Unit 2 - Chapters 3 and 5 Biological Processes Flashcards
Nervous System
The nervous system consists of the central nervous system (CNS), made up of the brain and the spinal cord, and the peripheral nervous system (PNS), the neurons that link the CNS to our skin, muscles, and glands. We will see that our behaviour is also influenced in large part by the endocrine system, the chemical regulator of the body that consists of glands that secrete hormones.
Neurons
The nervous system is composed of more than 100 billion cells known as neurons. A neuron is a cell in the nervous system whose function it is to receive and transmit information. Neurons are made up of three major parts: a cell body, or soma, which contains the nucleus of the cell and keeps the cell alive; a branching treelike fibre known as the dendrite, which collects information from other cells and sends the information to the soma; and a long, segmented fibre known as the axon, which transmits information away from the cell body toward other neurons or to the muscles and glands.
Neurotransmitter
A neurotransmitter is a chemical that relays signals across the synapses between neurons.
Drugs act like neurotransmitters
- An agonist is a drug that has chemical properties similar to a particular neurotransmitter, which allows it to mimic the effects of the neurotransmitter
- An antagonist is a drug that reduces or stops the normal effects of a neurotransmitter.
Hormones
As well as neurotransmitters, the body has another chemical messenger at its disposal: hormones. Glands in the endocrine system, such as the pancreas, thyroid, and ovaries, are responsible for the production of hormones, such as insulin, melatonin, and testosterone, which are secreted into the bloodstream.
Our brains
- The brain is divided into hindbrain, midbrain, and forebrain structures that must work together.
- The cerebral cortex, made up of billions of neurons and glial cells, is divided into the right and left hemispheres, and these are further divided into four lobes.
- The frontal lobe is primarily responsible for thinking, planning, memory, and judgment. The parietal lobe is primarily responsible for bodily sensations and touch. The temporal lobe is primarily responsible for hearing and language. The occipital lobe is primarily responsible for vision. Other areas of the cortex act as association areas, responsible for integrating information.
- The brain changes as a function of experience and potential damage in a process known as plasticity. The brain can generate new neurons through neurogenesis.
- The motor cortex controls voluntary movements. Body parts requiring the most control and dexterity take up the most space in the motor cortex.
- The sensory cortex receives and processes bodily sensations. Body parts that are the most sensitive occupy the greatest amount of space in the sensory cortex.
- The left cerebral hemisphere is primarily responsible for language and speech in most people, whereas the right hemisphere specializes in spatial and perceptual skills, visualization, and the recognition of patterns, faces, and melodies.
- The severing of the corpus callosum, which connects the two hemispheres, creates a “split-brain patient,” with the effect of creating two separate minds operating in one person.
- Studies with split-brain patients as research participants have been used to study brain lateralization.
- Neuroplasticity allows the brain to adapt and change as a function of experience or damage.
Nervous system
- The body uses both electrical and chemical systems to create homeostasis.
- The central nervous system is made up of bundles of nerves that carry messages to and from the peripheral nervous system.
- The peripheral nervous system is composed of the autonomic nervous system and the somatic nervous system. The autonomic nervous system is further divided into the sympathetic, which is activating, and parasympathetic, which is calming, nervous systems. These divisions are activated by glands and organs in the endocrine system.
- Specific nerves, including sensory neurons, motor neurons, and interneurons, each have specific functions.
- The spinal cord may bypass the brain by responding rapidly using reflexes.
- The pituitary gland is a master gland, affecting many other glands.
- Hormones produced by the pituitary and adrenal glands regulate growth, stress, sexual functions, and chemical balance in the body.
- The adrenal glands produce epinephrine and norepinephrine, the hormones responsible for our reactions to stress.
- The sex hormones — testosterone, estrogen, and progesterone — play an important role in sex differences.
Evolution and Psychology
Adaptations are evolved solutions to problems that historically contributed to reproductive success.
Error management theory is a theory of selection under conditions of uncertainty in which recurrent cost asymmetries of judgment or inference favor the evolution of adaptive cognitive biases that function to minimize the more costly errors.
Evolution is change over time, but is the definition changing?
Gene selection theory is the modern theory of evolution by selection by which differential gene replication is the defining process of evolutionary change.
Intersexual selection is a process of sexual selection by which evolution — that is, change — occurs as a consequences of the mate preferences of one sex exerting selection pressure on members of the opposite sex.
Intrasexual competition is a process of sexual selection by which members of one sex compete with each other, and the victors gain preferential mating access to members of the opposite sex.
Natural selection is differential reproductive success as a consequence of differences in heritable attributes.
Psychological adaptations are mechanisms of the mind that evolved to solve specific problems of survival or reproduction, conceptualized as information processing devices.
Sexual selection is the evolution of characteristics because of the mating advantage they give organisms.
Sexual strategies theory is a comprehensive evolutionary theory of human mating that defines the menu of mating strategies humans pursue, the adaptive problems women and men face when pursuing these strategies, and the evolved solutions to these mating problems.
Genes and Environments: Nature and Nurture
Behavioural genetics is the empirical science of how genes and environments combine to generate behaviour.
Adoption study is a behaviour genetic research method that involves comparison of adopted children to their adoptive and biological parents.
Twin studies are a behaviour genetic research method that involves comparison of the similarity of identical twins, known as monozygotic twins, and fraternal twins, known as dizygotic twins.
Quantitative genetics is the scientific and mathematical method for inferring genetic and environmental processes based on the degree of genetic and environmental similarity among organisms.
Heritability coefficient is an easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals.
Sensation and Perception
Sensation is the process of receiving information from the environment through our sensory organs. Perception is the process of interpreting and organizing incoming information so we can understand it and react accordingly.
Transduction is the conversion of stimuli detected by receptor cells to electrical impulses that are transported to the brain.
Although our experiences of the world are rich and complex, humans have sensory strengths and sensory limitations, like all species do.
Sensation and perception work together in a fluid, continuous process.
Our judgments in detection tasks are influenced by both the absolute threshold of the signal as well as our current motivations and experiences. Signal detection analysis shows how both sensation and judgment are important in perception.
The difference threshold, or just noticeable difference, is the ability to detect the smallest change in a stimulus about 50% of the time. According to Weber’s law, the just noticeable difference increases in proportion to the total intensity of the stimulus.
Research has found that stimuli can influence behaviour even when they are presented below the absolute threshold (i.e., subliminally). The effectiveness of subliminal advertising, however, has not been shown to be of large magnitude.
Selective attention is our ability to focus on some sensations while ignoring others.
Sensory adaption occurs when repeated exposure to a stimulus results in lower perceived intensity.
Perceptual constancy occurs when our perception of a stimulus is unchanged, even when the activation of sensory receptors by that stimulus has changed.
Seeing
Vision is the process of detecting the electromagnetic energy that surrounds us. Only a small fraction of the electromagnetic spectrum is visible to humans.
The visual receptor cells on the retina detect shape, colour, motion, and depth.
Light enters the eye through the transparent cornea and passes through the pupil at the centre of the iris. The lens adjusts to focus the light on the retina, where it appears upside down and backward. Receptor cells on the retina are excited or inhibited by the light and send information to the visual cortex through the optic nerve.
The retina has two types of photoreceptor cells. Rods detect brightness and respond to black and white, whereas cones respond to red, green, and blue. Colour blindness occurs when people lack function in the red- or green-sensitive cones.
Feature detector neurons in the visual cortex help us recognize objects, and some neurons respond selectively to faces and other body parts.
The Young-Helmholtz trichromatic colour theory proposes that colour perception is the result of the signals sent by the three types of cones, whereas the opponent-process colour theory proposes that we perceive colour as three sets of opponent colours: red-green, yellow-blue, and white-black.
The ability to perceive depth occurs as the result of binocular and monocular depth cues.
Motion is perceived as a function of the size and brightness of objects. The beta effect and the phi phenomenon are examples of perceived motion.
Hearing
Sound waves vibrating through media such as air, water, or metal are the stimulus energy that is sensed by the ear.
The hearing system is designed to assess frequency, which is our perception of pitch, and amplitude, which is our perception of loudness.
Sound waves enter the pinna, which is the outer ear, and are sent to the eardrum via the auditory canal. The resulting vibrations are relayed by the three ossicles, causing the oval window covering the cochlea to vibrate. The vibrations are detected by the cilia, which are hair cells, and sent via the auditory nerve to the auditory cortex.
Conductive hearing loss is caused by physical damage to the ear or eardrum and may be improved by hearing aids or cochlear implants. Sensorineural hearing loss, caused by damage to the hair cells or auditory nerves in the inner ear, may be produced by prolonged exposure to sounds of more than 85 decibels.
Tasting, Smelling and Touching
The ability to taste, smell, and touch are important because they help us avoid harm from environmental toxins.
The many taste buds on our tongues and inside our mouths allow us to detect six basic taste sensations: sweet, salty, sour, bitter, piquancy, and umami.
In olfaction, transduction occurs as airborne chemicals that are inhaled through the nostrils are detected by receptors in the olfactory membrane. Different chemical molecules fit into different receptor cells, creating different smells.
The ability to smell diminishes with age, and, on average, women have a better sense of smell than men.
We have a range of different nerve endings embedded in the skin, combinations of which respond to the four basic sensations of pressure, hot, cold, and pain. However, only the sensation of pressure has its own specialized receptors.
Proprioception is our ability to sense the positions and movements of our body parts. Postural and movement information is detected by special neurons located in the skin, joints, bones, ears, and tendons, which pick up messages from the compression and the contraction of muscles throughout the body.
The vestibular system, composed of structures in the inner ear, monitors the head’s position and movement, maintaining the body’s balance.
Nociceptors are involved in the experience of pain. Gate control theory explains how large and small neurons work together to transmit and regulate the message of pain to the brain.
Accuracy and Inaccuracy in Perception
Sensory interaction occurs when different senses work together, for instance, when taste, smell, and touch together produce the flavour of food.
Selective attention allows us to focus on some sensory experiences while tuning out others.
Sensory adaptation occurs when we become less sensitive to some aspects of our environment, freeing us to focus on more important changes.
Perceptual constancy allows us to perceive an object as the same, despite changes in sensation.
Cognitive illusions are examples of how our expectations can influence our perceptions.
Our emotions, motivations, desires, and even our culture can influence our perceptions.
