Chapter 3 Body and mind

3.1 The Nervous System The Nervous System regulates our internal functions 2 parts: Central Nervous System—brain and spinal cord Peripheral Nervous System—nerve cells that send messages between the central nervous system and the body

Neurons Neurons—communicate with each other and structures in the body, such as muscles and glands Components of a neuron: Cell body—produces energy that fuels activity Dendrites—receive information from other neurons and pass them through the cell body Axon—carries messages away from the cell body Usually only one axon per neuron Axon terminals—passes message to next neuron, or structure

Communication Process In order for a message to be sent, it must cross a synapse. A synapse is a junction between the axon terminal of one neuron and the dendrites of another Messages travel in only one direction Sensory neurons carry information to the CNS Motor neurons carry information away from the CNS New synapes form as we learn something new Sometimes the messages-sending process can be disrupted

Neurotransmitters: Chemical messengers Neurotransmitters are chemicals that are stored in sacs The neurotransmitter will leave one axon terminal, cross a synapse, and be received by the dendrite of the next neuron Neurotransmitters fit into a specific site (lock & key) Acetylcholine—muscle control (skeletal) Dopamine—motor behavior Noradrenaline—preparing the body for action Serotonin—emotions and sleep

Central Nervous System The central nervous system consists of the brain and the spinal cord The spinal cord transmits messages between the brain and the muscles and glands throughout the body Spinal Reflex—simple, automatic response to something The brain is not involved in this spinal reflex Example: Doctors check knee-jerk reaction to make sure your neurons are firing the way they are supposed to

Peripheral Nervous System The peripheral nervous system is responsible for transmitting messages between the CNS and all parts of the body There are 2 parts: Somatic Nervous System—transmits sensory messages to the CNS Enables us to experience sensation Autonomic Nervous System (involuntary)—regulates the body’s vital functions (heartbeat, breathing, digestion, blood pressure) Sympathetic—activated when a person is going into action “Fight or Flight Response” Suppresses unnecessary body functions and heightens others Suppressed—digestion Heightened—heart rate and reparations Parasympathetic—restores the body to normal state Heart rate, breathing, blood pressure, digestion all return to normal

3.2 The Brain-Our Control Center

The Brain 3 Sections Hindbrain Midbrain Forebrain

Hindbrain Medulla—regulates heart rate, blood pressure, and breathing Pons—regulate body movement, attention, sleep, and alertness Cerebellum—balance and coordination

Midbrain Involved in vision and hearing Also arousal, sleep, and attention

Forebrain Thalamus—serves as the relay station for sensory simulation Hypothalamus—regulates body temperature, stores nutrients, and various aspects of motivation and emotion (hunger, thirst, sexual behavior, caring for offspring, and aggression) Limbic System—involved in learning and memory, emotion, hunger, sex, and aggression Cerebrum—concerned with thinking, memory, language, emotions, complex motor function, perception, and much more

3.3 The Endocrine System The endocrine system consists of glands that secrete substances called hormones These glands include pituitary gland, thyroid gland adrenal gland, and the testes and ovaries

Pituitary Gland Size of a pea Secretes the growth hormones

Thyroid Gland The thyroid produces thyroxin which affects the body’s metabolism Metabolism is the conversion of food into energy Hypothyroidism leads to weight gain Hyperthyroidism leads to weight loss

Adrenal Gland Adrenal Gland secretes Cortical Steroids which increase resistance to stress and promote muscle development They also secrete adrenaline and noradrenaline which enables a person to deal with stress

Testes (males) and Ovaries (females) These glands produce testosterone, estrogen, and progesterone Testosterone—aids in growth of muscles and bones as well as primary and secondary characteristics Primary characteristics—reproduction Secondary characteristics—distinguishing characteristics between males and females Estrogen—female sex hormone and fosters primary and secondary characteristics Progestogen—helps regulate the menstrual cycle

3.4 Heredity-Our Genetic Background Heredity is the transmission of characteristics from parents to offspring Includes: Physical traits—height, hair, eye color Psychological traits—shyness, leadership, and aggressiveness Environment can also play a role in shaping these traits Psychological disorders may also be passed down through heredity (anxiety, depression, schizophrenia)

Genes and Chromosomes Genes are the basic building blocks of heredity Traits are determined by pairs genes—one from each parent (eye color or blood type) Genes are found in threadlike structures called chromosomes 46 or 23 pair in each cell 22 are similar for males and females, the 23 pair determines sex (male or female) Males—XY, Females—XX When a child is born without 46 chromosomes, physical and behavioral disorders may result

Nature vs Nurture Nature refers to what people inherit biologically from their parents Nurture refers to environmental factors, or what a person is exposed to in life (family, education, culture, living conditions)