Unit 3 Flashcards
(135 cards)
1
Q
The Central Nervous system
A
Made of the spinal cord and the brain
2
Q
The Peripheral Nervous System
A
Is made up of neurons throughout the rest of the body
3
Q
Sensory neurons
A
Take impulses into CNS from sense organs
4
Q
Motor neurons
A
Take impulses from CNS to muscle and glands
5
Q
Somatic Nervous System
SNS
A
Controls skeletal muscles and is involved in mostly voluntary actions
Also responsible for involuntary reflex actions
6
Q
Automatic Nervous System (ANS)
A
Regulates internal structures such as heart and blood vessels etc
Occurs through autonomic involuntary activities which involve sensory and motor neurons
Involves homeostatic control
7
Q
What groups is the ANS divided into
A
Sympathetic and parasympathetic System
8
Q
Sympathetic system
A
Speeds up heart rate and breathing rate while slowing down peristalsis and intestinal secretion
9
Q
Parasympathetic Nervous System
A
Changes this in the opposite way to the sympathetic Nervous System
10
Q
Neurons are connected to others in many different ways in the CNS. This allows….
A
Many complex interactions to occur between neurons and so allows the Nervous System to carry out many complex functions
11
Q
What are the three main neural pathways?
A
Converging
diverging
Reverberating
12
Q
Converging neural pathways
A
Impulses from several neurons travel to one neuron
This increases the sensitivity to excitatory or inhibitory signals
13
Q
Give an example of a converging neural pathway
A
The convergence of the neurons from the rod cells in the retina of the eye
14
Q
Diverging neural pathways
A
Impulses from one neuron travel to several neurons
This affects more than one destination at the same time
15
Q
An example of diverging neural pathways
A
Threading a needle
16
Q
Reverberating neural pathways
A
Neurons later in the pathways link with earlier neurons, sending the impulse back through the body
This allows repeated stimulation of the pathway
17
Q
Cerebral cortex
A
Centre of conscious thought
Recalls memories and alters behaviour in the light of experience
18
Q
Functions of the cerebral cortex
A
Receives sensory information
Co-ordinates voluntary movement
Making decisions based on experience
19
Q
Localisation of function in the cerebral cortex
A
Within the cerebral cortex, there are three main areas, each of which deals with a particular function
By this means, coordination of voluntary movement is achieved
20
Q
Sensory area
A
Receives information as sensory impulses from receptors (e.g sense organs)
21
Q
Association area
A
Analyse and interpret impulses received from the sensory areas and deals with
Through processes, language, personality, imagination and intelligence
22
Q
Motor area
A
Act on information from associated areas by sending motor impulses to effectors
23
Q
The cerebrum is divided into two halves
A
The left central hemisphere Deals with information from the right visual field and controls the right side of the body
24
Q
Corpus callosum
A
Band of nerves between the cerebral hemispheres allows the transfer of information between the cerebral hemispheres
Enabling the brain to act as an integrated whole
25
Split brain syndrome
Damaged or no corpus callosum
26
Memory
The capacity of the brain to store information, retain it and retrieve it when required
Memories include past experiences, knowledge and thoughts
27
All information entering the brain passes through....
Sensory memory and enters the short term memory (stm)
| Information is then either transferred to the long term memory (ltm) or is discarded
28
Sensory memory
Only selected visual images and auditory sounds are encoded into STM
Sensory memory lasts only a few seconds
29
Describe sensory memory
Forms sensory images from visual and auditory output from continuous flow of information from environment
It then transfers relevant sensory images but most sensory information is quickly lost
30
Short term memory
STM has a limited storage capacity or memory span holding information for a short time
31
Describe how memory is lost by displacement
The pushing out of 'old' information by new information
32
Describe how memory is lost by decay
The breakdown of 'memory trace'
33
How can short term memory span be measured
By finding out the number of individual items they can reproduce correctly and in order
34
Rehearsal can help keep items in the STM and help transfer the information to the long term memory, describe this
Repeating a piece of information many times either silently or aloued
35
Describe chunking
The organisation of many pieces of information into smaller chunks of information
Eg. Breaking phone numbers into smaller groups
The capacity of STM can be improved by chunking
36
Describe the serial position effect memory pattern
When information is viewed in a sequence, the first and last few pieces of information are remembered best
37
Explain why the serial position effect occurs
The first few pieces of in formation are remembered as there has been time for rehearsal and it has been transferred to LTM
The middle pieces of information are quickly forgotten as STM gets crowded
The last pieces of information are remembered as they have not been displaced yet
38
On average how many pieces of information can be recalled in short term memory
7
39
Describe long term memory
The long term memory has an unlimited capacity and holds information for a long time
Information must be encoded and converted to a form that the brain cells can process and store to allow it to be transferred from STM to LTM
40
Name and describe three ways information can be transferred from STM to LTM
Rehearsal- repeating information
Organisation- grouping information into categories
Elaboration- linking with previous memories
41
Describe the benefits of rehearsal
Helps to extend the length of time information is retained within STM
Facilitates the transfer of information from STM to LTM
42
Describe the benefits of organisation
Organising information into logical groups or categories makes it more easily transferable into LTM
43
Describe the benefits of elaboration of meaning
Allows us to make information easier to transfer and store in the LTM by building it into a bigger story
44
Describe retrieval
Information stored in the LTM should be able to be retrieved
Retrieval is aided by the use of 'contextual cues'
These relate to the time and place when the information was encoded
The more elaborate and detailed the memory the more easily it is retrieved
45
Describe what the basic structure of a neutron is composed of
Dendrites
A cell body
Axon
46
Describe the path if nerve impulses
Dendrite➡️cellbody➡️Axon
47
Cell body
Contains a nucleus and cytoplasm
The cytoplasm contains organelles such as mitochondria to provide energy for impulses and ribosomes which synthesise proteins (e.g enzymes) for the synthesis of neurotransmitters
48
Dentrites
Receive nerve impulses and cary then towards the cell body
49
Axon
Carries nerve impulses away from the cell body
50
Myelin sheath
The axons are surrounded by a layer called the myelin sheath which:
Insulates the axon
Increases the speed of impulse conduction
51
Myelination is....at birth
Not complete, it continues until adolescence
52
Myelination is not complete at birth hence...
Responses to stimuli in the first 2 years of life are not as rapid or coordinated as that of an older child or adult
53
How can certain diseases affect coordination
By destroying the myelin sheath e.g polio, MS
54
Glial cells
Physically support neurons
| Produce the myelin sheath
55
Synapse
The tiny area between the ending of the axon of one neuron and the dendrite of another is known as a synapse
56
Synaptic cleft
The plasma membranes of each neuron are in very close contact and are separated by a narrow space known as a synaptic cleft
57
Presympathetic neuron
The neuron before the synaptic cleft
58
Post sympathetic neuron
The neuron after the sympathetic cleft
59
Neurotransmitters
Messages are passed across synaptic clefts by chemicals called neurotransmitters
E.g acetylcholine and noradrenaline (norepinephrine)
60
When a nerve impulse passes through a neuron and reaches the end of the axon (axon terminal)...
Many vesicles containing neurotransmitters are stimulated
61
When vesicles move to and fuss with membranes at the surface of the axon terminal....
The neurotransmitters within the vesicles are then released into the synaptic cleft
62
Why must neurotransmitters be rapidly removed as soon as the impulse is transmitted?
To prevent continuous stimulation of the post synaptic neuron so that the membrane is sensitive to the next stimulus
Otherwise the neurotransmitter would continue to have an effect
63
How can neurotransmitters be removed?
Enzymes
| Re-uptake
64
Excitatory signals
Causes an increase in action e.g causes muscles to contract )
65
Inhibitory
Causes a decrease in action, e.g slows heart rate
66
The type of receptor cell found on post synaptic neurons determines whether the signal is....
Excitatory
| Inhibitory
67
A nerve impulse will only be transmitted across a sympathetic cleft if...
It causes the release of a sufficient number of neurotransmitters (known as the threshold)
68
Weak stimuli cannot cause the transmission of a nerve impulse so...
The impulse is flittered out
69
A series of weak stimuli....
Can bring about an impulse
70
The cumulative effect of many weak stimuli is known as
Summation
71
Endorphins
Endorphins are neurotransmitters that stimulate neurons involved in regulating the intensity of pain
72
Endorphin production increases in response to...
Severe injury
Prolonged continuous exercise
Physical and emotional stress
Certain foods
73
Increased levels of endorphins can also bring about...
Euphoric feeling
Regulation of appetite
Release of sex hormones
74
Dopamine
A neurotransmitter which increases the feeling of pleasure
Involved in reinforcing particular behaviours by activating the reward pathway in the brain when an individual engages in a behaviour that is beneficial to them
75
Agonists
Chemicals that bind to stimulate specific receptors on postsynaptic nerves
Agonists mimic the action of natural neurotransmitters at the synapses and so normal cell responses can occur
76
Antagonists
Chemicals that bind to and block specific receptors on postsynaptic nerves
By blocking the receptor sites they prevent the normal neurotransmitters from acting
Can greatly reduce or even stop the normal transmission of nerve impulses
77
Inhibitors
Other drugs know aa inhibitors inhibit the enzyme which degrades neurotransmitters or inhibits re-uptake
78
Recreational drugs can act as ...
Antagonists or agonists and therefore affect neurotransmission at a synapse
79
Recreational drugs can lead to change in...
Mood(happier, more confident/ aggressive
Cognitive (poorer at carrying out complex mental tasks)
Perception (misinterpreted environmental stimuli)
Behaviour (stay awake longer/ talk to themselves)
80
Many recreational drugs affect...
Neurotransmitters in the reward pathway of the brain
81
What leads to drug addiction?
Repeated use of drugs that are antagonists (e.g nicotine) cause an increase in the number and sensitivity of neurotransmitter receptors
82
Describe drug tolerance
Repeated use of drugs that are agonists (e.g cannabis) cause a decrease in the number and sensitivity of neurotransmitter receptors
83
Pathogens
Organisms such as bacteria, fungi and viruses which can cause disease
84
What is the function of the immune system?
To defend the body against pathogens and diseases
85
What two groups is the immune system divided into?
1: non-specific defences
2: specific defences
86
Epithelial cells
Physical defence
Non-specific defence
Closely packed epithelial cells are found in the skin and inner linings of breathing and digestive systems
They form a physical barrier against pathogens
87
Chemical defences
Chemicals secretions are also produced as non-specific defence against invading pathogens
Secretions include tears, saliva, mucus and stomach acid
88
The inflammatory response
A non-specific defence which is triggered when an injury or infection occurs
89
Mast cells
Immune cells that activate and start the inflammatory response by releasing histamines
90
Histamines
Cause vasodilation and increased capillary permeability
| The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection
91
What is stage 1 of the inflammatory response
Begins with injury or infection
92
What is stage 2 of the inflammatory response
Mast cells become activated
93
What is stage 3 of the inflammatory response
Histamine released, causing vasodilation and increased capillary permeability
94
What is stage 4 of the inflammatory response
Immune cells reach site of injection
95
What is stage 5 of the inflammatory response
Phagocytes engulf and destroy pathogens
96
What is stage 6 of the inflammatory response
Clotting elements clot the blood to help seal the wound
97
Phagocytes
A non-specific type of white blood cell
| They recognise foreign antigen molecules on the surface of pathogens and destroy them by phagocytosis
98
Phagocytosis
Is when the phagocyte engulfs the pathogen and destroys it by using digestive enzymes contained within lysosomes inside the phagocyte
99
Lysosome contain
Powerful digestive enzymes
100
Cytokines
During infection, phagocytes can also release cytokines
They are protein molecules that act as a signal to attract other white blood cells to the site of infection
They also activate the body's specific immune defences
101
Lymphocytes
The white blood cells involved in specific immune response
| Made in the bone marrow from stem cells
102
What are the two types of lymphocytes
B lymphocytes
| T lymphocytes
103
Where do T lymphocytes mature
Thymus gland
104
Where do B lymphocytes mature
Stay in bone marrow
105
Each lymphocyte has a different membrane receptor which is....
Specific for one antigen
106
Each lymphocyte has a different membrane receptor which is specific for one antigen. This means....
You can recognise all possible antigen types from invading pathogens
107
When a lymphocyte binds to its particular antigen on the surface of the pathogen, the lymphocyte....
Becomes active
108
An active lymphocyte....
Divides repeatedly to produce a clonal population of identical lymphocytes, which are specific to the particular pathogen which activated it
109
Activated B lymphocytes
Can produce a protein specific to an antigen called antibodies
110
Antibodies
Are able to bind to the antigen creating an antigen, antibody complex
111
Describe antibody action
The binding of antibodies causes the inactivation of the pathogen (or the toxin it produces) and the pathogen to become more susceptible to phagocytosis
112
Describe an allergy
B lymphocytes sometimes over-react to harmless substances like dust. pollen and penicillin
The B lymphocytes release antibodies which cause mast cells to release histamine
Allergies can be so severe that they trigger anaphylactic shock which can be life threatening
113
T lymphocytes
Destroy in infected body cells by releasing antigens of the pathogen on the cell membrane and inducing apoptosis
114
Apoptosis
Programmed cell death
115
Describe how a T lymphocyte induces apoptosis
The T lymphocyte inserts a protein into the infected cell causing it to produce self-destructive enzymes
These destroy the cell and the remains are then removed by phagocytosis
116
Describe autoimmunity
T lymphocytes can normally distinguish between self-antigens on the body's own cells and non-self antigens on infected cells
Autoimmunity is a condition when T lymphocytes attack the body's own cells
117
Name 3 autoimmune diseases
Type 1 diabetes, multiple sclerosis, rheumatoid arthritis
118
Primary response
When a pathogen infects the body, it takes time to raise an immune response and select the correct T and B lymphocytes (clonal selection) and produces anti bodies
Very often this is too slow to prevent the pathogen from causing illness
119
Describe memory cells
The primary response is often too slow to prevent illness however if the person survives and they come across the pathogen a second time they have memory T and B cells left over
120
Secondary response
If a foreign antigen is recognised by memory cells , they very rapidly divide and form many clones of both T lymphocytes and antibody producing B lymphocytes
This means there are more antibodies produces faster and for a longer duration
121
Hiv
The human immunodeficiency virus (HIV) attacks and destroys T-lymphocytes
This leads to the infected individual developing Aids (Acquired Immunodeficiency Syndrome)
Individuals with aids have a damaged immune system and so are vulnerable to infections
122
Vaccines
Immunity can be developed by vaccination using antigens from infectious pathogens
This allows the body to create memory cells against the pathogen without the risk of disease
123
Describe the antigens in vaccines
The antigens in vaccines can be inactivated pathogen toxins, dead pathogens, parts of pathogens and weakened pathogens
In all these cases, the antigen must be intact if an immune response is to be caused
124
How do vaccines work
The aim is for B lymphocytes to produce antibodies and cause what is known as a primary immune response
Follow this primary response, memory cells remain in the body give a faster secondary immune response if we ever come across the pathogen again
125
Why are antigens usually mixed with an adjuvant when producing a vaccine
An adjuvant is a substance which makes the vaccine more effective by enhancing the immune response
126
Describe herd immunity
Occurs when a large percentage of a population are immunised
Non immune individuals are protected as there is a lower probability they will come into contact with infected individuals
127
What is the herd immunity threshold?
The percentage of the population who need to be immunised by the vaccine to offer protection for people who are not vaccinated
128
What are three factors that the herd immunity threshold depends on
The type of disease
Effectiveness of the vaccine
The density of the population
129
Why do some populations not have herd immunity
In developing countries, widespread vaccination is not possible due to poverty and vaccines are sometimes rejected by a percentage of the population
130
Why can't all diseases be eradicated by vaccines ?
Antigenic variation
131
Antigenic variation
Some pathogens have evolved mechanisms that evade the immune system
Pathogens can change their antigens so that antibodies and memory cells are not effective against them
132
Give some examples of antigenic variation
Occurs in the parasite which causes malaria
Occurs in the influenza virus, which is why its a major public health problem and why those at risk require a new vaccine each year
133
Describe clinical trials
Vaccines and drugs are subject to clinical trials to established the safety and effectiveness before licensed for use
134
How is bias eliminated in clinical trails
Subjects in clinical trails are divided into groups in a randomised way in which neither the subject nor the researchers know which group they are in.
Once group receives the drug, the other the placebo control to ensure a valid comparison
At the end the results are compared to determine any statistical significant differences
135
In clinical trails how can the magnitude of experimental error be reduced
Groups must be of a subtable size
