Physiology is the study of the function of organisms
Psychology challenges us to think of how physiology might affect our behavior
Mind Body Problem: Does our mind affect our body? Does our body affect our mind? Some think that brain=behavior, therefore if you can understand the brain, then you can understand behavior.
Descartes claimed that the pineal gland was the interface between mind and the rest of the brain. Interactions between the mind and body are two-way. In perception, the physical states of the world influence our bodies which influence our brains which via the pineal gland influence our behavior.
If you give a computer a command it has never encountered and is not programmed to understand then it will not do the command--this is same for the human brain. However, over time the brain can learn this information, but the computer will never know the command unless it is programmed differently.
PET scans(position emission tomography) uses the brain’s metabolic activity
Basic unit of nervous system
there are many of them ~10-12 billion in humans
mostly found in the Central Nervous System ~70%
Three types of Neurons:
Afferent or Sensory neurons-run from sensory organs to CNS
Efferent of Motor Neurons-run from CNS to muscles
Interneurons or Multipolar neurons-found mostly in the brain and are connected to other neurons
Axon- or nerve fiber is a very special part of the neuron, it carries the information away from the cell in the form of bioelectric signals also known as nerve impulses.
Nerve Conduction within Neurons
In most animals and in humans nerve conduction is electro-chemical process
Electric occurs within the neuron
Chemical occurs between the neurons
Depolarization makes it electrical, this is when the membrane becomes less negative. When the neuron is at rest it is not conducting an impulse then it is polarized, this is due to the inside of the membrane is more negatively charged than the outside of the membrane. The neuron can change from polarized to depolarized by the movement of Na+ and K+ ions across the membrane.
Neurotransmitters are biological messenger molecules that carry information.
Neurotransmitters communicate across a synapse in two ways:
1)EPSP (excitatory postsynaptic potential)-information is transmitted
2)IPSP (inhibitory postsynaptic potential)- transmission is ceased
Myelin is layers which have a higher proportion of lipids than other surface membranes. Myelin is wrapped around Schwann cells.
There are two functions of myelin:1.)insulation for the axon 2.)to speed nerve conduction
Myelinated axons appear to be whiter, therefore are called white matter. They are mostly found in the peripheral nervous system.
Unmyelinated axons appear to be gray, therefore are call gray matter. They are mostly found in the central nervous system.
All-or-None Law This is the concept of how neuron impulse conduction. If a neuron responds, then it responds completely. Thus, a nerve impulse is conducted whenever a stimulus of threshold intensity or above is applied to an axon and all impulses carried on that axon are the same strength. A greater stimulation causes the rate of the neuron impulses to increase not the intensity of the impulse. The rate of the impulses can only be so high, though, due to the refractory period of the neuron. Each neuron must have a brief refractory period which is where the threshold stimulus will not trigger another impulse on an axon.
Nervous System The central nervous system (CNS) includes the brain and the spinal cord. The peripheral nervous system is everything else. The autonomic nervous system is a part of the peripheral nervous system, and it is the part that regulates functions that run without our conscious control, such as breathing, heart rate, and digestion.
Organization of the Brain The brain is made up of neurons. One organizing principle of the brain is redundancy (different parts of the brain contribute to solving the same problems) Another organizing principle is bilateral symmetry (divides the brain into a right and a left half). Animals that do not show this left-right symmetry are rare. The brain and body are connected contralaterally (the left side of the brain controls the right side of the body and vice-versa). The last organizing principle is evolutionary organization. The areas nearest to the spinal cord end are the oldest, and the areas furthest from the spinal-cord end are the newest. The oldest areas are the most important for survival.
Hemispheric Specialization The brain is divided into a left and a right half, and those halves are connected by a fibrous band of tissue called the corpus callosum. The corpus callosum serves as a bridge for information from one half of the brain to the other. Although the two halves are physically similar, they function differently. Bilateral symmetry is the symmetry everybody is aware of, and to many people this is symmetry itself. Bilateral symmetry occurs when two halves of a whole are each other's mirror images. It is also called mirror symmetry .
The left hemisphere: Is in charge of language functions and logical thought. Speech, song, and writing are all examples of left hemisphere functions; however, functions such as speech and song are controlled by different areas in the left hemisphere. The right hemisphere: Is responsible for such things as the perception of rhythm, spatial-relation skills, and abstract or intuitive thought. The right hemisphere is less controlled by logic. *There are some people who show the opposite pattern of hemispheric specialization. Those people have language functions in the right hemisphere, and rhythm, spatial relation skills, and abstract/intuitive thought in left hemisphere. Hemispheric Specialization Cont.
Hind Brain The medulla is the first part of the hind brain from the spinal cord. The medulla contains the centers that regulate breathing and heart rate. That is why damage to the medulla is usually fatal. The pons are the next brain area up from the spinal cord. The pons are centers that control wakefulness and alertness. The reticular formation contains information. It is a small tube that is inside the larger tube of the brain stem. Within are many axons, which communicate with the body. The cerebellum is the first big bump on the brain. Its main job is the control of gross motor function.
Hind Brain Pic
Pons: Controls paradoxical sleep
Medulla: Controls vital functions
(breathing, heart rate, and respiration)
Spinal Cord: Mediates spinal reflexes,
receives sensory information (afferent),
transmits motor information (efferent)
Colliculi The inferior colliculus is responsible for reflexive responses to auditory stimuli. It controls your response to loud noises; although sometimes you can control your response. The superior colliculus controls visual reflexive stimuli. It is responsible for making you look at bright lights and other things. Together, the inferior and superior colliculus make up the colliculi.
Cerebrum Also called the cortex, or neocortex. The newest and largest part of the brain. A great deal of the surface has no function that can be determined. Those surface areas are called associative areas, and are probably responsible for a great deal of our cognitive capacity. The cortex is divided up into five lobes. The four lobes on the surface are the frontal, parietal, occipital, and temporal. The fifth lobe is underneath the surface lobes, and is called the limbic lobe or limbic system.
Cerebrum Cont. The frontal lobe : The frontmost portion, this area controls motor functions or movements. Also, it controls higher order functions, planning, thinking, and worrying. The body parts being controlled are mapped onto this portion of the cortex. Some parts, such as the hands and lips, receive more brain tissue than other parts, such as the torso. The parietal lobe: This area monitors sensory information and body awareness. The body parts here are also mapped onto the sensory areas of this parietal lobe, but that map is not exactly like the one mentioned above.
Cerebrum Cont. The temporal lobe: Receives sensory input from the ears. Sounds are analyzed and interpreted as language. The occipital lobe: Receives sensory input from the eyes. It analyzes and interprets visual stimuli. The analysis and interpretation of vision is extremely complex and accounts for the largest percentage of the brain's activity. The limbic lobe: Also called the limbic system. This is the ancient cortex, sometimes called the paleocortex. The neocortex has taken over most of the limbic system's original functions. Now, the limbic system primarily controls emotional behaviors and memories.
Brains and Evolution Brain power evolves because there is a need for it. Some environments require all of it for us to survive and reproduce. Evolutionary changes are constrained by physical and temporal factors. Going up the evolutionary chain, we see more bumps or convolutions (folds) on the brains of the “higher” evolved animals. Animal brains are laid out horizontally, but the human brain is laid out at nearly a right angle. When humans evolved into creatures that walked upright, our heads rotated forward and the brain had to follow. Making the head bigger might have been a solution, but the size of the human female's birth canal put a constraint on that. The brain got bigger, the head stayed about the same size, and the brain folded up to fit inside the size of the head.
Endocrine System This is an integrating system (a system that helps to organize behavior and physiology). This system uses ductless glands that are specialized tissues that secrete hormones directly into the bloodstream. Hormones are fairly simple chemicals that are absorbed by other tissues, known as target sites, and then used by those tissues. Endocrine action includes physical growth and the menstrual cycle. In humans, physical growth is mediated by a somatotrophic hormone (growth hormone) and it ceases to work during adulthood. During adolescence, growth hormone and the sexual hormones combine to produce the adolescent synergistic growth spurt. A synergism is when two or more elements combine to produce a greater effect. Synergistic effects also happen when certain drugs are taken.