Biopsychology Flashcards
(27 cards)
what is the nervous system?
-a specialised network of cells in the human body that is based on electrical and chemical signals and is our primary internal communication system
-divided into the CNS and PNS
what are the main functions of the NS?
-to collect, process and respond to information in the environment
-to co-ordinate the working of different organs and cells in the body
what is the central nervous system?
-consists of the brain and the spinal cord and is the origin of all complex commands and decisions
what is the brain?
-the centre of all conscious awareness
-its outer layer ( the cerebral cortex ) is only 3 mm thick and covers the brain
-the brain is only found in mammals, but is highly developed in humans and is what distinguishes our higher mental functions from those of animals
-divided into two hemispheres
what is the spinal cord?
-an extension of the brain that passes messages to and from the brain and connects neurons ( nerve cells ) to the PNS
-it is responsible for reflex actions such as pulling your hand away from a hot plate
what is the peripheral nervous system?
-relays messages from the environment to the CNS via sensory neurons, and from the CNS to effectors ( muscles and glands ) via motor neurons
-subdivided into the ANS and SNS
what is the somatic nervous system?
-transmits information from sensory receptors belonging to each of the 5 senses to the CNS, and receives information from the CNS that directs effectors to produce a response ( e.g. muscle movement ) via motor neurons
what is the autonomic nervous system?
-transmits information to and from internal bodily organs, and controls involuntary, vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
-subdivided into the sympathetic and parasympathetic branches which work as part of an antagonistic pair during the rest and digest response, and are crucial in producing the physiological arousal needed to maintain the fight ot flight response
what is the sympathetic NS?
-a network of nerves that helps the body activate its fight or flight response
-it increases breathing and heart rate, dilates pupils, inhibits digestion and saliva production, and contracts rectum
what is the parasympathetic NS?
-a network of nerves that helps the body relax and return to its resting state for its rest and digest response
-it decreases breathing and heart rate, constricts pupils, stimulates digestion and saliva production, and relaxes rectum
what is the endocrine system?
-the body’s main chemical messenger system where hormones are secreted into the bloodstream from glands, and then are transported towards target organs and cells in the body with complementary receptors
-acts more slowly than the NS ( seconds instead of milliseconds ) but has widespread and powerful effects
what are the main endocrine glands?
-hypothalamus = co-ordinates the ES and produces hormones that control body temperature, heart rate, hunger etc.
-pituitary = ‘master’ gland because it controls the release of hormones from all the other glands in the body
-thyroid = releases thyroxine which affects cells in the heart ( increases heart rate ) and the body, increasing metabolic rates and in turn affecting growth rates
-adrenal = releases adrenaline which creates the physiological arousal necessary for the fight or flight response by increasing the activity within the sympathetic branch of the ANS
-pancreas = releases insulin and glucagon which affect cells in the liver to help maintain blood sugar levels
-ovaries ( female ) = releases estrogen and progesterone
-testes ( male ) = releases testosterone
how does the ES and ANS work together in the fight or flight response?
-the body senses and becomes aware of a stressor in the environment e.g. the sound of a speeding car
-through sensory receptors and sensory neurons in the PNS, this information is sent to the hypothalamus in the brain which coordinates a response and triggers activity in the sympathetic branch of the ANS
-adrenaline is released from the adrenal medulla and is transported to target effectors via the blood and through the action of the ES
-this results in the rectum contracting, saliva production and digestion being inhibited and a greater breathing and heart rate, which creates the physiological arousal needed to sustain the fight or flight response, enabling us to escape the stressor and increase the likelihood of our survival
-once the stressor is no longer a threat, the hypothalamus triggers less activity in the sympathetic branch and more activity in the parasympathetic branch of the ANS, which is sometimes referred to as the rest and digest response as it reduces the activities of the body that were increased by the sympathetic branch, returning the body to its resting state
what are neurons?
-the basic building blocks of the nervous system which provide it with its primary means of communication
-specialised nerve cells that process and transmit messages through electrical and chemical signals
-there are 100 billion neurons in the human NS, 80% of which are located in the brain
-three types = sensory, relay and motor neurons
what are sensory neurons?
-neurons that carry messages from the PNS to the CNS
-long dendrites and short axons
-located in the PNS in clusters known as ganglia
what are relay neurons?
-neurons that connect sensory neurons to motor neurons or other relay neurons
-short dendrites and short axons that aren’t surrounded by myelin sheaths
-97% of all neurons are relay neurons, and most are in the brain and visual system
what are motor neurons?
-neurons that connect the CNS to effectors in the PNS such as muscles and glands
-short dendrites and long axons
-cell bodies may be in the CNS but long axons form part of the PNS
what is the structure of a neuron?
-cell body ( or soma ) = includes a nucleus which contains the genetic material of the cell and controls the cell’s activites
-dendrites = branchlike structures that protrude from the cell body and carry nerve impulses from neighbouring neurons towards the cell body
-axon = carries the electrical impulse away from the cell body down the length of the neuron
-myelin sheath = protects and insulates the axon, and speeds up electrical transmission
-nodes of Ranvier = gaps in the axon that speed up the transmission of the impulse by forcing it to jump along the axon
-terminal buttons = connect the neuron to other neurons ( or directly to effectors ) using a process known as synaptic transmission
when is the inside of a neuron negatively charged?
-when it is in a resting state
when is the inside of a neuron positively charged?
-when it is activated by a stimulus, the inside becomes positively charged for a split second causing an action potential to occur, which creates an electrical impulse that travels down the axon towards the end of the neuron
what is synaptic transmission?
-the process by which neighbouring neurons communicate with each other by sending chemical messages across the gap ( the synapse ) that separates them
what are neurotransmitters?
-chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another
-can be broadly divided into those that have an excitatory effect and those that have an inhibitory effect on the neighbouring neuron
what happens at a synapse?
-when the electrical impulse reaches the presynaptic terminal ( the end of the neuron ) it triggers the release of neurotransmitters from tiny sacs called synaptic vesicles
-neurotransmitters diffuse across the synapse and combine with postsynaptic receptor sites on the dendrites of the next neuron where the chemical message is converted back into an electrical impulse
why can neurons only transmit information in one direction at a synapse?
-it is the binding of the neurotransmitter to the receptor which enables the information to be transmitted to the next neuron
-the synaptic vesicles containing neurotransmitters are only released from the presynaptic membrane, and the receptors for neurotransmitters are only present on the postsynaptic membrane
-the diffusion of neurotransmitters means they can only go from high to low concentration, so can only travel from the presynaptic to the postsynaptic membrane
