science

• Nervous system


  Connects all body parts and transmits signals from one part to another. It is a system of cells, tissues, and organs that regulates the body's responses to internal and external stimuli
• Major divisions and parts of the nervous system


  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Central Nervous System (CNS)


  Serves as the main processing center for the entire nervous system. Consists of the brain and spinal cord
• Parts of the brain

  • Cerebrum
  • Cerebellum
  • Brain stem
• Spinal cord


  Serves as a channel for signals between the brain and the rest of the body, and controls simple musculoskeletal reflexes without input from the brain
• Divisions of the Peripheral Nervous System (PNS)


  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  Associated with the voluntary control of body movements
• Parts of the Somatic Nervous System

  • Spinal Nerves
  • Cranial Nerves
• Autonomic Nervous System


  Associated with the involuntary control of body movements
• Subdivisions of the Autonomic Nervous System


  • Sympathetic
  • Parasympathetic
• Sympathetic


  Activated when the body is in a dynamic role or stress (e.g., increased heart rate and breathing, dilation of pupil, sweating, etc.)
• Parasympathetic


  Maintains body functions and restores the body to normal or relaxed mode
• Nerve cell


  The basic unit of the nervous system, also called a neuron
• Parts of a neuron

  • Cell body
  • Dendrites
  • Axons
• Dendrites


  Carry impulses towards the cell body
• Axons


  Carry impulses away from the cell body
• Nerve impulse


  A combination of an electrical charge and a chemical reaction, an electrochemical signal moving along a neuron
• A nerve impulse cannot jump from one neuron to another
• Neurotransmitter


  A chemical released at the end of an axon that stimulates the nerve impulse to start in the next dendrite
• Five sense organs


  • Eyes
  • Ears
  • Nose
  • Tongue
  • Skin
• Stimulus


  Any factor in the environment that may trigger a nerve impulse
• Response


  A reaction to a stimulus
• An organism must be able to respond to a stimulus in order to survive
• Endocrine system


  Composed of glands that secrete different types of hormones that affect almost every cell, organ, and function of the body
• Functions of the endocrine system

  • Regulating growth and development
  • Regulating metabolism
  • Regulating reproductive processes
  • Regulating mood
• Hormones


  Chemicals secreted by endocrine glands that are carried in the bloodstream to target organs
• Major endocrine glands


  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas
  • Ovaries
  • Testes
  • Thymus
• Hormones act in very small amounts, and an increase or decrease in hormonal levels may result in body disorders due to hormonal imbalance
• Reproductive system


  The system involved in sexual reproduction, consisting of internal and external organs in both males and females
• Functions of the female reproductive system

  • Produces female sex cells
  • Receives sperm cells from the male
  • Nurtures the development of and provides nourishment for the new individual
• Menstrual cycle


  The cyclical changes in the female reproductive system, involving the ovaries and uterus, that make pregnancy possible
• Important events during the menstrual cycle

  1. The pituitary gland controls and starts the cycle

  2. The pituitary gland releases hormones that cause the egg in the ovary to mature

  3. The ovary releases an egg on day 14

  4. The egg moves through the oviduct and enters the uterus

  5. The uterine lining continues to thicken

  6. The egg has not been fertilized, so the thick uterine lining breaks off and is lost through menstruation

  7. After menstruation, the cycle starts again
• Feedback mechanisms in the menstrual cycle

  Follicle stimulating hormone (FSH) stimulates the ovaries to release estrogen, which then prevents further production of FSH

  Estrogen stimulates the release of luteinizing hormone (LH) from the pituitary gland, which controls the production of progesterone, and high levels of progesterone then inhibit the further release of LH
• Both the nervous system and endocrine system work together to maintain homeostasis in the body
• Menstrual cycle


  1. Uterine lining continues to thicken

  2. Egg not fertilized, does not attach to uterus

  3. Thick uterine lining breaks off and leaves vagina, unfertilized egg and blood lost (menstruation)

  4. Cycle starts again after menstruation
• Feedback mechanisms in menstrual cycle

  1. Follicle stimulating hormone (FSH) stimulates ovaries to release estrogen, high estrogen prevents further FSH production

  2. Estrogen stimulates release of luteinizing hormone (LH) from pituitary, high progesterone inhibits further LH release
• Nervous system and endocrine system

  • Important in enabling the body to maintain homeostasis
  • Regulate bodily functions to maintain normal range of variables like body temperature, water amount, metabolic wastes, blood calcium, hormone levels
• What might happen to a person whose nervous and endocrine systems fail to maintain homeostasis?
• Boy skips lunch, blood sugar drops below normal

  Glucagon from pancreas helps body cope
• Girl eats too many sweets, blood sugar rises above normal

  Insulin from pancreas helps body cope