Neural and Hormonal Systems Module 4 Psychology 7e in Modules

Neural and Hormonal Systems Neural Communication Neurons How Neurons Communicate How Neurotransmitters Influence Us The Nervous System The Peripheral Nervous System The Central Nervous System The Endocrine System

History of the Mind Plato correctly located mind in the brain Aristotle believed that mind was in the heart. Today - mind and brain are faces of the same coin. Everything that is psychological is biological. OBJECTIVE 4-1| Explain why psychologists are concerned with human biology, and describe the ill-fated phrenology theory. Psychology 7e in Modules

History of the Mind Phrenology In 1800, Franz Gall - bumps of the skull represented mental abilities. His theory is incorrect, but proposed different mental abilities were modular. Today - Biological Psychologists study the links between biology and psychology Bettman/ Corbis Psychology 7e in Modules

Neural Communication Neurobiologists and other investigators understand that information processing in humans and animals operate similarly. Note similarity of brain regions involved with information processing of similar kind. Psychology 7e in Modules

Neurons - the basic cell that makes up the nervous system and which receives and sends messages within that system. Nerves – bundles of axons in the body that travel together through the body. OBJECTIVE 4-3| Describe parts of a neuron and explain how its impulses are generated. Psychology 7e in Modules

Parts of a Neuron Cell Body: Life support center of the neuron. Dendrites: Branching extensions at the cell body. Receives messages from other neurons. Axon: Long single extension of a neuron, covered with myelin [MY-uh-lin] sheath to insulate and speed up messages through neurons. Terminal Branches of axon: Branched ending of axons. Transmitting messages to other neurons.

Other Types of Brain Cells Glial cells - grey fatty cells that: provide support for the neurons to grow on and around, deliver nutrients to neurons, produce myelin to coat axons, clean up waste products and dead neurons.

Kinds of Glia Cells Astrocytes provide nutrition to neurons. Oligodendrocytes and Schwann cells insulate neurons as myelin. Astrocytes

Generating the Message: Neural Impulse LO 2.2 Neurons and nerves Ions – charged particles. Inside neuron – negatively charged. Outside neuron – positively charged. Resting potential - the state of the neuron when not firing a neural impulse. Action potential - the release of the neural impulse consisting of a reversal of the electrical charge within the axon. Allows positive sodium ions to enter the cell. All-or-none - referring to the fact that a neuron either fires completely or does not fire at all. Return to resting potential.

Action Potential A neural impulse. A brief electrical charge that travels down an axon generated by the movement of positively charged atoms in and out of channels in the axon’s membrane.

Depolarization & Hyperpolarization Depolarization: Depolarization occurs, when positive ions enter the neuron, making it more susceptible to fire an action potential. When negative ions enter the neuron making it less susceptible to fire, hyperpolarization occurs.

Threshold Threshold: Each neuron receives depolarizing and hyperpolarizing currents from many neurons. When the depolarizing current (positive ions) minus the hyperpolarizing current (negative ions) exceed minimum intensity (threshold) the neuron fires an action potential.

Refractory Period & Pumps Refractory Period: After a neuron has fired an action potential it pauses for a short period to recharge itself to fire again. Sodium-Potassium Pumps: Sodium-potassium pumps pump positive ions out from the inside of the neuron, making them ready for another action potential.

LO 2.2 Neurons and nerves Menu

Synapse Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft. OBJECTIVE 4-4| Describe how nerve cells communicate. Synapse was coined by Lord Sherrington (1857-1952) who inferred it through behavioral experiments. Cajal (1852-1934) described the synapse based on his anatomical studies of the brain. Psychology 7e in Modules

LO 2.3 Neuron communication Menu

Neurotransmitters Neurotransmitters (chemicals) released from the sending neuron, travel across the synapse and bind to receptor sites on the receiving neuron, causing it to generate an action potential. Excitatory neurotransmitter - neurotransmitter that causes the receiving cell to fire. Inhibitory neurotransmitter - neurotransmitter that causes the receiving cell to stop firing.

Reuptake Neurotransmitters in the synapse are reabsorbed into the sending neurons.

How Neurotransmitters Influence Us Serotonin pathways are involved with mood regulation. OBJECTIVE 4-5| Describe how neurotransmitters affect behavior and outline the effects of acetylcholine and endorphins. From Mapping the Mind, Rita Carter, © 1989 University of California Press Psychology 7e in Modules

Dopamine Pathways Dopamine pathways are involved with diseases like schizophrenia and Parkinson’s disease. From Mapping the Mind, Rita Carter, © 1989 University of California Press

Neurotransmitters

Lock & Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. OBJECTIVE 4-6| Explain how drugs and other chemicals affect neurotransmission, and describe the contrasting effects of agonists and antagonists. Psychology 7e in Modules

Agonists

Antagonists

Nervous System Central Nervous System (CNS) Peripheral Nervous System Brain and Spinal cord Peripheral Nervous System (PNS) OBJECTIVE 4-7| Describe the nervous system’s two major divisions, and identify the tree types of neurons that transmit information through the system. Psychology 7e in Modules

The Nervous System Nervous System: Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system. Central Nervous System (CNS): the brain and spinal cord. Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

The Nervous System

Interneuron Neuron (Unipolar) Kinds of Neurons Sensory Neurons carry incoming information from the sense receptors to the CNS. Motor Neurons carry outgoing information from the CNS to muscles and glands. Interneurons connect the two neurons. Interneuron Neuron (Unipolar) Sensory Neuron (Bipolar) Motor Neuron (Multipolar)

Peripheral Nervous System Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles. Autonomic Nervous System: Part of the PNS that controls the glands and other muscles. OBJECTIVE 4-8| Identify the subdivisions of the peripheral nervous system, and describe their functions. Psychology 7e in Modules

The Nerves Nerves consist of neural “cables” containing many axons. They are part of the peripheral nervous system, and connect muscles, glands, and sense organs to the central nervous system.

Autonomic Nervous System (ANS) Sympathetic Nervous System: division of the ANS that arouses the body, mobilizing its energy in stressful situations. Parasympathetic Nervous System: division of the ANS that calms the body, conserving its energy.

Autonomic Nervous System (ANS) Sympathetic NS “Arouses” (fight-or-flight) Parasympathetic NS “Calms” (rest and digest)

Central Nervous System The Spinal Cord and Reflexes OBJECTIVE 4-9| Contrast the simplicity of the reflex pathways with the complexity of neural networks. Simple Reflex Psychology 7e in Modules

Central Nervous System The Brain and Neural Networks Interconnected neurons form networks in the brain. Theses networks are complex and modify with growth and experience. Complex Neural Network

The Endocrine System Endocrine System is the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands. OBJECTIVE 4-10| Describe the nature and functions of the endocrine system and its interaction with the nervous system. Psychology 7e in Modules

Hormones Hormones are chemicals synthesized by the endocrine glands and secreted in the bloodstream. Hormones affect the brain many other tissues of the body. For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar and feelings of excitement during emergency situations.

Pituitary Gland Is called the “master gland.” Anterior pituitary lobe releases hormones that regulate other glands. Posterior lobe regulates water and salt balance.

Thyroid & Parathyroid Glands Regulate metabolic and calcium rate.

Adrenal Glands Adrenal glands consists of adrenal medulla and cortex. Medulla secretes hormones (epinephrine and norepinephrine) during stress and emotions, and adrenal cortex regulates salt and carbohydrate metabolism.

Gonads Sex glands are differentially placed in men and women. Regulate bodily development and maintain reproductive organs in adults.