Nervous System

Nervous System

• Enables you to understand the words you read in a book

Central Nervous System (CNS)

• Main function is to process information and form a response

Neurons

• Specialized nerve cells that help you gather information about your environment, interpret the information, and react to it
• Transmit electrical signals to various organs in the body
• Consist of three main regions:
  • The dendrites
  • A cell body
  • An axon

Hypothalamus

• Regulates body temperature, thirst, appetite, and water balance
• Also partially regulates blood pressure, sleep, aggression, fear, and sexual behavior.
• An example is the hypothalamus when you are hungry
• Receives information from the nervous system and initiates responses through the endocrine system

Motor Neurons

• Carry impulses away from the brain and spinal cord to a gland or muscles, resulting in secretion or movement
• An example is a motor neuron stimulating your arm to move to swat a fly

Pancreas

• Produces enzymes that digest carbohydrates, proteins, and fats
• Secretes the hormones insulin and glucagon, which work together to maintain homeostasis and the level of sugar in the blood
• Diabetes mellitus is a disease that occurs when it does not regulate the amount of glucose in the blood

Menstruation

• If an embryo does not implant in the endometrium, the endometrium is shed in a process called menstruation
• Does not occur if the egg is fertilized

Chemical Digestion

• Starts in the mouth, with saliva breaks down food

Nicotine

• Increases the amount of dopamine released into a synapse
• Its immediate effect is constricted blood vessels

Stimulant

• Drugs that increase alertness and physical activity
• Example: Coffee

Testosterone

• A steroid hormone that is necessary for the production of sperm
• Influences the sex characteristics that appear during puberty
  • Secondary sex characteristics include:
    • Facial chest hair
    • Broader shoulders
    • Increased muscle movement
    • Deeper voice

Dendrites

• Receive impulses from other neurons and conduct impulses to the cell body
• The cell body contains the nucleus and other organelles
• The axon passes those impulses on to the other neurons or muscles

Sensory Neurons

• Three kinds: sensory, interneurons, and motor neurons
• Sensory neurons send impulses from receptors in the skin and sense organs to the brain and spinal cord
• Interneurons carry impulses to motor organs

Zygote

• A fertilized egg
• Around 30 hours after fertilization, the zygote undergoes its first mitosis and cell division

Placenta

• Provides food and oxygen and removes waste
• Two sides:
  • The fetal side that forms from the chorion and faces the fetus
  • The maternal side that forms from the uterine tissue
• One of the main functions is to provide nutrients to the fetus

Puberty

• The period of growth when sexual maturity is reached

Other Items to Know

• Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate the gonads to mature
• An immediate effect of nicotine includes increased heart rate and blood pressure
• The largest part of the brain is the cerebrum
• Sound waves first enter the outer ear, specifically in the Pinna
• The placenta provides oxygen and nutrients to the fetus, removes waste products from the fetus blood, and produces hormones to support pregnancy
• The nervous system enables you to understand the words you read in a book.
• The function of the nervous system is to receive, process, and respond to sensory input, and to control body functions and actions.