Chapter 26 ( The Nervous System ) Brain and spinal cord part Flashcards
Why is the nervous system an essential part of an advanced organism?
It allows an organism to react to environmental and internal changes and to make appropriate behavioural modifications.
Organisation of the nervous system?
Picture Learn and Memorise off by heart :)
Function of the cerebrum
Largest part of brain
Consists of 2 hemispheres.
Surface covered by layer of nerve cell bodies - called cerebral cortex (highly folded)
- Controls conscious thought processes, emotional responses, understanding, use of language and intelligent thought (reasoning + ability to draw conclusions)
Left cerebral hemisphere - receives sensory inputs from receptors on right hand side of body. - controls voluntary muscles in right side from motor cortex.
VICE VERSA - The right hemisphere carries out same functions for left side of body.
Brain picture?
Print off, all angles
https://www.google.com/search?q=the+brain+labelled+from+underneath+&tbm=isch&ved=2ahUKEwiP-uKQ8Nn1AhULNBoKHQ-YCGIQ2-cCegQIABAA&oq=the+brain+labelled+from+underneath+&gs_lcp=CgNpbWcQA1D2C1j2C2C9DmgAcAB4AIABUYgBoAGSAQEymAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=Kbr2Yc_BEovoaI-wopAG&bih=821&biw=1440&safe=active&ssui=on#imgrc=Y_uRQwnalIxu7M
Neurones in reflex arc pathway?
Stimulus → receptor -→ sensory neurone → central nervous system (relay neurone) → motor neurone → effector → response
Structural organisation of the nervous system.
DIAGRAM!!!!! ( page 180) of bible, and 1 of notes.
Central nervous system info?
Brain and spinal cord
Peripheral nervous system info
All neurones that connect CNS with rest of body.
Consist of sensory neurones which carry nerve impulses from receptors to CNS. Motor neurones carry impulses away from CNS to effectors.
Further divisions.
Somatic nervous system info
Part of Peripheral NS
- under conscious control
- used for voluntary actions (eg, moving arm)
carries impulses to skeletal muscles
single neurone links CNS to effector cells
Autonomic nervous system info
Part of Peripheral NS
- Works constantly
- Under subconscious control
- Used when body does something automatically without any decision, ie, involuntary
(eg, heartbeat)
-carries nerve impulses to endocrine glands, smooth muscle (indigestive tract and blood vessel walls), cardiac muscle and SAN in RA wall.
Further divisions
Further divisions of autonomic nervous system
Sympathetic
- Fight or flight
- generally increases activity
post ganglionic NT = noradrenaline
Parasympathetic
- Rest or digest responses
- generally decreases activity
post ganglionic NT = acetylcholine
Regions of the brain
Cerebrum Cerebellum Medulla oblongata Hypothalamus Pituitary gland Pons
Functions of the nervous system
Detect stimuli, interpret them, coordinate response
Function of the cerebellum?
Controls coordination of muscles and non-voluntary movement, balance and posture.
Takes sensory inputs from retina and other receptors, eg, spindle fibres in muscles and organs in inner ear.
Function of the medulla oblongata?
Controls autonomic activities in the body
Contains regulatory centres of the ANS
Controls reflex activities
eg, heart rate, breathing rate, blood pressure, peristalsis in gut muscles.
Function of hypothalamus?
Has 2 centres, one controls PNS, once controls ANS
Controls body temperature, osmoregulation, secretion of hormones via pituitary gland.
Monitors composition of blood plasma, so has very rich blood supply.
Produces hormones secreted
controls most homeostatic mechanisms, eg, water balance, temperature, (expect blood glucose levels)
Function of pituitary gland?
Controls most endocrine glands in the body
2 sections:
Posterior lobe - stores and secretes hormones produced by hypothalamus eg, ADH.
Anterior lobe lobe: produces and secretes hormones, eg, FSH.
What is brain damage?
Acquired brain damage (ABD) = any brain injury occurring after birth.
Two types
- Traumatic brain injury
- Non-traumatic brain injury
There are also progressive neurodegenerative diseases, eg, Alzheimer’s, Parkinson’s.
What is a traumatic brain injury?
Occurs following severe blow to head
Eg, road traffic accident, fall, assault
What is a non-traumatic brain injury?
Doesn’t involve severe blow to head
Eg, stroke, infection, anoxic injury.
What are some neuro-imaging techniques
Important in diagnosing ABD Determine location and extent of damage Enable professionals to determine necessary treatment, surgery or rehabilitation required. MRI fMRI CT scans PET scan EEG
Info on MRI scans?
Magnetic resonance imaging scans.
Uses magnetic field and pulses of ratio wave energy to produce images of structures inside body.
Detailed images
Used to detect tumours, strokes, areas of infarction, areas of demyelination in CNS.
Benefits of MRI scans
- Provide better soft tissue contrast than CT
- Provide detailed images ( better than CT)
- Don’t use ionizing radiation, so patients aren’t exposed to harmful effects of radiation.
Disadvantages/ Risks of MRI scans
- Expensive
- Can disrupt body tissues due to exposure to magnetic forces
- some patients may experience claustrophobia
- patient’s have to remain still to produce good quality images, so infants/patients who can’t need to be anaesthetised - causes risks - slow breathing, low BP.
Info on fMRI?
Functional MRI scans
Identifies activity in specific areas of brain due to increase blood flow.
Technique relies on fact that cerebral blood flow and neuronal activation are coupled.
NOT FINISHED
!HFHFGHISUEGFS IFGOS
Info on CT scans?
Computed tomography scans
- Use x rays that penetrate the body to varying extents depending on density of structures.
Black and white images.
-creates detailed cross-sectional images.
- further detail can be obtained by using CT perfusion - injected with substance to show areas that are adequately supplied with blood - better differentiation between tissues - better image.
Advantages of CT scans?
- Painless
- Non invasive and accurate
- Fast, ie, images available immediately
- Ability to image bone, soft tissue and blood vessels at the same time
- Examinations are fast and simple - vital in emergency cases.
Disadvantages of CT scans?
- slight risk of cancer from excessive exposure to radiation
- can’t be carried out when pregnant.
Info on PET Scans
Positron emission tomography scans
Radioactive form of glc (FDG) introduced to vein - ie, uses radioactive tracers.
FDG taken up by active tissue
scanner detects positrons released from glc - produces image
Damaged/cancerous cells process glc differently - different positrons released - different colour images.
Allows health professionals to distinguish between healthy and non-healthy tissue.
Rarely used foR TBI as tissues not always biochemically active due to damage.
Advantages of PET scans
low radiation exposure to patient as doses of radio-tracer administered are small
no long-term adverse effects from low dose exposure
Disadvantages of PET scans
Radioactive drug (tracer) can cause major allergic reaction.
- Nursing mothers should wait for 24 hours after contrast material before resuming breast-feeding.
- Injection of the radio tracer may cause slight pain and redness.
Info on EEG
Electroencephalogram.
Direct measure of brain function
detects small electrical impulses sent from brain cells to other brain cells.
Impulses recorded and monitored for any abnormal readings.
Can indicate epilepsy, dementia, brain inflammation, head injury, coma.
Advantages of EEG
Non invasive
painless
Disadvantages of EEG
Can cause seizure in person with epilepsy
Time consuming - can take between 45 mins and several hours to complete EEG.
What is the spinal cord
Long, thin, tubular bundle of nervous tissue and support cells. Extends from medulla oblongata in the brainstem to the lumbar region of the vertebral column
Part of the central nervous system
What is a SCI
Spinal cord injury
Damage to the spinal cord that causes changes in its function, either temporary or permanent
- symptoms can vary widely, eg, pain, numbness, paralysis, incontinence depending on location and severity along the spinal cord.
Common causes of SCI
Vehicle accidents Falls Violence Medical/surgical complications cancer - spinal tumours Blood loss
Function of pons?
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Info on CSF
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What are the effects of brain damage
Depends on region that is damaged and degree/extent of damage
Cause of strokes
- Blood vessel supplying brain becomes blocked (by clot usually)
- Also due to bleeding into brain from ruptured or damaged blood vessel.
- Oxygenated blood supply to brain interrupted.
- Type of damage depends on area of brain that doesn’t receive blood.
How may a stroke affect an individual
Minor damage - patient may be unaware
Medium damage - make partial/full recovery
Major - continued disability or death.
Rehabilitation for stroke victims
Can help patient regain some or many life skills lost
Works by compensating with new neural pathways
Which areas of the brain my be affected by TBI’s
- Damage may occur to hypothalamus or pituitary gland
- Results in disruption to production and release of hormones (ADH, thyroxine, FSH, LH)
- Can lead to problems with water balance, menstrual cycle.
What is extensive brain damage?
- can result in vegetative state - brain stem still functions - possible slim chance of recovery
- patient declared clinically dead when brain stem function is permanently lost (heart beat and oxygen supply artificially maintained)
- Organ used for transplant if consented.
What is drug addiction?
Uncontrolled, compulsive behaviour
Tolerance to drug builds up -> increasing quantities of drug required to produce same effect.
What is tolerance due to?
Increasing due to:
- Inc conc of enzymes that metabolise + break down drug
- Reduced sensitivity of receptors to drug
- Reduced distribution of receptors to drug
Types of dependency and info?
Psychological dependency
- Body may not physically need drug but there is psychological need (due to habit/social pressure)
Physical drug dependency
- Drug required for body to function normally. If drug stopped abruptly, withdrawal symptoms (maybe death)
Reasons for drug dependency?
Social pressure
Peer pressure
Emotional issues, depression
Anxiety issues
Personal consequences of drug addiction?
: Desire to take more drugs escalates
: Becomes overwhelmingly dominant event in their daily life.
: Leads to exclusion of other aspects in life, eg, sleeping, eating, personal hygiene, care for family members
: can lead to criminal activity to fund habit and obtain drugs
Consequences to society of drug addiction?
- Direct healthcare costs
- Loss of tax contributions by drug abuser as they lose job/ fail to work.
- Policing costs, eg, law enforcement + drug detection
- Reduction in benefits as loss of job can lead to claiming income support + benefits.
- Financial costs due to theft by addicts
What is the spinal cord?
Long, thin, tubular bundle of nervous tissue and support cells
Extends from medulla oblongata in the brainstem to the lumbar region of the vertebral column.
is part of the CNS.
What is a SCI?
Spinal cord injury
- damage to the spinal cord that causes changes in its function, either temporary or permanent.
- Symptoms vary - pain, numbness, paralysis, incontinence.
Other effect - Lowe blood pressure, chronic pain, reduced control of body temp due to inability to sweat below level of injury.
Common causes of SCI?
Vehicle accidents Falls Violence (primarily from gunshot wounds) Sports injury medical/surgical complications cancer - spinal tumours.
Types of SCI?
Complete SCI - No function below level of injury, both sides equally effected.
Incomplete SCI - Some function below primary level of injury. May be able to move one limb more than another.
Effects of SCI on daily life?
Ability to speak is sometimes impaired Requires assistance with daily life activities, eating, dressing, bathing. Won't be able to drive car on own. Tetraplegic - all 4 limbs affected paraplegic - below waist.
Diagnostic tests for SCI?
CT scan, MRI scan, x-ray enable practitioners to see exactly where spinal cord injury has occurred. Complete neurological exam done days after injury to allow any swelling to subside - more accurate .
Definition of paralysis?
Loss of muscle function for one or more muscles. usually caused by damage in nervous system
Incomplete paralysis - partial damage to spinal cord - some nervous signals are able to travel past injured area of cord.
Potential treatment of SCI using stem cells risks and benefits?
Risks Risk of rejection Risk of further injury or infections with many injections May not be successful Long term effect unknown.
Benefits
Reduces symptoms
Replaces damaged cells
Patients could move + walk again.
Ethical
Destroying embryos
Gives hope to patients - wellbeing and mental health implications - also gives false hope.
Advantages of fMRI?
Doesn’t use radiation
Non invasive
High resolution images produced
Disadvantages of fMRI?
Expensive
Can only capture a clear image if person being scanned stays completely still.
What medicinal drugs can be used to treat certain forms of BD?
Examples of recreational drugs?
Alcohol Heroin Marjuana Mathamphetamines Nicotine
Effect of alcohol on body?
Affects coordination + motor skills by inhibiting neurotransmission across synapse.
Binds to receptors on postsynaptic membrane, eg GABA receptors
GABA = inhibitory neurotransmitter - opens Cl- ions channels -> negative change in membrane potential ->inhibits further transmission for short time
The binding of alcohol - Cl- ion channels opens for longer, more cl-ions enter -> hyperpolarisation of postsynaptic neurone -> prolongs inhibition -> depressant effect
Effect of heroin on your body?
An opiate
Converted to morphine in brain
Binds to opioid receptors
Slows heart rate and breathing rate - life threatening
Effect of methamphetamines on your body?
Affects excitatory synapses by increasing release of dopamine
Drug is slowly broken down -> prolonged stimulatory effect of dopamine.
Effect of nicotine?
Nicotine has similar shape to Ach, so binds to Ach receptors in postsynaptic membrane, which leads to stimulation of synapses in ganglia of SNS.
Role of dopamine in your body?
Limbic system of brain involved with long term memory, behaviour and emotions.
Influences both endocrine and ANS.
Acts as brain’s reward centre- experiences ‘highs’ due to recreational drug taking
Dopamine involved in reward-motivated behaviour.
Increased dopamine in brain leads to overwhelming desire to continue activity - dependency.
In chronic drug abuse, ongoing dopamine release activates limbic brain areas -> critical brain alterations -> occasional user can become an addict.
Effect of marijuana on body?
Inhibitory neurotransmitters normally present in dopamine synapses inhibit release of dopamine.
Body naturally produce cannabinoid substance called anandamide, which binds to cannabinoid on neurones that produce inhibitory neurotransmitters
ASK MRS PARKER!!!!!
It contains chemical THC.
