neurological system

what are the two major divisions of the nervous system

the central nervous system (CNS) and peripheral nervous system (PNS)

what structures make up the CNS

the brain and spinal cord

what structures make up the PNS

cranial nerves, spinal nerves, ganglie, and peripheral sensory receptors

divisions of the PNS

autonomic and somatic nervous systems

what is the main function of the somatic nervous system

voluntary control of skeletal muscles and conscious sensory perception

what is the main function of the autonomic nervous system (ANS)

regulation of involuntary visceral functions such as heart rate, digestion, and thermoregulation

what are the two divisions of the autonomic nervous system

sympathetic and parasympathetic nervous systems

how do sympathetic and parasympathetic systems usually affect organs

they usually have opposite effects on the same target tissues (antagonistic)

what is homeostasis

maintenance of a stable environment

what are the four major anatomical regions of the brain

telencephalon, diencephalon, brainstem, and cerebellum

what structures are included in telencephalon

cerebral cortex and deep cerebral structures

what structures are included in the diencephalon

thalamus and hypothalamus

what structures form the brainstem

midbrain, pons, and medulla oblongata

what are the major functions of the brainstem

regulation of vital functions such as breathing, heart rate, and consciousness

what is the main function of the cerebellum

coordination of movement, posture, and balance

what protects the brain physically

the skull, meninges, and cerebrospinal fluid (CSF)

what are the functions of cerebrospinal fluid (CSF)

cushioning, insulation, buoyancy, and maintaining the brain’s environment

what is the blood-brain barrier

a selective barrier that controls which substances enter brain tissue

what are neurons

excitable nerve cells that receive, conduct, and transmit signals

what are the three main parts of a neuron

cell body, dendrites, and axon

what is the function of the cell body

contains the nucleus and maintains neuro function

what is the function of dendrites

receiving incoming signals

what is the function of the axon

carrying signals away from the neuron

what is a synapse

the junction where signals pass from one neuron to another

how are signals transmitted across synapses

by release of neurotransmitters from axon terminals

approximately how many synapses are in the human brain

around 500 trillion

what is grey matter

areas rich in neuron cell bodies

what is white matter

areas rich in myelinated axons

what is myelin

a fatty insulating sheath around axons that increases conduction speed

what are nodes of Ranvier

gaps in the myelin sheath containing ion channels

what is saltatory conduction

neurons carrying signals towards the CNS

what are glial cells

support cells that protect, nourish, and insulate neurons

what is encephalisation

evolutionary increase in brain size relative to body size

which brain regions are associated with higher cognitive functions

the front and upper parts of the cerebrum

what are examples of higher cognitive functions

conscious awareness, reasoning, decision-making, and personality

why are primitive brain systems still important

they regulate essential survival functions

what factors influence brain development and behaviour

genetics, environment, experience, epigenetics, and synaptic plasticity

what is synaptic plasticity

the ability of synapses to strengthen or weaken over time

where do sympathetic preganglionic neurons originate

thoracic and lumbar spinal cord

where do parasympathetic preganglionic neurons originate

brainstem and lower spinal cord

which neurotransmitter is released by all preganglionic autonomic neurons

acetylcholine

what neurotransmitter is usually released by sympathetic postganglionic neurons

noradrenaline

what neurotransmitter is released by parasympathetic postganglionic neurons

acetylcholine

what is unique about the adrenal medulla

it acts like a modified sympathetic ganglion and releases adrenaline and noradrenaline

what are the two main arterial supplies to the brain

internal carotid arteries and vertebral arteries

which part of the brain is mainly supplied by the internal carotid arteries

the anterior two-thirds

which part of the brain is mainly supplied by the vertebral arteries

the posterior one-third

what is the circle of willis

an arterial anastomosis at the base of the brain providing collateral circulation

why is the circle of willis clinically important

it can maintain blood supply if one artery becomes narrowed or blocked

which arteries form the circle of willis

anterior, middle & posterior cerebral arteries and communicating arteries

what is a stroke (cerebrovascular accident)

interruption of blood supply to the brain causing cell death

what are the two major types of stroke

ischaemic and haemorrhagic

what causes an ischaemic stroke

blockage of a blood vessel supplying the brain

what causes a haemorrhagic stroke

rupture or leakage of a blood vessel

which type of stroke is most common

ischaemic stroke (approximately 85%)

what are common clinical manifestations of strok

weakness on one side, speech problems, visual loss, and altered consciousness

why is rapid treatment essential in stroke

brain tissue dies quickly without oxygen

what imaging methods are commonly used in stroke diagnosis

CT, MRI, PET, and angiography

why must imaging be performed before stroke treatment

to distinguish between ischaemic or haemorrhagic stroke

what are common risk factors for stroke

hypertension, smoking, diabetes, obesity, atrial fibrillation, and high cholesterol

how many cranial nerves are there

12 pairs

how many spinal nerves are there

31 pairs

what is the primary function of the CNS

to process, integrate, store and respond to information from the PNS

what is the primary function of the PNS

to detect stimuli and transmit information to and from the CNS

what is the somatic nervous system responsible for

conscious sensation and voluntary skeletal muscle control

what is the autonomic nervous system responsible for

involuntary regulation of visceral functions and homeostasis

what are sensory (afferent) neurons

neurons carrying signals toward the CNS

what are motor (efferent) neurons

neurons carrying signals away from the CNS to organs or muscles

what are interneurons

neurons connecting other neurons within the CNS

what are multipolar neurons

neurons with many dendrites and one axon

where are multipolar neurons commonly found

in the CNS and among motor neurons

what are bipolar neurons

neurons with one dendrite and one axon

where are bipolar neurons commonly found

retina and olfactory system

what are unipolar neurons

neurons with a single process that divides into two branches

what type of neurons are most sensory neurons

unipolar neurons

which brain structure is essential for forming new memories

the hippocampus

what is anterograde amnesia

inability to form new memories after brain injury

how do neuronal connections support learning and memory

through synaptic plasticity and strengthening of neural pathways

why are emotional memories often strong

emotion enhances memory consolidation

which disease commonly causes progressive memory loss

alzheimer’s disease

which brain regions are especially affected in alzheimer’s disease

hippocampus and cerebral cortex

what are the two major ways memory is classified

by type and duration

what is the limbic system

a group of brain structures involved in emotion, behaviour, and memory

which major structures form the limbic system

hippocampus, amygdala, hypothalamus, and limbic cortex

what is the role of the amygdala

processing emotions, especially after fear and aggression

what is the role of the hypothalamus in the limbic system

regulates autonomic and endocrine responses to emotion

what happens after amygdala lesions

reduced aggressive behaviour

what symptoms can occur with limbic system dysfunction

depression, schizophrenia, emotional disturbance, and memory problems

why are dopamine receptors in the limbic system clinically important

many antipsychotic drugs target them

what are the two major components of diencephalon

thalamus and hypothalamus

main function of the thalamus

relay of sensory and motor information to the cerebral cortex

how much of the diencephalon is made up by the thalamus

approx 80%

main functions of the hypothalamus

endocrine regulation, autonomic control, and limbic functions

what are the three major functions of the brainstem

conduit, cranial nerve, and integrative functions

what are long tracts in the brainstem

ascending and descending pathways carrying sensory and motor information

what clinical problems can result from brainstem damage

cranial nerve deficits, motor and sensory loss, coma, and death

why is the brainstem essential for life

it contains vital physiological centres controlling breathing and cardiovascular function

what symptoms may indicate cranial nerve dysfunction from brainstem injury

facial weakness, swallowing difficulty, speech problems, and eye movement abnormalities

what is the primary role of the cerebellum

coordination and prediction of voluntary movement

what information does the cerebellum receive from the body

proprioceptive and vestibular information