Distinguish between genotype and phenotype; homozygous and heterozygous

Genotype is the gene makeup of the organism Ex: Gg while phenotype is the physical description to the trait Ex: green

Homozygous is when both alleles for the trait are the same Ex: GG and gg while heterozygous is when the alleles are different Ex: Gg

Explain nerve impulse transmission from a receptor to effector in the simplest nerve pathway.

<ul> <li>Receptor: It all starts with a receptor, which is like a sensor in your body that detects a stimulus (like touch, heat, light, etc.). For example, if you touch something hot, the receptors in your skin detect the heat.</li> <li>Sensory Neuron: When the receptor detects a stimulus, it sends a signal along a sensory neuron. Think of a sensory neuron as a messenger that carries the message from the receptor to the next stop.</li> <li>Spinal Cord: The sensory neuron sends the signal to the spinal cord, which is like a relay station in your body. It's a bundle of nerves that runs down your back.</li> <li>Interneuron (Optional): Sometimes, the signal might need to pass through an interneuron in the spinal cord. Interneurons help process and relay information within the spinal cord.</li> <li>Motor Neuron: Once the signal reaches the spinal cord (or sometimes directly from the sensory neuron), it travels along a motor neuron. Motor neurons carry messages from the spinal cord to muscles or glands.</li> <li>Effector: Finally, the signal reaches the effector, which is the muscle or gland that responds to the stimulus. For example, if you touched something hot, the effector might be the muscles in your arm that quickly pull your hand away.</li> </ul> <br>

Explain the transmission of a nerve impulse along an axon- an Action potential

1. Resting State: The axon (a part of the neuron) is like a tiny wire with a negative charge inside.
2. Stimulus: When something triggers the neuron, like a touch, it lets positive ions inside. This makes the inside less negative, or "depolarized".
3. Depolarization: This change in charge starts a chain reaction where nearby areas of the axon also become less negative, creating a wave called an action potential.
4. Propagation: The action potential travels along the axon like a wave, pushing the message forward.
5. Recharge: After passing, the axon recharges by pushing positive ions out, making the inside negative again.
6. One-Way Traffic: Once it fires, the axon needs a moment to recharge before it can fire again. This ensures the message moves in one direction.
7. Passing the Message: At the end of the axon, the message is passed to the next neuron by releasing chemicals called neurotransmitters into a gap.

Describe the changes in polarity along an axon during an action potential

• Resting State: At rest, the inside of the axon is negatively charged compared to the outside. This is because there are more negative ions inside and positive ions outside.
• Depolarization: When a stimulus triggers the neuron, like a touch, sodium channels open, allowing positive sodium ions to rush into the axon. This makes the inside less negative and starts depolarization.
• Action Potential: As more sodium ions flow in, the inside becomes positive compared to the outside. This rapid change in charge along the axon is the action potential.
• Repolarization: After the action potential passes, potassium channels open, allowing positive potassium ions to leave the axon. This restores the negative charge inside, repolarizing the axon.
• Hyperpolarization (Optional): Sometimes, potassium channels stay open a bit longer, causing the inside of the axon to become even more negative than at rest. This is called hyperpolarization.
• Resting State Restored: Eventually, the sodium-potassium pumps work to restore the original balance of ions, bringing the axon back to its resting state.

Describe the transmission of a nerve impulse across a synapse

• Release: When a nerve impulse reaches the end of a neuron, it releases chemicals called neurotransmitters into a small gap, the synapse.
• Connection: These neurotransmitters connect with the next neuron at specific points called receptors.
• Message Passed: This connection either tells the next neuron to "fire" or not, continuing the message along.
• Cleanup: After the message is passed, leftover neurotransmitters are either taken back up or broken down.

Describe the function of neurotransmitters like Ach, Serotonin and Endorphins etc

• Acetylcholine (ACh):
  • Function: ACh is involved in muscle movement, memory, and learning.
  • Example: When you move your arm, ACh is released to signal your muscles to contract.
• Serotonin:
  • Function: Serotonin helps regulate mood, appetite, sleep, and memory.
  • Example: When you feel happy or calm, it's often because serotonin levels in your brain are balanced.
• Endorphins:
  • Function: Endorphins act as natural painkillers and can also induce feelings of pleasure or euphoria.
  • Example: After a tough workout, your body releases endorphins, which can reduce feelings of pain and promote a sense of well-being.
• Dopamine:
  • Function: Dopamine is involved in motivation, reward, pleasure, and movement.
  • Example: When you achieve a goal or experience something enjoyable, your brain releases dopamine, making you feel good and reinforcing the behavior.
• GABA (Gamma-Aminobutyric Acid):
  • Function: GABA is the primary inhibitory neurotransmitter in the brain, meaning it helps calm and regulate neural activity.
  • Example: When you feel relaxed or calm, it's often because GABA is inhibiting excessive neural firing.

describe how sympathetic and parasympathetic nervous systems affect the body

• Activation: The SNS is like the body's accelerator, kicking into action when you're under stress or facing a threat.
• Effects on the Body:
  1. Fight or Flight Response: It triggers a cascade of physiological changes preparing the body to fight the threat or flee from it.
  2. Increased Heart Rate and Blood Pressure: To pump more oxygen-rich blood to muscles and vital organs.
  3. Dilated Pupils: To improve vision and help detect potential dangers.
  4. Increased Breathing Rate: To take in more oxygen for energy.
  5. Decreased Digestion: Digestive functions slow down since they're not essential for immediate survival.
  6. Sweating: To help cool the body during heightened activity.

Parasympathetic Nervous System (PNS):

• Activation: The PNS acts as the body's brakes, promoting rest, relaxation, and digestion.
• Effects on the Body:
  1. Rest and Digest Response: It promotes activities that occur when the body is at rest, such as digestion and repair.
  2. Decreased Heart Rate and Blood Pressure: Since there's no immediate threat, the heart rate and blood pressure decrease to conserve energy.
  3. Constricted Pupils: As there's no need for heightened awareness, the pupils constrict to focus on nearby objects.
  4. Increased Digestion: Digestive functions are enhanced to absorb nutrients from food.
  5. Relaxed Breathing: Breathing slows down to a regular pace.
  6. Constricted Airways: Airways may constrict slightly since there's no need for increased oxygen intake.