Regulatory Systems, Kidneys, Immune Response, Circulation, and Reproduction

SBI4U – Grade 12 AP Biology – Homoeostasis Test Homeostasis Lab Transpiration & Circulatory Main Ideas Regulatory System – An attempt to control internal environment – Monitor (receptor) – detects when body it outside its normal limits – Coordinating Centre (Nervous System) – relays info to a regulator that the body is outside its normal limits – Regulator ( Hormones) – reacts to return body to its optimal condition – Negative Feedback – body responds in such a way to reverse the direction of change – Positive Feedback – change occurs in some variable that response is to amplify that change even more in the same direction Kidneys 3 functions of the kidneys Filtration – Occurs in the bowman’s capsule, squeezes blood to filter it – Moves through afferent arteriole into glomerulus – Not all materials can pass through only dissolved solutes Reabsorption – Transfer of essential solutes and H2O from nephrons back into blood – Via active and passive transport – Occurs until threshold level is reached Secretion -Excess NaCl is excreted with urine – Creates osmotic gradient that draws water from the nephron – As waster is reabsorbed solutes become more concentrated Immune System – Recognizes foreign bodies – Responds with the production of immune cells and proteins The ability to fight off pathogens without having been exposed to them is known as innate immunity. It consists of external barriers as well as internal cellular and chemical defenses, such as skin mucus and secretions. internal defenses: natural killer cells, phagocytic cells, antimicrobial proteins, inflammatory response. – Acquired Immunity – develops after exposure to agents such as microbes, toxins and other foreign substances ex. Antibodies, humoral response, cytotoxic, lymphocytes defend against infection in body cells, cell mediated response – Lymphocytes è thymus è t-cells – Lymphocytes è bone marrow è b-cells – B-cell receptors – bind to specific, intact antigens – Made up of two identical: heavy chains and light chains – The tips of the chains forms a constant region, which contains a variable region because it’s amino acid sequence varies extensively from one b cell to another – Acquired immunity has three important properties , has receptor diversity, a lack of reactivity against host cells and immunological memory Circulation & Gas Exchange – Open and closed circulatory system Blood Pressure – how fast blood flows through veins – Aldosterone increases Na+ reabsorption in nephron, this increases osmotic gradient thus more water moves out of the nephron Endocrine – Controls hormones, secretes chemical signals to Local Regulator, Hormones, Pheromones, Neurohormones and Neurotransmitters Local Regulators – Chemical signals that travel over short distances by diffusion – Paracrine – signal acts on cells near the secreting cell – Autocrine – act on the secreting cell itself Neurons -contact target cells at synapses At synapses – neurons often secrete chemical signals called neurotransmitters that diffuse a short distance to bind the receptors on the target cell Neurotransmitters play a role in sensation, memory, cognition and movement Neurohormones – class of hormones that originate from neurons in the brain and diffuse through the bloodstream Pheromones – chemical signals that are released from the body – Used to communicate with other individuals in the species – Marks trails to food sources, warn off predators and attract potential mates Hormones The same hormones may have different effects on target cells Insulin and glucagon (cycles) Neurons, Synapses & Signaling – 2 main parts – CNS (central nervous system) – – PNS ( peripheral nervous system) – Process information in three stages – Sensory input, integration and motor output – Animals have complex nervous systems which consists of – CNS where integration takes place; brain and nerves – PNS brings info into and out of CNS – Ion pumps and channels maintain the resting potential of a neuron – Every cell has a voltage across its plasma called a membrane called membrane potential – Messages are transmitted as changes in membrane potential – Formation of the Resting potential – Sodium Potassium pump è channel protein that makes Na+ and K+ using ATP – Concentration gradients rep chemical potential energy – Most Voltage-gated channels are closed, some K+ are open – When action potential is generated, voltage-gated Na+ open first that allows Na+ to flow into the cell – During the rising phase the threshold is crossed and membrane potential is increased – During the falling phase, voltage-gated Na+ channels become inactivated, voltage-gated K+ channels open and K+ flow out of the cell – The undershot, the membrane permeability to K + is at first higher than at rest, then the voltagegated K + channels close and resting potential is restored. Reproduction Male hormones – testosterone and androsterone Produced in interstitial cells between seminiferous cells Testosterone stimulates: muscles, facial hair, sperm, growth of larynx, increases secretion of bodily oils Female hormones Ovaries contain fibrous tissue called follicles Primary oocyte – matures in ovum Granulosa cells- source of nutrients for oocyte Follicles divide into primary and secondary Menstrual Cycle Approximately 28 days 1. Flow Phase – shedding of endometrium days 1-5 2. Follicular Phase when follicles develop, high estrogen levels, day 6-13 and ovulation on day 14 (LH/FSH surge) 3. Luteal Phase – when egg leaves the scar, corpus luteum present In the luteal phase, estrogen levels decline Corpus Luteum – Secretes both estrogen and progesterone – Prepares for embryo and inhibits ovulation If not fertilized corpus luteum degrades, estrogen and progesterone levels decline and then stimulates small contractions and begins shedding of the lining