Homeostasis & Coordination

• What does the CNS consist of?


  The brain and spinal cord
• What is the primary function of the CNS?


  To process information and coordinate responses
• What does the PNS consist of?


  Nerves outside the CNS
• How does the PNS function in relation to the CNS?


  It connects the CNS to the rest of the body for communication
• How do animals respond to stimuli?

  Using the nervous system
• How do plants respond to stimuli compared to animals?


  Plants respond slowly by changing growth direction or producing hormones
• What is a key feature of reflex actions?


  They happen without conscious thought
• Why are reflexes considered protective?


  They prevent injury by responding immediately to harmful stimuli
• What is the role of a receptor in a reflex arc?


  To detect the stimulus
• What does the sensory neuron do in a reflex arc?


  It carries the signal to the spinal cord
• What is the function of the relay neuron?


  Connects the sensory neuron to the motor neuron in the spinal cord
• What does the motor neuron do in a reflex arc?


  It sends the response signal to the effector
• What is an effector in a reflex arc?


  A muscle or gland that responds to the stimulus
• What is a synapse?


  The gap between two neurons
• How do neurotransmitters function at a synapse?


  They pass the signal across the gap from one neuron to the next
• What part of the eye controls light entry?

  The iris
• How does the pupil reflex work in bright light?


  The pupil contracts to become smaller
• What happens to the pupil in dim light?


  The pupil dilates to become larger
• What happens to the lens when focusing on near objects?


  The lens becomes thicker
• What is the role of ciliary muscles in accommodation?


  They control the thickness of the lens
• What is homeostasis?


  The process of maintaining a stable internal environment
• What are some examples of what homeostasis maintains?


  Temperature, blood sugar, and water levels
• What are the functions of the liver?


  Produces bile, stores glucose, detoxifies substances, regulates blood sugar
• How does insulin affect blood sugar levels?


  It lowers blood sugar levels by helping cells absorb glucose
• What is the role of glucagon in blood sugar regulation?


  It raises blood sugar levels by stimulating the liver
• What happens during vasodilation?


  Blood vessels widen, increasing blood flow to the skin
• How does sweating help regulate body temperature?


  Evaporation of sweat cools the skin
• What is the process of shivering?


  Muscles contract rapidly to generate heat
• What is vasoconstriction?


  Blood vessels narrow to reduce blood flow to the skin
• What are some examples of water loss in humans?


  Urination, sweating, breathing, and feces
• What is the function of auxin in plants?


  Promotes cell growth and directs growth in response to light and gravity
• What is gravitropism?


  A plant's growth response to gravity
• What is an example of positive gravitropism?


  Roots grow downward
• What is an example of negative gravitropism?


  Shoots grow upward
• What is positive phototropism?


  Shoots grow toward light
• What are the advantages of plant tropisms?


  They allow plants to grow toward light and roots to grow toward moisture
• What is sensitivity in living organisms?


  The ability to detect and respond to changes in the environment
• What is the function of a root hair cell?


  Increases surface area for water and nutrient absorption
• What is a sense organ?


  A sense organ detects specific stimuli and sends signals to the brain
• Can you name some examples of sense organs?


  Eyes, ears, nose, skin, and tongue