Review Test 2 Biology PDF

Review Test 2 Lecture 7-17 Genetics & Heredity Genes determine a phenotype (what we look like). Genes determine phenotype in all organisms. 2 alles, 1 from each parent: for each character we have 2 alleles (1 from mom + 1 from dad). Alleles: one of two or more alternative forms of a gene that are fo...

Review Test 2 Lecture 7-17 Genetics & Heredity Genes determine a phenotype (what we look like). Genes determine phenotype in all organisms. 2 alles, 1 from each parent: for each character we have 2 alleles (1 from mom + 1 from dad). Alleles: one of two or more alternative forms of a gene that are found at the same place on a chromosomes. 2 alleles for each gene, 1 copy from each parent, 1 of each chromosomes from each parent. (this is the case because during mieosis copies of the partents chromosoems are made) Sex chromosomes – Females have 2 copies/alleles of all 800 genes on the X-chromosomes. 775 in the X-specific region + 25 in the homologous region. Males have 2 copies of the 25 genes in the homologous region of the y-chromosomes. 1 copy of 55 gene in the y-specific (differential) region. Alleles in pea plants – the little stripe we see on the chromosomes is the allele. Homologous pair of chromosomes has genes for the same character. One inherited from the mother and on form the father. (Humans have 23 pairs of homologous chromosomes – total of 46). Genes: A segement of DNA at a specific locus on a specific chromosomes. It contains the info for making an RNA: if mRNA, then it codes for a particular protein (e.g. D is code for…). A pair of alleles: alternate versions of the same gene pair. The alleles can code for the same versions of the trait or different versions. Homozygous: 2 identical alleles at a particular locus (e.g. BB – bb). Heterozygous: 2 different alleles at a particular locus. 3 possible genotype – YY Yy yy. How genes determine phenotype – Genes code for a specific protein -> efect cell function. The actions of 1 or more proteins in our cells results in a trait, or inherited characteristic. Dominant Allele: cell makes a normal, functional protein - Exeption dominantly-inherited disorders: a mutant protein is make & it disrupts cell functioning ... 1 copy of the allele is enough to have the dominant phenotype Recessive allele: cell either does not mak any protein, that is either only partially functional or completely non-funtional. Punnet squares: Diagram that is used to predict the genotype of a particular cross. If both parents are heterozygous than there’s 75% chance the child will have a certain genotype or 25%. Dwarfism is a dominant trait. Recessively inherited disorders shows up in people who are homozygous recessive. Carriers: heteroxygous person who carries the recessive allele for the disoder but are phenotypically normal. (se)X-linked disorders – females are often carriers. A recessive allele on one X chromosomes is often masked in normal allele on the other X. Males are more likely to express the abnormal phenotype. Sex-linked genes (gene located on either sex chromosmes. X-linked = gene present only on X chromosomes. Y-linked = genes located only on the Y chromosomes. Colorblindness – it is a recessive gene only present on the x chromosmes – female need 2 recessive gene to be colorblind and male only need one recessive gene to be colorblind since the Y chromosomes doesn’t have a dominant gene to cover the recessive gene. 1) Incomplete dominance: if curly hair and straight hair show incomplete domiance because people can have wayve hair. 2&3) codominance & more then 2 alleles for 1 gene: 3 alleles on a single locus determine blood type (A B,O phenotype) – Neither A or B allele is dominant to the pther: they are codomiant but A,B are both domina t to allele O. 4) Many genes determine 1 phenotype e.g skin pigmentation. 5) genes & the environment – human height varies consideribaly, in part due to a large nuber of gene that influence it + environmental and nutritional factors. Genetically-modified organisms - add a gene into the DNA of a plant or animal OR turn off an undesirable gene. Goal – improve nutrient content of foods – make crops which can withstand harsh growing conditions. Gene therapy >4000 diseases traced to defects in single genes. Replacing mutated gene that causes disease with a healthy copy of he gene. Inactivating a mutated gene that is functioning improperly. Organ System – Respiratory System Pathway: Nostrils -> Nasal cavity -> (Mouth if breathing from mouth) -> Pharynx-> larynx -> thrachea -> Primary bronchi -> Smaller bronchie, then bronchioles -> Alveoli. Goal: Exchange respiratory gases with the environment (O2 in CO2 out). Mucociliary Escalator: From nasal cavity to conducting bronchioles NOT present in respiratory bronchioles. Nasal Cavity: 1. Moisten , warms, fliters, & cleans incominf air; cells make mucous (chemicals that kill some bacteria), have cilia to sweeo contaminated mucous to pharynx; 2. Houses olfactory receptors. The Pharynx (“thraot”) 1. Connects nasal cavity mounth to larynx & esophagus 2. Contains tonsils: traps and destroys pathogens. Strep Throat: Caused by the group A streptococcus bacteria. Swab oropharynx & tonsils. Trachea - contains the epiglottis + Vocal cords. Laryngitis: inflammation & swelling of the vocal cords interfering with vibrations. Epiglottis: prevents food & liquids from entering the trachea. Trachea branches into right & left primary bronchi widepipe. Extands from larynx to the primary bronchi. Each Bronchus branches into smaller bronchi, then into broncioles. Alveoli at the end of the smallest branches – they make up most of lung volume. Lung are made uo of airways and alveoli; most of the lung space is filled by alveoli. Exchange of O2/CO2 between alveoli & capillaries – from right ventricle to left atrium. (watch video) Homeostatic imbalance – Bronchitis[airways are inflammed due to infection or due to an irritant] (larger airways),Asthma [Airway are inflamed due to irritation anc bronshioles constrict due to msucle spasms (smaller airways), & pneumonia [Alveoli fill with thick fluid making gas exchange harder] (alveoli). SMOKING -> Damage the cilia: lining the airway: reduce ability to trap & remove debirs, including bacteria & viruses, =>> increase risk of colds, flus + pneumonia. Cardiovascular system 1. Heart (cardio) 2. Blood vessels (vascular) – Ateries + Veins + Capillaries: site pf exchange 3. Blood in blood vessels 1. Brings nutrients to cells – e.g. O2, vitamins, mineral…2. Transports wastes away from cells to be removed by the appropriate organ system. 3. Also transports hormones including insulin/glucagon needed for glucose homeostasis. The Heart is a pump that provides the force to push the blood in the bood vessels through the body. The blood is transported to and then awat from the cells of the body. Heart Chanbers: the left atrium – right atrium (upper chambers) & left ventricle + right ventricle (lower chmabers). Blood flow trhough the body: enters through Vena Cava (poor in O2) -> Right valve -> Right ventricle -> Pulmonary valve -> Pulmonary trunk -> Pulmonary arteries -> pulmonary (lung) capillaries (gas exchange) -> Pulmonary veins (O2-rich) Left atrium (O2 rich) -> Left valve -> left ventricle -> Aortic valve -> Aorta -> body capillaries (gas exchange) -> body veins -> Vena cava -> right atrium The cell of the heart need oxygen too – Blood in the heart chambers does not nourish the mayocardium(muscle tissue found in the walls of the chamber). The heart has its own nourishing circulatory system consisting of Coronary arteries that branch off from the aorta. Arteries branch into arterioles then capillaries when the gas & nutrient exchnage with the cells of the heart takes place. Coronary veins return O2-poor blood to the right atrium. Myocardial Infraction – Heart attacks noramlly result from a lack of blood flow + oxygen to a region of the heart, resulting in death of the cardiac muscle cells. Coronary artery can get blocked by blood clots or the buildup of atherosclerotic plaque. Types of blood vessels – Arteries: carry blood away from the heart – branch inot smaller vessels calles aterioles. Capilleries: exchange of gases, nutrients, wastes, hormone, etc… with tissue cells occurs here. Veins: carry blood towards the heart. Vanules: merge to from veins. Composition of blood – Fluid: hormones, nutrients, CO2 + other waste products. Cells: RBC (red blood cells) transport O2, WBC part of the immune system, Platelet for blood clotting. RBCs – 2 million are made per second – Anucleate; loses nucleus & all organelles during maturation in red bone marrow – full of hemogoblin (Hb). It transports O2 + CO2. Contain the protein hemoglobin, which binds oxygen. RBCs transport oxygen from the lungs to the body cells. Hb - red heme pigment bound to the protein globin. Anemia: blood has abnormally low O2-carrying capacity. CO poisoning: CO binds to Hb preventing Hb from binding O2. If RBC don’t transport enough O2 to body cells, don’t get the O2 they need, so they die. Digestive system Food is broken down mechanicaly & enzymaically. Digestive tract organs - Mouth, pharynx Swallowing ->Esophagus -> Stomach -> Small intestine -> Large intestine ->Anus: opening of LI. Accessory organs: Salvary glands, teeth, pancreas, liver, gal bladder, tongue. Accessory organs that secret into the track & help in digestion- Salivary glands: carbs, Liver: makes bile which emulsifies fats. Can release into SI or store in gallbladde. Gallbladder: stores & releases bile Pancreas: Produces - digestive enzymes for carbs, lipids, proteins - bicarbonate (buffer) to neutralize chyme from stomach Bile & enzymes enter into 1st part of small intestine & act on food coming from the stomach food never enters the accessory organs, instead the accessory organs secrete substances into the digestive tract. Bile made by liver breaks up (emulsifies) oil and fat chunks into small drops, so enzymes can digest it. Sort of like mechanical breakdown. Chewing: mechanical breakdown. Amylase in saliva begins to digest carbohydrates. Saliva: enzymes, fluid, & lysozyme (kills bacteria) Tongue: muscles move food, taste buds to taste food. Notice the epiglottis: prevents food from entering the trachea, food/liquid enters the esophagus instead. Halitosis is caused by bacteria at back of mouth. ESOPHAGUS: no digestion, just peristalsis (propulsion of food). Peristalsis, rhythmic contractions of the smooth muscle, moves food through the digestive tract STOMACH: mechanical breakdown, storage, digestion, & small amount of absorption. Peristalsis: grinds food (breakdown) & delivers small amounts at a time (stores partiallydigested food) to the SI. Gastric juice: Hydrochloric acid (HCl) + enzymes (digestion) Mucus: to protect the stomach lining from HCl. Absorption: small amount water, minerals. Also absorbs drugs & alcohol→ blood. SMALL INTESTINE: most digestion & absorption. ABSORPTION into cells then blood. Almost all in the small intestine: sugars, amino acids, fatty acids (+ glycerol), almost all vitamins, minerals, & water. Small amount in the large intestine: some vitamins & minerals, & a small amount of water. LARGE INTESTINE: absorption, storage, & elimination (no digestion). Some water, along with small amount of vitamins produced by gut microbes are absorbed into the blood. Nondigested matter forms feces → stored until eliminated (excreted) through rectum. Cells of large intestine don’t make any digestive enzymes, so no digestion, except for that done by intestinal bacteria. • Macronutrients digested → glucose, amino acids, fatty acids, glycerol – Energy (mitochondria) – Building blocks: cells, tissues… – Extra carbs stored in liver & muscle as glycogen, then as fat in fat cells – Extra amino acids (aa) stored as aa, then as fat – Extra fatty acids + glycerol→ stored as fat • Micronutrients: various functions – Extra fat-soluble vitamins stored (in liver + fat cells) – Extra water-soluble vitamins: mostly in urine – Extra minerals stored in bones, liver, & other organs • Water: excess water removed by kidneys Urinary system • Kidneys, a major excretory organ, maintain the body’s internal environment by: – Regulating total water volume & total solute concentration in water: works with digestive system to ensure that the extracellular fluid is isotonic to your cells ie your cells neither shrink nor burst (lyse). – Excreting metabolic wastes, toxins, drugs – Producing a hormone that promotes RBC production Contributing to vitamin D production ADH: antidiuretic hormone that is made by the hypothalamus & causes the kidneys to reduce the amount of water they remove from the blood that gets filtered by the kidneys Mouth→ esophagus → stomach → small intestine→ large intestine→ undigested food and unabsorbed water expelled thru anus liver→→vena cava→ Right atrium →R. Ventricle, lungs, LA, LV, Aorta Cardiovascular system circulates all the nutrients to every cell in the body, including to the heart When blood passes through kidneys, any excess water and minerals are removed. Along with toxins & metabolic waste products Organ systems work together to maintain homeostasis Nervous System (CNS & PNS) • Branches of the nervous system • Cells of the nervous system • Neurons: Structure & function • 3 types of neurons – Sensory (PNS) → interneurons (CNS) → motor (PNS) • Reflex arcs • ANS: motor output – Sympathetic – Parasympathetic The PNS, the peripheral nervous system, works with the CNS, the central nervous system to allow you to think about & respond to the environment in which you are found. For ex. the PNS brings sensory information like touch, smell, taste, sights & sounds to the CNS, which interprets & integrates all of the incoming sensory info, then activates motor neurons of the PNS which may cause a muscle to contract or a gland to secrete. We will see the different types of neurons, sensory, motor & interneurons in a couple of slides. Here you see the organization of the nervous system. I will use this slide to explain the functional connection b/w the CNS & PNS. The CNS (central nervous system) consists of the brain & spinal cord (FYI actually also includes the retinas of your eyes). It is represented by the pink box. EVERYTHING ELSE is the PNS (peripheral nervous system). The PNS can be divided into the Somatic NS & the Autonomic NS. Sensory information is brought by the Somatic NS to the CNS. Please find the 3 green boxes on the left giving examples of sensory input. If motor output is required, the CNS (see the pink box on the top) will activate motor neurons to give a motor output (please see the blue box where motor output is written). If voluntary movement is required (ex to move a leg) the motor neurons that the CNS will activate would be the motor neurons of the Somatic NS. In contrast, the CNS will activate the Autonomic NS if an involuntary activity is needed, for ex contraction of heart muscle or smooth muscle of your digestive system, or secretion from a gland. The Autonomic NS can be subdivided into the parasympathetic NS (the rest & digest component) and the sympathetic NS, the fight or flight component. To recap: sensory info is brought by the Somatic NS to the CNS which integrates this info & decides whether a motor output is needed. If a motor output IS needed then either the Somatic NS, for voluntary actions, or the Autonomic NS, for involuntary actions, will carry out the commands of the CNS. 2 cell types present: neurons & neuroglia. Neuroglia (aka neuroglial cells) perform many functions - Some make myelin - Some function like immune cells: they destroy pathogens & remove dead neurons - Some provide nutrients to the neurons. The differences in structure & function are due to differential gene expression. The myelin protects & insulates the axon, the long structure that transports electricity. Myelin ensures that the electricity of one axon doesn’t cross over to another axon. It’s very much the same way your electrical wires at home are covered by plastic or rubber. You don’t need to know how myelin increases the speed at which the electricity, the AP, travels down the axon, or how it helps in the repair of axons, only that myelin performs these functions. Synapse: Junction through which a neuron communicates either with another neuron or an effector cell (muscle or gland). The presynaptic neuron usually communicates by releasing a chemical signal, called a neurotransmitter (NT), shown as red dots in the figure above, into the space (called the synaptic cleft). The figure shows a generalized flow of how neurons communicate with each; there are some important details that need to be included as they are beyond the scope of this course. The dendrites of the neuron on the left responds to a stimulus, by creating an electrical message. This message passes through the cell body and reaches the axon. The electrical message that is carried down the axon is called an action potential (AP for short) occurs (see step 2. AP). The action potential, that electrical message, travels down the axon to the terminal or last part of the axon. Once the AP has reached the axon terminal, the axon will release chemicals called neurotransmitters (see step 3 in the figure) into a small space between the neurons called the synaptic cleft. The neurotransmitters released by the neuron on the left will bind to receptors in the plasma membrane of the neuron on the right, stimulating this postsynaptic neuron & causing it to have an AP (see step 4. AP). When the AP of the 2nd neuron (ie postsynaptic neuron) reaches the terminal part of its axon, NT will be released (step 5). Look at these 5 steps, then watch the 1minute video highlighted in pink above to see if you can find a dendrite, a cell body, and an axon. You will see positive + signs moving into & out of the axon: they represent Na (sodium) and K (potassium) ions. The movement of these ions into and out of the axon is what generates the electricity ie the action potential. You don’t need to know the specifics, I highlight this because you saw in an earlier lecture that electrolytes, like Na & K are important for neuronal function. You will also see some green spheres that contain orange molecules: these orange molecules are NT, which are released then bind to the surface of the 2nd neuron, causing a channel to open. The blue circles that enter the second neuron thru the channels are ions: either Na or Cl. If Na enters, the neuron gets stimulated & has an AP, if Cl enters, the neuron gets inhibited & won’t have an AP. synapse formation is the foundation for all communication & it turns out that sleep is necessary for synapse formation. Sleep is also a time when this fluid called CSF, that your brain produces, washes over the brain, removing chemicals that have built up over the day. The NT bind to these receptors, which are proteins, in a very specific way. The same way your house key will open the door to your house but not to mine, NT bind to specific receptors. NT can either excite or inhibit the neuron that they bind to. The NT are therefore classified as excitatory or inhibitory; in this figure, the excitatory NT are represented as green (like a green light) & the inhibitory NT are represented by red (like a red stop light). A single neuron may have 10,000 other neurons communicating with it: some of these neurons will release excitatory NTs, others will release inhibitory NTs. Ultimately, whether a neuron responds to these inputs by having an AP or not depends on how many of the inputs are excitatory vs how many are inhibitory. Basically, the neuron adds up all the excitatory & all the inhibitory signals & sees which is greater. It’s kind of like taking a vote on whether or not to have an AP. The 3 types of neurons and the way they interact with each other are illustrated here. Refer back to slide 5 to see which part of the nervous system these neurons are part of ie PNS or CNs. Sensory neurons bring sensory info to the interneurons of the CNS, these may be in the spinal cord and or the brain. The Interneurons of the CNS integrate this info, make a decision on what does & doesn’t need to be done, then sends out a command to the motor neurons to execute its decision. Sensory neuron: respond to sound, light, touch/stretch, odor molecules (smell), chemicals in food (taste), pH, … Bring this sensory info to interneurons. Interneuron: respond to input (NT) from sensory neurons & communicate with other neurons: interneurons and/or motor neurons. Motor neuron: respond to input (NT) from interneurons and release NT that cause muscles to contract & glands to secrete. the many activities that occur inside the body must be monitored. They can’t be monitored if they can’t be detected; they are detected by sensory neurons within organs throughout the body. Motor neuron synapse with – interneurons + effectors. - Involved in voluntary actions. Synapse with skeletal muscle for voluntary movement (Somatic NS) Involved in involuntary actions (Autonomic NS). If the brain has received information that it interprets to mean that you are in danger, it will activate the sympathetic nervous system. You must be ready to fight the danger or run away: in either case, you will need to see well, and your muscles must have everything they need to do more cellular respiration, so you will breathe deeper & faster and your heart rate will increase to get more O2 and nutrients to your muscle cells. Note that the sympathetic NS can be activated even during your sleep, by a nightmare! In contrast, if you have just finished a big meal, and it is calm and perhaps dark in your house, your brain will interpret this to mean that it should activate your parasympathetic NS, so your digestive system becomes more active and you may even feel sleepy. Nervous System Part 2 Brain anatomy & physiology – left side of brain controls movement o right side of body & viceversa – Sensoy info from right side of body ends up in left of brain. Corpus Callosum (axons) – connestcs left & right sides of the brain. Interneurons are found: Cerebelum, Corpus Callosum, Thalamus, Hypothalamus, cerebelum (helps provide smooth, coordinated body, movement), Brainstem (Responsible for sustaining the basic functions of life, such as breathing, heart rate, blood pressure, being conscious (ie not going into a coma). Gets its orders from the hypothalamus). Meninges – protective covering. The hypothalmus determines if parasympathetic or sympathetic NS activated AND makes ADH. The Cerebrum in the CNS all neurons are interneurons. There are different areas of the cerebrum that perform different functions. Ex sensory areas are made up of interneurons (not sensory neurons ), motor areas are made up of interneurons, not motor neurons. Motor & sensory neurons are part of the PNS, interneurons are part of the CNS. We’ll look at those interneurons that integrate the incoming sensory info (from the PNS) & the interneurons that will ultimately tell the motor neurons of the PNS what they should do. Sensory areas: helps us to make sense of sensory input. Primary areas, Unimodal association ares, Multimodal association areas. Motor areas of cerebrum control voluntary mucles. The cerebrum can be divided into 4 lobes based on function. Frontal lobe – Parietal lobe – Temporal lobe – Occipital lobe. Cerebrum: Surface is grey matter (mostly cell bodies & dendrites, few axons) called cortex, below cortex is white matter - Cerebrum divided into 4 lobes. - Specific areas within the lobes are associated with specific functions Flow of SENSORY information in the brain All sensory info except for smell passes along this route ↓ Thalamus ↓ Primary sensory areas ↓ Unimodal association areas ↓ Multimodal association areas Thalamus sends the sensory info to the appropriate Primary area (cortex) Association areas give meaning to the sensory information Multimodal association areas integrate all of the sensory information Multimodal association areas Sensory areas in the cerebrum • Primary sensory areas: regions of the five sensory systems in the cerebrum: taste, olfaction, touch, hearing & vision • Unimodal association areas: deals with information from one sense modality. Give meaning to/make associations with, a sensation. For ex. the visual association area is a unimodal association area that is devoted to the integration of different types of visual information. • Multimodal association areas: integrates information from multiple sense modalities • Seems to be where sensations, thoughts & emotions become conscious allows you to think, plan actions, if appropriate, create Primary area → association area Primary visual cortex: detects basic features of the visual world: edges, light and dark, location, direction of motion, speed, size, orientation … – Damage: can’t see objects, even if eyes are ok. – Visual association area: role in your ability to recognize objects (faces, dogs, cars, trees…) – Damage: can see objects but can’t recognize them. – Multimodal association areas: put all the sensory information together to form the basis of the highest mental processes, which do not depend on specific senses: language, thinking, planning, creativity… – 3 main areas: anterior association cortex, – The posterior association area is where visual, auditory and somatosensory association areas meet. This is what gives us our spatial awareness of our body. On the left side we have Wernicke’s area that deals with reading, naming things. On the right side this area helps us to understand emotional overtones/undertones of speech (the multiple ways of saying “I’m fine”). – The limbic association area helps form memories and translates that to motor responses and processes emotions and guides emotional responses. It’s very important for social interactions and expressions of the personality. – The anterior association area receives information from posterior association area and helps integrate that info with past experience with the help of the limbic association area. It has a lot to do with thinking and making judgements and it’s where you understand what’s socially acceptable, how to behave. – Includes an area of the brain called the prefrontal cortex. Prefronal cortex • Part of the anterior association area • Allows you to • Reason • Distinguish right from wrong • Make decisions • Plan for the future • Think about abstract concepts • Feel pleasure • Modulate your emotions • Plays a key role in determining your personality Primary Somatosensory corte The more sensitive an area of the body, more brain area dedicated to interpreting sensory stimuli. Somatosensory association area Integrates sensory information from the primary somatosensory cortex to construct an understanding of the object being felt (size, texture) Take home: b/c pathway involves the hippocampus, hypothalamus, & amygdala, we have odor memories that have motivational and emotional aspects to them. 2) The thalamus is involved, but not in the same way as for the other 4 senses (makes you conscious of an odor) Motor areas in frontal lobe . EXECUTION. Interneurons of the Primary motor cortex synapse with: A) spinal cord interneurons, which synapse with spinal motor neurons or B) with cranial motor neurons (ex to move eyes). Brain Reward Centre When we do certain things, the brain "rewards" us by making us feel good. The brain reward system is a brain circuit (include cerebrum & other structures) that causes feelings of pleasure when it's “turned on” by something we enjoy, like eating good food. Whenever this reward circuit is activated, our brains note that something important is happening that's worth remembering and repeating. Drugs activate the brain reward system in a similar manner. However, most drugs set off a surge of the brain chemical dopamine, so they produce a much stronger and longer-lasting “artificial” pleasure sensation than natural highs. Fetal Alcohol Syndrome (FAS): a set of serious, irreversible birth defects, including physical, mental, emotional, behavioural, and developmental problems. No safe dose Adolescent brain under construction • Brain reorganizes in a very fundamental way in adolescence. • The number of synapses in the prefrontal cortex decreases during adolescence – decrease in reasoning etc, emotional outbursts… – increasing impulsive, risk-taking behavior-and susceptibility to addiction. – Teens who start drinking by age 13 have a 43% chance of becoming alcoholics. Those who start drinking at 21 have only a 10% chance. Juddgements develop in the frontal lobe – until we’re 25 years old Brain Development - Surge of synaptogenesis in some areas - Pruning of other synapses - Myelination being completed: brain will become faster + more efficent - But – during pruning - brain function <optimal & more sensitive to the effects of drugs Reproductive system Reproductive organs – Primary organs are the gonads: testes in males – Ovaries in females • Gonads produce two products: – Gametes: sperm and eggs – Sex hormones: • Testosterone in testes • Estrogen & progesterone in ovaries • Accessory reproductive organs: include the ducts, glands, and external genitalia. The male reproductive system • Testes: make testosterone & sperm (100 million/day) in response to hormones (FYI testosterone & FSH) – in scrotum: away from body (cooler temp needed for sperm production) • Duct system (epididymis, vas deferens, urethra*) • Accessory glands (prostate gland, seminal vesicles, bulbourethral glands) make secretions – Semen = sperm + secretions • Penis: contains the urethra & erectile tissue • *also part of urinary system Meiosis in the testes Testes→epididymis→vas deferens→ejaculatory duct→urethra An enlarged prostate can squeeze the urethra, making it hard for urine and sperm to pass through the urethra Production of Semen • Semen = sperm + fluid • Sperm: made in testes, mature in epididymis, travels through vas deferens to the ejaculatory duct • Fluid: • Seminal vesicles secrete fluid (contains nutrients needed for sperm survival) into the ejaculatory duct • Prostate gland: add a small amount of additional fluid into the ejaculator duct • Ejaculatory duct merges with urethra. Semen transported through the urethra. Effects of testosteron • Stimulates sperm production • Male sex characteristics: hair, vocal cords thicken, size of reproductive organs (testes & penis) increase, increased sex drive • Increase muscle mass • Growth spurt at puberty: Stimulates growth in long bones of arms & legs Anabolic steroid a synthetic steroid hormone that resembles testosterone in promoting the growth of muscle. Such hormones are used medicinally to treat some forms of weight loss and (illegally) by some athletes and others to enhance physical performance. Meiosis in Ovaries Ovary→ oviduct (fallopian tube) → uterus → vagina Female reproductive system Note that the uterus is made up of 3 parts: the endometrium, myometrium, and perimetrium (look at images in the powerpoint) • Ovaries: eggs & the hormones estrogen + progesterone • Oviducts (aka fallopian tubes): transport egg or embryo to uterus – Fertilization (usually) here • Uterus: – Endometrium: implantation or (mostly) lost in menses (menstruation) – Myometrium: smooth muscles forces the baby out – Cervix: neck of uterus – Expands ~60x in size during pregnancy • Vagina: muscular passageway for baby or menstrual fluid Meiosis begins in the fetus and continues at puberty Ovarian & uterine cycles Progesterone (& to lesser degree estrogen) made by the ovary causes the endometrium to thicken: but will do so only for a few days If no pregnancy, ovary stops making estrogen & progesterone No progesterone: endometrium shed (menstruation) If pregnancy: the embryo makes a hormone that causes the ovary to keep making estrogen & progesterone. Endometrium thick to nourish the embryo Effects of female hormones • Estrogen: secondary sex characteristics including growth of breasts, increased deposition of subcutaneous fat in the hips, widening of the pelvis. • Pre-menstrual syndrome: mood swings, tender breasts, food cravings, fatigue, irritability, depression… – Estimated that as many as 75% of women have experienced some form of premenstrual syndrome. – Causes unknown, but several factors may contribute to the condition, including cyclic changes in hormones, since it disappears after menopause. Fertilization Oocytes live ~24 hours after ovulation. Sperm usually only ~48 hours, but can be as long as 5 days. SO: 5 days before ovulation & 24 hours after ovulation, can get pregnant • Various WBCs with different functions • Innate response: 1. Ingest (phagocytize) invaders (bacteria, viruses) 2. Release chemicals that can kill virus-infected cells. 3. Release chemicals to attract more WBCs & cause inflammation (redness & swelling) 4. Kill tumor cells • Adaptive response 1. Make antibodies: don’t kill cells but an important part of the immune response 2. Killer T-cells kill invaders Vaccines can activate the adaptive response Autoimmune diseases • What. Immune system fails to distinguish self from foreign & attacks body’s own cells. • How? Some of the WBCs didn’t properly complete their education on self-tolerance. • What triggers the WBCs? • Foreign particles that are similar to molecules on our cells, can cause our immune system to attack our cells by mistake. • Self-proteins not previously exposed to the immune system may appear in the circulation. These will be recognized as foreign and attacked. Fertilization happens in the oviducts (fallopian tubes) Embryo: 3-8 weeks Embryo makes HCG (human chorionic gonadotropin)- can detect in mom’s blood 7-9 days after fertilization (in urine ~14 days after fertilization: pregnancy test) Associated with morning sickeness Disorders of sex development • Aka inter-sex: discrepancy between the external genitals and the internal genitals (the testes and ovaries). • 46, XX INTERSEX: ovaries, uterus, oviducts & small penis… exposure to a lot of testosterone in utero • 46, XY INTERSEX: external genitalia poorly developed male, sometimes female. Insufficient testosterone or insensitive to testosterone. • 46, XX or XY: may have 1 ovary & 1 testis… cause unclear, possibly exposure to certain pesticides Androgen-insensitivity syndrome (XY genotype) • Partial or complete inability of the cell to respond to androgens (mainly testosterone): steroid hormones that regulates the development and maintenance of male characteristics • Can impair or prevent the masculinization of male genitalia in the developing fetus, as well as the development of male secondary sexual characteristics at puberty but does not significantly impair female genital or sexual development. • Clinical phenotypes in these individuals range from a normal male with mild spermatogenic defect or reduced secondary terminal hair, to a full female phenotype, despite the presence of a Y-chromosome. • STI • Bacterial: chlamydia, gonorrhea, syphilis • Treated with antibiotics • Viral: genital herpes, genital warts, hepatitis B, human papilloma virus (HPV) HIV • No cure. Symptomatic treatment for some, vaccines for others • STD • Occurs soon or long after infection has taken place • Causes damage to body tissues Transmission of STIs • Some may cause no symptoms (in either men or women) • Many have symptoms only months after infection • ↓ • So can transmit/be infected without knowing • Can be transmitted by oral & anal sex & by intercourse • Condoms decrease risk, don’t eliminate risk ie not 100% prevention Bacteria Chlamydia & gonorrhea can form scar tissue that blocks tubes through which eggs (oviducts), sperm (vas deferens, urethra) pass Can also infect cells of vagina, cervix & uterus. Syphilis: fatal if left untreated Herpes simplex viruses • HSV-1: cold-sores • HSV-2: on genitals • Oral sex can spread from 1 area to the area • These viruses never leave the body: stay dormant in ganglia & can be reactivated • Can be asymptomatic • No cure, but can treat outbreaks (fyi Acyclovir, Xerese) Human papilloma viruses • There many (>200) different types of the HPV virus. Most types are totally harmless & clear up by themselves. 15 are high-risk types: genital warts, cancer (cervical, penile or anal cancer) 2-3 months after infection before warts appear Cause cancer by mutating certain genes involved in regulating the cell cycle (see lecture on cell division) FYI: >80% of American women will have contracted at least one strain of HPV by age 50. Cervical cancer Pap test: Do a Pap smear… collect cells from cervix, look under a microscope for abnormalities. HPV test more accurate than PAP smear – Test DNA of samples from cervix: look for high-risk HPV strains known to cause cervical cancer. HIV Human immunodeficiency virus HIV infects & kills the WBCs (white blood cells) whose function is to warn other WBCs cells of the infection Endorcine System 2 categories of glands Exorcine – Endorcine Endocrine System = Endocrine glands + organs that contain some endocrine tissue Nervous vs endocrine system Endocrine glands secrete HORMONES into extracellular fluid → diffuses into blood capillaries Hormones: chemicals siganals of the endorcine system • Endocrine system: collection of glands and tissues within some organs, that secrete hormones into the blood • Hormones chemicals that regulate processes such as growth, & behavior by affecting the metabolism of their target cells • Most Travel: Gland → blood → target cells (far away or close) Hormones regulate processes such as growth, & behavior by affecting the metabolism of their target cells. Hormones travel throughout body in the blood BUT act only on target cells Hormones act on target cells • Each hormone binds only to a specific receptor (receptors are made up of amino acids ie they are proteins) • SO: Most hormones act on a limited number of cells in the body Receptors on plasma membrane Water-soluble hormones • These hormones can’t pass through the lipid bilayer of the plasma membrane, so they bind to a receptor embedded in the plasma membrane of the target cell • Binding initiates multi-step cascade of events: – series of enzymes activated in a cascade of reactions: relay the signal – final enzyme activates a protein that carries out the cellular response • Result: extracellular signal (hormone) triggers an intracellular response Receptors for Lipid-soluble hormones are INSIDE the cell Hypothalamus Regulates internal environment through. 1) Control of the autonomic nervous system (heart rate, body temp, peristalsis…) by releasing NT. 2) Release of hormones. Specialized neurons make hormones (instead of nt). 2.1) ADH & oxytocin - 2.2) Hormones that control the anterior pituitary gland: releasing hormones & inhibiting hormones Hypothalamus & Posterior Pituitary NEURONS from hypothalamus make ADH & oxytocin & store them in their axon terminals in posterior pituitary ADH & oxytocin released from axon terminals into capillaries in the posterior pituitary when needed 1. The hypothalamus makes these 2 hormones & stores them in their axons in the posterior pituitary. Anti-diuretic hormone (ADH) aka vasopressin – Stimulates the kidneys to absorb more water back into blood so less urine is made ie conserve water – See lecture on urinary system – Diabetes insipidus: not enough ADH or reduced sensitivity to ADH, a lot of urine (can lead to dehydration) 2. Oxytocin: – muscle contraction in uterus, breasts – important in: • Childbirth: uterine contractions • Nursing: milk letdown (milk exits breast) Oxytocin release: positive feedback loop Hypothalamus controls release of 6 hormones by the anterior pituitary Neurosecretory cells in the hypothalamus secrete releasing & inhibiting hormones ↓ Travel through blood to anterior pituitary & either stimulate or inhibit the release of the 6 hormones (FSH, LH, TSH, ACTH, Prolactin, GH) 1,2 FSH & LH • FSH: follicle stimulating hormone stimulates – follicle dev’t in ovaries: follicles secrete estrogen – sperm production in testes • LH: luteinizing hormone stimulates – Ovulation (& formation of corpus luteum which secretes) estrogen & progesterone – Testosterone production FSH, LH govern the onset of puberty, sexual development, & reproductive function. Notice: FSH stimulates the development of a follicle Follicle produces estrogen After ovulation, follicle is called a corpus luteum: secretes estrogen & progesterone Progesterone key in causing the endometrium to become thicker LH stimulates testosterone production FSH + testosterone stimulate sperm production 3. Growth Hormone - decrease in Adipose Tissue, (liver rpoduces IGF) – increae bone growth + increase muscle mass 4. Prolactin - Cause breasts to make milk 5. TSH (thyroid-stimulating hormone) makes thyroid release thyroid hormones: T3 & T4 5. TSH→Thyroxine (T4) • Almost all cells have receptors for thyroxine so this thyroid hormone has broad effects: • Regulate the body's metabolism & energy level • Hypothyroidism: Thyroid doesn’t make enough thyroxine – Children: poor growth, cognitive deficits – Adults: tons of symptoms (slow heart rate, ↓bp, ↓ alertness, weight gain, depression, ….) – Treat: give hormone orally • Hyperthyroidism: Thyroid makes too much – Symptoms: hyperactive, nervous, irritable, insomnia – Treat: destroy part of thyroid gland. • 6. ACTH causes steroid hormone release from adrenal gland • During long-term stress, the hypothalamus communicates with the anterior pituitary via hormonal signals (CRH). The anterior pituitary then sends hormonal signals (ACTH) to the adrenal cortex. • Mineralcorticoids • Reabsorption by kidneys of Na+ and H2O) • ↑ Blood volume & blood pressure • Glucocorticoids: • ↑ blood glucose levels • ↑ breakdown of protein & fat • ↓ inflammatory response Short-term stress response Adrenal glands release epinephrine & norepinephrine In response to NT, not hormones from the anterior pituitary gland Increase in: Heart rate, Breathing rate, Bronchodilation, Blood glucose levels (breakdown glycogen),Alertness Sympathetic NS: Fight or flight response (fyi released from adrenal medulla) Control of Blood Calcium • Two antagonistic hormones control calcium (Ca2+) homeostasis • Calcitonin (CT) from the thyroid gland lowers Ca2+ levels in blood: – Bone takes up Ca2+ • Parathyroid hormone (PTH) raises Ca2+ levels in blood: • release Ca 2+ from bones • Not enough calcium in bones can lead to osteoporosis Thyroid & adrenal glands are stimulated by multiple triggers • Hypothalamus → anterior pituitary → – TSH → thyroxine from thyroid (metabolism) – ACTH→ steroid hormones from adrenal gland • Regulation by non-hormonal signals – High blood calcium→ thyroid releases calcitonin – Low blood calcium→parathyroid gland releases PTH – NT→ epinephrine & norepinephrine from adrenal glands Pancreas • Pancreas detects high blood glucose levels Pancreas detects low blood glucose levels • Sympathetic NS stimulates release Parasympathetic NS stimulates release Pancreas hormones • Glucagon increases blood glucose levels by stimulating target cells in the liver to break down some of the stored glycogen into glucose & release it into the capillaries. • Insulin decreases blood glucose levels by stimulating various cells to increase their absorption of glucose from the blood. • Liver cells, muscle cells, and adipose cells store excess glucose as glycogen, then fat if the glycogen stores are full Why blood glucose levels must be tightly regulated – Brain relies heavily on glucose – Prolonged hyperglycemia can damage blood vessels, nerves, and organs, increasing the risk of conditions such as cardiovascular disease, kidney disease, nerve damage, and vision problems. • Hypoglycemia. Insufficient glucose supply to the brain can result in dizziness, confusion, seizures, and, if left untreated, loss of consciousness and potential brain damage. • Testosterone production in the testes (aka testicles) • Releasing hormone from hypothalamus→ LH from anterior pituitary→ testosterone from testes • FSH from anterior pituitary + testosterone from testes stimulates sperm production Effects of testosteron – on : skin, brain, liver, male sexual organ, kidnay, bone marrow, bone, muslce. • Estrogen & progesterone production in ovaries Releasing hormone from hypothalamus ↓ FSH from anterior pituitary ↓ Follicles in ovary produce estrogen & after ovulation also progesterone Effects of estrogen – hart, liver, bones, skin, ovary, uterus, breat, brain Pineal gland: Melatonin • Production stimulated by darkness and inhibited by light – important in regulating circadian rhythms • Too much melatonin: SAD (seasonal affective disorder) • Jet lag taking melatonin close to the target bedtime of the destination may reduce symptoms FYI Puberty blockers Possible side effects of GnRH block include: Swelling at the site of the shot, Weight gain, Hot flashes, Headaches, Mood changes, Restlessness • Possible long-term effects on: • Growth spurts. • Bone growth. • Bone density. • Fertility, depending on when the medicine is started. Microbes Most common bacterial cell shapes Spherical Coccus (pl. Cocci) Rod shape Bacillus (pl. Bacili) Spiral Spirillum (pl. spirilla) Spirochete Vibrio Cell structure Plasmids (DNA only, they are not chromosomes) Plasmids carry only a few genes. Under normal circumstances these genes are not essential for survival of the bacterial cell. Many bacteria have plasmids with genes that make them resistant to antibiotics. These plasmids can be shared between bacterial cells Bacteria can form biofilms Cells stick together & to the surface using capsules or pili (species-specific) Dental plaque is a sticky, colorless film of bacteria and sugars that constantly forms on our teeth. Bacteria reproduce asexually Binary fission: replicate their circular DNA, cell divides into 2 identical daughter cells (clones of each other). Each small daughter cell then grows to “adult” size Through binary fission, a single cell will produce a colony Cells are microscopic. Colonies are macroscopic the shape of the individual CELLS does NOT determine the shape of the colony Virus Structure Virus (~1000x smaller than a bacterium) Viruses are not considered to be alive: not made up of cell(s), reproduction and metabolism are dependent upon a host cell, some don’t have DNA Viruses DO have: organized structure made up of 4 macromolecules & they can evolve over time, but they are totally dependent on their host cell for survival (cellular parasites) Genetic material (DNA or RNA) enclosed in a protein coat called a capsid. They are not cells. Sometimes a lipid envelope surrounds the capsid. If an envelope is present, there may also be spikes (glycoproteins) which aid in their attachment to the surface of host cells. Many different shapes of viruses. Viral replication - once the virus gains entry, it is the host cell that replicates the virus. New virions are then released from the host cell. Normal bacterial residents - Bacteria are present on and in our bodies all the time: microbiota. (FYI This is sometimes referred to as our natural bacterial microbiota). There are more bacterial cells on & inside humans than there are human cells. (see notes below) Good Bacteria - The bacteria that normally reside on & within our bodies are beneficial to our health. Pathogenic microbes (bacteria, viruses, fungus, protists) - Pathogen: infectious agent (bacterium, virus, fungus) that can cause disease. Cause the flu, pneumonia, tonsillitis, chicken pox, measles, malaria, syphilis, vaginal candidiasis, leprosy, certain cancers etc. Bacteria are thought to cause ½ of all human diseases How microbes enter the body - 1) The lining of the respiratory tract is the most accessible way for bacteria & viruses to enter the body; they travel through the air on dust particles & water droplets. - 2) Others enter through the lining in the reproductive tract (ex STI), urinary tract (UTI), digestive tract (food poisoning) - 3) A few microbes can enter thru the unbroken skin. Unbroken skin is impenetrable by most microorganisms. - 4) Microbes can enter when the barriers are damaged (ex thru punctures, injections, bites, cuts, wounds, surgery…) HIV, hepatitis virus, & tetanus bacteria can be transmitted this way. Mode of Pathogenicity: Bacteria 1. They can cause direct damage to our cells by: 1) using the cells’ nutrients 2) filling the cells with waste products 3) sometimes causing the cells to rupture 2. They often produce toxins 3. They may induce hypersensitivity reactions (over-reactive immune response causes excessive release of chemicals that damage tissue). Bacterial toxins exotoxins: toxins secreted by living bacterial cells. Among the most lethal substances known. Endotoxins are released when a bacterium dies: they are the outer part of the cell wall of certain bacteria. Endotoxins cause macrophage cells to release lots of chemicals (fyi: cytokines): chills, fever, weakness, & generalized aches. tetanus & botulism are caused by exotoxins. Bacterial diseases – Lyme disease, tetanus, tuberculosis, Bacterial meningtisis, strep thraot Mode of Pathogenicity: viruses 1. Accumulation of large numbers of viruses in cells resulting in cell lysis (rupture). 2. Viral proteins disrupt the permeability of the host cell’s plasma membrane (make “holes” in the plasma membrane) 3. Our immune system kills virus-infected cells & also inhibits the metabolism of the neighboring uninfected host cells (ex reduced protein synthesis) so that if they do get infected, they won’t be able to replicate the virus (recall interferon). The reduction in metabolism is often lethal Fever and aches associated with viral infection are usually due to the body’s efforts to fight off the infection rather than being caused by the virus itself. (see Body defenses lecture) Viral diseases – common cold, influenza, aids, chicken pox, hepatit b, west nile Epidemic vs. Pandemic • Most caused by viruses, but can be caused by bacteria too • Epidemic: a widespread occurrence of an infectious disease in a community at a particular time. • Pandemic: an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people • Changes in the microbe • Small change (disguise) no problem. Adaptive immune cells can still destroy microbe • Big change (good disguise) Innate immune system still functional but the adaptive immune system no longer recognizes the microbe. Need to build an adptive immune response all over again….Takes time…. Gives microbe chance to reproduce in its host & to spread to other people. • This is how Microbe X can cause an epidemic or a pandemic Treating bacterial & viral infections • Antibiotics: kill bacteria (NOT viruses) • Different antibiotics have different ways of attacking bacterial cells, but all have to enter the cell to have an effect. – Penicillin for Gram positive, ampicillin for both Gram + & - (broad spectrum) • Don’t harm human cells, but can harm our good bacteria • Antiviral medications – work by inhibiting some aspect of the life cycle of viruses: • Inhibit binding to the host cell. • Inhibit replication of viral genetic material. – Limited number of drugs currently available (FYI acyclovir for HSV, AZT for HIV, antibodies for covid) Antibiotic Resistance That one bacterium with the plasmid that survived the antibiotic treatment can then reproduce asexually through binary fission rapidly creating clones, all with the plasmid. Bacterial resistance to antibiotics can be shared between bacteria Body defences Pathogens. Any microorganism which causes disease Your body is naturally full of microbes. However, these microbes only cause a problem if your immune system is weakened or if they manage to enter a normally sterile part of your body. Our own body cells: if they have mutated & formed tumors. Lines of defense- Don’t let them in: Barriers. Don’t let them make a home: Innate internal defenses include cells & proteins that kill invaders AND inflammation limits the infection to a local region. Know your enemy: Antibodyproducing B-cells and killer T-cells have good memories. Body Systems: Lines of Defense – Nonspecific do not distinguish one infectious agent from another. Specific Distinguishes particular toxins, microorganisms, abnormal body cells, & any substance marked as foreign. • Innate: born with. No priming needed. 1) Don’t let them in - Skin & mucous membranes create barriers - Reduce the ability of microbes to invade the body - Mechanical barriers • Chemical barriers • Biological barriers Skin as a mechanical barrier Dead epidermal cells that make up the surface of the skin are continuously being sloughed off so that microbes that do colonize this tissue are constantly being removed. Epidermal cells underneath the top dead layer are tightly joined together & make a lot of keratin: together this is a very effective mechanical (physical) barrier. Mucous membranes as a mechanical barrier Mucous membranes line all body cavities that are open to the external environment. Respiratory Tract, Gastrointestinal Tract, Urinary Tract, Reproductive Tract , Conjunctiva of the eyes. The lumens of tracts and hollow organs that open to the outside world are constantly being exposed to foreign microbes. Mucous & WBC make it hard for the microbes to attach & infect the cells lining these cavities Celia – pushes the mucus out - Ways of getting ride of microbes Coughing and sneezing Vomiting and diarrhea Flushing action of body fluids – urine, tears, saliva, & perspiration flush microbes from the body. Microbes that enter through the urethra are prevented from reaching the urinary bladder and kidneys mainly due to the vigorous flushing of urine out of the body through the urethra. Chemical Barriers The skin and mucous membranes produce a variety of chemicals that help protect them from foreign invaders- Acid, Enzymes, Mucin, Defensins Acid - The skin, stomach and vagina maintain acidic conditions that inhibit bacterial growth. If the ph changes it can increase the risk of microbes getting in Enzymes - Enzymes secreted into the mouth, stomach, respiratory tract & eyes digest bacteria. • (Pepsin) in the stomach breaks down peptide bonds holding amino acids of proteins together in food, but also protein on the surface of ingested bacteria, often killing them. *An enzyme found in saliva, respiratory mucus, and fluid of the eyes Mucin - The mucous membranes of the respiratory, gastrointestinal, and urogenital tracts secrete mucin. Mucin: substance that when dissolved in water turns into sticky mucous. Mucous creates a chemical barrier and traps microorganisms. Defensins - Broad-spectrum antimicrobial peptides that are secreted onto the skin (in sweat and sebum) and are also present in saliva. Disrupt cell membranes of bacterial and fungal cells & create a pore (hole). This causes cellular contents to leak out killing the microbe. Biological barries - Microbiota: microorganisms, including bacteria are present on and in our bodies all the time. This is referred to as our natural microbiota. They may reduce the ability of pathogenic bacteria to invade. There are more bacterial cells living on and in you than there are your own cells Good vs. Bad Bacteria Our resident bacteria (good) provide us with certain vitamins and other nutrients, and they will defend their home against pathogens (bad bacteria) Good bacteria help us fight off invading pathogenic bacteria by: 1. Forming an extra protective layer on top of the mucous membrane. 2. Competing with pathogens for resources. 3. Producing toxins harmful to them. Homeostatic imbalance: Clostridium difficile & antibiotics Good bacterial microbiota can be disrupted when a patient takes broad spectrum antibiotics The bacterium C. difficile, that causes antibiotic-associated colitis, are opportunistic bacteria that are normally held in check by bacteria of the microbiota. 2) DON’T LET THEN MAKE A HOME (internal defences) Innate defenses: internal 1. Phagocytes: WBCs that “eat” bacteria, dying cells, & foreign particles (ex dust in airways) 2. Natural killer cells: WBCs that kill virus-infected cells & tumor cells. 3. Inflammation: in response to physical trauma, intense heat, irritating chemicals, or infection by viruses, fungi, or bacteria. Damaged cells release inflammatory chemicals that attract WBCs, cause local vasodilation, leaky capillaries (for WBCs to get to damaged tissue): redness, heat, swelling, & pain. 4. Antimicrobial proteins: enhance the innate defenses by attacking microorganisms directly or by reducing their ability to reproduce. (interferon & complement proteins) 5. Fever: Fever ↑ WBC activity (fyi: pyrogens produced by certain WBCs) act on the hypothalamus, which resets its “thermostat”. Hart inflammation - Myocarditis – inflamtion of the msucle tissue - Pericarditis – inflammation of the perisardium – membrane where the heart is Virus-infected cells “warn” other cells by secreting interferon That cell will destroy RNA and reduce synthesis – the cell thst is infected will undergo apoptosis. This will activate the immune sytem. 3) Know you enemy - this is part of the adaptive immune system This is much more Specific -> Adaptive defense – Humoral immunity – Cellular immunity Characteristics of adaptive (acquired) immunity 1. Antigen specificity: recognizes & acts against specific antigens (foreign molecules). 2. Systemic response: immunity is NOT restricted to the site of infection/injury but is “bodywide”. Memory: specific defense system “remembers” & attacks in a stronger way the same pathogen when it encounters it a 2nd time Shortcoming: must be primed by initial exposure to specific foreign substance: Priming takes time Antigens are substances that the body recognizes as foreign They transfome into pplasma cells that will create antibodies Antigenic determinants: parts of antigen that antibodies or WBC receptors bind to. Most naturally occurring antigens have numerous antigenic determinants that: Mobilize several different WBC (fyi: lymphocyte) populations Form different kinds of antibodies against them ATTACK with antibodies & cytotoxins Plasma cells release antibodies: 1) mark the antigen (virus, cell) for phagocytosis and 2) prevent the antigen from binding to a body cell, inhibiting its ability infect a cell (neutralizing antibodies). Cytotoxic T-cells recognize & kill infected cells (infected cells display part of the microbe on their surface). Antibodies – it prevent virsus to enter the cell – they “eat” the viruses (eaten up by the white blood cells)