EXAM 2: CHAPTER 3 Flashcards
4 biological basis of behaviour
- Neurons
- Central/peripheral system
- The brain
- Epigenetics
Neuron
Single cell within the nervous system. A group of neurons form a nerve. They are filled with cytoplasm containing nucleus residence of chromosomes that contain genetic material, as well as organelles
Afferent neurons
Carries sensory information from the body to the CNS
Efferent neurons
Carries information out from the CNS to the muscles and glands
Interneurons
Neurons that have a short axon and serve as a relay between different classes of neurons. They communicate with both sensory and motor neurons
Glial cells
The other cells that make up the nervous system. It provides support and protection to neurons and maintains homeostasis, as well as cleans debris
4 main functions of glial cells (5)
- Create barrier between CNS and circulatory system to avoid virus and bacteria
- Control nutrient (glucose) supply to neurons
- Destroy and remove diseased and dead neurons
- Provide axons with myelin sheath
- Establish, maintain, rebuild synapses
3 main parts of a neurone
Dendrites, an axon, and a cell body (soma)
Dendrites
Receives information from other neurons
Axon
Transmits information to other neurons, muscles, and glands
Cell body
Nucleus with chromosomes
Myelin sheath
Helps efficient transmission of signals to other cells. Fatty white substance formed from glial cells that insulate the axons of many neurons
Nodes of Ranvier
Gaps in the myelin sheath that allow ions to diffuse in and out of neuron
Gray matter
Where synapses occur, and where interneurons are located
White matter
Myelinated nerve tracts (bundle of axons)
Resting potential
When a neuron is at rest, and not conducting an impulse
Voltage across membrane of axon at resting
-65v
Action potential
When a neuron fires, pores in the neuron (ion channels) open to let charged ions flow in and out of neuron (sodium-potassium pump) and the shift in electrical charge triggers axon terminals to release neurotransmitters
Refractory period
The time following an action potential. K+ ions are returned to inside of axon and Na to the outside back to original
Neurotransmitters
Chemical substances released by a transmitting neuron at the synapse that alters activity of a receiving neuron
Examples of major neurotransmitters
Acetylcholine, dopamine, serotonin, norpinephrine, endorphins
Acetylcholine
Enables muscle action, learning and memory. Important for stimulating muscles and communication between motor and sensory neurons (arousal, attention, memory)
Dopamine
Influences movement, learning, attention and emotion, produced by neurone in hindbrain
Serotonin
Affects mood, hunger, sleep arousal
Norepinephrine
Helps control alertness and arousal
Terminal buttons
Small knobs at the end of the axon that secretes neurotransmitters and plays a role in communication between neurons
Synapse
Junction between the axon tip of the sending neuron and the dendrite or cell body of receiving neuron
Reuptake
When neurotransmitter molecules have been released at a synapse are reabsorbed by the presynaptic neuron that released them
Neural networks
Complex webs of interconnected neurons that form with experience. Series of algorithms that endeavors to recognize underlying relationships in a set of data through process that mimics the way human brain operates
Significance of the nervous system
Without it, we would not have the 5 senses. We would not be able to move our muscles, talk, breathe, and cells would lack oxygen and nutrients required to live
Central nervous system (3)
- Brain and spinal cord
- Spinal cord is the primary means for transmitting messages between brain and body
- It interprets incoming information from the PNS and sends out messages to muscles, glands, and organs
Spinal cord
Portion of central nervous system that extends down from base of brain and mediates sensory and motor information
Spinal nerves
Part of the peripheral nervous system. Consists of 31 pairs made up of sensory/motor fibres attached to spinal cord and pertain to a specific body area
Significance of interneurons in spine
Triggers reflexes
Peripheral nervous system
Rest of the nervous system made up of long axons and dendrites. It handles input and output from the CNS about what is going on inside and outside of body
2 divisions of the PNS
- Somatic division: Voluntary nerves that go to skin and muscles
- Autonomic division: Involuntary nerves that connect the CNS to organs such as heart, stomach, and intestines
2 components of the autonomic nervous system
- Sympathetic nervous system: Significant for emergency situations because it triggers your fight or flight
- Parasympathetic nervous system: Promotes all internal responses associated with a relaxed state
Weight of a brain
3lbs
4 lobes of cerebrum:
- Frontal
- Parietal
- Temporal
- Occipital
Occipital lobe
Lobe of the cortex at back of skull important for visual information (Color, patterns, etc)
Parietal lobe
Lobe of cortex involved in processing information related to touch and complex visual information, particularly about locations and contains somatosensory strip
Temporal lobe
Part of cortex important in processing sound in speech, comprehension, and recognizing visual stimuli like face
Frontal lobe
Lobe of cortex located front of brain (behind forehead). Important for temporal planning, understanding social relationships and movement
Prefrontal lobe
Portion of frontal cortex involved in higher-order thinking, like memory, moral reasoning and planning
Left hemisphere of brain significance
Referred to as the logical side
Right hemisphere of the brain significance
Referred to as the intuitive side
Corpus callosum
Transmits impulses between the two cerebral hemispheres (right and left sides of the brain)
Motor cortex
Located at the back of frontal lobe next to the parietal lobe and generates signals to direct the movement of the body
Sensory cortex
Located at the end of the parietal lobe responsible for receiving and processing sensory information from across the body, such as touch and temperature
2 kinds of plasticity
General experiences and idiosyncratic experiences
Brain plasticity and significance
Refers to the capacity of the brain to be affected by experience. Without this ability, any brain would be unable to develop from infancy through to adulthood
Neurogenesis
Process by which new neurons are formed in the brain
Epigenetics
Environmental influences that determine whether genes are expressed, or the degree to which they are expressed, without altering the basic DNA sequences that constitute the genes themselves
Examples of epigenetics
Rat studies, what happens when children see abuse, eating patterns/effects
DNA methylation
- Biological process by which methyl groups are added to the DNA molecule
- Critical regulatory mechanism implicated in development, learning, memory, and disease
Histone modification
Adds chemical modification to proteins (histones) that package DNA. Can switch genes off and on. This modification influences gene expression but not DNA sequence
Research results from DNA methylation 1
Research found that 12 men who had suffered abuse had increased levels of DNA methylation at hippocampal receptor gene
Research results from DNA methylation 2
Men who had been sexually abused went on to hurt children. Whereas the others were less likely to display violent behavior than the average population