urethral to penile
arterioles supply to penile and
urethral glands
arterioles  
Mucus Penile arterioles
dilate   Lubrication
Erection  
Compresses veins


-
-

10
Ejaculation (1)

• A spinal reflex
• Occurs when excitement stage reach a climax
• Consists of two phasesemission phase and
  expulsion phase
• Emission phase Symphatetic impulse will cause
  sequences of smooth muscle contraction at
  prostate gland, vas deferens and seminal
  vesicles. The prostatic fluid, seminal vesicles
  fluid and spermatozoa will drained into urethra

11
Ejaculation (2)

• Expulsion phase The sphincter at the bladder
  will close to prevent semen from entering urethra
  with urine
• Entry of semen into urethra will trigger impulses
  that activates skeletal muscles at the base of
  the penis
• Rhythmic contractions of these muscles (intervals
  of 0.8 s) together with pressure on pelvis will
  cause ejaculation

12
(No Transcript)
13
Puberty (1)/adolescence

• Morphology, physiology and behavioral changes
  that occurs to an individual
• Rapid changes of adolescence start gradually, 9
  to 11 years old for girls, 13 years old for boys.
  
• Hormone changes responsible actually begin some
  years earlier and may produce periods of
  moodiness and restlessness
• Girls start these changes before boys and will,
  for the first three or four years, appear to be
  maturing much faster.
• Male growth spurt two years later than female

14
(No Transcript)
15
Physical changes

• Sign of puberty (female) menstruation (first
  time), male (first ejaculation usually without
  sperm)
• After 2-4 years, other changes occurs to the body
  and sexual organs
• Changes dependent on sex steroids from gonads and
  adrenal glands and also growth hormone
• Adolescent growth spurt minimum growth
  velocity, peak height velocity, decreased growth
  velocity and cessation of growth at epiphyseal
  fusion
• Shoulders broader in men, hips broader in women
• Lean body mass (1.5X gt in males), body fat (2X gt
  in females), skeletal mass (1.5X gt in males). Is
  that why men are stronger?

16
Secondary Sexual Characteristics

• Growth and development of breasts
• Growth and change in sexual organs
• Monthly periods, vaginal secretions
• Moustache, beard
• Change in voice pitch (lower and deeper in boys)
• Activation of sweat glands (acne and body odour)
• Development of body hairs (auxillary etc) and
  pubic hair
• Testosterone influences male secondary sexual
  characteristics while estrogen is for female
• These changes occurs at different age in
  different individuals

17
Stages of puberty (females)
18
Stages of puberty (males)
19
Common problem faced by adolescents

• Emotional problems (Depression)
• Sexual Problems
• Boys more aggressive than girls
• Both have sexual desires
• A few years after attaining puberty, if a pair of
  adolescents have sex, the girl will become
  pregnant
• REALLY! YES! REALLY!.this is because the ovaries
  have release ova and the testes have produce
  spermatozoa
• If fertilization occurs, then this will result in
  an unwanted pregnancy

20
(No Transcript)
21
(No Transcript)
22

• Behaviour problems

23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26

• Eating problems
• Drugs, solvents and alcohol
• Abuse
• - Any physical, emotional and sexual abuse may
  occur in adolescence and may cause many of the
  problems mentioned
• Families with these problems need expert advice
  and should seek help.
• It is important to remember that once a child or
  teenager has been subjected to any form of abuse,
  they grow up to become abusers themselves

27
Adolescence Health Problems

• High blood pressure
• Glandular fever
• Obesity
• Orthodonthics
• Other health problems when active in sports
• Gynaecological and menstrual problems