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31.1 Pathogens and Human Illness KEY CONCEPT Germs cause many diseases in humans. 31.1 Pathogens and Human Illness Germ theory states that microscopic particles cause certain diseases. • Germ theory proposes that microorganisms cause diseases. – proposed by Louis Pasteur – led to rapid advances in understanding disease 31.1 Pathogens and Human Illness • Koch’s postulates support the theory. (DON”T COPY) • Disease-causing agents are called pathogens. (COPY) 31.1 Pathogens and Human Illness There are different types of pathogens. • Bacteria are single-celled organisms. – cause illness by destroying cells – release toxic chemicals 31.1 Pathogens and Human Illness • Viruses are genetic material surrounded by a protein coat. – force host cells to make more viruses – very small 31.1 Pathogens and Human Illness • Fungi can be multicellular or single-celled. – take nutrients from host cells – occur in warm and damp places 31.1 Pathogens and Human Illness • Protozoa are single-celled organisms. – use host cells to complete their life cycles – take nutrients from host cell 31.1 Pathogens and Human Illness • Parasites are multicellular organisms. – grow and feed on a host – possibly kill the host 31.1 Pathogens and Human Illness • READ BUT DON’T COPY • Different pathogen cause common infectious diseases. 31.1 Pathogens and Human Illness Pathogens can enter the body in different ways. (READ BUT DON’T COPY) • Pathogens can be transferred by direct or indirect contact. • Indirect contact does not require touching an infected individual. – touching an infected surface – breathing in infected air 31.1 Pathogens and Human Illness • READ BUT DON’T COPY • Vectors carry a pathogen and transmit it into healthy cells. • Direct contact requires touching an infected individual. Includes: – kissing – sexual intercourse – hand shaking tick 31.1 Pathogens and Human Illness 31.2: Immune System KEY CONCEPT The immune systems consists of organs, cells, and molecules that fight infections. 31.1 Pathogens and Human Illness 31.2: Immune System Many body systems protect you from pathogens. • The immune system is the body system that fights off infection and pathogens. • Many other tissues and systems help the immune system. – Skin is a physical barrier to infection. – Mucous membranes trap pathogens entering the body. – The circulatory system transports immune cells. 31.1 Pathogens and Human Illness 31.2: Immune System Cells and proteins fight the body’s infections. • White blood cells attack infections inside the body. READ – Phagocytes engulf and destroy pathogens. BUT – T cells destroy infected cells. DON’T COPY – B cells produce antibodies. 31.1 Pathogens and Human Illness 31.2: Immune System READ BUT DON’T COPY Immunity prevents a person from getting sick from a pathogen. • In all immunity, pathogens are destroyed before you get sick. • Passive immunity occurs without an immune response. – mother’s milk – genetics • Active immunity occurs after a specific immune response 31.1 Pathogens and Human Illness 31.3: Immune Responses KEY CONCEPT The immune system has many responses to pathogens and foreign cells. 31.1 Pathogens and Human Illness 31.3: Immune Responses • In fever, body temperature increases. – Low fevers stimulate white blood cells to mature. – High fevers can cause seizure, brain damage, and even death. 31.1 Pathogens and Human Illness 31.3: Immune Responses (READ BUT DON’T COPY) The immune system rejects foreign tissues. • Tissue rejection occurs in organ or tissue transplants. • Tissue rejection is the result of an immune response. – immune system detects protein markers on the donor (READ tissue BUT DON’T – makes antibodies against the donor’s tissue COPY) 31.1 Pathogens and Human Illness 34.1: Reproductive Anatomy KEY CONCEPT Female and male reproductive organs fully develop during puberty. 31.1 Pathogens and Human Illness 34.1: Reproductive Anatomy The female reproductive system produces ova. • There are two main functions of the female reproductive system. – produce ova, or egg cells – provide a place where a zygote develops fallopian tube uterus ovary cervix pubic bone urinary bladder urethra rectum vagina 31.1 Pathogens and Human Illness 34.1: Reproductive Anatomy • Estrogen has three main functions. – develop female sexual characteristics – develop eggs – prepare uterus for pregnancy 31.1 Pathogens and Human Illness 34.1: Reproductive Anatomy The male reproductive system produces sperm. • There are two main functions of the male reproductive system. – produce sperm cells – deliver sperm to the female reproductive system urinary bladder seminal vesicle vas deferens pubic bone prostate gland rectum penis urethra epididymis scrotum testis bulbourethral gland 31.1 Pathogens and Human Illness 34.1: Reproductive Anatomy • Testosterone has two main functions. – developing male sexual characteristics – producing sperm 31.1 Pathogens and Human Illness 34.2: Reproductive Processes KEY CONCEPT Human reproductive processes depend on cycles of hormones. 31.1 Pathogens and Human Illness 34.2: Reproductive Processes Eggs mature and are released according to hormonal cycles. potential egg – meiosis produces eggs and polar bodies – each egg has 23 chromosomes – meiosis is completed at fertilization Meiosis I Completed first polar body Meiosis II Completed only after sperm enters second polar body ovum (egg) 31.1 Pathogens and Human Illness 34.2: Reproductive Processes • Hormones, including estrogen stimulate the release of eggs. – Begins with ovulation (release of an egg from ovary) – egg travels into fallopian tube, then to uterus fallopian tube uterus 5 to 7 days to uterus follicle egg cell egg released ovary uterine wall corpus luteum 31.1 Pathogens and Human Illness 34.2: Reproductive Processes READ BUT DON’T COPY Eggs mature and are released according to hormonal cycles. • The menstrual cycle has three phases. – 1. endometrium sheds – 2. ovulation occurs – 3. corpus luteum forms 31.1 Pathogens and Human Illness 34.2: Reproductive Processes • The menstrual cycle stops at menopause. – cycle continues until a woman’s mid-40’s or 50’s – decline in hormone levels make cycles irregular – eventually, cycle stops altogether 31.1 Pathogens and Human Illness 34.2: Reproductive Processes Sperm production in the testes is controlled by hormones. • Hormones stimulate sperm potential production. sperm – one sex cell divides into four sperm – each sperm has 23 chromosomes Meiosis I Meiosis II 4 sperm cells 31.1 Pathogens and Human Illness 34.2: Reproductive Processes Fertilization occurs when a sperm cell joins an egg cell. • Sperm penetrates an egg. – membrane keeps out other sperm – nucleus of sperm joins with egg – zygote formed 31.1 Pathogens and Human Illness 34.2: Reproductive Processes (READ BUT DON’T COPY) • Multiple zygotes can result from fertilization. – identical twins from the same egg – fraternal twins from two separate eggs • Infertility makes reproduction difficult or impossible. 31.1 Pathogens and Human Illness 34.2: Reproductive Processes (READ BUT DON’T COPY) Sexually transmitted diseases affect fertility and overall health. • Sexually transmitted diseases (STDs) are passed from one person to another during sexual contact. – bacterial STDs include chlamydia, syphilis, gonorrhea – viral STDs include hepatitis B, genital herpes, human papillomavirus, and HIV HIV 31.1 Pathogens and Human Illness 34.2: Reproductive Processes (READ BUT DON’T COPY) • Bacterial STDs can be treated, and in many cases, cured with antibiotics • Viral STDs can be treated, but there is no cure for these diseases. • STDs attack reproductive organs. – can cause infertility – untreated, some can be fatal A parasite causes trichomoniasis, which • STDs can be avoided by can affect fertility. abstinence or by using a condom. 31.1 Pathogens and Human Illness 32.3 KEY CONCEPT Development progresses in stages from zygote to fetus. 31.1 Pathogens and Human Illness The fertilized egg implants into the uterus and is nourished by the placenta and umbilical cord. • The zygote becomes a blastocyst and implants in the uterus. READ – ectoderm develops into skin and nervous system BUT DON’T – mesoderm develops into Internal tissues and organs COPY – endoderm develops into digestive organs and their lining blastocyst uterine wall Implantation of blastocyst 31.1 Pathogens and Human Illness • The blastocyst becomes an embryo. • Embryonic membranes protect and nourish the embryo. – amniotic sac cushions embryo. – placenta connects placenta mother and embryo. umbilical – umbilical cord cord connects embryo to uterus placenta. amniotic sac 31.1 Pathogens and Human Illness A zygote develops into a fully formed fetus in about 38 weeks. • Human pregnancies are divided into trimesters. – 1st trimester: body plan and early development – Leave a few lines for notes here 31.1 Pathogens and Human Illness – 2nd trimester: fetus more active, developed – Leave a few lines for notes here 31.1 Pathogens and Human Illness – 3rd trimester: all organs fully formed – Leave a few lines for notes here • After about 38 weeks, fetus is ready to be born. 31.1 Pathogens and Human Illness READ BUT DON’T COPY The mother affects the fetus, and pregnancy affects the mother. • The fetus depends on the mother for all its nutrition. – mother's diet must support fetal health – mother must avoid toxic chemicals 31.1 Pathogens and Human Illness • READ BUT DON’T COPY • The mother’s health is affected by pregnancy in a number of ways. – increase in Calories and body weight – pregnancy hormones affecting homeostasis – regular medical checkups needed
