Nerves and Hormones

1. CNS

   Nota:

   • The CNS- Brain and Spinal Cord
2. Stimulus

   Nota:

   • Stimuli- Change in the surroundings
   1. Receptor

      Nota:

      • Receptor -> along Sensory Neuron -> Relay neuron and CNS -> Motor Neuron -> Effector
      1. Coordinating Centre
         1. Effector
            1. Response
3. Receptor

   Nota:

   • Receptors- cell detecting change
   1. Light

      Nota:

      • Light- Eye
   2. Sound

      Nota:

      • Sound- Ear
   3. Position

      Nota:

      • Position-Ear
   4. Touch

      Nota:

      • Touch- Skin
   5. Pressure

      Nota:

      • Pressure- Skin
   6. Chemical

      Nota:

      • Chemical- Tongue, Nose, Blood Vessels. Blood vessels affect the breathing rate by measuring pH levels 
   7. Temperature

      Nota:

      • Temperature - In body, blood vessels. Outside body, skin.
4. Effector

   Nota:

   • Effector- Organ that responds
5. Response

   Nota:

   • Response- How body reacts to stimulus
6. Nervous System

   Nota:

   • Nervous System;  Brain, Spinal Cord, Nerves, Sensory/Relay/Motor Neurons 
7. Impulse is electrical
8. Nerve Structure
   1. Synaptic Gap

      Nota:

      • Synapse- Where two neurons connect. Synaptic Gap- The gap between dendrites of one and axonal terminal of the other. Neurotransmitters diffuse across gap causing transmission of impulse
9. Fast, local response

Nota:

• Reflex Action; An action you can't control- it happens without you thinking about it. Very quick.

1. Reflex Arc

   Nota:

   • Reflex Arc-  Shortest route, bypassing brain, path taken by impulse in reflex action
2. Takes 1/30th of a second

1. Homeostasis

   Nota:

   • Homeostasis; Keeping the conditions the same
   1. So enzymes operate at the optimum speed
2. Enzymes
   1. Temperature
   2. Concentration
      1. Water
      2. Salt
   3. Glucose Levels

Nota:

• Chemical messages released by glands.

1. Glands
   1. Pituitory
      1. Master Gland

         Nota:

         • Controls all other glands in body
      2. Growth Hormone

         Nota:

         • Growth Hormone; controls growth in body
   2. Adrenal
      1. Adrenaline Hormone

         Nota:

         • Adrenaline; blood sugar surge, fight/flight response, faster heart beat, energy boost
   3. Gonads

      Nota:

      • Gonads- Sex Glands
      1. Testosterone

         Nota:

         • Testosterone; Puberty and fertility, sperm production, sexual development
      2. Oestrogen

         Nota:

         • Oestrogen; Control puberty and fertility, controls menstrual cycle, sexual development
   4. Thyroid
      1. Thyroxine

         Nota:

         • Thyroxine; controls metabolic rate inside cells
   5. Pancreas
      1. Insulin

         Nota:

         • Insulin; causes body to store extra sugar as glycogen for use between meals
         1. Lack of; Type 1 diabetes
         2. Too much of; Type 2 diabetes
2. Long-term response
3. Bloodstream
4. Slow, widespread response

Nota:

• Menstrual cycle; Oviduct (fallopian tube), ovaries, cervix, uterus, follicles, eggs, ovulation, 28 days, Day 0-7, lining breaks down

1. FSH
   1. Causes egg to mature in ovary
   2. Stimulates ovaries to release oestrogen
   3. Pituitory Gland
2. Oestrogen
   1. Stops FSH production
   2. Thickens blood
   3. Stimulates pituitory gland to release LH
3. LH
   1. Causes ovulation

      Nota:

      • Ovulation - Day 14
4. Progesterone
   1. Maintains lining of uterus
   2. Inhibits production of LH and FSH

1. Oral contraceptive pill
   1. Synthetic oestrogen and progesterone
      1. Inhibits FSH so follicle doesn't mature
2. In vitro fertilisation
   1. Extra FSH

      Nota:

      • Extra FSH- more eggs mature
      1. Removal of eggs
         1. Fertilisation in laboratory

            Nota:

            • Fertilisation in laboratory- 2-3 days 
            1. Return embryos to uterus
               1. Sometimes multiple babies

Nota:

• Tropism- A growth movement of a plant in response to external stimulus, direction of stimulus determines direction of growth

1. Auxin

   Nota:

   • Auxin- Plant hormone responsible for controlling direction of growth in roots and stems. Made at tip of stem and roots.
   1. Plant cell growth
   2. Changes elasticity of cells
   3. Diffuses
2. Roots
   1. Negatively Phototropic
   2. Positively Geotropic
3. Stem tips

   Nota:

   • If covered- auxin evenly distributed, even growth. If sunlight on one side- auxin accumulates on shady side and the plant bends. The bit underneath is then shady so it repeats and shoot bends upwards.
   1. Negatively Geotropic
   2. Positively Phototropic

1. Herbicides

   Nota:

   • Herbicides- spray auxin on weed and it grows too quickly and dies
2. Growth Promoters

   Nota:

   • Growth Promoters- use cuttings to clone plants, rooting powder contains auxin so that cutting develops roots