Balanced Nutrition and Healthy Eating

• Healthy, balanced nutrition provides our body with energy via catabolism, as well as water, mineral salts, and vitamins for anabolism

Composition of Food

• Carbohydrates, proteins, and lipids are organic nutrients and the body's primary energy source
• Mineral salts are needed in large amounts
• Micronutrients are also essential
• Vitamins are essential factors that cannot be produced by the body's own metabolism
• Dietary fibres and water are crucial

Food and Energy

• The unit for energy is the Joule (1000J = 1kJ)
• The older unit for energy is food calories (1000 calories = 1kcal)
• 1kcal equals 4.184 kJ
• Constant body weight is maintained when energy input equals energy consumption
• Energy input exceeding energy consumption leads to overweight or obesity
• Energy input less than energy consumption leads to weight loss or anorexia nervosa

Healthy Eating

• Consume three main meals a day with small snacks in between and eat different types of food
• Drink regularly and consume 3-5 portions of vegetables or fruits daily for dietary fibres, vitamin C, and other vitamins
• Regular physical activity, sufficient sleep, and mental well-being are also important factors

Reproduction

• Reproduction is the creation of new individuals by existing members of the same species
• Parent generation passes on genetic material (chromosomes) to the next generation
• Mammals reproduce sexually
• Two gametes (specialized sex cells) fuse to form a zygote, resulting in a new individual through fertilization
• Gamete formation involves meiosis, halving the normal chromosome number
• Gametes are haploid (23 chromosomes), and fertilization restores the diploid number (46 chromosomes)

Male Reproductive System

• Testes (singular: testis) are endocrine glands in the scrotal sac, which provides optimal temperature for sperm production (2-3° lower than normal body temperature); they produce male gametes/sperms and testosterone
• The epididymis stores sperms
• The sperm duct carries sperm in fluids (seminal fluid) for ejaculation
• Ducted or exocrine glands (seminal vesicles, prostate gland) secrete nutritive seminal fluid
• Urethra carries semen during ejaculation and urine during urination
• The penis contains spongy erectile tissue that fills with blood during sexual stimulation, causing enlargement, lengthening, and erection

Female Reproductive System

• Ovaries are endocrine glands producing female gametes/ova/egg cells and estrogen and progesterone, along storing eggs
• Oviducts transport egg cells from the ovary to the vagina and have hair-like structures that create a liquid flow
• The uterus has a thick, muscular wall and is where eggs are fertilized and/or where embryo development occurs
• The endometrium is the inner lining of the uterus, richly supplied with blood vessels, and prepares for implantation each month, disintegrating during menstruation if fertilization doesn't occur
• The vagina is a muscular tube that can enlarge to allow entry of the penis or exit of a baby
• The cervix is the neck of the uterus, opening to the vagina

Embryonic Development

• XX indicates a girl, while XY indicates a boy
• Up to the seventh week of gestation, gonads (ovaries, testes), ducts, and the structure of external genitalia are similar in both sexes
• Male differentiation beings when a "master switch" on the Y chromosome, named SRY (sex-determining region of the Y-chromosome), is triggered
• SRY triggers the development of primitive Sertoli cells in the embryonic gonads
• Testosterone production begins from the eighth week, resulting in the prenatal development of the epididymis, sperm duct, seminal vesicles, testes, and prostate gland
• In females, the absence of SRY results in no testosterone production, and the ovary, female ducts, and genitals develop
• Estrogen and progesterone are produced, leading to prenatal female reproductive organ development
• The homologous organ of the male penis in females is the clitoris
• The homologous organs of female labia in males are the testes

Hormone System

• Hormones are chemical substances produced and secreted by hormone glands (endocrine glands)
• Distributed throughout the body by the blood circulation system in small quantities they are very powerful, even small amounts have significant effects
• Hormones act only on specific organs (the target organs)
• Target organs have specific protein molecules on their surface or inside their cells, called hormone receptors

General Principle of Hormone Action

• Hormone gland produces hormone
• Hormones are secreted into the blood circulation system
• The blood circulation system distributes hormones evenly in the whole body
• Hormones act specifically on organs with specific receptors (lock and key principle)
• Hormone binding activates receptors, inducing a response inside the organ

Control of Reproduction

• The reproductive system remains in a juvenile state for the first 10 years

• Puberty initiates the development of secondary sexual characteristics, marking the beginning of sexual maturation and increase production of sex hormones (testosterone, estrogen, progesterone)

• The effects of female sex hormones are less marked than those of testosterone, and the onset of puberty in females occurs three years earlier on average

• Female: Maturation of ovaries, enlargement of the vagina and uterus, development of breasts, widening of the pelvis and deposition of fat under the skin of the buttocks and thighs, monthly ovulation and menstruation

• Male: Development and enlargement of the testes, scrotum, penis, and glands of the reproductive system, increased skeletal muscle development, enlargement of the larynx (deepening the voice), growth of pubic, underarm and body hair, continuous sperm production (with occasional erections and seminal fluid discharge), changes in behavior

• Primary sexual characteristics (ovaries, vagina, penis, testes) are visible at birth

• Secondary sexual characteristics appear later during puberty

Female Menstrual Cycle

• Hormones start to control a monthly cycle, occurring with the onset of puberty (10-14 years)
• This cycle prepares one oocyte (egg cell) per month for fertilization, and bleeding occurs is no fertilization occurs
• Hormones released from the pituitary gland (in the brain) and the ovaries control this cycle
• The cycle ends when a woman reaches menopause (around 50 years)

Menstrual Cycle Details

• FSH (follicle stimulating hormone) is secreted from the hypothalamus by the anterior pituitary gland: ovaries → growth of the follicle → secretion of estrogen

• Estrogen inhibits FSH

• LH (luteinizing hormone) is secreted: ovaries → ovulation → corpus luteum secretes progesterone

• Progesterone inhibits LH

• Falling levels of LH+FSH allow corpus luteum to degenerate and levels of progesterone and estrogen fall

• The endometrium breaks down and restarts the cycle

• The menstrual cycle is a classic example of a cyclic process controlled by hormones via negative feedback

• Negative feedback: the first process triggers a second process, and the second process stops the first process

• Progesterone → less LH released → progesterone inhibits LH

• Estrogen → less FSH released → estrogen inhibits FSH

• FSH matures the egg cell inside the follicle

• Estrogen builds up the endometrium

• LH and FSH are high at the time of ovulation

• Day 1: Endometrium of the uterus breaks down, starting menstrual bleeding

• Ovarian Cycle: Changes in the ovaries (follicle growing, ovulation, corpus luteum, degeneration)

• Uterine Cycle: Endometrium growth and breakdown in the uterus

• Corpus luteum: develops from the remains of the follicle after the release of the egg cell and secretes progesterone (which inhibits the release of LH)

• Fertile days: are 3-4 days before ovulation and 1-2 days after

Sex, Fertilization, Pregnancy and Birth

• Formation of egg cells begins in the female fetus before birth
• The ovaries of a young girl contain about two million oocytes
• By puberty, roughly 200'000 to 400'000 oocytes remain
• Monthly, one oocyte is selected, starts maturation, and is released to the oviduct after about two weeks

Sperm Journey

• Testis → coiled tubes (epididymis) → spermatic cord (sperm duct and blood vessels) → urethra → vagina → cervix → uterus → oviduct (where it meets the egg cell and fertilization occurs)

Fertilization

• In the oviduct, the fusion of egg cell and sperm cell (only the head without the tail) forms a cell nucleus with 46 chromosomes (23 pairs)
• The egg cell contributes chromosomes
• Sperm cell contributes x or y chromosomes, deciding gender

Early Development

• Egg cell is transported in the oviduct after fertilization, starts dividing until it reaches the uterus, and implants into the endometrium (7-14 days after fertilization)

• Placenta and umbilical cord function: exchange of expiratory gases, water, excretory products of the fetus, and passive immunity

Development in the first 12 weeks of pregnancy

• Almost all major organ systems (skeletal, muscle, arms, legs, stomach, central nervous system) are developed
• Induced abortion is legal until week 12, because the organ systems are almost finished and because the fetus becomes a 'living being'

Stages of Birth

• Entry into the Pelvic Inlet
• Passing through the bony pelvis (head rotates 90° forward)
• Exit from the Pelvic Outlet (back of the head, forehead, face, and chin are delivered in sequence)
• Birth of the Shoulders and the Rest of the Body (another 90° rotation)

Human Reproduction, Problems and Intervention

• Contraception methods:
  • Hormonal: pill (most reliable), affects hormonal regulation of the menstrual cycle
    • Prevents follicle maturation and ovulation
    • Slows down of the building up of the endometrium
    • Prevents implantation, builds up mucus in the cervix becomes not penetrable for sperm cells
  • Special hormonal pills ("Pille danach") can be taken up to three days after sex, only for emergencies due to high hormone dose
  • Mechanical: condoms, Behavioral: temperature measurement (less reliable)

STDs

• Diseases transmitted during sexual intercourse
• STDs cause infertility, can become chronic, affect inner organs, and become life-threatening if not treated
  • Bacterial Infections:
    • Chlamydia: Can lead to infertility, Syphilis: distributed in the body and damages the heart and brain, Gonorrhea: infection of the urethra
  • Viral Infections:
    • AIDS (acquired immunodeficiency syndrome: caused by HIV (human immunodeficiency virus) and affects the immune system, Herpes genitalis, Papilloma viruses, Hepatitis B: can lead to chronic inflammation of the liver
  • Risk factors: Baby gets it from an infected mother, frequent change of sex partner, and no barrier (condoms)

Pregnancy and Miscarriage

• Fertility declines with age
• Success rate at 36: 15% (waiting time: approx. 6 months)
• Success rate at 40: 8% (waiting time: approx. 1 year)

Infertility

• Male:

  • Failure to achieve or maintain an erect penis
  • Structurally abnormal sperms
  • Sperms with poor mobility, short-lived sperms
  • too few sperms or a blocked sperm duct

• Female:

  • Condition of the cervix causes sperm death
  • Conditions in the uterus that prevent implantation of the blastocyst
  • Eggs failing to mature or be released
  • Blocked or damaged oviducts

• Men are responsible 40% of the time, women 40%, adn both are responsible 20% of the time

IVF (In Vitro Fertilization)

• Requires multiple steps if a couple is unable to conceive:
  • Hormonal therapy with the woman controls the precise time of ovulation
  • Man erection problems - sperms can be collected artificially and inserted into uterus is called insemination
  • Normal menstrual cycle steps blocked temporarily (pituitary gland activity is suppressed by injection of a drug)
  • Synthetic FSH is injected which stimulates ovaries to develop many egg cells called superovulation
  • A semen sample is required, and several eggs are removed by laparascope
  • Eggs and sperm are mixed in a shallow dish, checked by microscopic examination and incubated for 2-3 days
  • A genetic test may be performed
  • Up to three embryos are transferred into the uterus
    • embryos can be frozen for later use

Additional relevant points for IVF

• Pregnancies even though infertile
• Low success rate (1/3) from disadvantages
• Superovulation disadvantages
• Induced abortion is legally allowed up to week 12, only allowed from week 13 an abortion if doctor sees a severe physical or mental problem

Early Animal Development

• Embryonic phase: Eggs and amnion (ends with hatching/birth)
• Youth: Growth, development, learning (sexual maturity stage)
• Adult phase: phase of reproduction (end unclear)
• Senescence, aging and death are phase in humans and are often associated with diseases

Early Embryonic Development

• From Zygote to Blastula Stage
• Zygote (fertilized egg) 2-cell stage, 4-cell stage, 8-cell stage, early/late Blastula
• Gastrulation
  • Blastula to Gastrula
• The cells move to form the archenteron, extending to the mesenchyme Cells attach to the ectoderm, mouth is formed where the archenteron meets

Neurula Stage

• Ectoderm thickens to form the neural plate that develops the neural tube
• The neural tube turns into the brain and spinal cord

Germ Line and Soma

• Germ line: cell line that directly passes genetic information to next generation
• Soma: All other cells, some cells are known as stem cells
  • Has cells that can differentiate into many different kinds of cell types, and can renew themselves
  • Our bodies need these cells for cells that are in the red blood, skin and damaged cells

Different Kinds of Stem Cells

• Adult cells = multipotent stem cells
• Embryonic stem cells - Pluripotent stem cells
  • Found in embryos, scientist get them from IVF and culturing cells
• IOD - Induced Pluripotent Stem Cells
  • Somatic
  • skin cells are reprogrammed to behave like embryonic stem cells again, regaining the ability to differentiate into any cell type
  • Has a similar application with other stem cells, but are easier to harvest and are not rejected by patients body
  • Most of the research is going towards IOD instead of embryonic stem cells due to less ethical considerations

Stem cells and the process of medicine

• To replace broken stem cells
• Input of transcription
• IPS cells are reprogrammed to pluripotent cells
• They undergo in vitro differentiation and transplanted to patient
• This process allows repairing and creating personalized Medicaments
• Benefits for stem cell medicine includes no regection of donor organ
• Stem cells use treatment of patients through heart bypass and stem cell growths in blood vessels

iPS Cells

• Artificial is made using work in the lab
• there is mutations and DNA damage that occur
• The larger and the more transcription occurring is an issue in stem cells

Gene Regulation

• Living beings regulate genes performance by switching on and off
• Some genes are permanently active or inactive
• All differentiated cells of a multicellular organisms have genetic material but have some inactivated
• Enzymes accelerate a reactions
• Gene regulation is molecular

Adult Stem Cells

• Hamburger/meat from the lab
• Animals need muscle tissue that turns into muscle fibers and grounded up
• Great benefit due to animal welfare and it's better for the environment
• It's hard to create the meat and very expensive to produce