Topic 8 Flashcards
1
Q
What is responsible for out senses?
A
- Nerve impulses
- Being passed from one neuron to another
- Emotions, memories and thoughts
2
Q
What is the nervous system made up of?
A
Please Stay Away Somewhere Pedo
**CNS**
- Brain
- Spinal Cord
**Peripheral Nervous System**
- Sensory Nerves - Sensory information from receptors to CNS
- Motor Nerves - Motor Commands from CNS to effectors
****Somatic Nervous System******
- Voluntary
- Simulates Skeletal Muscle
********Autonomic Nervous System**********
- Involuntary
- Stimulates
Sympathetic Nervous System
- Prepares body for fight or flight response
Parasympathetic Nervous System
- Prepares body for ‘rest and digest’
3
Q
What is the CNS made up of?
A
**CNS**
- Brain
- Spinal Cord
4
Q
What is the peripheral nervous system?
A
**Peripheral Nervous System**
- Sensory Nerves - Sensory information from receptors to CNS
- Motor Nerves - Motor Commands from CNS to effectors
5
Q
What is the somatic nervous system?
A
****Somatic Nervous System******
- Voluntary
- Simulates Skeletal Muscle
6
Q
What Autonomic Nervous System?
A
********Autonomic Nervous System**********
- Involuntary
- Stimulates
7
Q
What is the sympathetic and parasympathetic nervous system?
A
Sympathetic Nervous System
- Prepares body for fight or flight response
Parasympathetic Nervous System
- Prepares body for ‘rest and digest’
8
Q
What is the structure a neurone?
A
- A neurone is a single cell
- A nerve is amore complex structure
- Bundle of axons
- Surrounded by a protective covering
9
Q
What are the cell body extension?
A
- Very fine dendrites conduct impulses towards the cell body
- A single long process axon which transmits impulses from away the cell body
10
Q
What is the Structure of the Schwann cell
A
11
Q
What do motor neurones?
A
- AKA Effector Neurones
- Cell body in the CNS
- Axons extends out conducting impulses CNS to effectors
- Axons can be extremely long
12
Q
What do motor neurones?
A
- AKA Effector Neurones
- Cell body in the CNS
- Axons extends out conducting impulses CNS to effectors
- Axons can be extremely long
13
Q
What do sensory neurones do + Structure?
A
- Carry impulses from sensory cells to the CNS
14
Q
What do relay neurones do?
A
- AKA Connector neurones / interneurons
- Found mostly within the CNS
- Large number of connections with other nerve cells
15
Q
What is the reflex arc?
A
- Simple nerve pathways
- Responsible for rapid involuntary responses to stimuli
16
Q
What are the steps in reflex arc?
A
- Detects a stimulus to generate a nerve impulse
- Sensory neurones construct a nerve impulse to the CNS via the sensory pathway.
- Sensory neurones enter the spinal cord through the dorsal route
- Sensory neurone form a synapse with a relay neurone
- Relay neurone forms a synapse with motor neurones that leaves the spinal cord through the ventral route
- Motor neurone carries impulses to an effector which produces a response (contraction of a muscle)
17
Q
What is the pupil reflex?
A
- How the pupil dilates and contracts
- Depending on the light intensity of the surroundings
18
Q
How does the muscles of the iris respond to the light?
A
- In the iris there is a pair of antagonistic muscles
- Radical and circular muscles
- Controlled by autonomic nervous system
- Radical controlled by sympathetic muscles
- Circular controlled by parasympathetic reflex
- One dilates and the other constricts the pupil
19
Q
What are the steps in controlling pupil size?
A
- Detects high levels of light in the retina
- Sending nerve impulses to the optic nerve to sites in the CNS
- Impulses caused by photoreceptors sends impulses
- Along parasympathetic motor neurones to the circular muscles in iris (contracting them)
- Where he radial muscles also relax
- Constricting Pupil size reducing amount of light entering eye
20
Q
What is the relationship between voltage and cells
A
Cells have a potential difference across the surface membrane
21
Q
What is resting potential?
A
- When one electrode is in solution and an axon
- A potential difference of -70 millivolts
- Axon internal is more negative than eternal
- (Membrane is polarised)
22
Q
What are the steps in sending impulses across an axon?
A
- Neurone is stimulated
- Action potentials across axons are triggered
- The membrane becomes depolarised at the site of action potential
- Local electrical current is created
- Charged sodium ions flow between the depolarised part of the membrane and the adjacent resting region
- Depolarisation spreads to adjacent region
- Na+ gates will open
- Triggering another action potential
- Repolarisation occurs
- K+ gates will open
- K+ will leave the membrane
- Membrane becomes more negative
23
Q
What is the refractory period?
A
- 5ms where a new action potential cannot be generated in a section of the membrane
- Lasts until all voltage-dependent sodium and potassium channels are closed
- Where the resting potential is restored
- Ensuring impulses only move in one way
24
Q
What does the size of the stimulus effect?
A
- Frequency of impulses (High)
- The number of neurones that are conducting impulses (Many)
25
What determines the speed of conduction?
- Diameter of axon
- The wider the diameter the faster the impulse travels
- Normal axons have slower impulses than giant ones
26
What is the role of the myelin sheath?
- Acts as an insulator
- preventing any flow of ions across the membrane
- Nodes of Ranvier (Gaps) are at regular intervals
- Which is where depolarisation
- Ions flow across the membrane in one node reducing the voltage
- Inducing another action potential
- Allows for jumping of impulses (saltatory conduction)
27
What is a synapse?
- Where two neurones meet
- No cell-to-cell contact - a gap in between is the synaptic cleft
28
What is the synapse structure?
- Synaptic cleft separates the presynaptic membrane
- The gap is 20-50nm and a nerve pulse meaning the neurone
29
What is the synapse transmission and impulse?
- Action potential at the presynaptic membrane
- Release of neurotransmitter into the synaptic cleft and diffuses across the gap
- Results in depolarisation of the postsynaptic membrane
- Leading to the propagation of the impulse along the next cell
- Requires a considerable amount of energy to produce neurotransmitters and package them into vesicles
30
What is neurotransmitter release?
- The presynaptic membrane is depolarised by action potential
- Channels on the membrane open and increase the permeability of the membrane to calcium ions
- Calcium ions greater con outside of the cell diffusing across the membrane into the cytoplasm
- Increased Ca2+ causes synaptic vesicles containing acetylcholine to fuse with the presynaptic membrane
- Release their contents into the synaptic cleft by exocytosis
31
How does the stimulation of the postsynaptic membrane work?
- Neurotransmitter sent from synaptic cleft to postsynaptic membrane
- The postsynaptic membrane contains receptor proteins
- Bind site complementary to the ************************************************acetylcholine molecule************************************************
- The **********************************************acetylcholine molecule********************************************** binds to the receptor
- Changing the shape of the protein
- Opening the cation Channels
- Increasing permeability to the sodium ions
- The flow of sodium ions across causes depolarization which can cause an **********************action potential**********************
- Which is propagated across the postsynaptic neurone
32
How does the inactivation of the neurotransmitter work?
- Some are taken up by the presynaptic membrane and recycled
- Some are rapidly diffused away from the synaptic cleft
- Or taken up by other cells in NS
- ******************************Acetylcholinesterase breaks down acetylcholine******************************
- Can no longer bind to receptors
- Which the products can be reabsorbed into the presynaptic membrane and reused
33
What are the two roles of synapses?
- Control nerve pathways - flexible response routes
- Integration of information from different neurones - coordinated response
34
What factors affect the likelihood of postsynaptic membrane depolarization?
- Type of synapse
- Number of impulses received
35
What is the excitatory synapse?
- Excitatory
- Makes the postsynaptic membrane permeable to sodium ions
- Single excitatory synapse doesn't depolarise membrane enough to produce an action potential
- Summation is required where multiple synapses must work together
36
What is the inhibitory synapse
- This makes it less likely an action potential will result in the postsynaptic cell
- Where the neurotransmitter opens chloride and potassium ion channels
- Which carries out negative and positive charges which will cause a greater potential difference (hyperpolarisation)
- Decreasing likeliness of depolarisation
37
What is spatial summation?
- Impulses form different synapses
- From different neurones
- The number of sensory neurones stimulated is reflected in the control of the response
38
What is temporal summation?
- Several impulses arrive at the synapse
- From a single neurone one after the other (q)
- Combined release of neurotransmitter generation an action potential in the postsynaptic membrane
39
What do plants use instead of a nervous system to coordinate activity?
- Chemicals are used to coordinate growth, development and responses to environment
- Plant hormones, plant growth regulators or plant growth substances
- Gibberellins - Stimulate flowering and seed germination
- Cytokines - Stimulate cell division and cell differentiation
- Ethene - Stimulates fruit ripening and flowering
- Abscisic acid - Involved in leaf fall
- Produced in low conc and transported to where they cause a response
40
What is tropism?
- Response of a plant to a directional stimulus
- Through regulation of growth
- Positive tropism is growth towards the stimulus (shoots)
- Negative tropism is growth away from the stimulus (roots)
41
What is geotropism?
- Growth of plant in response to gravity
- Shoots are negatively geotropic and grow upwards
- Roots are negatively geotropic and grow downwards
42
How do plants detect light?
- Photoreceptors called phytochromes
- Found in the leaves, seeds, roots and stems
- Control range of responses
- Such as flowering under a specific amount of sunlight
- Molecules that absorb light with two states
- Pr which absorbs red light
- Pfr which absorbs far-red light
- Which is used to determine the season which then determines what genes are transcribed
43
What is the changes in state in phytochromes?
- Pr is quickly converted into Pfr when is exposed to red light
- Pfr is quickly converted into Pr when its exposed to far-red light
- Pfr is slowly converted into Pr when its in darkness
44
What is auxin?
- A plant growth substance
- Through regulating transcription of genes related to cell elongation
- Moves through diffusion and active transport as well as the phloem
45
How does auxin effect phototropism?
46
What parts of the brain were involved in interpreting sight?
- the axons of the ganglion cells that make up the optic nerve
- Pass out of the eye and extend to several areas of the brain (including thalamus)
- Impulses are sent along neurones to primary visual cortex to be processed
47
What is grey matter?
The outer layer of the brain
48
What are the different parts of the cortex?
- Left and right hemisphere
- Each hemisphere contains
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
49
What is white matter?
- Below the grey matter cortex
- Millions of nerve axons that connect neurones in different parts of the brain
- White color from myelin sheath
50
What is the corpus callosum?
- Separates Cerebral hemispheres
- White band of matter
- Allowing communication between the two hemispheres
51
What are the functions of the cerebellum?
- Coordination of muscles and posture
- Learning motor skills
- Maintaining balance and equilibrium
52
What are the functions for the midbrain?
The functions of the midbrain include:
- Relaying signals between the hindbrain and the forebrain
- Coordinating eye movements and pupil constriction
- Regulating arousal and alertness
- Involved in auditory processing and the startle reflex
53
What are the functions of the medulla oblongata?
Controls vital autonomic functions such as breathing, heart rate, blood pressure, digestion, sneezing and swallowing.
54
What is the frontal lobe?
- Higher brain functions
- Decision making, reasoning, planning and consciousness of emotions
- Forms associations and with ideas
- Includes primary cortex
- Neurones connecting directly to the spinal cord and the stem of the brain
- Sending information to the body via motor neurones
55
What is the partial lobe?
- Orientation
- Movement
- Sensation
- Calculation
- Recognition
56
What us the occipital lobe?
- Visual cortex
- Processing information from the eyes
- Vision
- Colour
- Shape
- Recognition
57
What is the temporal lobe?
- Processing auditory info
- Hearing, sound, recognition and speech
- Involved in memory
58
What is the hypothalamus?
- Below the thalamus
- Contains thermoregulatory center
- Monitors core body temperature and skin temperature
- Controls sleep, thirst and hunger
- Acts as a endocrine gland
- Connects to pituitary gland
59
What is the hippocampus?
Involved in laying down long-term memory
60
What is the basal ganglia?
- Collection of neurones deep in each hemisphere
- Responsible for selecting and initiating stored programmes for movement
61
What is CT?
- Computerised Axial Tomography
- Overcomes limitations of X-rays
- Where x-rays cant image soft tissue as they are only absorbed by denser materials like bone
- Produces frozen moment pictures looking at structures in the brain rather than the functions
62
How does CT scans work?
- Thousands of narrow-beam X rays rotated around patient
- Passes through tissue from different angels
- Narrow beam strength is reducing strength according to the density of tissue
- Creating a image of a thin slice of the bran on a computer
- Where soft tissues within the brain can be distinguished
63
What is MRI?
- Uses magnetic field + radio waves to detect soft tissues
- Magnetic field will line up the nuclei of atoms in the direction of the magnetic field
- Where the Hydrogen atoms in water are monitored in MRI
- Due to high water content in tissues
- Where hydrogen tends to line up in magnetic field
64
How does MRI work?
- Magnetic field runs down center of the tube
- Another magnetic field superimposes the first magnetic wave
- Comes from magnetic component of high frequency radio waves
- Combined waves cause hydrogen nuclei to change spin taking energy from the radio waves
- Which is released when the radio waves are turned off which is detected by a computer
65
What is fMRI?
- Functional Magnetic Resonance Imaging
- Provides information about brain in action
- Allowing for study of Memory, Language and Consciousness
66
How does fMRI work?
- Deoxyhaemoglobin absorbs radio wave signal
- Oxyhaemoglobin does not
- Increased neural activity in a brain area results in increased demand for oxygen and increased blood flow
- This causes a large increase in oxyhaemoglobin where less of the signal is absorbed increasing level of activity on computer
67
What is PET scan?
- Positron Emission Tomography
- Produces detailed images allowing structure and functioning tissues to be evaluated
- Diagnosing cancer and heart disease
68
How does PET scans work?
- Uses isotopes with short half life (radiotracers)
- That are incorporated into water
- And bind to receptors
- Decays and releases positrons
- Realised on tracers being detected as the more blood flow goes to a certain area causing an increase in radiotracers in that area
69
What is the limitations of PET scans?
- Can only be done twice a year for safety
- Expensive
- Cannot be used for routine screening
70
How can PET scans be used for Alzheimer's?
- Neurones die leaving peices of Beta-amyloid protein
- At myelin sheath in clusters of plaque
- Blocking synapses
- Accumulation of B-amyloid is an early sign of alheimers
- Which can be detected by PET scan and can be monitored
71
What parts of the brain were involved in interpreting sight?
- the axons of the ganglion cells that make up the optic nerve
- Pass out of the eye and extend to several areas of the brain (including thalamus)
- Impulses are sent along neurones to primary visual cortex to be processed
72
How does the brain act after interpreting a visual or auditory stimulus?
- Some neurones in each optic nerve branch off into the midbrain
- Which are connected to motor neurones control pupil reflex and movement of the eye
- Audio signals arrive at midbrain which quickly turn eyes in direction of visual or auditory stimulus
73
What increases brain size after birth?
- Elongation of axons
- Myelination
- Development of synapses
- Where after division immature neurones migrate to final position
- Starting to wire themselves
- Axons lengthen
- Allowing correct connections in order for a function
74
What is the visual cortex?
- Area cerebral cortex at the back of your brain
- Receives and processes visual information
75
What are ocular dominance columns?
- Neurones in visual cortex receive information from either your left or right eye
- Neurones are grouped together in columns called ocular dominance columns
- If they are from the right or left eye
- They are called the left or right eye dominance columns
76
Who was Hubel and Wiesel?
- Discovered the structure of the visual cortex
- Used animal models to study electrical activity of neurones in the visual cortex
- Linked left and right eye to left and right ocular dominance column
77
How was the kittens involved in the animal models
1. Stitched one eye shut of each kitten (several months)
2. Ocular dominance columns for the stitched up eye were a lot smaller than normal (vise vera for other eye)
3. Open eye had expanded to take over the other columns that weren’t being stimulated
1. The neurones in the visual cortex are said to have switched dominance
78
How was the adult cats involved in the animal models?
- Stitched shit one eye of a cat (several months)
- Eyes unstitched - Eyes hadn't gone blind
- Cats fully recovered their vision and their ocular dominance columns remained the same
79
How does cataracts effect brain development?
- If cataracts aren’t removed before 10
- Resulting in permeant impairment of the persons ability to perceive shape or form
- Difficulties in face recognition
80
What is the critical window
- Period that development of basic skills needs to happen
- Otherwise development of these skills will be harder
81
What happens during the critical window?
- Brain will adapt to certain functions
- By formation of new synapses
- Allowing for basic skills like motor skills and sight
82
Where are memories stored?
- Not localised in one part of the brain
- Distributed throughout the cortex with different sites
- For short and long term memory
- Different types of memory controlled by different parts of the brain
- Understood by looking at people with lost parts of brain
83
How are memories stored?
- Every neuron connects with many other neurones making up a complex network
- Memories can be made by altering
- Pattern of connection
- Strength of synapses
84
What is habituation + give examples?
- Type of learning
- Where you ignore unimportant harmless stimuli
- In order to spend energy on potentially more dangerous stimuli
Examples
- Ignoring the fact you have socks on
- Tuning out different sounds
85
What happens during habituation?
- The ability to ignore unimportant repetitive stimuli
- So sensory, attention and memory resources can be concentrated
- To more threatening of rewarding stimuli
86
What happens during habituation?
- Neurones involved in the reflex decrease neurotransmitter release
- Where repeated stimulations cause fewer Ca2+ ions to move into presynaptic membrane
- During depolarisation of the presynaptic membrane
- Resulting in less action potentials to be made from Ca2+ opening cation channels on the post synaptic membrane
87
What is Parkinson’s linked to?
- Where the motor cortexes of people don’t receive enough dopamine
- Resulting in loss of control in muscular movement
88
What are the main symptoms of Parkinson’s?
1. Stiffness of muscles
2. Tremor of muscles
3. Slowness of movement
4. Poor balance
5. Walking problems
****Depression + Difficulties with speech and breathing can also occur****
89
List off the different Treatments for Parkinson’s?
1. Monoamine Oxidase Inhibitor (MAO like Selegiline)
2. L-dopa (Dopamine Precursor)
3. Dopamine Agonists (Dopamine Receptor Activators)
4. Gene therapy
5. Deep Brain Stimulation (DBS Surgery)
90
How does MAOA and MAOB work?
- Slows the loss of dopamine
- Inhibits monoamine oxidase
- Which breaks down dopamine
- By reducing this enzyme dopamine availability increases
91
How does L-dopa work?
- Dopamine can’t be given to patient directly
- Can’t travel through blood barrier
- L-dopa is a precursors to dopamine
- Once in brain converts to dopamine
- Increasing conc of dopamine controlling symptoms
92
What happens if there is too much dopamine?
- Can cause schizophrenia
- Treated with drugs that block the binding of dopamine to the receptors
- Side effect is to induce the symptoms of Parkinson’s disease
93
What causes depression to occur?
- Determines a persons mood
- Lack of serotonin causes depression
- As well as genetics determining susceptibility depending on genes
- As well as environmental conditions like trauma
94
How is depression treated?
- MAOIs break down neurotransmitters
- Rarely used due to wide range of side effects
- SSRI’s (Selective Serotonin Reuptake Inhibitor)
- Blocks uptake of serotonin
- So that there is higher levels of serotonin in the synaptic cleft
95
How does drugs affect synaptic transmission?
96
What does ecstasy effect and why?
MDMA in Ecstasy causes:
- Thinking
- Mood
- Memory
************As well as long term effects with changes in behaviour and brain structure************
97
How does MDMA effect synapses?
- Increases concentration of serotonin in the synaptic cleft
- Binds to molecules that transport serotonin back into the cytoplasm
- Can also cause molecules that transport the molecules to work in reverse
- Increasing conc of serotonin outside the cell
98
What are the short term effects of using MDMA?
- Euphoria, well being and enhanced senses
- Clouded thinking, agitation and disturbed behaviour
- Sweating and dry mouth
- Caused by MDAS disruption to body temp regulation
- Repeated doses can cause hyperthermia and high blood pressure
- With fatal muscles breakdown and kidney failure
99
What are the long term effects of MDMA?
- Insomnia and depression
- Due to overstimulation of serotonin release
- Cells cannot synthesis enough to meet demand once off MDMA
- Resulting in depression
100
What is the Human Genome Project?
- Mapping out all the genes and DNA in a human
- 3.2 Billion base pairs long
- Through international collaboration
- All data is shared under 24hr of discovery
101
What are the findings with explanation?
- Allows for identification of mutations (BRAC1,BRAC2)
- Going to change your environment
- Preventative medicine to remove cancers
- Personalised medicine depending on gene response to drugs
- Due to new identification of new target
- Evolution to track of ancestors as well as genetic risk factors
102
What are the ethical issues surrounding?
- Discrimination due to pay as not everyone can afford personalised medicine
- Certain genes will not be favourable for health insurance
- Employer discrimination due to sick pay being expensive
- Phycological uptake when receiving chance of being at risk of cancer
103
What is the human genome?
All of the DNA and genes in a hunman
104
What is a GMO?
- Artificial introduction of genetic material
- From another organism using genetic modification
- Produces transgenic / genetically modified organism
105
What is the overview for bacterial modification?
1. Restriction enzymes cut sections of the plasmid out
2. Another enzyme allows for a piece of DNA from another species to be inserted into the plasmid
3. Plasmid then inserted back into the bacteria
4. Bacteria allowed to multiply in the fermenter
5. Protein produced from the bacteria is collected
106
How does artificial selection work?
GM Plants (Artificial Selection)
- Artificial Selection - Breeding plants based on their characteristics
- Selects alleles for desired characteristics
- Resulting in steady improvement
107
How does GMO plants work?
GMO Plants
- Faster than artificial selection
- Introducing new genes for desired characteristics
- Creating GMO’s
108
How does plants link to drugs?
GM Crops and Drugs
- Produce drugs cheaply
- Through creating proteins for healing wounds and treating conditions
- Cirrhosis of the liver (Hardening due to alcohol)
- Anaemia
- CF
109
What it is the genetic modification method using bacteria?
************Bacteria************
- bacterium infects many species of plant
- Genes from bacteria plasmid gets incorporated into the chromosomes of the plant cells
- Desired genes inserted previously into plasmid
110
What it is the genetic modification using minute pellets?
****************************Minute Pellets****************************
- Minute pellets covered in DNA
- Carries desired genes
- Shot into plants using particularly gun
111
What is the genetic modification using viruses?
************Viruses************
- Viruses infect cells inserting DNA or RNA
- Used to transfer the new genes into cells
112
What is a gene marker?
- A gene used for antibiotic resistance
113
What are the steps in genetic screening?
- Uses a marker gene and the desired gene
- Plant cells are incubated (antibiotics in high enough doses is toxic)
- Antibiotic then kills off any cells which have not taken up the new gene
- Which leaves the cells that have successfully incorporated the new genes
- Plant cells are then cultured in agar forming a callus and then platelets
114
What are the different DNA insertion methods?
- Injecting DNA into nucleus of fertilised Egg
- With 1% chance of DNA being incorporated into the genome of the embryo
- Viruses have been used to introduce new genes into fertilised eggs
- Incorporating viral DNA into hosts DNA
115
What are the different Health Conditions with GMO's?
1. Transfer of antibiotic resistance genes to microbes
2. Formation of harmful products by new genes
3. Transfer of viruses from animals to humans
116
How can antibiotic resistance occur from GMO?
Antibiotic Resistance
- Antibiotic genes from crops can be transferred to bacteria in a human when eaten
- Allowing for for building up of resistance to certain antibiotics
- Leading to the industry wanting to remove the antibiotic marker genes
