Bio 1040 Exam #2

what is a pathogen?

disease-causing agent

how do bats relate to human health?

they transfer diseases to humans (ex: covid-19)

what is the general function of the lymphatic system?

to check for infection in fluids and return them back into the circulatory system

what is the function of lymph nodes and how are macrophages involved in them?

they filter lymphatic fluid and macrophages engulf and destroy foreign objects

what are the four lines of defense?

INNATE (immediate response):
1. external barriers

2. innate immune cells

ADAPTIVE (5-7 day response):

3. humoral immune response

4. cell-mediated immune response

examples of external barriers (INNATE)

• skin

• mucous membranes

examples of innate immune cells (INNATE)

• neutrophils: first responder phagocytes attracted to infections; component of pus

• macrophages: phagocytes that patrol fluids

• natural killer cells: attack cancer and virus-infected cells

what happens during the humoral immune response (ADAPTIVE)?

free-floating antibodies and lymphatic fluids are produced by B cells (helper T cells help)

what happens during cell-mediated immune response (ADAPTIVE)?

cells that are infected are eliminated by cytotoxic T cells; perforin helps break cell membranes with the help of helper T cells

what do interferons guard against?

viruses; antiviral proteins are produced in infected cells to signal defense

what are the steps of the local inflammatory response?

1. mast cells release histamine, causing capillaries to swell and leak

2. platelets from blood plasma start healing and neutrophils migrate to the area

3. bacteria is engulfed

what are the two functions of fever during the systematic inflammatory response?

1. raise metabolic rate

2. throw off temperature sensitive pathogens

what allows an adaptive immune response?

the antigen must have been encountered before at least once

what is the difference between B and T cells?

• B: makes antibodies

• T: destroys harmful pathogens

what happens when a B cell recognizes its antigen for the first time?

clonal selection

what happens during clonal selection?

1. cell is cloned

2. effector B cells are produced: produce large amounts of antibodies

3. memory B cells are produced: migrate to lymph nodes to respond to invasions (activated by helper T cells)

what are the three functions of antibodies?

1. mark pathogens for destructions

2. neutralize pathogens by blocking binding sites

3. aggregate clumps of pathogens together for easy destruction (agglutination)

what is autoimmune disease?

healthy tissue gets attacked by the nervous system (ex: type 1 diabetes)

what are the two stages of an allergic reaction?

1. sensitization: first exposure

2. overreaction: overstimulation of inflammatory response during later exposures

how does the endocrine system signaling differ from that of the nervous system?

nervous system has faster responses and shorter duration than the endocrine system

what happens during water-soluble signaling? (RECEPTION)

hormones bind to plasma membrane receptors on target cells, but don’t pass through membrane (nucleus = regulates gene expression; cytoplasm = enzyme activation)

what happens during lipid-soluble signaling? (RECEPTION)

hormones pass through plasma membrane and into nucleus by diffusion, forming a hormone-receptor complex (HRC = transcription fact that binds to DNA at specific genes to promote/prevent transcription)

what are the three stages of hormone signaling?

1. reception: binding of hormone to receptor protein

2. signal transduction: converts signal from one form to another

3. response: change in the behavior of the receptor cell

what does a gland do?

produces and secretes chemicals

what does an endocrine gland do?

secretes hormones that are carried to all other parts of the body through the bloodstream

what is the main control center of the endocrine system and what does it control?

hypothalamus/brain; controls pituitary gland

what does the thyroid gland do?

influences metabolism and cellular respiration

what can be used to treat thyroid cancer and why?

radioactive iodine; it kills the excess iodine

what does the pineal gland do?

secretes melatonin and regulates circadian rhythm

what are the two gonads?

male testes and female ovaries

what do gonads do?

secrete sex hormones and produce eggs/sperm

what are the female sex hormones?

estrogens and progestins (influences uterus preparation/lining)

what are the male sex hormones?

androgens

what is an endocrine disruptor?

chemical that interferes with hormone signaling

why is it important to research and regulate endocrine disruptors?

they can cause harm including cancer and their levels in the environment are unhealthy

what do pancreatic hormones do?

regulate blood glucose levels

how do pancreatic hormones function?

they maintain homeostasis in an antagonistic way by regulating glucose levels

what happens when blood sugar is high?

insulin signals cells to store glucose

what happens when blood sugar is low?

glucagon signals cells to convert fat and amino acids into glucose and release it for use

what happens with type 1 diabetes?

insulin is not produced (autoimmune)

what happens with type 2 diabetes?

receptors do not respond to insulin; associated with obesity

what are the advantages of asexual reproduction?

allows fast population growth, reproduction where mates are not available, and beneficial in stable habitats

what are the disadvantages of asexual reproduction?

lack of genetic diversity and limited ability to respond to environmental change

what are the advantages of sexual reproduction?

increased genetic variability, greater adaptability

what are the disadvantages of sexual reproduction?

mates required, slower reproduction

what is a hermaphrodite?

organism with both male and female reproductive organs that are twice as likely to find a mate

what are ovaries?

female gonads that produce and mature eggs; produce female sex hormones

what are oviducts?

aka fallopian tubes; channels that capture and direct eggs from the ovary to the uterus; site of fertilization

what is the uterus?

place where embryo develops

what is the endometrium?

inner lining of uterus where blastocyst is implanted

what is the cervix?

opening of the uterus into the vagina that secretes mucus to enhance sperm movement

what is the vagina?

female sex organ and birth canal

what are the testes?

male gonads that produce sperm and male sex hormones

what is the epididymis?

a duct attached to the testes where sperm is collected and stored

what is the vas deferens?

thick tubes that transport sperm from epididymis to ejaculatory duct

what is the penis?

male sex organ that delivers semen

what does the bulbourethral gland do?

secrete alkaline fluid that neutralizes acid in the vagina; lubricates tip of penis; may carry sperm birth control should be used)

what hormone stimulates sperm production?

follicle stimulating hormone (FHS)

what does meiosis produce in males through spermatogenesis?

4 haploid sperm cells; happens in seminiferous tubules

what are the steps of meiosis in females through oogenesis?

1. fetal development until 3 months; stops at prophase 1

2. meiosis 1 resumes at puberty for one oocyte per ovarian cycle

3. meiosis 2 continues but stops at ovulation with metaphase 2

4. meiosis 2 is completed only if fertilization occurs

what is the ovarian cycle?

maturation and release of egg

what is the menstrual/uterine cycle?

preparation of uterine lining for a zygote

what does FSH do in the female cycle?

stimulates growth and maturation of a follicle that releases estrogen; triggers ovulation and formation of corpus luteum

after being secreted by the corpus luteum, what do estrogen and progesterone do during the female cycle?

thicken endometrium; low levels trigger shedding of endometrium (menstruation)

t/f: there is only one reason for missing a period—pregnancy

false

what is it called when sperm and egg unite?

diploid zygote

how does sperm penetrate the egg?

the head contains acrosome that has enzymes for penetration

when is the fertile window?

the 4 days before ovulation day, ovulation day, and the day after ovulation day (around 6 days)

how long can sperm survive in a female?

5 days

how long can an egg survive after ovulation?

1 day

what happens during cleavage?

embryo begins to develop; rapid cell divisions that make zygote into a blastocyst

how are identical twins created?

embryo splits into 2

how are fraternal twins created?

2 eggs are released from ovaries and fertilized

what happens during implantation?

blastocyst attaches to the endometrium

what is the trophoblast?

outer layer of blastocyst that degrades endometrium, facilitates implantation, and helps form placenta

what is induction?

adjacent cells communicate to influence development of an embryo

what is cell migration?

cells follow chemical trails secreted by other cells during development of an embryo

what do homeotic genes (HOX) do?

determine how, when, and where body parts develop during embryo development

what is the role of the placenta?

exchanges nutrients and gases; eliminates fetal wastes

what does chorion do?

produces the pregnancy hormone

what does the amnion do?

grows to surround the embryo and gets filled with fluid to protect it

what happens in the first trimester?

rapid growth; embryo is susceptible to damage; called fetus after 8-9 weeks

when does cardiac tissue begin to contract in an embryo?

week 5 of pregnancy

by when does the fetal heart fully develop?

week 10 of pregnancy

what causes 50% of miscarriages?

chromosomal issues

what happens in the second trimester?

placenta secretes progesterone

when is the earliest a fetus can be viable if born early?

late in the second trimester

how do hormones induce labor?

estrogen forms oxytocin which makes uterus contract; oxytocin continues to be released due to positive feedback

what are the three stages of labor?

1. dilation of the cervix

2. expulsion (active labor/delivery)

3. delivery of the placenta (afterbirth)

what percentage of couples are infertile?

around 15%

what is the most common reproductive technology?

IVF: embryo is implanted; has increased rate of embryo splitting into twins

what are the three main functions of the nervous system?

1. sensory input: perception of stimuli (receptors « CNS)

2. integration: analysis of signals and formation of responses

3. motor output: execute response (CNS « effectors)

what is the functional unit of the nervous system?

neuron

what does the cell body of a neuron contain?

nucleus

what do dendrites do?

receive signals from sensory receptors or other neurons

what do axons do?

transmits impulses to other neurons or cells

what does the myelin sheath do?

insulate the axon to enhance signal transmission

what are the three types of neurons?

1. sensory neurons: sensory receptors « CNS

2. interneurons (CNS): integrate sensory info and determine response to send to motor neurons (unmyelinated)

3. motor neurons: signals « effector cells

what supports neurons and what is the ratio?

gilia, 1:1

what is membrane potential?

charge difference across a membrane due to ion distribution