Biology

• Homeostasis


  The organism's ability to maintain internal stability despite external changes by regulating temperature, pH, and bodily functions within an optimal range
• Negative feedback


  1. Process where adjustments are made to bring a mechanism back to its original state

  2. When body temperature rises above a set point, sensors detect the increase and signal the brain's hypothalamus to initiate responses to cool the body

  3. As body temperature returns to the set point, the signals to cool the body diminish, and the responses decrease, maintaining temperature within a narrow range
• Positive feedback


  1. Process where a small effect is amplified (less common in the body)

  2. During labor, the hormone oxytocin is released, causing the uterine muscles to contract

  3. As the contractions intensify, more oxytocin is released, leading to stronger contractions

  4. This cycle continues until the baby is born and the stimulus (pressure on the cervix) is removed, halting the oxytocin release and contractions
• Dynamic equilibrium


  When there is a fluctuation in the body like temperature there is a range where it is okay for it to be in but once it goes below or above that set limit it is no longer in equilibrium
• Hypothalamus


  • Region of the vertebrate's brain responsible for maintaining homeostasis
  • It receives messages from the senses all over the body and initiates a response to maintain homeostasis
  • Control centre of the brain
• Thermoregulation


  • We get goosebumps because when you are cold, nerve messages are carried to smooth muscle cells that surround the hair follicles in your skin, causing hair to stand up
  • This creates goosebumps, which traps warm air and helps reduce heat loss
• Parts of the nervous system

  • CNS (brain and spinal cord)
  • PNS (relay information between CNS and other parts of the body)
• Somatic nerves


  • Median nerve: Forearm and hand muscles, thumb to half of ring finger
  • Femoral nerve: Thigh muscles and inner leg sensation
  • Radial nerve: Forearm extensor muscles and back of hand sensation
• Autonomic nerves


  • Sympathetic (prepare the body for stress, fight or flight, uses norepinephrine)
  • Parasympathetic (return the body to normal resting levels, rest and digest, no stress)
• Parts of the brain and their functions

  • Frontal - decision making, problem solving, emotions, and voluntary movement
  • Temporal - hearing, memory, language, face recognition, long-term memory formation, sensory interpretation, and emotions
  • Parietal - touch, temperature, pain, spatial awareness, and perception
  • Occipital - visual information, interpreting what we see, and is vital for visual perception, color, and object recognition
• Neurotransmitters and their general purpose

  • Excitatory (increases chance of future action potentials, opens Na channels)
  • Inhibitory (decreases chance of future action potentials, opens K channels)
• Action potentials


  Short electrical impulses that travel along a neuron's membrane, crucial for neuron communication and triggered by stimulation exceeding a neuron's threshold
• Parts of a neuron

  • Cell Body (Soma): Contains nucleus
  • Dendrites: Receive signals
  • Axon: Transmits signals
  • Axon Terminals: Release neurotransmitters
  • Myelin Sheath: Insulates axon
  • Nodes of Ranvier: Gaps in myelin sheath
  • Schwann cells: Type of glial cells that produce myelin sheath
• How an action potential occurs

  1. Resting state: Outside of the neuron is positively charged relative to the inside

  2. Depolarization: A stimulus must excite the neuron so that the minimum threshold of excitation is reached (-55mV)

  3. Action Potential: Once the threshold (-55mV) is reached, an action potential occurs

  4. Repolarization: Na+ channels close, K+ open, potassium ions can move out again to return back to a resting potential

  5. Hyperpolarization: Excess K+ ions move outside the cell which results in hyperpolarization (>-70mV), this is called the refractory period (0.001s)
• How drugs affect the nervous system

  Drugs can affect the nervous system by altering neurotransmitter levels, disrupting communication between neurons, and impacting brain function
• Consequences of eating too much protein

  • Kidney damage due to increased workload
  • Digestive issues like constipation or diarrhea
  • Weight gain and nutrient imbalances
  • Increased risk of heart disease and osteoporosis
• Parts of the urinary system

  • Renal arteries/veins: Carry blood to and from the kidney
  • Kidney: filters waste in blood
  • Ureters: carries waste to bladder
  • Bladder: Stores Urine
  • Urinary Sphincter: valve to control urine release
  • Urethra: carries urine outside the body
• Parts of the nephron

  • Afferent arterioles - carries blood to the glomerulus
  • Efferent arterioles - carries blood away from the glomerulus
  • Peritubular capillaries - sends nutrients or takes waste away
  • Glomerulus - high pressure capillary bed
  • Proximal tubule - the first part of the nephron where reabsorption occurs
  • Loop of Henle - U shaped tube that connects the proximal tubule and distal tubule
  • Distal tubule - It brings the reabsorption portion and brings it down to the collect duct
  • Collecting duct - collect urine
• Osmoregulation


  The process by which organisms regulate the balance of water and solutes within their bodies to maintain internal stability despite changes in the surrounding environment
• Osmoreceptors


  Specialized cells or structures that detect changes in the concentration of solutes in the body's fluids, helping regulate water balance
• Stages of urine formation

  1. Filtration: Movement of fluids from the blood into the bowman's capsule

  2. Reabsorption: Transfer of essential solute and water from nephron back into the blood

  3. Secretion: Movement of materials from blood back into nephron
• Flow of specific ions in the nephron

  • Glomerulus and Bowman's capsule: Na, Cl, H2O, H, Glucose, Amino Acids, Vitamins, Minerals, Urea, Uric acid
  • Proximal Tubule: HCO3, NaCl, H2O, K, H, NH3, Glucose, Amino acids, Vitamins, Urea
  • Descending limb of loop of Henle: H2O
  • Ascending limb of loop of Henle: NaCl, K, H2O, H HCO3, Uric Acid
  • Distal Tubule: NH3
  • Collecting Duct: H2O, NaCl, Urea, Uric Acid, Minerals
• How osmotic pressure is controlled in the excretory system

  Osmotic pressure is controlled primarily through the regulation of water and solute levels in the urine by the kidneys, achieved through filtration, reabsorption, and secretion in the nephrons. Hormonal signals, such as ADH, also play a role in regulating water reabsorption in the collecting ducts.
• How blood pressure is controlled in the excretory system

  Blood pressure is primarily controlled by regulating the diameter of the afferent and efferent arterioles in the kidneys, achieved through mechanisms such as the RAAS, which adjusts blood vessel constriction and fluid retention to maintain blood pressure within a normal range.
• Proper terminology from slides

  • Pathogen: disease-causing organisms
  • Leukocytes: white blood cells that can engulf invading pathogens or produce antibodies
  • Phagocytosis: process when a white blood cell engulfs and chemically destroys a microbe
  • Macrophages: phagocytic white blood cells found in lymph nodes or in the blood of bone marrow, spleen and liver
  • Neutrophil: A type of white blood cell that is an important part of the immune system and helps the body fight infection
  • Localized inflammatory response: occurs within the area affected by the harmful stimulus
• Specific adaptive immunity


  The body's ability to recognize and remember specific pathogens, such as bacteria, viruses, or toxins, and mount a targeted response to eliminate them. Involves specialized immune cells like T cells and B cells.
• Immune system components


  • Complement proteins: Foreign organisms activate complement proteins present in the circulatory system
  • Antibodies: Proteins made by immune cells that latch onto foreign substances
  • Antigen-antibody binding sites
• 1st line of defense

  • Physical or chemical barrier to prevent pathogen entry (skin, tears, mucous)
• Second line of defense

  • Innate immune responses, which are nonspecific and rapidly activated upon encountering pathogens. Examples include phagocytic cells like macrophages and neutrophils and inflammation responses. These components work together to detect and eliminate pathogens or infected cells.
• Specific adaptive immunity


  The body's ability to recognize and remember specific pathogens, such as bacteria, viruses, or toxins, and mount a targeted response to eliminate them. This immunity involves specialized immune cells, such as T cells and B cells, which undergo activation and proliferation upon encountering specific antigens.
• Complement proteins


  • Foreign organisms activate complement proteins present in the circulatory system
• Antibodies


  Proteins made by immune cells that latch onto foreign molecules called antigens. The antigen-antibody binding sites are specific regions where they connect. This binding marks antigens for destruction or neutralization, aiding in the immune response.
• T cells vs B cells

  T cells primarily target infected or abnormal cells directly, while B cells produce antibodies to neutralize pathogens. Both types of cells play complementary roles in orchestrating effective immune responses.
• A fever affects a person and their immune system

  It stimulates the immune system, enhancing the activity of immune cells like white blood cells and speeding up the production of antibodies to fight off pathogens. Additionally, higher body temperatures can inhibit the growth and reproduction of certain bacteria and viruses, helping to limit the spread of infection.
• Poison affects some cells in your bodies and not others

  If a virus/ pathogen/ microbe/ poison can't attach or find a receptor-site, it will float around and wait until it mutates to a receptor site
• Antibodies come into play

  Antibodies can also attach to antigens and alter shape of virus, preventing entry
• Allergies


  Exaggerated immune responses to substances that are normally harmless to most people. These substances, called allergens, can trigger allergic reactions when they come into contact with the body, leading to symptoms such as sneezing, itching, runny nose, watery eyes, or skin rashes.
• Autoimmune diseases


  Occur when the immune system mistakenly attacks healthy cells and tissues in the body, causing inflammation and damage. Normally, the immune system defends the body against foreign invaders like viruses and bacteria, but in autoimmune diseases, it becomes confused and targets the body's own cells.
• Malfunctions to the immune system

  • Allergies
  • Autoimmune disease
  • Bacteria
  • Virus
  • HIV
  • Prions
  • Vaccines
  • Antibiotics
  • Antibiotic resistance
• Allergies


  When the immune system mistakes harmless cells for harmful invaders