- Control Systems in Plantso Types of plant hormones Auxins- Stem elongation, differentiation, apical dominance Cytokinins- Cell division, germination Gibberellins- Seed, bud, fruit development- Stem elongation (different than auxins) Abscisic acid- Inhibits growth, closes stomata, prevents germination Ethylene- Promotes fruit ripening, programmed cell death, leaf abscission, response to mechanical stress Brassinosteroids- Normal growth and development, xylem differentiation, pollen tube elongation Strigolactones- Apical dominance, germination, attract mycorrhizal fungi to the rooto Examples of hormone function Auxin in stem elongation- Apical meristem produces auxin- Transported down the shoot (only)- Produces a decreasing concentration gradient- High concentrations of auxin inhibit stem elongation- Low concentrations of auxin promote stem elongation by activating H+ active transport mechanisms Auxin and Cytokinin in Apical Dominance- Auxins inhibit lateral shoot development- Cytokinins stimulate lateral shoot development o High concentration in roots, low concentration in stem- Opposite impacts on root branching Key Features- Broad effects controlling major physiological processes- Most occur in antagonistic pairs Plant Rhythms- Some plant processes (flowering, etc.) follow a daily cycle suggesting plants have rhythms- How do plants keep track of time?o How much of something is degraded or produced Photoperiodism- Some plants flower only when the days are long- Some flower only when the days are short- What is the mechanism?- Night length is what is critical- Plants contain pigments call phytochromeso One part functions as a photoreceptor, the other a protein kinase How does this control flowering?- Short day plant (long night)- At night Pfr is slowly naturally converted to Pr- Light flashes can reverse this process- Chemical Signaling in Animalso Two major systems Endocrine:- Hormones secreted into blood stream Nervous:- Neurotransmitters secreted into the synapse (junction) between neuronso Differences Endocrine system:- Broadcasts the signal throughout a broad area (via blood stream) Nervous system:- Sends the signal directly to a target cell (via neuron/s)o Similarities Many hormones are neurotransmitters Some neurons secrete hormones Both systems involve cells communicating with other cells- Types of Hormoneso Lipid soluble Bind to cytoplasmic receptorso Water soluble Bind to membrane bound receptors- Speed of Responseo Gene regulation: Most often results in a slow response (steroid hormones)o Direct Cytoplasmic Response: Generally a rapid response (water soluble hormones)- Endocrine Glandso Glands that secrete (release) hormones into the blood streamo TABLE 45.1 Major ones, kinds, and functionso FIGURE 45.4 Left side onlyo Hypothalamus: 2 types of hormoneso Pituitary: Posterior:- 2 hormones, secreted by neurosecretory cells in the hypothalamus Anterior:- 7 hormones- Controls other endocrine glands- Portal vesselso Heart artery capillary portal vessels capillary vein heart- Endocrine System Regulationo Antagonistic pairso Example: blood glucose levels Glucagon, and insulin- Both produced by the pancreas- Glucagono Stimulates the breakdown of glycogen to glucose- Insulino Stimulates the conversion of glucose to glycogen- If blood glucose levels rise, what happens?o Insulin released- If they fall, what happens?o Glucagon released If you eat a big meal and blood glucose levels rise sharply, what happens?- Insulin release increases Six hours after that meal blood glucose levels are dropping, what happens?- Glucagon release increaseso Negative feedback system Example: thyroid hormones, regulate overall metabolism Hypothalamus THR+ anterior pituitary TSH+ thyroid thyroxine triiodothyronine (-) hypothalamus/anterior pituitary/thyroid What would be expected to happen to the levels of TSH if the TRH receptors in the anterior pituitary are constantly bound and stimulated with TRH like active molecules?- Increase- Type 1 Diabetes occurs when the pancreas stops producing insulin, type 2 diabetes occurs when your cells no longer respond to insulin, both result in uncontrollable blood glucose levels. Basedon the data below, choose the most likely diagnosis for the Patient 1.Blood Glucose InsulinMg/dL mU/mLNormal 90-100 32Patient 1 210 162CORRECT ANSWER: Type 2 Diabetes- Integration of Endocrine and Nervous Systemso Neurosecretory cells: Neurons that secrete hormones Form an important link between endocrine and nervous systems- Turkey and Sleepo Tryptophan is required for serotonin and melatonin synthesiso Serotonin is a neurotransmitter (signal molecule), linked to sleep and sleep patternso Melatonin is a hormone related to circadian rhythm- Nervous Systemo Composed of specialized cells that can transmit action potentials from one cell to another (one location in the body to another).o Neurons Types of neurons- Sensoryo Receptor to CNS- Interneurono Between sensory and motor neurons- Motoro From CNS to effector cell Structure of neurons- Cell body- Dendrites- Axon- Axon hillocko Place where cell body and axon are connected- Myelin sheath (some)o Schwann cell, wraps around axono Not continuous coat- Membrane Potentialso All cells have and electrical gradient or electrical potential across their cell membraneo Measured with outside being = 0o Inside is generally -50 to -100 mVo High [Na+] outsideo High [K+] insideo High [organic molecules] (-) insideo Na-K pump pumps ions unequallyo Na and K diffuse across the membrane at different rates- Action potentialso All cell have membrane potentialso Muscle and nerve cells are excitable They can generate a change in membrane potentialo If a depolarization is great enough (threshold) it will stimulate an action potential This involves voltage-gated channels- Gated channelso Excitable cells have special ion channels called gated ion channels A stimulus will cause a change in the gated channelso If K+ channels open causes? Hyperpolarizationo If Na+ channels open causes? Depolarization- Voltage-Gated Channelso Differ in: Ions allowed through Number of gateso Can have Na+ and K+ Na+ Channels: 2 gates- Activation gate (opens)- Inactivation gate (closes) K+ Channels: 1 gate- Opens slow- Action potential o Is the result of the Na+ gate opening causing a rapid
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