Nervous System Flashcards

Question

What are astrocytes?

Answer 1

Astrocytes are star shaped cells found in the brain. - most numerous glial cell - regulate electrical impulses - provide neurons with lactate for nutrients - contain channels for K+ transport - regulates blood flow - takes part in neural repair - stores glycogen

Answer 2

Oligodendrocytes make myelin in the CNS

Answer 3

Schwann cells make myelin in the PNS

Answer 4

The blood brain barrier consists of high density endothelial cells that prevent the passage of pathogens, antibiotics, and chemicals into the brain. - Some molecules such as CO2, O2, water, glucose, and amino acids can cross. - Bottom line: It protects the brain from toxic substances and pathogens

Answer 5

Multiple Sclerosis is an auto-immune disease - A part of the blood brain barrier breaks down allowing T-lymphocytes to cross over and attach the myelin sheath. - It results in communication issues with your brain and the rest of the body.

Answer 6

Epilepsy is uncontrolled seizures. | - Also shown to be caused by failures of the blood brain barrier.

Answer 7

When the sympathetic nervous system is stimulated it: - Increases heart rate - Increases blood pressure - Increases respiration - Increases blood flow to skeletal muscles - Pupil Dilation - Stimulates adrenal medulla (epinephrine and norepinephrine) - Stimulates glycogenolysis - Slows intestinal and stomach movements - Salivary gland secretion decreases - Decreases urine production - Relaxes urinary bladder (takes away urge to pee) - Fight or Flight

Answer 8

When the parasympathetic nervous system is stimulated: - Decreases heart rate - Decreases blood pressure - Decreases blood flow to skeletal muscles - Pupil constriction - Stimulates intestinal and stomach movements - Salivary gland secretions increase - Increases urinary production - Tenses urinary bladder (makes you want to pee) - Rest and digest

Answer 9

The enteric nervous system is part of the autonomic nervous system. - It extends the entire length of the alimentary tract (esophagus to anus) - It controls the secretory and motile functions of the digestive tract - Contains a large number of neurons (100 million), that's more than the spinal cord. - Sometimes dubbed the second brain, it can work independent of parasympathetic or sympathetic systems, or in tandem with them. - Makes over 30 neurotransmitters - 90% of our serotonin and a good percentage of our dopamine is made here.

Answer 10

The Myelin sheath is a fatty substance surrounding some axons that increase the speed of impulse along the axon - Electrically insulating - needed for proper functioning - made up of cholesterol, lipids, and about 20% proteins - Made by schwann cells in the PNS - Made by oligodendrocytes in the CNS - Unmyelinated fibers have slower impulse speed

Answer 11

In the brain: - Grey matter: consists of mainly unmyelinated axons - White matter: consists of mainly myelinated axons

Answer 12

The axolemma is the cell membrane surrounding the axon.

Answer 13

The nodes of ranvier are gaps between adjacent schwann cells. - At these nodes, the axolemma is especially permeable to Na+ and K+. - These nodes are only present when the axon is myelinated - Action potentials can jump between these nodes in what is called saltatory conduction.

Answer 14

As the neural impulse travels down the axon, it starts to lose some of its strength. At the nodes of ranvier, the impulse of the axon triggers the release of more action potential effectively boosting the signal of the impulse. This perpetual boosting of the signal through the myelinated axon increases the speed dramatically vs an unmyelinated axon.

Answer 15

- A Myelinated neuron can transmit an impulse at 120 m/s | - An unmyelinated neuron can transmit an impulse at less than 1 m/s

Answer 16

The cerebrum is: - The largest part of the mature brain (80%) - Consists of two hemispheres connected by a deep bridge of nerve fibers called the corpus callosum - Each hemisphere is surrounded by an outer covering of grey matter called the cerebral cortex - The inner portion of the cerebrum consists of white myelinated matter that acts as the communication portion of the brain.

Answer 17

The corpus callosum is a deep bridge of nerve fibers that connects the two hemispheres of the brain. - It is composed of white matter for quick communication between hemispheres - It is the largest white matter structure in the brain

Answer 18

The cerebral cortex is the outer covering of grey matter that surrounds the cerebrum. - Cortex means outermost layer. Cerebral means of the cerebrum

Answer 19

The gray matter consists of: - Unmyelinated portions of axons - cell bodies - glial cells - dendrites Most of the brain's neuronal cell bodies are here. They gray matter includes regions of the brain involved with seeing, hearing, memory, speech, emotion, and decision making, among others

Answer 20

The cortex is wrinkled to allow more gray matter to fit into the small amount of space in our skull. The wrinkles are called covolutions or gyri, which are separated into two categories: - Shallow groove: sulcus - Deep groove: Fissure

Answer 21

The four lobes of the brain include: - Front - Parietal - Occipital - Temporal This is sufficient for the DAT

Answer 22

The brain's white matter: - connects various areas of gray matter to each other and carry impulses between neurons. - Bundles of nerve fibers are called tracts. - Tracts are used to describe the myelinated axons of the white matter - Bottom Line: White matter is a relay and communication region of the brain.

Answer 23

The basal ganglia: - located in the deep white matter - Allows us to feel the passage of time. - Helps us select the behaviors associated with decisions

Answer 24

The meninges are three membranes that envelope the brain and the spinal cord. - Dura Mater: * Outermost layer * Many Nerves and blood vessels * Tough and Fibrous - Arachnoid Mater * Middle Layer * No blood vessels * Thin delicate layer - Pia Mater * Innermost Layer * Very Vascular * Intimately attached to the brain and spinal cord

Answer 25

CNS is located between the Arachnoid Mater and the Pia Mater in the meninges.

Answer 26

Inflammation of the meninges is called Meningitis - It can be bacterial or viral - It will usually involve the arachnoid and pia maters

Answer 27

The right hemisphere of the brain controls the left side of your body and vice versa

Answer 28

The cerebellum - is involved with balance and muscle coordination - fine motor movement (ex: moving your finger tip) - equilibrium - posture - motor learning

Answer 29

The parts of the brain that control fine motor movement are: - The cerebellum - The basal ganglia, which includes * Caudate nucleus * Putamen * Globus Pallidus

Answer 30

The Hypothalamus is: - the link between the endocrine and the nervous system - part of what is called the limbic system, dealing with emotions, motivation, behavior, and is still very unknown. - Makes ADH and oxytocin and releasing hormones. - Involved with a range of bodily functions including: * fluid balance * blood pressure * body temperature * maintaining homeostasis * emotions * sex drive * thirst * production of digestive juices - Main take away: Link between nervous system and endocrine system

Answer 31

The limbic system, is a complex system that deals with emotions, motivation, memory, and behavior. It's still very unknown. It's made up of the: - Hypothalamus - amygdala - hippocampus - thalamus The Hippocampus is associated with long term memory. The rest we don't need to know in any more detail

Answer 32

The Medulla Oblongata: - Helps regulate functions such as breathing, heart rate, swallowing, and digestion - Center for respiration and circulation - Involved with involuntary functions - Contains both myelinated and unmyelinated fibers - Cardiac, respiratory, sneezing, and vomiting centers are located here. - Chemoreceptors can tell whether the blood is acidic or not. Chemoreceptors send signals to the medulla which can respond by increasing breathing rate - This part of the brain was very early to develop. It's found fully developed in Agnathans (jawless fish, the first fish, hagfish and lampreys)

Answer 33

Agnathans are the first fish to have developed in the world. - Include: Hagfish and lampreys - They are jawless - Posses a fully developed medulla

Answer 34

The Thalamus is: | - A relay station in the brain. It relays sensory information to the proper areas of the brain.

Answer 35

Tay-Sach's disease is a disease that is caused from a deficient lysosomal enzyme that's involved with lipid breakdown. - Neurons are destroyed in the brain and spinal cord - The ganglioside (type of lipid) content of the brain is elevates in an infant. - The disease is usually fatal by the age of 3

Answer 36

The cerebrospinal fluid bathes, nourishes, and protects the brain and spinal cord from injury

Answer 37

The choroid plexus is a network of cells that produce cerebrospinal fluid. - Found in the ventricles of the brain - The plexus consists of cells called ependymal cells. - Also involved with removing waste, excess neurotransmitter, and foreign substances from the cerebrospinal fluid. - Four Ventricles are involved, within these cavities you find the choroid plexus

Answer 38

Microglia are phagocytic cells located in the CNS. They account for 5% of the glial cells

Answer 39

A stroke is when blood flow is shut off to a certain area of the brain. Deprivation of O2 causes cell death. Symptoms include: - Trouble with speaking - numbness of the arm, leg, or face - visual problems - headache - trouble walking

Answer 40

TIA is a transient ischemic attack (mini stroke). It occurs when a clot or debris blocks the flow of blood to your brain.

Answer 41

The three classes of nuerons are: - Sensory (afferent) - Interneuron - Motor (efferent)

Answer 42

Sensory (afferent) neurons are closely related with receptor cells. - They respond to external stimuli or internal conditions and relay them to brain and spinal cord.

Answer 43

An interneuron is located between sensory and motor neurons - Integrates sensory input and motor output - Acts as a relay station for impulses between sensory and motor neurons

Answer 44

A motor neuron (efferent) carries impulses out from the brain or spinal cord to effectors such as muscles or glands

Answer 45

Most nerves are mixed nerves, a mixture of sensory and motor fibers

Answer 46

An axon hillock is the part of the cell body that connects to the axon. - This is where action potentials originate

Answer 47

A synapse is the junction where one neuron communicates with another neuron. - Neurotransmitters diffuse across here.

Answer 48

A pre-synaptic cell stores the neurotransmitters like acetylcholine in vesicles. - Can be a muscle, neuron, or even a gland.

Answer 49

A post-synaptic cell is the cell that has receptors that bind to specific neurotransmitters

Answer 50

The synaptic cleft is the space between the pre-synaptic and post-synaptic membrane

Answer 51

A neuron is negative at its resting state. - A sodium-potassium pump is actively pumping 3 Na+ ions out for every 2 K+ ions in against their gradient to maintain this negative resting potential. - There are large negatively charged proteins in the neuron that don't move outside the membrane. - There also exists Cl- ions that generally reside in the neuron as well.

Answer 52

- At a neuron's resting potential, there is a high concentration of K+ ions inside the cell, and a high concentration of Na+ ions outside the cell. - Both want to travel down their gradient to either get out of the cell (K+), or get into the cell (Na+). There also exists an electrical gradient. Both K+ and Na+ want to get into the cell since from an electrical gradient perspective, since the cell is more negative. - If K+ could flow impeded out of the cell without Na+ moving, there would be a net negative increase in potential - If Na+ could flow impeded into the cell, there would be a net positive increase in potential. - The sum of the electrical and concentration gradients, as well as the active pumping of 3 Na+ ions out for every 2 K+ ions in by the sodium-potassium pump against their gradient, makes it so there is a net negative charge across the cell membrane.

Answer 53

- A nerve impulse will open up the Na+ ion channels which cause Na+ to flow into the neuron. - This brings the potential to a positive value. - As this happens we see a large change in the membrane voltage. This is action potential. - If the potential is high enough, it will carry the impulse along the axon.

Answer 54

Depolarization occurs when Na+ ion channels open and the membrane potential swings to positive. - We can see a swing of -70 mV to +40 mV during a nerve impulse.

Answer 55

Hyperpolarization occurs when K+ ion channels open and the cell becomes more negative. - This is an inhibitory stimulus

Answer 56

A voltage gated channel is a class of transmembrane proteins that form channels that can open or close due to a voltage. - They are usually ion specific. - We see voltage gated channels for Na+, K+, Cl-, and Ca++.

Answer 57

A nueron cell must reach a certain voltage before it can trigger. - For most mammalian neurons, the voltage must increase to -55 mV for an action potential to occur and the neuron to trigger. - These can be additive. If multiple dendrites are sending signals to open positive Na+ channels, then their combined effect can increase to the threshold amount where a single one would have failed.

Answer 58

After a neuron has generated an action potential, there is a short refractory period before it can trigger again. There are two parts: - Absolute Refractory Period: No stimulus, no matter how strong can generate another action potential. This is due to the Na+ pumps deactivating for a short time after it hits its max voltage. - Relative Refractory Period: The Na+ pumps are active, but a hyperpolarization has occurred that makes the cell more negative than usual. Therefore, a very strong stimulus would be needed to generate an action potential.

Answer 59

IT DOESN'T - Speed is constant along the axon once an action potential is generated. - A stronger impulse can generate more action potentials, but it won't affect the speed of the impulse down the axon.

Answer 60

Neurons are unidirectional. | Pre-synaptic cell -> Synaptic Cleft -> Post-synaptic Dendrite -> Cell body -> Axon Hillock -> Axon -> Presynaptic Cleft.

Answer 61

Dental injections block Na+ channels from opening up at pain receptors, thus blocking the action potential from generating.

Answer 62

The larger the diameter, the faster the impulse can move along the axon. -NB: Know for the DAT

Answer 63

A pre-synaptic neuron releases neurotransmitters through the following process: - Neurotransmitters exist in the cell inside vesicles bound to membrane proteins on the inside of the cell membrane. - When the action potential arrives, Ca++ voltage gated channels open and Ca++ moves into the cell across its concentration gradient. - Ca++ binds to the membrane proteins, causing the proteins to undergo a conformational change that fuses the vesicle into the membrane and exocytoses the neurotransmitter into the synaptic cleft - The neurotransmitter then binds to the post-synaptic cell membrane's receptors. - The receptors can be inhibitory or excitatory. If it's inhibitory, it will cause K+ to flood into the neuron. If it's excitatory, it will cause Na+ to flood into the neuron.

Answer 64

After neurotransmitters bind to the receptors, they can: - Diffuse away - Be broken down by enzymes - Be taken up by the synaptic terminal

Answer 65

Acetylcholine is a neurotransmitter involved with learning and memory enhancement. - It also is the chief neurotransmitter of the parasympathetic nervous system

Answer 66

Dopamine is a neurotransmitter involved with keeping focused, paying attention, and promoting feelings of pleasure - It is a catecholamine like epinephrine and norepinephrine - It's classified as only a neurotransmitter, but there's debate as to whether it should be classified as a hormone as well.

Answer 67

Serotonin is a nuerotransmitter that is involved with keeping you happy. Depression can occur with deficiency

Answer 68

Norepinephrine is both a hormone and a neurotransmitter involved with mental alertness and memory

Answer 69

GABA is the body's inhibitory neurotransmitter. It keeps you calm and without anxiety. - Alcohol is thought to mimic the effect of GABA in the brain, decreasing anxiety and inhibitions.

Answer 70

Glycine is a neurotransmitter that works with GABA to help decrease anxiety among other functions

Answer 71

- The chief neurotransmitters of the sympathetic nervous system are norepinephrine and epinephrine. - The chief neurotransmitter of the parasympathetic nervous system is acetylcholine

Answer 72

Neuropeptides are small peptide molecules that can be used as neurotransmitters by nerve cells for communication. - These small molecules can bind to cell surface receptors. - Example: Substance P is made up of 11 amino acid residues and is involved with pain and inflammation.

Answer 73

Endorphins are our bodies natural analgesics that decrease our perception of pain. - These are a type of neuropeptide - They also produce a euphoric or happy feeling in us. - Laughing and running are activities that increase endorphins. This is what the runners high is.

Answer 74

Cnidaria include hydra and sea anemones. - They contain a loose mesh of nerve cells called a nerve net. These nerves can interact with sensory and contractile cells.

Answer 75

Arthropods have a small, but intricate nervous system that allows them to detect and respond to the world around them. - They posses a brain and a ventral nerve cord. - Despite their small size, many insects have axons bigger than what is seen in humans. Thus their fast speed.

Answer 76

Flatworm nerves - Contain nerve net - Also have long nerve cords connected to cerebral ganglia in the head region. - Have bilateral nervous system, with long nerves running along the lengths of both sides, with transverse nerves connecting the two. - Earthworms have all of this, as well as a brain and ganglia.

Answer 77

Echinoderms (sea stars, sea urchins, sea cucumbers, and sand dollars) - Do not have brains - have nerves running along the mouth down each arm.

Answer 78

They don't have any! - Only multi-nucleated animal that lacks a nervous system - No nerve or sensory cells

Answer 79

A reflex is an automatic, unconscious response to certain stimuli - Helps to protect the body from harm

Answer 80

A reflex arc is the pathway in which are reflexes occur. The path is as follows: 1. Receptor (dendrite) 2. Sensory neuron (relays impulse to CNS) 3. Reflex center (composed of interneurons) makes arc 4. Motor neuron conducts impulse to effector 5. Effector (muscle or gland) reacts. Example: - You touch a hot stove. - Pain receptors in your skin are stimulated and the message is sent to the the sensory neuron - The message is then sent to the spinal cord. (no decision by the brain is needed. The body just reacts involuntarily to the pain.) - At the reflex center in the spinal cord, interneurons transmit impulses to the motor neuron - The motor neuron transmits impulses to the effector. - The muscles contract and you move your hand, all without brain power!

Answer 81

The spinal cord is made up of: - Gray matter (neurons found here): Looks like a butterfly. - White matter (axons found here): contains the spinal tracts, sensory, and motor

Answer 82

A spinal cord has two roots that emerge - Dorsal root: Transmits sensory information (sensory root) - Ventral root: This is the motor root and it carries information towards the limbs and organs. Sucky DMV (Sensory Dorsal, Motor Ventral)

Answer 83

Hyperpolarization occurs either from the movement of K+ ions out of the neuron, or Cl- ions into the neuron. - This can be caused by inhibitory impulses or after an action potential has been reached, to repolarize the membrane - This hyperpolarization either completely prevents a new stimulus from being received by the neuron, or dramatically increases the threshold needed. - Eventually, the Sodium Potassium pump reestablishes the resting potential.

Answer 84

EPSP is Excitatory Post-synaptic potential | - It's an event that causes the release of Na+ ions into the neuron to increase depolarization

Answer 85

IPSP is Inhibitory Post-Synaptic Potential - It's an event that causes the release of K+ ions out of the cell, increasing the negative charge of the cell and causing hyperpolarization.

Answer 86

Many neurons in the CNS have both inhibitory and excitatory synapses - Neurotransmitters can be either excitatory or inhibitory. - Based on the effect of both EPSPs and IPSPs, the cell may or may not reach the action potential needed for the Na++ ion voltage gated channels to open at the axon hillock.

Answer 87

Temporal Summation involves a SINGLE synapse. | - EPSPs occur one after another and are added together where they overlap in charge

Answer 88

Spatial summation involves multiple synapses - EPSPs occur at the same time.

Nervous System Flashcards

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