biological bases Flashcards
central nervous system
made of brain and spinal cord including neurons:
motor neurons: descending tract, send messages/impulse down to muscles
sensory neurons: ascending tract, send messages up to brain
interneurons: are within the spinal cord and connect/pass on messages to sensory/motor neurons and vice versa
spinal reflex
is an adaptive response means that brain avoids potential harm/injury/death, it is quick and occurs as the sensory message from PNS is still being sent to the brain for processing (reaches spinal cord and is sent back to site of injury/issue
peripheral nervous system
Made up of nerves that branch out from spinal cord to muscles and organs and branch out from sensory receptors to spinal cord
Structure of PNS
PNS -> somatic nervous system (controls voluntary actions) and autonomic nervous system (automatically controls actions of internal organs, smooth muscle/glands) -> sympathetic nervous system (activates fight/flight/freeze response during threat) and parasympathetic nervous system (restores body to state of calm)
frontal lobe
performs executive functions, control of socially unacceptable responses, control of movement, problem solving, symbolic thinking, risk analysis, contains primary motor cortex which controls contralateral organisation
parietal lobe
bodily sensations, pain, temp, touch, spatial awareness (proprioception), contains the primary somatosensory cortex
occipital lobe
vision,contains primary visual cortex which is responsible for visual perception, colour recognition, visuospatial processing, distance, depth perception
temporal lobe
responsible for hearing, auditory processing, language recognition, memory, long term memory associated with emotion visual memory, facial recognition, auditory memory
Broca’s area
Responsible for speech production, in left frontal lobe
structure and function of neuron
dendrite detect and recieve information from presynaptic neuron, has receptors so messages can be received from different chemical messengers
soma: collects and integrates information from thousands of of other neurons then transmits along axon
axon: single, tube like extension that transmit neural info to other neurons, nerves are cable like bundles of multiple axons
myelin: fatty white substance that surrounds and insulates axon, allows for rapid movement of message along axon
nodes of ranvier: separates segments of myelin causing messages to jump from node and speed up transmission
axon terminals: small knob like swelling at end of each branch, stores and secretes neurotransmitters manufactured by neuron and carries chemical messages to other neurons
sensory neurons
recieve and carry sensory information from both internal and external environments
Motor neurons
Carries message from CNS to cells in skeletal muscles, organs, glands to stimulate activity
interneuron
Sends message between sensory and motor neurons within CNS relaying information from one to the other
action potential
- occurs when a neurons sends info down an axon away from cell body, electrical signal that passes through neuron depends on infra and extra cellular fluids being electrically different meaning there is more sodium ions on the outside of the neuron compared to potassium ions on the inside of the neuron which gives it an overall negative charge. - the membrane is semipermeable
- Resting potential: when a neuron is not sending a signal as it is at rest, inside of neuron is negatively charged (-70mV)
- A stimulus causes depolarising current and resting potential moves towards 0mV,when depolarisation reaches -55 mV a neuron will fire an action potential (if it doesn’t reach -55 then its a failed initiative: all or nothing phenomena), continues to depolarise (sodium ions rush in) until it reaches peace action potential (+40 mV),
- repolarisation potassium channels open to let out potassium ions (AP starts to go down
- hyperpolarisationm AP goes lower than -70mV but then gradually returns to resting potential (-70mV)
role of synapse
synaptic transmission relies on chemical imbalances in cells and electrical transmission of impulses through neuron
neurotransmitter
chemical substance produced by a neuron that carries a message to other neurons or cells
transport of neurotransmitters
works by binding to receptor on site of post synaptic neurons that are specialised to recieve specific neurotransmitters,
- neurotransmitters that do not bind to receptors in postsynaptic neurons go through reuptake: where they are reabsorbed into terminal buttons of presynaptic neuron
- lock and key processm each type of neurotransmitters has a chemically distinct shape and searches for correctly shaped receptor site on dendrites of post synaptic neuron, binding unlocks post synaptic neurons response to neutron transmitter, causes change to neuron, resulting in inhibiting or excitatory effect
excitatory neurotransmitter
stimulate or activate postsynaptic neurons to perform their functions (encourage action potential to be fired down to next neuron)
inhibitory
block or prevent postsynaptic neurons from firing
serotonin
inhibitory neurotransmitter
- regulates mood, anxiety, sleepy cycle, body temp,
- adequate amounts of serotonin are necessary for stable mood and to balance any excessive excitatory neurotransmitters firing in the brain
- deficit of serotonin has been linked to depression
- drug SSRI (selective serotonin reuptake inhibitor) increase availability of serotonin in some brain regions
Dopamine
can be either excitatory or inhibitory depending on receptors present
- creates feelings of motivation/drive
- involved in liking, attention, pleasurable sensations, learning, movement
- degeneration of neurons that produce dopamine in one area of the brain cause Parkinson’s disease
Endorphins
regulates feelings and perceptions of pain, body’s natural pain killing drugs and manufactured and released when body is stressed or when you experience a positive mood e.g runners high
Hormones
Chemical messengers produced by endocrine glands, travel through blood stream and affect other parts of the body, slower than neurotransmitter
Hormones vs neurotransmitter
Origin: glands of endocrine system / neurons of NS
Transport medium: blood / neurons
Target: organs/glands / local receptors on nerve cells
Action: slow (few days) / fast (almost instant)
Duration of effect: short and long lived / short
Response: involuntary / voluntary & involuntary
Adrenaline
Makes individual more fearful/agitated heightened in exercise, can enhance physical strength
Noradrenaline
Vigilance function keep us alert increase arousal, affects attention and focus promotes stress avoiding behaviour, both work in conjunction with sympathetic nervous system
Sympathetic nervous system
controls muscle contraction, increase breathing rate, heart rate, pupil dialation, even after emergency has passed feeling may continue as a result of hormones still in bloodstream
Role of genetics
Plays large role in areas of physical growth, intelligence and development
Mitosis
When when cells die need repair or when cells split part, only one division occurs which results in w genetically identical daughter cells with 46 chromosomes each (diploid)
Meiosis
for sexual reproduction of sperm/ova , occurs in gonads, one mother cell divides twice ms crossing over occurs after first division and results in 4 genetically different daughter cells that have 23 chromosomes each (haploid)
