IB Biology Exam Notes PDF

+-----------------------------------+-----------------------------------+ | **Parts of a neuron** | axon, myelin sheath, button | | | terminals, Nodes of Ranvier, | | | dendrites, nucleus, and cell body | |...

+-----------------------------------+-----------------------------------+ | **Parts of a neuron** | axon, myelin sheath, button | | | terminals, Nodes of Ranvier, | | | dendrites, nucleus, and cell body | | | (soma) | +===================================+===================================+ | **Soma** | cell body | | | | | | metabolic center of the neuron | | | | | | contains: | | | | | | nucleus of the cell | | | | | | neurotransmitter-synthesizing | | | mechanisms | | | | | | energy producing and story | | | structures | +-----------------------------------+-----------------------------------+ | **dendrites** | input unit | | | | | | branchlike extensions that | | | receive information from other | | | neurons | +-----------------------------------+-----------------------------------+ | **axon** | output unit | | | | | | extends from cell bodied to | | | target cells and transmits | | | information to other cells | | | | | | vary from 1 meter to a few | | | centimeters | +-----------------------------------+-----------------------------------+ | **axon hillock** | small bump between axon and cell | | | body where axon originates | +-----------------------------------+-----------------------------------+ | **oligodendrocytes** | myelinates axons in the central | | | nervous system | +-----------------------------------+-----------------------------------+ | **Schwann cells** | myelinates axons in the | | | peripheral nervous system | +-----------------------------------+-----------------------------------+ | **Pre-synaptic terminals** | fingerlike projections at the end | | | of axon | | | | | | belongs to the neuron | | | transmitting information | +-----------------------------------+-----------------------------------+ | **Post-synaptic terminal** | area on dendrite, cell body, or | | | axon which receives the signal | | | transmitted from pre-synaptic | | | terminal | +-----------------------------------+-----------------------------------+ | **synaptic cleft** | space between two terminals | +-----------------------------------+-----------------------------------+ | **neurotransmitters** | chemical compounds that transfer | | | information about its activity | +-----------------------------------+-----------------------------------+ | **what is the only direction | pre-synaptic terminal to | | information can be transferred | post-synaptic terminal | | in?** | | +-----------------------------------+-----------------------------------+ | **Nodes of Ranvier** | spaces in the myelin sheath not | | | covered by a fatty substance | | | | | | important for saltatory | | | conduction and aid in speed of | | | signal transmission | +-----------------------------------+-----------------------------------+ | **How do Nodes and Ranvier aid in | signal jumps over myelinated | | speed?** | areas like leapfrog rather than | | | flowing down length of axon | +-----------------------------------+-----------------------------------+ | **Action potential** | ALL or NONE Principle: either the | | | stimulus is strong enough or not | | | to result in action potential | +-----------------------------------+-----------------------------------+ | **Excitatory Post-Synaptic | EPSP | | Potential** | | | | positive charges that cause the | | | next neuron to move towards the | | | action potential | +-----------------------------------+-----------------------------------+ | **Inhibitory Post-Synaptic | IPSP | | Potential** | | | | negative charges that cause next | | | neuron to move away from action | | | potential | +-----------------------------------+-----------------------------------+ | **Absolute Refractory period** | period immediately following an | | | action potential during which a | | | neuron cannot fire another action | | | potential, regardless of stimulus | | | strength | | | | | | time of firing levels to 1/3 of | | | the way through repolarizing | +-----------------------------------+-----------------------------------+ | **Relative Refractory Period** | period following an action | | | potential during which a neuron | | | can fire an action potential, but | | | requires a stronger stimulus than | | | usual | | | | | | last 2/3 of rest of the potential | +-----------------------------------+-----------------------------------+ | **Temporal Summation** | | +-----------------------------------+-----------------------------------+ | **Spatial Summation** | occurs when positive charges keep | | | coming in over and over | +-----------------------------------+-----------------------------------+ | **Describe an action potential** | -Resting potential: -60 mV | | | | | | -Stimulus causes cell to reduce | | | negativity (move in positive | | | direction) to -50 or -45 mV | | | | | | -At the threshold for a cell to | | | fire (-50), receptor proteins | | | open and sodium rushes in (sodium | | | is positively charged) | | | DEPOLARIZATION | | | | | | -Depolarization continues until | | | cell crosses 0 | | | | | | -At peak (35 to 40 mV) cell pumps | | | out potassium and begins to move | | | in a negative direction | | | REPOLARIZATION | +-----------------------------------+-----------------------------------+ | **hyperpolarization** | state in which it is hard for a | | | cell to fire | | | | | | results in absolute refractory | | | and relative refractory periods | +-----------------------------------+-----------------------------------+ | **consequences of positive and | positive charges cause resting | | negative charges** | potential to increase and can | | | cause action potential | | | | | | negative charges cause resting | | | potential to decrease and do | | | nothing regarding action | | | potentials | +-----------------------------------+-----------------------------------+ | **relationship between strength | stronger stimulus - shorter | | of stimulus and latency** | latency | +-----------------------------------+-----------------------------------+ | **sensory nervous system** | vision | | | | | | hearing | | | | | | touch | | | | | | smell | +-----------------------------------+-----------------------------------+ | **measuring sensitivity in | level of sensitivity is based on | | sensory nervous system** | how many nerve fibers are | | | affected | +-----------------------------------+-----------------------------------+ | **motor nervous system** | causes muscles to assume various | | | degrees of contraction | +-----------------------------------+-----------------------------------+ | **ration of nerve and muscle best | low nerve to muscle ratio | | for fine motor movement | | | (innervation ratio)** | 1 to 1 is better than 1 to 100 | +-----------------------------------+-----------------------------------+ | **What are the three layers of | Dura Mater | | the meninges?** | | | | Arachnoid Mater | | | | | | Pia Mater | +-----------------------------------+-----------------------------------+ | **Dura Mater** | outermost layer, thick and non | | | elastic | | | | | | made of two united layers | | | | | | has two folds of tissue that | | | protect brain from displacement: | | | | | | falx cerebri | | | | | | ternorium cerebelli | +-----------------------------------+-----------------------------------+ | **subdural space** | space below dura filled with | | | cerebrospinal fluid (CSF) | +-----------------------------------+-----------------------------------+ | **Arachnoid Mater** | inferior to subdural space | | | | | | bridges the sulci and projects | | | into venous sinuses to form | | | arachnoid villi- important for | | | uptake of CSF into bloodstream | +-----------------------------------+-----------------------------------+ | **subarachnoid space** | below arachnoid mater and filled | | | with CSF | | | | | | important because all cerebral | | | arteries, veins, and cranial | | | nerves pass through this space | +-----------------------------------+-----------------------------------+ | **Pia Mater** | closely adheres to surface of the | | | brain (cannot be removed without | | | destroying cerebral cortex) | | | | | | bridges gyri and extends down to | | | sulci | +-----------------------------------+-----------------------------------+ | **ependyma** | membrane that lines the | | | ventricles to form chiroid plexus | | | - produces CSF | +-----------------------------------+-----------------------------------+ | **What are the ventricles?** | Lateral Ventricles | | | | | | Third Ventricle | | | | | | Fourth Ventricle | +-----------------------------------+-----------------------------------+ | **Lateral Ventricles** | paired structures, but considered | | | as one | | | | | | C-shaped | | | | | | choroid plexus located on medial | | | aspect | +-----------------------------------+-----------------------------------+ | **Name and locations of the | Body: parietal lobe  | | division of the Lateral | | | Ventricle** | Anterior horn: frontal lobe | | | | | | Posterior horn: occipital lobe | | | | | | inferior horn: temporal lobe | +-----------------------------------+-----------------------------------+ | **Third Ventricle** | located between thalamis | | | | | | small slit that is connected to | | | lateral ventricle by foramen of | | | Munro and to fourth ventricle by | | | aqueduct of Sylvius | | | | | | chiroid plexus located on rood of | | | ventricle | +-----------------------------------+-----------------------------------+ | **Fourth Ventricle** | anterior to cerebellum and | | | posterior to pons & upper hald of | | | medulla | | | | | | continuous with cerebral aqueduct | | | and central canal | | | | | | chiroid plexus is T shaped | +-----------------------------------+-----------------------------------+ | **Four parts of Fourth | roof | | ventricle** | | | | walls (2) | | | | | | floor | +-----------------------------------+-----------------------------------+ | **Major foreamen of Fourth | lateral formina of Luschka | | ventricle** | | | | foreamen of Magendie  | | | | | | empties CSF into subarachnoid | | | space | +-----------------------------------+-----------------------------------+ | **Major function of ventricles** | To provide circulation of CSF | | | | | | buildup of CSF- hydrocephalus | +-----------------------------------+-----------------------------------+ | **Cerebral spinal fluid** | colorless fluid that protects | | | brain and spinal cords by | | | separating them from bones | | | | | | functions: | | | | | | protection | | | | | | provide nourishment to nervous | | | tissue | | | | | | regulate intracranial pressure | | | | | | pressure can be measured for | | | diagnostic purposes | +-----------------------------------+-----------------------------------+ | **Divisions of the Brain** | Hindbrain | | | | | | Midbrain | | | | | | Forebrain | +-----------------------------------+-----------------------------------+ | **Hindbrain** | Rhombencephalon | | | | | | lowest level of the brain | | | | | | two subdivisions: | | | | | | Afterbrain | | | | | | Marrowbrain | +-----------------------------------+-----------------------------------+ | **Afterbrain** | Metencephalon | | | | | | Subdivision of Hindbrain | | | | | | includes pons and cerebellum | +-----------------------------------+-----------------------------------+ | **Marrowbrain** | Myelencephalon | | | | | | subdivision of Hindbrain | | | | | | consists of medulla oblongota | +-----------------------------------+-----------------------------------+ | **Medulla** | smallest part of the brain | | | | | | location where some cranial | | | nerves enter and exit | | | | | | attaches to spinal cords in | | | higher areas | +-----------------------------------+-----------------------------------+ | **Midbrain** | Mesencephalon | | | | | | consists only of midbrain | | | | | | highest part of brainSTEM with | | | some connections leaving midbrain | +-----------------------------------+-----------------------------------+ | **Forebrain** | Prosencephalon | | | | | | highest part pf the brain | | | | | | consists of endbrain and | | | interbrain | +-----------------------------------+-----------------------------------+ | **Endbrain** | Telencephalon | | | | | | made of cerebral hemispheres and | | | basal ganglia (crucial for motor | | | control and higher cognitive | | | function) | +-----------------------------------+-----------------------------------+ | **Interbrain** | Diencephalon | | | | | | consists of thalamus and | | | hypothalamus | +-----------------------------------+-----------------------------------+ | **thalamus** | first stop for all sensory | | | information (besides | | | olfaction)and first area with | | | connections to arousal | +-----------------------------------+-----------------------------------+ | **hypothalamus** | important for basic functions | | | (body temp. and hunger) | | | | | | regulates sensation | +-----------------------------------+-----------------------------------+ | **Major arteries of the brain** | vertebral | | | | | | internal carotid | | | | | | communicating | +-----------------------------------+-----------------------------------+ | **Vertebral arteries** | form basilar artery at base of | | | pons which splits to form | | | posterior cerebral arteries - | | | supply posterior temporal lobe | | | and occipital lobe | +-----------------------------------+-----------------------------------+ | **Internal Carotid Arteries** | anterior cerebral artery: | | | supplies medial aspects | | | | | | middle cerebral artery: supplies | | | lateral aspects | +-----------------------------------+-----------------------------------+ | **communicating arteries** | important incase of blockages | | | | | | posterior: attaches front and | | | back arteries | | | | | | anterior: attaches left and right | | | arteries | +-----------------------------------+-----------------------------------+ | **Circle of Willis** | system of arteries | | | | | | defense mechanism to provide | | | blood flow is blockage occurs | +-----------------------------------+-----------------------------------+ | **Cranial nerves** | 12 pairs (24 total) | +-----------------------------------+-----------------------------------+ | **Cranial nerve I** | Olfactory | | | | | | sensory | | | | | | smell | +-----------------------------------+-----------------------------------+ | **Cranial nerve II** | Optic | | | | | | sensory | | | | | | sight | +-----------------------------------+-----------------------------------+ | **Cranial nerve III** | Oculomotor | | | | | | motor | | | | | | eye movement | +-----------------------------------+-----------------------------------+ | **Cranial nerve IV** | trochlear | | | | | | motor | | | | | | movement for 1 eye muscle | +-----------------------------------+-----------------------------------+ | **Cranial nerve V** | trigeminal | | | | | | both sensory and motor | | | | | | S: face and mouth | | | | | | M: chewing and soft palate | +-----------------------------------+-----------------------------------+ | **Cranial nerve VI** | abducens | | | | | | motor | | | | | | moving eyes outward | +-----------------------------------+-----------------------------------+ | **Cranial nerve VII** | facial | | | | | | both sensory and motor | | | | | | S: tongue and outer ear | | | | | | M: facial expression | +-----------------------------------+-----------------------------------+ | **Cranial nerve VIII** | auditory/vestibular | | | | | | sensory | | | | | | hearing and balance | +-----------------------------------+-----------------------------------+ | **Cranial nerve IX** | glossopharyngeal | | | | | | both sensory and motor | | | | | | S: tongue and tympanic membrane | | | | | | M: sylophayngous - important for | | | swallowing and speech) | +-----------------------------------+-----------------------------------+ | **Cranial nerve X** | vagus | | | | | | both sensory and motor | | | | | | S: lower pharynx and inner larynx | | | | | | M: pharynx and larynx muscles | +-----------------------------------+-----------------------------------+ | **Cranial nerve XI** | spinal accessory | | | | | | motor | | | | | | soft palate, larynx, and neck | | | muscles | +-----------------------------------+-----------------------------------+ | **Cranial nerve XII** | hypoglossal | | | | | | motor | | | | | | tongue movement/tongue control | +-----------------------------------+-----------------------------------+ | **plasticity** | ability to rebound after brain | | | damage | | | | | | decreases with age | +-----------------------------------+-----------------------------------+ | **theory of equipotentiality** | any neural tissue can subserve | | | any function (can process any | | | type of information within | | | reason) | +-----------------------------------+-----------------------------------+