2020 exam revision Flashcards
function of cerebrum:
includes association area (intellectual and emotional processes), motor area (controls muscular movements) and sensory area (interprets impulses), mental activities such as thinking, learning, memory, intelligence.
function of thalamus:
relays motor and sensory signals to cerebral cortex
function of hypothalamus:
releases hormones, regulates body temp
function of pons varolii:
controls breathing and communication between parts of the brain.
functions of medulla oblongata:
controls autonomic functions eg breathing, digestion, heart and blood vessel function.
functions of cerebellum:
receives info from sensory systems, spinal cord and regulates motor movements. exercises control over balance, posture and fine coordination/ muscle movement.
function of ventricles:
produces cerebrospinal fluid + transports it
functions of corpus callosum:
thick band of nerve fibres that divide cerebral cortex lobes into left + right hemispheres, connects left + right sides of the brain allowing for communication.
function of midbrain:
serves in motor movements eg eye movements and visual processing.
function of meninges:
protects the CNS
function of spinal cord:
relays messages from brain to body, to perform an action and to pass along messages from sensory receptors to the brain/coordinate reflexes that are managed by spinal cord alone.
structure of cerebrum:
- outer surface of grey matter
- 2-4mm thick is cerebral cortex
- below cortex is white matter
- inside grey matter is basal ganglia
- convolutions separated by fissures
structure of corpus callosum:
-wide band of nerve fibres under cerebrum
structure of cerebellum:
- surface folded into parallel ridges
- outer part is grey matter, inside is white matter that branches to all parts of cerebellum.
structure of medulla oblongata:
- continuation of the spinal cord
- 3cm long
structure of spinal cord:
-cylindrical extending from foramen magnum to the 2nd lumbar vertebra
what are the 3 types of nerve cells + examples
- unipolar (sensory neurons)
- bipolar (sense organs eg eyes)
- multipolar (connector and motor neurons)
dendrite:
where a nerve impulse enters the cell body
cell body:
contains nucleus, is the site of many chemical reactions
cell body nucleus:
controls the size, shape and function of the cell
axon:
a very long extension of the cell body, where the nerve impulse passes through the cell
shwann cell:
surrounds and insulates the axon
neurilemma:
the outside membrane of the shwann cell, produces a fatty substance called myelin
myelin:
insulates axon
axon termination:
the end of an axon where the nerve impulse can be passed on to the next nerve cell
node of ranvier:
a gap between successive shwann cells, it allows for the movement of transmission chemicals.
what is a reflex?
a rapid, automatic response to a stimulus
what are the 9 types of reflexes?
involuntary rapid innate stereotypical protective visceral monosynaptic polysynaptic learned
what is a monosynaptic reflex?
when a sensory neutron connects directly to a motor neurone (only one synapse) eg knee jerk reflex
what is a polysynaptic reflex?
when a sensory neuron connects to a connector neuron, then to a motor neuron (2 synapses) eg withdrawal reflex
what are the 3 layers of the meninges?
- dura layer= toughest layer, helps to protect brain
- arachnoid layer= filled with a web of collagen fibres, contains cerebrospinal fluid
- pia matter= softest layer, attached to surface of the brain, contains blood capillaries that nourish tissue
function of cerebrospinal fluid?
delivers nutrients, acts as a shock absorber, expels waste
what is a synapse?
the gap between neurons, essential so we can create specific nerve pathways around our body.
what composes the CNS?
brain
spinal cord
what composes of the peripheral nervous system?
somatic NS
autonomic NS
what composes of the autonomic NS?
- cannot be controlled-
- sympathetic and parasympathetic NS
what composes of the somatic NS?
- cranial nerves
- spinal nerves
what is visceral reflex?
-automatic response within the body organ (heart rate, digestion)
describe the transmission of a nerve impulse across a synapse.
- nerve impulse is the movement of na+ ions
- na+ causes calcium channels to open in axon terminal membrane
- calcium ions enter axon terminal
- these calcium ions cause the vesicles containing acetylcholine to rupture, causing acetylcholine to fill the synapse
- receptor proteins on the dendrite membrane detect this, causing na+ channels to open
- these na+ ions move to the dendrite.
what is a synapse?
-the gap between neutrons, is essential so that we can create specific nerve pathway.
difference in speeds between axons?
- unmyelinated = 140ms-1,
- myelinated= 2ms-1
describe the transmission of a nerve impulse along an unmyelinated axon:
- the na+/k+ pump maintains resting membrane potential at -70 mV
- large negatively charged organic molecules make the inside of the axon negatively charged
- the nerve impulse itself is a flow of na+ ions from the cell body along the axon to the axon terminal
- as na+ ions enter axon, membrane potential is raised from -70mV to -55mV
- at -55mV, Na+ gates open, more Na+ ions rush through
- membrane potential is raised to +30mV, then the na+ gates close and the K+ open. K+ ions rush out of axon.
- the leaving K+ ions cause the membrane potential to fall to -70mV, K+ gate closes.
- the sodium/potassium pump switches back on and maintains resting membrane potential.
describe the transmission of a nerve impulse across a myelinated axon:
Is faster because the impulse jumps from node of ranvier to node of ranvier
what is a steady state control system?
maintains a system or function at optimum level by the following means Stimulus Receptor Modulator Effector Response Feedback
what is saltatory propagation?
when the nerve impulse appears to jump from one node of ranvier to the next (transmission along a myelinated axon)
what are thermorecpetors?
- found in the skin
- inform the brain of changes to outdoor temperatures
- Internal thermoreceptors found in hypothalamus (detecting temp of blood flow through the brain)
what is a nephron?
-functional units of the kidney, carrying out the roles of excretion and water regulation.
what does ADH do in terms of kidneys?
- controls the permeability of the walls of distal convoluted tubule.
- when concentration of ADH in plasma is high, tubules are permeable to water-leaving tubules and joining surrounding capillaries.
- when ADH conc in plasma is low, tubules are not very permeable to water, and little water is reabsorbed by capillaries.
what is the difference between protein, amine and steroid hormones?
- protein and amine hormones bind to receptors on the membrane of the cell
- steroid hormones bind to receptors inside the cell
what hormones does the anterior lobe produce? (6)
- FSH
- LH
- prolactin
- ACTH
- TSH
- growth hormone
what hormones does the posterior lobe produce?
- oxytocin
- ADH
role of the thyroid gland:
- releases thyroxin upon recieving stimulus of TSH from anterior
- thyroxine controls body metabolism by releasing more energy for reactions.
role of parathyroid glands:
-secrete the parathyroid hormone (parathormone) which controls calcium and phosphate in blood.
role of the thymus:
-secretes thymosins, which influence maturation of disease fighting cells (T lymphocytes)
role of the adrenal glands
- secrete adrenaline and noradrenaline (fight or flight)
- secretes aldosterone (reduces sodium and increases potassium in urine) and cortisol (promotes normal metabolism)
role of the pancreas (islets of langerhans):
- releases insulin (reduces amount of glucose in blood, in the liver causes conversion of glucose to glycogen and fat, in skeletal muscles causes conversion of glucose to glycogen and acts as storage in fat tissue)
- releases glucagon, (works to increase blood glucose, by promoting breakdown of glycogen to glucose in the liver)
what is grey matter (when referring to nerve cells)
-consists of nerve cell bodies and unmyelinated fibres
what is white matter (when referring to nerve cells)
-consist of myelinated fibres (lipid covered)
what is the ANS?
- controls bodies internal environment
- operates without conscious control, regulated by nerve cells in medulla oblongata, hypothalamus and cerebral cortex
- controls blood pressure, temperature, digestion, defecation, urination
difference between autonomic and somatic NS?
- autonomic is involuntary muscles and glands, somatic is voluntary skeletal muscles
- autonomic is response to homeostasis, somatic is response to external forces
what are the 3 types of reabsorption in ultrafiltration?
- facultative reabsorption
- selective reabsorption
- active secretion