Biological Influences Flashcards
Spinal Chord
- cable of nerve fibres that stretches from base of brain to the lower back
- transmits messages between brain and PNS
- Receives sensory information brought by PNS
- sends out appropriate responses decided by brain to specific body part in PNS
Afferent track
sensory neutrons delivering information (towards)
Efferent track
delivering instructions from brain (away)
Somatic Nervous System
system of nerves communicating information from the sensory organs to the CNS and motor messages from the CNS to voluntary muscles (conscious control)
- Controls voluntary muscle movement and skeletal nervous system
- Connects CNS to organs, muscles and skin
- carries sensory messages to CNS and sends out motor messages from CNS
Autonomic Nervous System
system of nerves that carry neural messages between the CNS and the heart and other organs/glands
- Controls involuntary functions of our internal organs, muscles and glands
- “self governing” and operate independently (unconscious control)
- ie breathing/heart rate
- Parasympathetic and Sympathetic
Sympathetic
Fight or Flight
- dominates when we are highly aroused and need sudden bursts of energy
- increases the arousal of muscles, organs and glands to prepare body for vigorous activity
- prepare for body to deal with potential threat/danger ie autonomic response to fight or flee
- ie heart rate increases and bladder function decreases
Parasympathetic
Rest and Digest
- Automatically calms body when threat is no longer present
- Responsible for reversing the effects of the SNS and returning boys internal systems to natural level of functioning
- Maintains homeostasis; function of body when no threat is present
- heart rate decreases and bladder function increases
Neurons
neurons receives, process and or transmit information to other neurons in the form of neural impulses
Sensory Neurons
afferent/receptor (found in PNS)
specialised cells that receive information from both the external environment and from within the body and transmit this information to the CNS
Motor Neurons
efferent/effector (found in PNS)
- transmit messages from the CNS to the muscles, glands and organs for a response to be initiated
found primarily in PNS
- causes muscles to relax/contract or glands to increase/decrease their function
Interneurons
located in CNS and form a direct connection between motor and sensory neurons
formed reflex arc; inter neurons in spinal chord have relayed information From sensory neurones to motor, bypassing the involvement of the brain
Synapses
specialised junction where an axon terminal contacts another neutron or cell type, 2 types are chemical and electrical
Chemical synapse
- use neurotransmitters (chemical mediator) for transmission of impulse
- transmission is one way
- seen at most of the synaptic junctions in the body
Electrical synapse
- impulse is transmitted through gap junctions or low resistance bridges
- transmission is two way
- found only in special areas like retina, olfactory bulb, cerebral cortes and hippocampus etc.
Axon Terminal and Neurotransmitters
Axon terminals contain mitochondria for energy to cell functions and vesicles (membrane bound sacs) that contain neurotransmitters
Nerve Impulse
a signal transmitted along a nerve fibre. It consists of a wave of electrical depolarisation that reverses the potential difference across the nerve cell membranes.
Electrochemical Charge
Reduction-Oxidation
It refers to electrochemical processes involving electron transfer to or from a molecule or ion changing its oxidation state.
Via external voltage or release of chemical energy.
Membrane Potential
The potential inside a cell membrane measured relative to the fluid just outside; it is negative under resting conditions and becomes positive during an action potential.
CNS Structure and Function
Structure: brain and spinal chord –> 12 pairs of cranial nerves and 31 pairs of spinal
Function: acts as the control centre receiving messages from all parts of the body, interpreting these messages and sends the information back to body parts to instruct what to do
PNS Structure and Function
Structure: sensory receptors and nerves outside of CNS
Function: informs the CNS of changing conditions, connects the CNS to rest of body specifically the limbs, skin, muscles and organs, serving as a communication pathway that goes back and forth between brain and extremities
Consists of Somatic and Autonomic
Forebrain Structure and Function
S: The uppermost part of brain, consists of the cerebrum (cerebral cortex), limbic system, thalamus and corpus callosum.
F:sensory integration, voluntary movement and intellectual functions
Cerebrum
dominates the forebrain and is responsible for complex thoughts and control voluntary functions
Divided into 4 lobes; temporal, occipital, frontal and parietal
Thalamus
relays motor and sensory information, memory, alertness consciousness and cognition
Hind Brain Structure and Function
S: formed by the pons, medulla oblongata, and the cerebellum (lowest part of brain)
F:govern our autonomic body systems, controlling heart, breathing, and sleep patterns to our bladder function, sense of equilibrium, and fine motor control.
Cerebellum
- controls motor movement and coordination
- Nerve connections that go topmost of the sense organs and to motor cortex
- Integrates input from sensory systems of other parts of brain
Pons
- regulates breathing, tase and autonomic functions
- bridges the brain with the cerebellum
- Facial expressions and facial movements, ability to bite chew and swallow
Medulla
- controls vital functions you don’t think about
- Cardiac rate/patterns, breathing rhythms, dilation and contraction of blood vessels
Resting Membrane Potential
- is the voltage (charge) difference across the cell membrane when the cell is at rest
- is negative relative to the outside -0.70mv (more K inside/Na outside)
- K+ ions can cross the membrane more easily, but Na+ have a difficult time crossing
Na/K Gates
Gates normally are closed but with stimulus open —> opening/closing allows for depolarisation and re-polarisation.
Na atoms larger than K
ie when membrane depolarises Na channels opens and Na+ enter cells
Action Potential
- occurs when a neuron sends info down an axon away from the cell body as a “impulse” for the A.P
- due to the exchange of ions across neurons membrane
- (stimulus) causes the resting potential to move towards 0mv (depolarised) when hits - 55mv fires an A.P (threshold)
Threshold
depolarisation reaches -55mv the neuron fires an action potential known as the “threshold”
“all or nothing event” –> if does not reach will not fire A.P
Depolarised
the process of reversing the charge across a cell membrane, causing an action potential
inside of membrane becomes more positively charged and outside becomes more negatively charged (Na+ rapidly entering cell)
Hyperpolarisation
change in a cell’s membrane potential that makes it more negative
Opposite of depolarisation –>inhibits A.P by increasing stimulus required to move membrane potential to threshold
Refractory Period
a period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation. (another stimulus would not cause 2nd A.P)
Action Impulses in myelinated vs unmyelinated neurons
- nerve impulse is faster in transmission, due to the myelin sheath acting as an electrical insulator (quicken transmission
- can jump node’s of ranvier to another over the myelin sheath
Saltatory Conduction
Involves an impulse jumping from node to node along a myelinated axon
Neurotransmitters
- Carry chemical messages across the synapse to dendrites of a receiving neuron, allows for neural energy to travel from sensory receipts to the brain.
- Can assist (excite) or block (inhibit) transmission
Excitatory
Acetylcholine
Dopamine
Noradrenalin
Acetylcholine Function and Effects
- excitatory
- found in motor neuron and produces muscle contractions, memory, learning and intellectual function
Excess: violent muscle contractions
Deficit: paralysis + Alzheimers (loss memory)
Dopamine Function and Effects
- excitatory
- voluntary muscle controlled, attention, emotional arousal and rewarding sensations
Excess: Schizophrenia like symptoms (hallucinations) and addiction
Deficit: Muscle rigidity and Parkinson’s disease (degeneration of neurons containing dopamine)
Noradrenalin Function and Effects
- excitatory and inhibitory
- increasing heartbeat, arousal, eating and learning
Excess: anxiety
Deficit: Depression
Inhibitory
Serotonin
GABA
Noradrenalin
Endorphins
Serotonin Function and Effects
- mood, sexual behaviour, sleep, pain perception, maintaining normal temperature + hormonal states
Excess: Autism
Deficit: Anxiety, insomnia, obsessive compulsive disorder and depression
GABA Function and Effects
- communicates msg to other neurons, balance excitatory messages, allergies
Excess: sleep and eating disorders
Deficit:Hungtinton disease –> tremors, loss of motor control and personality changes
Endorphins Function and Effects
- regulates pain perceptions, sexuality, brains natural opiate (positive emotions), pregnancy
Excess: body wont give adequate warning on pain
Deficit: body experiences pain
Frontal Lobe
higher mental processes, attention, controlling behaviour/ emotions, coordinates sensory info and other lobes to make behavioural responses
Damage: personality/emotional changes ie Phineas Gage
Association Areas: Broca’s and Primary Motor Cortex
Brocas Area
Specific cortical area located in the left frontal lobe next to the motor cortex (control the muscles of the face/tongue)
production of articulate speech (speech that is clear and fluent) + muscle movement required and supplying this info to cortex area
Brocas Aphasia
unable to put grammatically correct sentences together ie “boy went beach” (connecting words)
Affects speaking and writing, but not comprehension
Primary Motor Cortex
receives, processes and sends information about voluntary bodily movements
directs skeletal muscles, generates neural impulses that pass down spinal chord to plan and control movement
- left controls right side and vice versa
- amount corresponds to the importance of bodily areas not their size.
- represented on the cortex in opposite position, ie mouth and ears on bottom.
Parietal
concerned with reception and processing of sensory info from the body
bodily somatic sensations such as touch, temperature and pressure
spatial awareness
Damage: lose sensation in body areas, clumsy movements, suffer from spatial neglect
Somatosensory Cortex
Somatosensory Cortex
- receives and processes information from our senses
- Sensations detected in sensory receptors of body/skin are registered and processed
- left side of body goes to cortex in right
- sensitivity of bodily areas rather than size (Homunculus) ie lips are large and back is small
- represented in opposite order to their position on body, ie face sensations are registered at bottom.
Temporal Lobes
- concerned with memory, emotion, hearing and language
- Auditory information received by ears is transmitted to lobe “hearing registers”
- memory/ facial recognition
Damage: unable to recognises faces/objects/past skills and inappropriate emotional responses
Auditory cortex and Wernicke’s area
Auditory cortex
registers and processes auditory information
right temporal lobe = processes non verbal sounds
left temporal lobe = processes verbal sounds associated with language
Auditory processed by cortex in left temporal cannot be properly understood until goes through Wernicke’s
Wernicke’s Area
specific area in the temporal lobe of the LH only, next to the primary auditory cortex and connected to Broca’s area
comprehension of speech; interpreting sounds of speech and formulating meaningful sentences
responsible for accessing words in stored memory to express meaning
Wernicke’s Aphasia
- severely limit the ability to use language
- unable to locate that word from their memory, thus the sentences/words they hear is meaningless.
- unable to produce coherent (understandable) speech
Occipital Lobes
registers and processes visual information transmitted from retina of both eyes, providing quick responses to visual environment
Damage: visual impairment ie tumours may cause blind spots
Primary Visual Cortex
Primary Visual Cortex
receiving and processing visual input from the eyes (visual perception/colour recognition is interpreted)
specialised neurons select/integrate info from cortex and sends visual info to other parts of brain to process input into meaningful form
Information from right visual field processed in left cortex
Association Cortex
Areas which integrate sensory, motor and other information and are involved in more complex mental abilities
Combine and process sensory information and link it with pre existing ideas/memories (crucial to conscious recognition)
Found in all areas of brain (mainly partial/frontal)
ie visual cortex see rose (register shape/colour/) and association cortex link to knowledge ie thorns
