Bio exam final

• Know all the major organs of the alimentary canal and what role they play in the digestive process. Think of the pathway that the food takes as it moves from mouth to anus

  -Mouth: mastication and Saliva. Mastication chewing/mixing food with saliva. When you chew your salivary glands produce saliva which moistens food so it can move smoothly from your esophagus to your stomach. Saliva has an enzyme(amylase)that breaks down starches in your food.

  -Pharynx: moves food & water to your esophagus, but makes sure that no food or water end up in your trachea/lungs.
• Major organs of the alimentary canal and what role they play in digestion (continued)

  -Esophagus: Connects your mouth to your stomach. When you swallow food, the wall of the esophagus contract and moves the food down to the stomach.

  -Stomach: Store food/ Churns food to mix with gastric secretions/ begins protein digestion/ Kills bacteria in food (acid)/ moves food into small intestine in the form of chyme.
• Major organs of the alimentary canal and what role they play in digestion (continued)

  -Small intestine: Complete the digestion of carbohydrates, proteins, and fats. Absorption of nutrients, where sugars/lipids/amino acids/and iron absorbed in the duodenum and jejunum. Bile salts/ Vitamin B12/ water/ electrolytes in ileum.

  -Large intestine: absorb water and salts from the material that has not been digested as food, and get rid of any waste products left over. Absorption of water, electrolytes, vitamin K, and some B vitamins and stores feces.
• Major organs of the alimentary canal and what role the play in digestion (continued)

  -Rectum: Stores feces until it can be pushed out of your anus

  -Anus: When it is safe to defecate voluntary motor neurons are inhibited allowing the relaxation of the external anal and sphincter so that our feces can pass.
• Review the major enzymes that facilitate chemical digestion (where are they made and what organic molecule they are used for).

  -Protease: stomach/ pancreases/ small intestine. Breaks down proteins into amino acids

  -Amylase: pancreas/salivary glands. Breaks carbohydrates into simple sugars(glucose)

  -Lipase: Pancreas. Breaks triglycerides into fatty acid and glycerol molecules.
• Be sure to review the process of HCl and pepsin secretion in the stomach

  -occurs in the parietal cells, basically carbon dioxide and water are combined to form carbonic acid, which is broken into bicarbonate and a hydrogen. The bicarbonate is pumped out of the partial into the bloodstream in exchange for chloride, and goes into the parietal cells. Hydrogen is then pumped out of the parietal cell and into the lumen of the stomach. Hydrogen naturally attracts the chloride out of parietal cell and HCl is formed.
• We spent some time discussing the importance of the large intestine and its microbial community.

  -Several hundred different species of bacteria live in large intestine; microflora, gut bacteria. The bacteria produces vitamin K and Vitamin B/Make fatty acids from cellulose, help absorb electrolytes such as sodium, calcium, bicarbonate, magnesium, and iron/ Outcompete harmful species of bacteria/ can lead to bowel disease if disrupted.
• The physiology of water resorption

  -Water is absorbed passively following the osmotic gradient set up by Na+/K+ pumps. Sodium is absorbed by the sodium/potassium pump in the colon, which diffuses potassium and sodium in opposite directions due to the formation of concentration gradients.
• Process of osmosis

  -osmosis is the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane.
• Review the hepatic portal system

  -The hepatic portal vein carries nutrient-rich blood from the intestine and other parts such as the gallbladder, pancreas and spleen to the liver. Hepatic veins are blood vessels that return low-oxygen blood from your liver back to the heart. The veins are key players in the supply chain that moves the blood that delivers nutrients and oxygen to every cell in your body. Products absorbed in intestines delivered toliver via hepatic portal vein.
• The formation of bile including the importance of bilirubin


  -Bile is made from Bile pigment (bilirubin)/ Bile salts/ phospholipids/ cholesterol and inorganic ions. Bilirubin is derived from the heme (minus iron) of hemoglobin and is yellowish pigment that is made from the breakdown of red blood cells. When bilirubin gets digested it gives poop it's brown color.

  -Some used to make bile, and some stays in blood to be filtered by kidneys

  -high levels of Bilirubin can lead to liver disease
• Review the Hypothalamus-Pituitary-Gonad axis (negative feedback loop) as it relates to both male and female systems


  -An increased level of steroid hormones inhibits GnRH production through a negative feedback loop. rising levels of testosterone acting on the hypothalamus and anterior pituitary to inhibit the release of GnRH, FSH, and LH. As for females there is both a positive and negative feedback due to menstrual cycles.

  
• Receptors for the two different gonadotropic hormones in the testicles


  -FSH receptors are found on Sertoli cells and influences spermatogenesis

  -LH receptors found on Leydig cells and testosterone secreted in response to LH-In men, LH stimulates testosterone production from the interstitial cells of the testes (Leydig cells). FSH stimulates testicular growth and enhances the production of an androgen-binding protein by the Sertoli cells, which are a component of the testicular tubule necessary for sustaining the maturing sperm cell
• Pathway for sperm during formation/maturation/ejaculation


  Sperm formation: Seminiferous tubules → Rete testis → efferent ductules → Epididymis.

  Sperm maturation: Epididymis is site of sperm maturation and storage; sperm become motile(the sperm can move more efficiently).

  ejaculation: → ductus deferens→ Ejaculatory duct → Urethra. Sperm and semen travel through the urethra and are ejaculated out of the penis.
• HCl and Pepsin secreted in the stomach(continued)


  -Pepsin is formed by pepsinogen which are existing peptides in the stomach, and the presence of the newly formed HCl causes the pepsinogen to turn into pepsin.

  -Pepsin breaks down protein.
• HCl and Pepsin pump


  -When Bicarbonate is pumped out, chloride is actually entering the parietal cell (like a trade).

  -trading compounds and using ATP in the H+/K+ pump. Basically the pump allows for the movement of hydrogen from parietal cells to the stomach lumen. So once Cl is in the lumen the K+/H+ pump activates, potassium moves back into the parietal cells while hydrogen moves into the lumen. From their H+ reacts with Cl- and makes stomach acid.
• What are the pathways that lead to erections

  Conscious sexual thought: Hypothalamus --> spinal cord --> penis

  Sensory stimulation: penis --> spinal cord --> penis

  -An erection begins with sensory and mental stimulation in your brain. Your brain sends messages to your penis via your nerves. Essentially, these messages tell the muscles of your corpora cavernosa (this contains the sponge-like material) to relax, allowing blood to flow in and fill the open spaces.

  -Blood flow into erectile tissues of penis: corpora cavernosa and corpus spongiosum.
• How does an erection relate erectile dysfunction

  -Erectile dysfunction: inability to produce or sustain erection sufficient for intercourse. This can be due to a mans mental and physical health.

  -psychological problems include: depression, performance anxiety, stress, guilt, low self esteem, relationship problems.

  -Physiological problems include: Diabetes, chronic alcoholism, multiple sclerosis, heavy metal poisoning, spinal cord and nerve injuries, and nerve damage from pelvic operations.
• Basic process of follicle and oocyte maturation all the way to ovulation

  -A mature (Graafian) follicle is characterized by the development of a liquid-filled cavity called the Antrum. Immediately prior to ovulation, the Graafian follicle begins meiosis II and arrests at metaphase II. This process is only completed if the oocyte is fertilized.
• Roles of hormonal control in menstrual cycle

  -Follicular phase: it starts on day one of your period before ovulation. this is when estrogen and FSH start to rise. Increasing levels of estradiol production from granulosa cells, around day 12

  -Ovulation: starts 24 hours after the egg is released, there is a surge in LH and estrogen.

  -Luteal phase: During the luteal phase, progesterone produced by the corpus luteum (the empty follicle left in the ovary after an egg has been released) helps thicken the womb lining in preparation to receive a fertilized egg (LH stimulates the corpus luteum)
• How does cycle impact the ovaries and the uterus

  -During each menstrual cycle, an egg develops and is released from the ovaries. The lining of the uterus builds up. If a pregnancy doesn't happen, the uterine lining sheds during a menstrual period. Then the cycle starts again.

  -The lining of the uterus, or endometrium, prepares each month for the implantation of an embryo. This preparation occurs under the influence of estrogen and progesterone from the ovary. If no pregnancy develops, the endometrium is shed as a menstrual period, about fourteen days after ovulation.
• environmental/lifestyle factors that impact this cycle

  -Pheromones can synchronize menstrual cycles due to our olfactory system that can affect the secretion of GnRH.

  -Stress and other emotions can affect menstrual cycles b/c of the limbic system where stress can cause amenorrhea (lack of menstruation). When a woman is stressed around the time of her period her period can be delayed and there will be no signs of bleeding

  -Cessation of menstruation caused by inadequate FSH and LH from inadequate GnRH.
• environmental/ lifestyle impact a cycle & the pill

  -Low body fat: Women that have a low BMI produce a reduced amount of estrogen which can lead to an abnormal menstrual cycle.

  -Birth control (the pill): Synthetic estradiol and progesterone, extends the luteal phase, and inhibits the secretion of GnRH. The pill prevents your body from making hormones involved in ovulation and menstruation.

  -when on the pill you can experience a change in diet and exercise/ weight gain. Diet can affect hormone levels and ovulation. If either are disrupted, you may experience a delayed or missed period
• Negative feedback loop: maintaining homeostasis.

  -Negative feedback loop of homeostasis: a system of control in the body that responds to a stimulus to oppose the change made by it, to get back to set point.

  Ex: if your body temperature is too high, a negative feedback loop will act to bring it back down towards the set point, or target value
• How the body maintains homeostasis: body temperature

  
• Negative feedback loop: Anterior pituitary 


  -The increased amount of thyroid hormones in the circulation causes negative feedback by inhibiting the anterior pituitary to secrete TSH as well as inhibiting the hypothalamic production of TRH which in turn causes the reduction of TSH and thyroid hormones.

  -same thing for Gonads(sex hormones)
• Negative feedback loop: Anterior pituitary example

  
• Negative feedback loop: Activation of Pituitary-Adrenal Axis by Nonspecific Stress

  -Once the stress response has been initiated, and cortisol enters the circulation, cortisol itself is able to act on the hypothalamus and pituitary and inhibit production of CRH and ACTH. This is called a negative feedback loop; the active hormone (cortisol) can shut off its own production.
• Negative feedback loop: Stress

  
• Negative feedback loop: Ovulation cycle

  
• Negative feedback loop: Ovulation cycle


  -the luteal phase of the ovulation cycle is a negative feedback loop b/c the corpus luteum produces progesterone/estrogen which gets increased after ovulation and inhibits the secretion of FSH and LH from the anterior pituitary and shuts off the secretion of GnRH from the hypothalamus.

  -Where as the follicular and ovulation phase are both positive and negative feedback

  GnRH: Gonadotropin-releasing hormone
• Sympathetic vs Parasympathetic: organ systems that are in a state of rest and digest are in the parasympathetic state/ sympathetic activates fight or flight.

  
• Review the basic physiology of an action potential


  -Reaching Threshold. A stimulus is received by the dendrites of a nerve cell.

  -Depolarization

  -sodium channels close and potassium channels open

  -Active sodium and potassium pumps begin to repolarize

  -hyperpolarization

  -Resting potential

  -Action potentials can be all or nothing, so it can either fire off entirely or not at all.
• Action potential: Depolarizes at threshold (-55 mv), voltage gated sodium channels open, rush in and make membrane potential positive(40+ mv). Repolarizes, sodium channels close and potassium ions rush out. Hyperpolarization is when repolarization overshoots resting potential. Goes back to resting potential once potassium channels close.

  
• Action potential: hearing


  -the stapes bone vibrates, pushing fluid through the cochlea, which moves the organ of Corti. This motion triggers hair cells causing potassium and calcium to flow into the cell, firing an action potential. Signals travel to the brain via the auditory nerve. The influx of Ca2+ stimulates the release of neurotransmitter

  -when sound waves enter scala media, the tectorial membrane vibrates, bending the stereocilia.
• Action potential: smell


  -Stimulation of ORs converts the chemical information encoded in the odorants, into respective neuronal action-potentials which causes depolarization of olfactory sensory neurons. 

  -odorants are transported into the nasal cavity upon air inhalation where they are detected by olfactory receptor neurons (ORNs)
• think about how the different organ systems work together to maintain homeostasis or interior milieu. Think about the basic functions each provide and how they interact with one another.

  -The Brain and the lungs work together to control your breathing and the body's need for oxygen.

  -Specifically the medulla oblongata and the pons. The medulla gets info about the blood and pons gets info from the lungs. The medulla oblongata sends signals to the heart and diaphragm in reaction to carbon dioxide and oxygen levels, allowing for easier breathing. Pons regulates our breathing rate
• Organ systems working together to maintain homeostasis (continued)

  -to maintain homeostasis, the hypothalamus(CNS) works with the anterior pituitary(endocrine) to control hormone production. This includes the thyroid and parathyroid glands, adrenal glands, pancreas, ovaries (in females), and testis (in males).