Why are Psychologists Concerned With Human Biology

Why are psychologists concerned with human biology Psychologists from the biological perspective study the links between our biology and our behavior and mental processes, Principles of Biological Psychology ● Everything psychological is simultaneously biological. ● The nervous system is complexity built from simplicity. ● The brain is both specialized and integrated. ● The nervous system is “plastic” especially at the early ages of development. ☆Neural Communication☆ Neurobiologists and other investigators understand that humans and animals operate similarly when processing information. The body’s information system is built from billions of interconnection cells called “neurons.” Neuron: A nerve cell that is the basic building block of the nervous system. ● About 100 billion neurons (nerve cells) in the human brain. Recent estimates put it at about 86 billion. ● About 100 trillion connections amongst these neurons. ● Neurons have many of the same features as other cells. ○ Nucleus ○ Cytoplasm ○ Cell Membrane Sensory Neuron Motor Neuron Interneuron (Unipolar) (Multipolar) (Bipolar) Afferent Efferent Carry information from Carry information Carry information sensory systems to the from the brain to between other neurons. brain. muscles and glands. Brain Activity Map Project: Starting in 2013, this project is attempting to map the connection of every neuron in a human brain by 2032. ❋Parts of a Neuron❋ Resting Potential: Meuron at a state of rest. Ready to fire the cell body. Soma: Life support center of the neuron; cell body. Dendrites: Branching extension at the cell body. Receive messages from other neurons. Axon: Long, single extensions of a neuron cover with myelin sheath to insulate and speed up messages through neurons. Axon Hillock: Located at the end of the soma and controls the firing of the neuron if the strength of the signal exceeds the threshold limit of the axon hillock the structure will fire a sign/a signal down the axon. Vesicles: Containers for Neurotransmitters. Neurotransmitters: Chemical messengers. Neurotransmitters (chemical) released from the sending neuron travel across the synapse and bind to receptors sites on the receiving neuron, thereby influencing it to generate an action potential. Synapse: A junction between the axon-tip of the sending neuron and the dendrite or cell body of the receiving neuron. Glial Cells: Nourish neurons. Astrocytes provide nutrition to neurons. Oligodendrocytes (CNS) and Schwann cells (PNS) insulate neurons as myelin. ● Cells that insulate and support neurons. ● Create the myelin sheath. ● Provide nourishment ● Prevent harmful substances from entering the brain. ● Forms white matter in the brain that helps communication across the brain. ● Gray matter is un-myelinated brain tissue. Myelin: Important to motor function-not finished developing until 25 and loss can cause multiple sclerosis. Issues Multiple Sclerosis: A disorder of the CNS that affects 2.5 million people worldwide. In MS, the myelin coating in various sites throughout the brain and spinal cord becomes inflamed due to an immune response and is eventually destroyed, leaving scars called sclerosis that block the underlying neurons from transmitting messages. Symptoms reflect the effects of the specific neurons and may be intermittent so diagnosis could take a while. The first symptoms are blurred vision and numbed limbs. Guillain-Bare: An autoimmune disorder in which the immune system attacks healthy nerve cells in your peripheral nervous system leading to demyelination. This leads to weakness, numbness, and tingling. It can eventually cause paralysis. Symptoms include prickling/pin-and-needles sensations in your fingers, toes, ankles, or wrists. Weakness starts in your legs and spreads to your upper body. Neural Communication 1. Resting potential (-70 millivolts Mv) a. Negative ions inside the axon. 2. Message received by the dendrites. a. 2 Categories i. Excitatory ii. Inhibitory 3. Cross Threshold (known as trigger zone) a. Reached -55 millivolts Mv 4. Action Potential (All or Nothing) a. A neural impulse. A brief electrical charge that travels down an axon membrane. 5. Depolarization or hyperpolarization. a. Depolarization occurs when positive ions enter the neurons making it more prone to fire an action potential. b. Hyperpolarization occurs when negative ions enter the neurons, making it less prone to fire an action potential. 6. Sodium/Potassium pumps push sodium out NA+/K+ pump. a. Gates channels become permeable. 7. Neural impulse pushes down to the axon terminal. 8. Vesicles in terminal release neurotransmitters. a. Electrical to the chemical process. Again...Excitatory or inhibitory! 9. Neurotransmitters a. Cross the synaptic cleft and synaptic gap. b. Bind to the receptors of the receiving neuron in key-lock mechanisms. 10. Reuptake 11. Refraction Threshold: Each neuron received depolarizing and hyperpolarizing currents from many neurons. When the depolarizing current (positive ions) minus the hyperpolarizing current (negative ion) exceeds minimum intensity (threshold) the neuron fires an action potential. (Axon Hillock) Nodes of Ranvier: Contain Na+/K+ ATPases, Na+/K+ exchangers, and the high density of voltage-gated Na+ channels that generate action potentials. The action potential travels from one location in the cell to another, but ion flow across the membrane occurs at the Nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath. The clustering of voltage-gated sodium-potassium ion channels at the noes permits this behavior. Sodium-Potassium Pumps: Pump positive ions out from the inside of the neuron, making them ready for another action potential. Reuptake: Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action. Refractory Period: After a neuron fires an action potential, it pauses for a short period of recharge itself to fire again. Addiction How neurotransmitters influence us… Serotonin pathways are involved with mood regulation Dopamine Pathways: Are involved with schizophrenia, Parkinson’s, and other diseases. Lock and Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. Agonists: This agonist molecule excites. It is similar enough in structure to the neurotransmitter molecule that it mimics its effects on the receiving neuron. Morphine, for instance, mimics the action of endorphins by stimulating receptors in brain areas involved in mood and pain sensations. Antagonists: This antagonist molecule inhibits. It has a structure similar enough to the neurotransmitter and block its action, but not similar enough to stimulate the receptor. Curare poisoning paralyzes its victims by blocking ACh receptors involved in muscle movement. Brain Reward System: A network of neurons that is activated when we perform functions that help us stay alive.