Homeostasis and Nervous System Overview

Homeostasis

• The maintenance of a constant internal environment.
• Involves controlling factors like blood glucose concentration, temperature, and body salts.
• Negative Feedback Loop: A system where a change in a variable is detected and a response is triggered to counteract the change.
  • Stimulus Increase: A stimulus detected as being too high triggers a response to decrease the stimulus.
  • Stimulus Decrease: A stimulus detected as being too low triggers a response to increase the stimulus.

Nervous System

• Responsible for rapid communication within the body.
• Stimulus Detection: Receptors detect a change in the environment, generating an electrical impulse.
• Sensory Neurons: Carry the electrical impulse from receptors to the central nervous system (CNS).
• Synapses: Junctions between neurons that allow transmission of electrical impulses.
• Central Nervous System (CNS): Includes the brain and spinal cord, where decisions are made.
  • The brain makes decisions for conscious actions.
  • The spinal cord handles unconscious actions (reflexes).
• Motor Neurons: Carry electrical impulses from the CNS to effectors.
• Effectors: Muscles or glands that produce a response.
• Example: Touching a Hot Object
  • Stimulus: Hot object.
  • Receptors: Pain receptors in the hand.
  • Sensory Neurons: Carry signal to the spinal cord.
  • CNS (Spinal Cord): Processes signal and initiates a response.
  • Motor Neurons: Carry a signal from the spinal cord to the muscles in the hand.
  • Effectors: Muscles in the hand contract to pull the hand away.

Reflex Arc

• A pathway that bypasses the brain for rapid responses to harmful stimuli.
• Example: If you touch something hot, a reflex arc is triggered, causing the hand to withdraw directly without the brain processing the information.
• Stimulus: Harmful stimulus.
• Receptors: Detect harmful stimulus.
• Sensory Neuron: Carries signal directly to the spinal cord.
• Spinal Cord: Processes signal and initiates a response.
• Motor Neuron: Carries signal from the spinal cord to the effector.
• Effector: Muscle or gland that responds to the stimulus.

Endocrine System

• Uses hormones to regulate bodily functions.
• Major Glands and Hormones:
  • Pituitary gland (brain): "Master gland" that controls other glands.
  • Thyroid gland (neck): Produces thyroxine, regulating heart rate, metabolism, and temperature.
  • Adrenal glands (above kidneys): Produce adrenaline for the "fight or flight" response.
  • Pancreas (below stomach): Produces insulin and glucagon to regulate blood glucose levels.
  • Testes (males): Produce testosterone, controlling puberty and sperm production.
  • Ovaries (females): Produce estrogen, involved in the menstrual cycle.

Blood Glucose Maintenance

• Insulin: Released when blood glucose levels are high; lowers them.
• Glucagon: Released when blood glucose levels are low; increases them.
• Diabetes: A condition where the body cannot regulate blood glucose properly.
  • Type 1 Diabetes: Pancreas does not produce enough insulin. Treated with insulin injections.
  • Type 2 Diabetes: Body becomes resistant to insulin; often due to lifestyle factors (obesity, unhealthy diet). Managed with lifestyle changes, medication, and sometimes insulin.

Menstrual Cycle

• A monthly cycle of hormonal changes that prepares the female body for pregnancy.
• Four Stages:
  • Stage 1 (Days 1-4): Menstruation - the shedding of the uterine lining.
  • Stage 2 (Days 5-14): The uterine lining rebuilds; follicles in the ovaries develop.
  • Stage 3 (Day 14): Ovulation - an egg is released from the ovary.
  • Stage 4 (Days 15-28): The uterine lining is maintained, preparing for implantation.
• Four Key Hormones:
  • FSH (Follicle Stimulating Hormone): Stimulates follicle development and estrogen production; produced by the pituitary gland.
  • Estrogen: Causes the uterine lining to thicken and stimulates LH production; produced by the ovaries.
  • LH (Luteinizing Hormone): Triggers ovulation; produced by the pituitary gland.
  • Progesterone: Maintains the uterine lining in preparation for pregnancy; produced by the ovaries.

Explore the essential concepts of homeostasis and the nervous system in this quiz. Understand the processes involved in maintaining a constant internal environment and the role of the nervous system in detecting stimuli and coordinating responses. Test your knowledge on negative feedback loops and the components of the CNS.