Nervous System Flashcards
Which systems allow us to respond to internal and external stimuli
Nervous + endocrine
What is the difference between the endocrine and nervous system
Endo = produces hormones that are transported in blood system, hormones are generally slow acting
Nervous = responds to external stimuli and involves co-ordination of muscles and some glands, results in quick short lived respones
What do hormones play a role in
Reproduction, controlling growth and homeostasis
What can nervous systems be divided into
Pns and cns
Hat is the difference between pns and cns
Cns - brain and spinal cord
Pns - nerves that conduct impulses to and from brain
How can the pns be further subdivided
Pns can be either sensory neurons or motor neurons
Motor neurons can be either somatic (= skeletal muscle) or autonomic =(cardiac muscle, smooth muscle, glands)
Autonomic nervous system consists of the sympathetic and parasympathetic nerves
How is the central nervous system protected
Brain= skull
Spinal cord = vertebrae
Brain surrounded by three membranes aka meninges
Cerebrospinal fluid found in between meninges
What are the functions of cerebrospinal fluid
Act as shock absorber
Supply cns with nutrients and oxygen
Remove waste
Prevents dehydration
What is the difference between grey and white matter
Grey = contains cell bodies of neurons
White = contains elongated axons of neurons
Where is white and grey matter found in the brain and spinal cord
Brain - grey matter on the outside, surrounds white matter
Spinal cord - white matter on outside surrounding grey matter
What are the three main parts of the brain
Cerebrum
Cerebellum
Medulla oblangata
What are other important parts of brain besides the 3 main parts
Hypothalamus
Corpus callosum
Hypophysis/pituitary
What is the corpus callosum important for
Brain divided into left and right hemisphere
Left side controls right side body and right side controls left side body
Neurons cross from one side to the other in corpus callosum
What is the cerebrum responsible for
Higher mental functions e.g reasoning, judgement, thought, intelligence
Origin for all voluntary actions
Receiving and interpreting senses
What is the cerebellum responsible for
Balance
Co-ordinating and controlling voluntary actions
Muscle tone and posture
How is the medulla oblangata different from the rest of the brain
Has grey matter on the inside
What is the medulla oblangata responsible for
Transmits electric impulses between spinal cord and brain
Controls autonomic function e.g heartbeat, rate and depth of breathing, peristalsis, constrict and dilation of blood vessels
What is the structure of the spinal cord
Grey matte forms h shape on inside
Spinal nerves arise from both sides
Each nerve has dorsal and ventral root
Dorsal has sensory neurons, ventral has motor neurons
Nerves enter spinal cord between vertebrae
What is the spinal cord responsible for
Pathway for nerve impulses to and from brain
Reflex action
What is the hypothalamus responsible
Plays role in maintaining homeostasis : regulates bp, heartbeat, bdy temp, water levels
Controls emotions
Controls release of emotions from hypophysis (pituitary gland)
What does PNS consist of
Motor and sensory neurons
How can motor nerves be subdivided
Somatic nerves - conduct impulses from CNS to voluntary muscle
Autonomic nerves - conduct impulses from CNS to involuntary muscles (smooth muscle and cardiac muscle)
How many cranial and spinal nerves are there
Cranial - 12 pairs that connect to the brain
Spinal - 31 pairs
What is the function of the PNS
To conduct impulses from the receptor the CNS and to conduct impulses from the CNS to effectors (muscles and glands)
How can autonomic motor neurons be further subdivided
Sympathetic - prepare body for emergency by increasing heart rate, depth and rate of breathing, and bp
Parasympathetic - antagonistic to sympathetic nerves, drop levels of nearest etc. back to normal
What is the general structure of neurons
Cell body that consists of nucleus and nissl granules
Two outgrowths from cell body - dentrites and axons
Axons = impulse away from cell body; dentrites = impulse to cell body
Most axons and dendrites surrounded by myelin sheath
Myelin she at made up of Schwann cells
There are gaps between the Schwann cells = nodes of ranvier
Outermost membrane of myelin sheath = neurilemma
Why is the myelin sheath important
Acts as an insulator so prevents nerve impulses from jumping sideways from neuron to another
How can neurons be classified according to function
Sensory - receptor to CNS
Motor - CNS to effector
Interneurons - connect motor neuron to sensory neuron
How can neurons be classified according to structure
Unipolar - one outgrowth : sensory neurons
Bipolar - two outgrowths : interneurons
Multipolar - many outgrowths : motor and interneurons
What is a synapse
A microscopic gap between two consecutive neurons where impulses travel
How is a nerve impulse transmitted from one neuron to the next
Impulse has jump across synapse to reach next neuron
Axon releases chemical = neurotransmitter
Neurotransmitter diffuses across synaptic cleft to next neuron
Neurotransmitter only produced one side of neuron = one direction flow of impulse
How can an impulse be strengthened
Impulse from many neurons combined in one synapse
What happens to insignificant stimuli
Filtered ou to prevent overloading the brain
What is a reflex action
Fast, automatic response of an effector to a stimulus received by a receptor
Where are reflex actions controlled
Mainly spinal cord
Reflexes such as coughing, sneezing controlled by medulla oblangata
What is a reflex arc
The pathway along which nerve impulses are carried from a receptor to an effector to bring about a reflex action. Ut is the functional unit or the nervous system
What is alzheimer’s disease
Irreversible disease that gradually becomes worse causing memory loss and decreased intellectual abilities
Caused by plaque building up between neurons, affected parts of brain shrink
What are symptoms of alzheimer’s
Simple forgetfulness progressing to not being able to recognize friends and family
Can lose ability to speak
Loss of bodily functions leading to death
How can alzheimer’s be treated
No treatment to slow the disease
Treatment to help maintain mental functions and control behavioural symptoms like aggression and sleeplessness
What is multiple sclerosis
Auto-immune disease where your own immune system starts to attack the neurons of the brain and spinal cord
Slowly destroys myelin sheath
Results in gradual loss of muscle control
What are the causes of multiple sclerosis
Viral infections can be trigger
Genetic factors
What are the symptoms of multiple sclerosis
Loss of vision, inability to walk, loss of speech
Treatment for multiple sclerosis
No treatment
Physiotherapy can help to cope with loss of muscle control
What is the difference between traumatic brain injury and acquired brain injury
Traumatic - caused by blow to the head
Acquired - caused by internal dmage as a result of stroke, hypoxia, cancer, infections etc.
What are the effects of brain injury
Loss of consciousness
Concussion
Headaches
Poor judgement
What can cause spine damage
Car accidents, sports injuries, diseases like polio
What are symptoms of spine damage
Range from loss of sensation to paraplegia and quadraplegia
How can brain and spine damage be prevented
Don’t play violent sports
Wear seatbelts
Don’t drink and drive
What is a drug
A substance that changes normal body functions
What do drugs do to neurotransmitters
Stimulate or inhibit
What are the three categories of drugs and what are examples of drugs in each category
Stimulant - accelerate impulses : caffeine, nicotine, dagga
Depressant - slow doen impulses : alcohol, dagga, heroine
Hallucinogens - distort perceptions : dagga, ecstacy, LSD
What can dagga cause after intake
Drowsiness, decreased co-ordination, euphoria uncontrollable talking
What can high dosage of dagga lead to
Paranoia and hallucination
How does heroin work
Extracted from poppy plants
White/brown powder usually injected
Mimics endorphins
What is ecstacy
Stimulant commonly used at dance parties for extra energy
How does ecstacy work
Increases heart rate, bp and body temp
Has negative effect on emotions, memory and ability to learn
What is tik used for
To stay awake for long periods of time
How does tik work
Causes excessive release of dopamine which over-stimulates the neurons of brain
Createsfeeling of euphoria but damages neurons
What can long term use of til lead to
Insomnia, anxiety, paranoia
