1
Q
Neurons
A
Excitable cells that process and transmit information; they give the nervous system its unique functions (thinking, sensing, moving).
2
Q
Glia
A
Support cells that help neurons function (nutrition, insulation, cleanup, etc.).
3
Q
About how many neurons and glial cells are in the human nervous system?
A
~100 billion neurons (give or take ~100 million). About 10 times as many glia as neurons.
4
Q
What are the main parts of a typical neuron?
A
Cell body (soma), Dendrites (input branches), Axon (output cable), Axon terminals / synaptic terminals.
5
Q
What is the soma (cell body) and what is its approximate size?
A
The soma is the main part of the neuron that contains the nucleus and most organelles. It is about 20 μm in diameter.
6
Q
What is cytoplasm?
A
Everything inside the cell membrane except the nucleus (organelles + cytosol).
7
Q
What is the function of the nucleus in a neuron?
A
Contains chromosomes (DNA), which hold genetic information. Site of gene expression: DNA → (transcription) → mRNA mRNA → (translation on ribosomes) → protein.
8
Q
What are ribosomes and what do they do?
A
Ribosomes are the sites where proteins are made (protein synthesis).
9
Q
What is the difference between rough and smooth endoplasmic reticulum (ER)?
A
Rough ER: Has ribosomes; important for protein synthesis. Smooth ER: Lacks ribosomes; helps transport and modify proteins and in some cells helps with lipid synthesis and detox.
10
Q
What is the main function of mitochondria in neurons?
A
They perform metabolic functions and make ATP, the cell’s main energy source.
11
Q
What does the Golgi apparatus do in neurons?
A
It performs post-translational modification of proteins and helps package and sort them for delivery.
12
Q
Why is the neuronal membrane so important?
A
Because membrane structure and its proteins (ion channels, pumps, receptors) determine how neurons generate electrical signals and communicate.
13
Q
What are the two main types of neurites?
A
Axons, Dendrites.
14
Q
What are key features of axons?
A
Each neuron usually has one axon. Conducts nerve impulses away from the soma to other neurons or muscles. Can be up to 1 meter long. Conduction speed increases with axon diameter.
15
Q
What are key features of dendrites?
A
Usually short and branched (rarely > 2 mm). Often arranged symmetrically around the soma. Act as “antennae” that receive input from other neurons. All the dendrites together are called the dendritic tree.
16
Q
What do “afferent” and “efferent” mean?
A
Afferent: Carry information into a structure (toward CNS or toward soma). Efferent: Carry information away from a structure (from CNS or from soma).
17
Q
What is a synapse and what is its main function?
A
A junction where an axon terminal of one neuron contacts another cell (neuron, muscle, gland). It is the site of neurotransduction: electrical signal → chemical signal → new electrical/chemical signal.
18
Q
What are the structural elements of a typical chemical synapse?
A
Presynaptic terminal / axon terminal, Synaptic vesicles with neurotransmitter, Synaptic cleft (tiny space between cells), Postsynaptic membrane (usually on a dendrite) with receptors.
19
Q
What is a neurotransmitter and what is a receptor?
A
Neurotransmitter (NT): Chemical released by presynaptic neuron that carries the signal. Receptor: Specialized protein on the postsynaptic membrane that binds the NT and transduces the signal into a change inside the cell.
20
Q
What are glial cells and what is their general role?
A
Glia are support cells in the nervous system that help neurons survive and function (clean up neurotransmitters, insulate axons, regulate environment).
21
Q
What do astrocytes do?
A
Regulate extracellular space around neurons. Help remove neurotransmitters from synapses. Help maintain ion balance and may help form the blood-brain barrier.
22
Q
What do oligodendrocytes and Schwann cells do?
A
They are myelinating glia: Oligodendrocytes: Myelinate axons in the CNS. Schwann cells: Myelinate axons in the PNS. Their wrapping forms the myelin sheath, which insulates axons and speeds conduction.
23
Q
What is the Node of Ranvier?
A
A small gap in the myelin sheath where the axon membrane is exposed; it is the site where action potentials are regenerated in myelinated axons.
24
Q
What is the resting membrane potential?
A
The voltage difference across the neuronal membrane when the neuron is at rest, with the inside negative relative to the outside (about –65 to –70 mV).
25
What three big things determine the resting membrane potential?
Ionic concentration differences inside vs outside. Selective permeability of the membrane (ion channels). The Na⁺/K⁺ pump that moves ions using ATP.
26
What are the main ions involved in neuronal electrical activity?
Cations: Na⁺, K⁺, Ca²⁺ Anions: Cl⁻ and negatively charged proteins.
27
What is diffusion in this context, and what two things are needed for ions to diffuse across a neuronal membrane?
Diffusion: Net movement of ions from high concentration to low concentration. Needs: A concentration gradient, An ion channel specific for that ion.
28
What is an electrical potential (voltage)?
The difference in charge between two points (like inside vs outside the neuron) that creates a force pushing charged particles to move.
29
What is electrochemical equilibrium for an ion?
The point where the diffusion force (due to concentration gradient) and the electrical force (due to voltage) are equal and opposite, so there is no net ion movement.
30
What does the sodium-potassium pump do, and why is it important?
It uses ATP to pump 3 Na⁺ out and 2 K⁺ in. This creates and maintains high Na⁺ outside, high K⁺ inside, and makes the inside more negative. It uses ~70% of the brain’s energy.
31
At rest, what do K⁺ and Na⁺ “want” to do and why don’t they move freely?
K⁺: Wants to move out (higher inside) but is pulled in by the negative inside; balance of these forces helps set resting potential. Na⁺: Wants to move in (higher outside and attracted to negative inside) but Na⁺ channels are tightly closed at rest.
32
What is an action potential (AP)?
A rapid, brief reversal of membrane potential where the inside of the neuron becomes positive relative to the outside, then returns to rest.
33
What are three key properties of action potentials?
Do not diminish as they travel (no decrement). Fixed size and duration (for a given neuron). All-or-none: Either they occur fully or not at all.
34
What do “depolarization” and “hyperpolarization” mean?
Depolarization: Membrane potential becomes less negative (moves toward zero or positive). Hyperpolarization: Membrane potential becomes more negative than resting.
35
What is “threshold” in terms of action potentials?
The critical level of depolarization needed to open enough voltage-gated Na⁺ channels to trigger an action potential.
36
Name and briefly describe the phases of an action potential on a voltage vs. time graph.
Rising phase: Rapid depolarization due to Na⁺ influx. Overshoot: Inside of cell becomes positive. Falling phase: Repolarization due to K⁺ efflux. Undershoot: Membrane becomes more negative than rest (after-hyperpolarization).
37
What ion mainly causes the rising phase of the action potential?
Na⁺ influx through voltage-gated Na⁺ channels.
38
What ion mainly causes the falling phase and undershoot of the action potential?
K⁺ efflux through voltage-gated K⁺ channels and leak K⁺ channels.
39
What are voltage-gated Na⁺ channels and how do they behave during an AP?
Open quickly when the membrane depolarizes (around –65 to –45 mV). Allow Na⁺ to rush in → rising phase. Then inactivate (close) after ~1 ms. They cannot reopen until the membrane returns to near resting potential.
40
What are voltage-gated K⁺ channels and how do they behave during an AP?
Open more slowly (delayed) after depolarization. Open as Na⁺ channels inactivate → K⁺ leaves the cell → falling phase. Do not inactivate quickly; stay open until membrane approaches K⁺ equilibrium, causing undershoot.
41
What is the absolute refractory period? What causes it?
Time during which no new AP can be generated. Caused by inactivated Na⁺ channels that cannot reopen until the membrane is repolarized.
42
What is the relative refractory period?
A period after the absolute refractory period when another AP can occur, but it requires a stronger-than-normal stimulus because the membrane is hyperpolarized and some Na⁺ channels are still recovering.
43
Why can’t an action potential just passively spread along the axon without regeneration?
Because the membrane is leaky; passive current decays with distance, so an active, regenerating process is needed to carry signals long distances.
44
How does an action potential propagate down an axon?
AP at one segment → Na⁺ influx → local depolarization. This passive current spreads to the next segment, depolarizing it to threshold. New AP occurs there. Upstream Na⁺ channels are inactivated and K⁺ channels open, so the AP moves forward only.
45
Where are action potentials usually initiated in a neuron in vivo? Why?
At the axon hillock (initial segment) because it has a high density of voltage-gated Na⁺ and K⁺ channels, making it very sensitive to depolarization.
46
How does axon diameter affect conduction velocity?
Larger diameter → less internal resistance to current flow → faster conduction velocity.
47
What is saltatory conduction and how does myelin affect conduction?
Saltatory conduction: APs “jump” from one Node of Ranvier to the next in myelinated axons.
Myelin:
Acts as insulation, reducing current leak.
Decreases membrane capacitance, so voltage changes spread faster.
APs only need to be regenerated at nodes → greatly speeds conduction.
48
What is an electrical synapse and how common is it in adult mammals?
Uses gap junctions (connexons) that allow direct current flow between cells.
Synaptic cleft is very narrow (~5 nm).
They are rare in the adult mammalian nervous system.
49
What is a chemical synapse?
A synapse where an electrical signal in the presynaptic neuron is converted into a chemical signal (neurotransmitter release), which then generates an electrical/chemical response in the postsynaptic cell. This is the predominant type in the CNS.
50
List the main steps of synaptic transmission at a chemical synapse.
AP arrives at axon terminal.
Voltage-gated Ca²⁺ channels open; Ca²⁺ enters terminal.
Ca²⁺ triggers exocytosis of NT vesicles at the active zone.
NT diffuses across synaptic cleft.
NT binds to postsynaptic receptors.
Postsynaptic cell responds (ion flow and/or second messenger effects).
NT is removed/inactivated (reuptake, breakdown, diffusion, etc.).
51
What are four main ways neurotransmitters are inactivated?
Enzymatic degradation
Reuptake into presynaptic terminal or glia
Diffusion away from synapse
Bioconversion into inactive forms.
52
What three criteria must a substance meet to be considered a classical neurotransmitter?
Must be synthesized and stored in the presynaptic neuron.
Must be released when the presynaptic neuron is stimulated.
When applied to the target cell, it must produce the same effect as the natural presynaptic release.
53
What are the two main size classes of neurotransmitters? Give examples.
Small-molecule NTs:
Amino acids: glutamate, aspartate, GABA, glycine, acetylcholine.
Biogenic amines: dopamine, norepinephrine, epinephrine, serotonin (5-HT).
Neuropeptides: short chains of amino acids (3–30 aa), e.g., met-enkephalin.
54
What does “cholinergic neuron” mean and where is ACh used?
Cholinergic: neuron that uses acetylcholine (ACh) as its NT.
ACh is NT at:
Neuromuscular junction
Preganglionic neurons of both sympathetic and parasympathetic ANS
Postganglionic parasympathetic neurons
Some basal forebrain and brainstem neurons.
55
How is acetylcholine synthesized and broken down?
Synthesized from acetyl-CoA + choline, by enzyme choline acetyltransferase (ChAT).
Broken down in the synaptic cleft by acetylcholinesterase.
56
What are the three catecholamine neurotransmitters and from what amino acid are they made?
Dopamine (DA)
Norepinephrine (NE)
Epinephrine (EPI)
All are synthesized from the amino acid tyrosine and have a catechol group.
57
How are catecholamine neurotransmitters inactivated, and what drugs affect this?
Mainly inactivated by reuptake into presynaptic terminals.
Cocaine and amphetamine block reuptake, prolonging their activity.
58
What is serotonin (5-HT), and what is its role?
Full name: 5-hydroxytryptamine (5-HT).
Inactivated by reuptake.
5-HT systems help regulate mood, emotional behavior, and sleep.
59
How do SSRIs like Prozac affect serotonin signaling?
They block the reuptake of serotonin, so 5-HT stays longer in the synaptic cleft and its activity is prolonged.
60
What are the main amino acid neurotransmitters in the CNS and their main actions?
Glutamate (Glu): primary excitatory NT in CNS.
GABA: main inhibitory NT in CNS.
Glycine: also an inhibitory NT, especially in spinal cord.
61
What is a diffuse neuromodulatory system?
A system where small groups of neurons (often in the brainstem) send widely spreading axons that release modulatory NTs (like DA, NE, 5-HT, ACh) to large areas of the brain, influencing many neurons at once.
62
Where are dopamine neurons located and what are two major DA systems?
Many DA neurons have cell bodies in the substantia nigra and ventral tegmental area (VTA).
System I (nigrostriatal): Substantia nigra → involved in movement control.
System II (mesolimbic/mesocortical from VTA): involved in reward and reinforcement.
63
Where are most serotonin cell bodies found and what do they influence?
Located in the raphe nuclei of the brainstem.
Influence sleep, mood, and emotional behavior.
64
Where are norepinephrine cell bodies found and what is special about their projections?
Most are in the locus coeruleus.
Each NE neuron makes extremely diffuse connections (hundreds of thousands of synapses) across brain regions, helping globally regulate brain activity and arousal.
65
Where does acetylcholine act as a neuromodulator in the brain?
In the basal forebrain and related structures, as well as the neuromuscular junction in the periphery.
66
What are the two major classes of neurotransmitter receptors?
Ligand-gated ion channels (ionotropic)
G-protein-coupled receptors (metabotropic)
67
What is an ionotropic (ligand-gated ion channel) receptor and how fast is it?
A receptor that is itself an ion channel; when NT binds, it opens and lets ions flow.
Produces fast synaptic transmission (EPSPs/IPSPs in 2–5 ms).
68
What is a metabotropic (G-protein-coupled) receptor and how fast is it?
A receptor that activates G-proteins inside the cell, which then act on ion channels or second messenger systems.
Produces slower effects (from hundreds of ms to minutes or longer), often with wider metabolic changes.
69
What is an EPSP and what types of ion movements usually cause it?
Excitatory postsynaptic potential (EPSP): small depolarization that brings the membrane closer to threshold.
Caused by cations entering (e.g., Na⁺ in) or anions leaving.
70
What is an IPSP and what ion movements usually cause it?
Inhibitory postsynaptic potential (IPSP): small hyperpolarization that moves the membrane away from threshold.
Caused by anions entering (e.g., Cl⁻ in) or cations leaving (e.g., K⁺ out).
71
How can EPSPs and IPSPs combine to control firing?
They sum:
Temporal summation: multiple PSPs at the same synapse closely spaced in time.
Spatial summation: PSPs from different synapses at the same time.
If enough EPSPs (minus IPSPs) bring the neuron to threshold, an AP fires.
72
What are examples of ligand-gated ionotropic receptors?
Nicotinic ACh receptor (nAChR) – ionotropic ACh receptor.
AMPA and NMDA glutamate receptors.
GABA_A receptors (Cl⁻ channels).
73
What are examples of metabotropic receptors?
mGluR (metabotropic glutamate receptors).
Muscarinic ACh receptors (m1–m5).
Adrenergic receptors: NE α₁, α₂, β₁, β₂.
Dopamine receptors: D1–D5.
GABA_B receptors.
Many serotonin receptors (e.g., 5-HT₁, 5-HT₂).
Most neuropeptide receptors.
74
What is the basic sequence of events for a G-protein-coupled receptor response?
NT binds to metabotropic receptor.
Receptor activates a G-protein.
G-protein activates an effector protein (ion channel or enzyme).
Effector changes ion flow or produces second messengers that alter cell function.
75
What is the role of adenylate cyclase and cAMP in second messenger signaling?
Adenylate cyclase converts ATP to cAMP (a second messenger).
cAMP can:
Directly open or close ion channels.
Activate protein kinase A (PKA) → phosphorylates target proteins (including ion channels) → changes their function and PSPs.
76
What does phospholipase C do and what second messengers does it generate?
Phospholipase C cleaves a membrane phospholipid to form:
IP₃ (inositol triphosphate)
DAG (diacylglycerol)
IP₃ releases Ca²⁺ from intracellular stores, and DAG activates protein kinase C, which can change the opening of many ion channels.
77
How can neurotransmitters ultimately affect gene expression?
Through second messenger cascades (like cAMP) that activate transcription factors such as CREB, leading to changes in gene expression and long-term changes in neuron function.
78
What do the terms anterior/rostral and posterior/caudal mean?
Anterior / rostral: Toward the front.
Posterior / caudal: Toward the back.
79
What do dorsal and ventral mean in human neuroanatomy?
Dorsal: Toward the back (or top of brain).
Ventral: Toward the belly/front (or bottom of brain).
80
What do medial and lateral mean?
Medial: Toward the midline.
Lateral: Away from the midline.
81
What do ipsilateral and contralateral mean?
Ipsilateral: On the same side of the body.
Contralateral: On the opposite side of the body.
82
What are the three main planes used to section the brain?
Coronal (frontal): Divides front and back.
Sagittal: Divides right and left (midsagittal is exact midline).
Horizontal (transverse): Divides top and bottom.
83
What is gray matter vs white matter?
Gray matter: Contains neuron cell bodies, dendrites, and synapses.
White matter: Contains myelinated axons (the myelin makes it look white).
84
What is a nucleus vs a ganglion (in neuroanatomy)?
Nucleus: Cluster of neuron cell bodies in the CNS.
Ganglion: Cluster of neuron cell bodies in the PNS.
85
What is a tract vs a nerve?
Tract: Bundle of axons in the CNS.
Nerve: Bundle of axons in the PNS.
86
What are gyri, sulci, and fissures?
Gyrus: Ridge/bump on the brain surface.
Sulcus: Shallow groove.
Fissure: Deep groove.
87
What are the two main functional divisions of the nervous system?
Central nervous system (CNS): Brain + spinal cord. Peripheral nervous system (PNS): Nerves and ganglia outside the CNS (somatic + autonomic).
88
How are gray and white matter arranged in the CNS vs PNS?
CNS (brain): Gray matter mostly on the surface (cortex, nuclei). White matter mostly deep/central. Spinal cord: Gray inside, white outside. PNS: Cell bodies (ganglia) are central in nerve roots. Axons form white bundles on the outside.
89
What are the three major functional areas of the cerebral cortex?
Motor areas: Control voluntary movement. Sensory areas: Conscious awareness of sensation. Association areas: Integrate information, thinking, planning, perception, etc.
90
What does “contralateral control” mean in relation to the cerebral hemispheres?
Each hemisphere mainly controls and receives sensory information from the opposite side of the body.
91
What does it mean that functions of the hemispheres are “lateralized”?
Some functions are more dominant in one hemisphere than the other (e.g., language often left, spatial processing often right).
92
What are the four main lobes of each cerebral hemisphere and one key function of each?
Frontal: Motor control, planning, personality. Parietal: Somatosensory processing, spatial awareness. Temporal: Hearing, language, memory. Occipital: Vision.
93
What does the central sulcus separate?
The frontal lobe (anterior) from the parietal lobe (posterior).
94
Where is the primary motor cortex located and what is its Brodmann area?
In the precentral gyrus of the frontal lobe. Brodmann area 4.
95
What is the main function of the primary motor cortex?
Conscious execution of voluntary movements via pyramidal (corticospinal) neurons.
96
What is a motor homunculus?
A body map on the primary motor cortex where regions of cortex correspond to control of specific body parts; areas needing fine control (hands, face) have larger representations.
97
What and where is the premotor cortex (Brodmann 6)?
Located just anterior to the primary motor cortex. Involved in planning and coordinating learned, patterned movements (like playing piano, typing).
98
What is Broca’s area (BA 44/45) and what does it do?
Located in the frontal lobe, usually left hemisphere. Controls motor planning for speech (muscles of tongue, lips, throat).
99
Where is the primary somatosensory cortex located and what are its Brodmann areas?
In the postcentral gyrus of the parietal lobe. Brodmann areas 1, 2, and 3.
100
What information does the primary somatosensory cortex process?
Somatic sensations: touch, pain, temperature, and proprioception (body position).
101
What is a somatosensory homunculus?
A body map on the somatosensory cortex; areas with more sensory receptors (like lips, fingertips) have larger cortical representation.
102
What does the somatosensory association cortex (BA 5 & 7) do?
It integrates somatic sensory information (e.g., shape, texture, size) to help you recognize objects by touch.
103
Where is the primary visual cortex and what is its Brodmann area?
In the occipital lobe, mainly along the calcarine sulcus. Brodmann area 17.
104
What do the visual association areas (BA 18 & 19) do?
They interpret visual information using past visual experience (recognizing faces, objects, motion, etc.).
105
Where is the primary auditory cortex (BA 41) and what does it process?
Located on the superior temporal gyrus (superior margin of temporal lobe). Processes pitch, rhythm, and loudness.
106
What does the auditory association area (BA 42 & 43) do?
Interprets sounds as meaningful experiences (speech, music, environmental sounds).
107
Where is the olfactory cortex located?
On the medial temporal lobe, especially the piriform lobe/uncus; processes smell.
108
Where is the gustatory cortex (taste) located?
In the parietal lobe deep to the temporal lobe, near the insula (Brodmann 43).
109
What is the prefrontal cortex and what are some of its functions?
Located in the anterior frontal lobe. Involved in personality, judgment, planning, decision-making, and complex learning.
110
What is the general interpretation (“gnostic”) area and where is it usually found?
A region involving parts of temporal, parietal, and occipital lobes, usually on the left. Stores and integrates complex sensory memories, helping you give meaning to what you see, hear, and feel.
111
Where is Wernicke’s area and what is its function?
In the posterior temporal lobe, usually left side. Important for language comprehension and “sounding out” unfamiliar words.
112
What are affective language areas and where are they located relative to Broca’s and Wernicke’s areas?
They are located on the opposite (contralateral) side of Broca’s and Wernicke’s, and they handle the emotional and nonverbal aspects of language (tone, emphasis).
113
How are neurons in the cortex generally organized?
In layers (laminae) parallel to the surface. In columns perpendicular to the surface, where cells share a common function.
114
What are the six neocortical layers (basic roles)?
Layer I: Mostly axons and dendrites, few cell bodies. Layers II & III: Pyramidal neurons that connect different cortical areas. Layer IV: Stellate cells that receive thalamic input and project locally. Layers V & VI: Pyramidal neurons that project to subcortical structures (thalamus, brainstem, spinal cord).
115
What structures make up the basal nuclei (basal ganglia)?
Caudate nucleus Putamen Globus pallidus
116
What is the main function of the basal nuclei?
They help with motor control: starting, stopping, and monitoring movements and inhibiting unnecessary movements.
117
What are the three main parts of the diencephalon?
Thalamus Hypothalamus Epithalamus
118
What is the thalamus and its main role?
A collection of multiple nuclei. Acts as the main relay station: processes and sends sensory (and some motor) information to the appropriate cortical areas.
119
Where is the hypothalamus located and what is its general function?
Below the thalamus, between the optic chiasm and mammillary bodies, connected to the pituitary by the infundibulum. It is the visceral control center: regulates autonomic functions, emotions, body temperature, hunger, thirst, circadian rhythms, and endocrine system.
120
What does the epithalamus include and what does it do?
Contains the pineal body (secretes melatonin, helps control sleep-wake cycles). Includes choroid plexus which helps produce CSF.
121
What are the three main parts of the brainstem?
Midbrain Pons Medulla oblongata
122
What are three general functions of the brainstem?
Controls many autonomic behaviors vital for life. Acts as a conduit for ascending and descending fiber tracts. Contains nuclei of many cranial nerves.
123
Name key structures of the midbrain and one function for each.
Cerebral peduncles: Fiber tracts connecting cerebrum to lower brain. Corpora quadrigemina (superior & inferior colliculi): Visual and auditory reflex centers. Substantia nigra: Dopamine neurons important in movement. Red nucleus: Motor reflex coordination. Part of reticular formation: Involved in arousal and motor control.
124
What is the main role of the pons?
Acts as a bridge between brain regions. Contains pontine nuclei that relay information between motor cortex and cerebellum. Contains cranial nerve nuclei (V, VI, VII).
125
What are the pyramids in the medulla and what happens there?
Pyramids: Large descending tracts (corticospinal tracts). Decussation of the pyramids: Motor fibers cross to the opposite side → explains contralateral control.
126
What vital centers are located in the medulla?
Cardiovascular centers: Cardiac and vasomotor. Respiratory centers: Control breathing rate and depth. Reflex centers: vomiting, hiccuping, swallowing, coughing, sneezing.
127
Where is the cerebellum located relative to other brain structures?
Dorsal to the pons and medulla. Inferior (caudal) to the occipital lobes.
128
What is the basic structure of the cerebellum?
Two cerebellar hemispheres connected by the vermis. Each hemisphere has anterior, posterior, and flocculonodular lobes. Gray matter outside, white matter inside. Connected to brainstem via cerebellar peduncles (fiber tracts).
129
What is the main function of the cerebellum?
It coordinates precise timing and patterns of skeletal muscle contractions, integrating sensory and motor information for smooth, coordinated movements and balance.
130
What is the limbic system and what is its main function?
A set of structures on the medial sides of the cerebral hemispheres and diencephalon (e.g., cingulate gyrus, hippocampus, amygdala, septal nuclei, hypothalamus). Involved in emotion, motivation, and memory (emotional and affective states).
131
What is the reticular formation and where is it located?
A diffuse network of nuclei and fibers in the central core of the brainstem (medulla, pons, midbrain). Has widespread connections throughout the brain and spinal cord.
132
What are two key functions of the reticular formation?
Maintains wakefulness and attention (reticular activating system). Helps coordinate muscle activity and modulate motor output.
133
What are the three main ways the brain is protected?
Bone: The skull. Membranes: The meninges. Fluid: Cerebrospinal fluid (CSF), plus the blood-brain barrier.
134
What are the three meningeal layers from outermost to innermost?
Dura mater (“tough mother”) Arachnoid mater (“spider mother”) Pia mater (“gentle mother”)
135
What are dural septa and dural sinuses?
Dural septa: Inward folds of dura that anchor the brain (falx cerebri, falx cerebelli, tentorium cerebelli). Dural sinuses: Spaces between dural layers that collect venous blood and drain it toward the jugular veins.
136
What is the subarachnoid space and what does it contain?
The space between arachnoid and pia mater, filled with CSF and traversed by blood vessels and arachnoid threads.
137
arachnoid villi (granulations)
Small projections of arachnoid into the dural sinuses that act as valves, allowing CSF to be absorbed into venous blood.
138
main functions of cerebrospinal fluid (CSF)
Provides a liquid cushion that protects the brain and spinal cord.
Helps nutrient delivery and waste removal.
CSF composition is monitored for autonomic regulation.
139
Where is CSF produced and where does it flow?
Produced by choroid plexuses in the ventricles.
Flows through lateral → third → fourth ventricles, exits to subarachnoid space, circulates around brain and spinal cord, and is reabsorbed via arachnoid villi into venous blood.
140
four ventricles of the brain
Two lateral ventricles (one in each hemisphere).
Third ventricle (midline in diencephalon).
Fourth ventricle (between pons/medulla and cerebellum).
141
blood-brain barrier (BBB) and what creates it
A selective barrier that limits the movement of substances from blood into brain tissue.
Formed mainly by tight junctions between capillary endothelial cells, plus astrocyte end-feet.
142
what can and cannot easily cross the blood-brain barrier
Pass: Glucose, some amino acids, certain ions, and fat-soluble substances (O₂, CO₂, alcohol, many drugs).
Restricted: most large, charged, or water-soluble molecules without specific transporters.
143
What protects the spinal cord?
Bone: Vertebral column.
Meninges: Single-layer dural sheath, arachnoid, pia.
CSF: In subarachnoid space.
144
Where does the spinal cord end, and what is the filum terminale?
Spinal cord usually ends around L1–L2 vertebra level.
Filum terminale: A fibrous extension of pia that anchors the cord to the coccyx.
145
denticulate ligaments
Extensions of pia mater that anchor the spinal cord laterally to the dural sheath.
146
How is gray matter organized in the spinal cord cross-section?
Looks like a butterfly or “H”.
Anterior (ventral) horns: motor neurons.
Posterior (dorsal) horns: interneurons receiving sensory input.
Lateral horns: autonomic (sympathetic) neurons in thoracic and upper lumbar segments.
147
dorsal root ganglion
A cluster of sensory neuron cell bodies located on the dorsal root just before it joins the spinal cord.
148
spinal nerve
A mixed nerve formed by the union of dorsal (sensory) and ventral (motor) roots, carrying both sensory and motor fibers.
149
information do the dorsal columns (fasciculi cuneatus and gracilis) carry
Touch, vibration, and conscious proprioception to higher centers.
150
information do the spinothalamic tracts carry
Pain and temperature sensation.
151
upper and lower motor neurons in descending pathways
Upper motor neurons: Cell bodies in brain (cortex or brainstem).
Lower motor neurons: Cell bodies in anterior horn of spinal cord that directly innervate muscle.
152
mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, and nociceptors
Mechanoreceptors: Respond to touch, pressure, stretch, vibration.
Thermoreceptors: Respond to temperature changes.
Photoreceptors: Respond to light (in retina).
Chemoreceptors: Respond to chemicals in solution (O₂, CO₂, taste, smell).
Nociceptors: Respond to painful stimuli.
153
exteroceptors, interoceptors, and proprioceptors
Exteroceptors: On or near body surface, sense external stimuli.
Interoceptors (visceroceptors): In viscera and blood vessels, sense internal conditions.
Proprioceptors: In muscles, tendons, joints, sense body position and movement.
154
difference between simple and complex receptors
Simple receptors: Bare nerve endings or small encapsulated endings; detect general senses.
Complex receptors: Sense organs for special senses (vision, hearing, smell, taste).
155
examples of encapsulated mechanoreceptors and what they detect
Meissner’s corpuscles: Light touch, low-frequency vibration.
Pacinian corpuscles: Deep pressure, high-frequency vibration.
Ruffini endings: Deep, continuous pressure and stretch.
Muscle spindles: Muscle stretch.
Golgi tendon organs: Tendon tension/stretch.
156
mixed nerve
A peripheral nerve that contains both sensory (afferent) and motor (efferent) fibers.
157
How many pairs of cranial nerves are there, and where do they originate?
12 pairs of cranial nerves.
Originate from brain and brainstem.
158
List cranial nerve I to XII by name (you don’t need functions here)
I Olfactory
II Optic
III Oculomotor
IV Trochlear
V Trigeminal
VI Abducens
VII Facial
VIII Vestibulocochlear
IX Glossopharyngeal
X Vagus
XI Accessory
XII Hypoglossal
159
Which cranial nerves are purely or mainly sensory?
I (Olfactory): Smell
II (Optic): Vision
VIII (Vestibulocochlear): Hearing and balance
160
Which cranial nerves are primarily motor (with some proprioceptive sensory)?
III (Oculomotor)
IV (Trochlear)
VI (Abducens)
XI (Accessory)
XII (Hypoglossal)
(V, VII, IX, X are mixed.)
161
How many pairs of spinal nerves are there and how are they named?
31 pairs:
8 cervical (C1–C8)
12 thoracic (T1–T12)
5 lumbar (L1–L5)
5 sacral (S1–S5)
1 coccygeal (Co1)
Named for the region of the vertebral column where they exit.
162
nerve plexus and which regions have them
A network of ventral rami that redistribute fibers to form peripheral nerves.
Found in cervical, brachial, lumbar, and sacral regions.
163
dermatome
An area of skin innervated by the cutaneous branches of a single spinal nerve. Dermatomes overlap.
164
reflex
A rapid, automatic, predictable response to a stimulus that is unlearned and involuntary.
165
five basic components of a reflex arc
Receptor (detects stimulus)
Sensory neuron (afferent)
Integration center (mono- or polysynaptic, often in spinal cord)
Motor neuron (efferent)
Effector (muscle or gland)
166
stretch reflex and what receptor mediates it
A reflex that contracts a muscle when it is stretched (e.g., knee-jerk).
Mediated by the muscle spindle, which detects stretch.
167
reciprocal inhibition during a stretch reflex
While the stretched muscle contracts, the antagonist muscle is inhibited, so it relaxes and does not oppose the movement.
168
somatic nervous system differ from the autonomic nervous system
Somatic: Voluntary control of skeletal muscles; one neuron from CNS to muscle.
Autonomic: Involuntary control of smooth muscle, cardiac muscle, and glands; uses two-neuron chain (preganglionic and postganglionic).
169
two main divisions of the ANS and their general functions
Sympathetic: “Fight or flight” – prepares body for emergencies and intense activity.
Parasympathetic: “Rest and digest” – supports maintenance, digestion, and energy conservation.
170
neurotransmitters are used by pre- and postganglionic neurons in the sympathetic and parasympathetic divisions
Sympathetic:
Preganglionic: ACh
Postganglionic: mostly NE
Parasympathetic:
Preganglionic: ACh
Postganglionic: ACh
171
pre- and postganglionic fiber lengths differ in sympathetic vs parasympathetic divisions
Parasympathetic:
Long preganglionic, short postganglionic (ganglia near/in organs).
Sympathetic:
Short preganglionic, long postganglionic (ganglia near spinal cord).
172
ganglia located in the parasympathetic vs sympathetic systems
Parasympathetic: Ganglia are in or near the target organs.
Sympathetic: Ganglia form the sympathetic chain (paravertebral) or prevertebral ganglia near the spinal cord.
173
typical sympathetic effects on the body
Pupil dilation
Inhibited salivation and digestive secretions
Increased heart rate, blood pressure, bronchodilation
Sweating, piloerection (goosebumps)
Glucose release, increased metabolism
Decreased GI activity
Ejaculation/orgasm responses.
174
typical parasympathetic effects on the body
Pupil constriction
Stimulated salivation and digestion
Decreased heart rate, mild bronchoconstriction
Increased GI motility and secretions
Erection (via vasodilation in genitals).
175
general types of receptors does NE act on in the ANS, and what is the usual effect
Acts on adrenergic receptors: α and β subtypes.
α receptors usually excitatory; β receptors usually inhibitory, except β₁ in the heart, which is excitatory (increases rate and force).
176
From which embryonic layer does the nervous system develop, and what initial structure forms?
Develops from ectoderm.
Ectoderm thickens to form the neural plate, which folds into the neural groove and then closes to form the neural tube.
177
neural tube give rise to
Anterior part forms the brain.
Posterior part forms the spinal cord.
178
neural crest and what does it form
A group of cells that break off from the neural folds.
Forms sensory neurons, autonomic neurons, and other PNS structures.
179
three primary brain vesicles formed from the anterior neural tube
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
180
secondary brain vesicles arise from the forebrain and what do they become
Telencephalon: becomes the cerebrum (cerebral hemispheres).
Diencephalon: becomes thalamus, hypothalamus, epithalamus.
181
secondary vesicles arise from the hindbrain and what do they become
Metencephalon: becomes pons and cerebellum.
Myelencephalon: becomes medulla oblongata.
A&P 2025
flashcards
Decks in class (54)
# Cards
-
Anatomical Organization38
-
1.3 structural and functional organization of the human body37
-
1.4 characteristics of life7
-
1.6 Terminology and the Body Plan58
-
3.1 Functions of the cell36
-
3.2 How we see cells8
-
3.3 Plasma membrane15
-
3.4 membrane lipids10
-
3.5 Membrane Proteins35
-
3.6 movement through the plasma membrane36
-
3.7 cytoplasm13
-
3.8 the nucleus and cytoplasmic organelles35
-
Tissues92
-
4.6 Nervous Tissue15
-
4.5 Muscle Tissue28
-
Integumentary System78
-
5.2 skin29
-
5.3 Subcutaneous Tissue12
-
5.4 accessory skin structure63
-
5.5 Physiology of the Integumentary System17
-
exam 1 review43
-
Anatomical Organization 270
-
expanded chapter 3 cell biology20
-
condensed chapter 3 cell biology100
-
Muscle Structure and Function24
-
Non-glandular Epithelial Tissue18
-
Connective Tissue0
-
Integumentary System0
-
Skeletal Tissue0
-
Axial Skeleton40
-
Appendicular Skeleton0
-
exam 2138
-
Axial Muscles39
-
NS181
-
Sliding Filament Theory33
-
Muscle Physiology41
-
Muscle Names39
-
Exam 4 - Neurotransmission, Neurochemistry93
-
exam 4 - Neuroanatomy63
-
Exam 421
-
Mitosis + Meiosis22
-
Insertions, Origins, and Actions of Muscles67
-
Master List of Muscles86
-
Anatomical Terminology83
-
Cell Division25
-
Vertebral Landmarks14
-
Thorax Landmarks12
-
Pectoral Girdle16
-
Pelvic Girdle19
-
Upper Limb26
-
Lower Limb30
-
Skull Landmarks41
-
Skull COPY73
-
Skull15
