bio test nervous system Flashcards
Our bodies are constantly working to remain in a stable state
- When you go for a run, your heart rate increases as the demand for ATP in your muscles goes up and the need for aerobic respiration (oxygen) increases.
- This response is your body attempting to keep interior conditions of the body stable
- Once you stop running, your heartrate will quickly begin to slow
- Your body is actively working to get back to “normal” conditions
Important variables within the body
blood sugar
fluid balance
body temperature
oxygen levels
blood pressure
pH
- These variables must stay within certain ranges.
- Changes in the external environment can cause these variables to change.
HOMEOSTASIS
- The process by which a constant internal environment is maintained despite changes in the external environment.
- The tendency of the body to maintain a relatively constant internal environment.
Sensor
1 of component of homeostatic control system
- function: detects a change in variable
- 5 senses
Control centre
2 of component of homeostatic control system
function: receives message from sensor and directs a response via effector
Effector
3 of component of homeostatic control system
- function: carries out the response initiated by the control centre, effecting change in variable
- does the actual response
- does the effect
The hypothalamus
- Part of the endocrine system (hormone system) that maintains homeostasis throughout the body
- controls everything in the body like hormones
Often serves as the coordinating/control centre:
- Receives messages from sensors/monitors
- Initiates a hormonal/nervous response
- sends response to pituitary gland, which sends the information to the rest of the body
- If there was a tumor that was affecting most of the body, it’s most likely to be pushing against the hypothalamus
Dynamic equilibrium
- Homeostasis is also called dynamic equilibrium
- chemical term of homeostasis
- Conditions do fluctuate, but within an acceptable range
- for example, at night, your body becomes more colder and during the day, it becomes hotter. This is within the range of the dynamic equilibrium, so it’s fine.
- Another example is when you have lots of blood fluid, which need to be rid of by peeing it out.
How is dynamic equilibrium maintained?
Feedback loops/systems:
- Negative feedback- reverse the change, return to normal, reduce system’s output
- Positive feedback - increase the change, move away from normal, increase system’s output
Negative feedback
- The response triggered by changing conditions serves to reverse the change
- E.g., Body temperature increases, Skin blood vessels dilate, Body temperature decreases
- example of homeostasis as it tries to balance everything out
- The negative feedback loop acts a balance trying to keep your body running smoothly!
Thermoregulation
- The maintenance of body temperatures within a range that enables cells to function effectively
- The internal temperature of our bodies is regulated to about 37°C
- this is because 37C is the optimal range for proteins in the body. If not 37, it will be denatured. This is also because of the fluidity of cell membrane. The best diffusion happens when the cell membrane is at 37C.
- Chemical reactions in the body are endothermic, and 37C allows the initiation of reactions in the body
- blood fluidity is also important and 37C is perfect for that
- involuntary
example:
- Receptors on the skin and deep inside the brain detect a stimulus (change in temperature)
- Signals are sent to the Thermoregulatory Centre (Hypothalamus)
- Hypothalamus triggers a response by the nervous system
- Response to Cold Temp:
Blood vessels constrict
Skin hairs raise up
Fat is burned so that energy is released from C-H bonds
Skeletal muscles vibrate (shivering) - Response to Hot Temp:
Blood vessels dilate
Skin hairs lower
Sweat glands activate
How does the body “know” when to regulate temperature, and “know” when to stop?
- Receptors in the nervous system detect changes in conditions due to a stimulus (temperature)
- Information is sent to control centers(hypothalamus) that will signal effectors(nerves, glands, muscles) to create a change in a positive or negative direction
Responses to Heat Stress
- Co-ordinating centre is the hypothalamus
Responses:
- Skin blood vessels will dilate
- Sweat glands will produce perspiration
- Both responses serve to lower body temperature to Return to normal range
Response to Cold Stress
- Coordinating/Control centre is the hypothalamus
Responses:
- Skin blood vessels will constrict
- Skeletal muscle will contract rapidly (shivering), increasing metabolism
- Smooth muscle around hair follicles will contract, producing goosebumps
- Responses serve to raise body temperature to Return to normal range
Summary of thermoregulation
Stimulus: cold
Physiological response:
- constriction of blood vessels in skin
- hairs on body erect
- shivering
Adjustment: heat is conserved and generated by increasing metabolism
Stimulus: heat
physiological response:
- dilation of blood vessels in skin
- sweating
- goosebumps: create unequal air flow regions. Idea was to trap heat in between goosebumps and allow the cold to flow over. Questionable effectiveness (moving towards vestigial trait).
Adjustment: heat is released
Positive feedback loops/systems
- The response triggered by changing conditions serves to move the variable even further away from its steady state
- never go back to normal
- E.g., When giving birth: uterine contractions are stimulated by oxytocin for baby to move towards cervix and more oxytocin is released
Importance of the nervous system
Both the nervous system and the endocrine system control the actions of the body, through a series of adjustments, to maintain the internal environment within safe limits.
Responses to change in the internal and external environments are made possible by either electrochemical messages relayed to and from the brain or by a series of chemical messengers.
The nervous system is an elaborate communication system that contains 100 billion nerve cells.
The Nervous system
The nervous system has two main divisions:
- central nervous system (CNS)
- peripheral nervous system (PNS)
The CNS consists of the brain and spinal cord and acts as a coordinating centre for incoming and outgoing information.
The PNS consists of the nerves that carry information between the organs of the body and the CNS.
CNS
- central nervous system
- The CNS consists of the brain and spinal cord and acts as a coordinating centre for incoming and outgoing information.
- integrates and processes information
- brain and spinal cord
- has spinal fluid
CNS is the structural and functional centre for the entire nervous system
site of neural integration and processing.
Myelinated neurons form white matter
Forms inner region of some areas of the brain and the outer area of the spinal cord.
Unmyelinated neurons form grey matter
found around the outside areas of the brain and forms the H-shaped core of the spinal cord.
PNS
- peripheral nervous system
- The PNS consists of the nerves that carry information between the organs of the body and the CNS.
- links CNS to the rest of the body
- peripheral nerves
- NOT protected properly, only protected by skin and muscles
organization of nervous system
two parts
- CNS (splits to brain and spinal cord
- PNS (splits to sensory pathways and motor pathways
- motor pathways splits to somatic nervous system (under conscious control- voluntary) and autonomic nervous system (not under conscious control- involuntary)
- Autonomic nervous system splits to sympathetic nervous system and parasympathetic nervous system
Neurons
- cells in the nervous system
- basic functional units
- conduct electrochemical impulses
- organized into nerve tissue (multiple neurons make up nerve tissue)
- We can classify neurons based on the structure they have
Glial cells
- support neuron cells
- nourish neurons, remove wastes, defend against infection
Structure of a Neuron
Variable shapes and sizes; four common features
dendrites
- receives initial signals
- signals come through the cell body through dendrites
- the more dendrites, the more signals the cell body will receive, the more important the neuron is
cell body
axon
- tail that sends the signal to the ends of the neuron
- main communication pathway
- surrounded by Schwann cells to protect it
- these also help to insulate axon and send signal a lot faster
- this makes the signals jump between the Schwann cells to make it faster
- the places where the signal touches are called nodes of Ranvier
- if no Schwann cells, the signal will be sent very slowly
branching axon terminals
axons
Some axons are insulated:
- fatty layer called the myelin sheath
- sheath is made of individual Schwann cells (type of glial cell)
- two functions: protection; increase speed of conduction
Myelin is needed:
- Keeps the signal on the axon
- Gaps in the sheath let the signal travel faster at certain points (it travels slow inside of the fatty parts)
multipolar
Structural Classification of Neurons
- location: CNS
- structure: several dendrites, single axon
- must be in CNS because they are the most important and they help to receive the most stimuli
- they can also be found in other parts of body, not just CNS
Bipolar
Structural Classification of Neurons
- location: PNS/CNS
- structure: single dendrite, single axon
- usually links PNS and CNS
Unipolar
Structural Classification of Neurons
- Location: PNS
- Structure: single process from cell body, dendrite and axon fused
- dendrite and cell body aren’t together
- in PNS because it only receives signals but doesn’t integrate them
- all unipolar neurons are sensory neurons
Sensory
Functional Classification of Neurons
- Location: PNS
- function: receive stimuli from environment and generates nerve impulse
- also known as afferent neurons
- sense and relay information from the environment to the CNS for processing.
- Sensory neurons are located in clusters called ganglia, which are outside the spinal cord.
- Examples- special sensory receptors in the eye, known as photoreceptors, respond to light; there are receptors in your nose and tongue, called chemoreceptors that are sensitive to chemicals.
Interneuron
Functional Classification of Neurons
- Location: CNS
- Function: process and integrate sensory info; generate a motor response
- multipolar neurons
- link neurons within the body.
- They are predominantly found in the brain and spinal cord. Interneurons integrate and interpret the sensory information and connect neurons to outgoing motor neurons.
- sends out information to respond to stimulus
Motor
Functional Classification of Neurons
- Location: PNS
- Function: carry info from CNS to effectors: muscles, glands, other organ
- also known as efferent neurons
- receives information from CNS and carries out the response of what the interneuron told it to do
- relay information to effectors. These effectors are muscles, organs and glands. They are classified as effectors because they produce responses.
- Motor neurons originate in the spinal cord and synapse with muscle fibres to make muscles contract.
- They are stimulated by interneurons, sometimes sensory neurons
- multipolar neurons
The Reflex Arc
- A shorter neuron pathway to produce involuntary, reflexive behaviours
e.g., knee-jerk reflex, withdrawal reflex - simpler than typical transmission pathway
- skips the brain processing (goes through spinal cord)
Effector carries out the action/response - motor response is generated before the brain integrates sensory input, rapid involuntary response
- This is why after stepping on a stone, you scream/feel pain after your foot has been pulled away. The brain has then had time to process the information
- This reaction occurs through the reflex arc. Most reflexes occur without brain coordination. The reflex arc contains 5 essential components:
- The receptor (pain receptor on the skin)
- The sensory neuron (passes an impulse to the interneuron)
- The interneuron in the spinal cord (relays an impulse to a motor neuron)
- The motor neuron (causes the muscle (effector) in the hand to contract and pull away)
- The effector (muscle contracting)
Electrical Nature
Nerves conduct electrical impulses to carry the message
By changing the concentration of Na+ and K+ inside and outside of the cell, electric current flows down an axon
Membrane potential: difference in charge separation across a cell membrane
- Potential energy
Conduct due to axon structure
Ion channels
- allow ions to pass through the cell membrane
- movement along concentration gradient (high to low)
- many ion channels are gated – (they open only in response to stimulus)
- voltage-gated: respond to changes in membrane potential, open or close
- ligand-gated: binding of a specific chemical compound, neuron transmitters
Resting Membrane Potential
- At rest, a nerve cell membrane has a potential of -70 mV (polarization)
- interior is negative compared to exterior
- when talking about a polarization of a nerve membrane, we talk about the interior
- This is a nerve that is not sending a signal (unstimulated)
- There are more + ions outside than inside
Why the membrane has a negative resting potential
- large, negatively-charged proteins in intracellular fluid (inside cell)
- “leaky” K+ channels
Mostly open at rest potential (-70mV)
allow K+ to diffuse out of cell, leaving interior negative. Since it’s leaky, the positive K would go out - high [Na+] outside; high [K+] inside
maintained by Na+/K+ pump
3 Na+ out, 2 K+ in
- Since there’s one more positive outside than positive inside, the inside is more negative
Sodium Potassium Pump
- primary active transport
- need atp for this to work
- move against concentration gradient
- low to high
- System involving a carrier protein in the plasma membrane that uses the energy of ATP to transport sodium ions out of and potassium ions into animal cell; important in nerve and muscle cells.
- most important factor that contributes to the resting membrane potential
- uses ATP to transport 3 (Na+) out and two (K+) into the cell (1 extra positive charge moves out of the cell each time)
- result is a constant membrane potential of -70 mV
Action potentials
A nerve impulse (signal) consists of a series of action potentials.
Action Potential: a change in charge that occurs when gates of K+ channels close and Na+ open after depolarization (caused by a stimulus)
Nerve cells are polarized because of a difference in charge across the membrane
- inside more negative than outside
Depolarization is when they are less polarized
- Membrane potential is less than resting potential
- Inside of cell less negative than outside
When Na+ channels open, ions rush into the cell, down the concentration gradient
A. A stimulus causes small, local depolarizations in nerve membrane potential.
- called graded membrane potentials
- these changes vary in magnitude, according to strength of stimulus
B. When a stimulus is strong enough to depolarize the membrane to a threshold (usually -50 mV), an action potential is produced.
- Voltage-gated Na+ channels open, causing the rapid depolarization.
- when overcoming the threshold, we can overfire neurons
- if stimulus isn’t strong enough, won’t be overfired because it can’t communicate
- Both sodium gated channels and potassium gated channels are closed in these steps
- this means that at rest, only the sodium-potassium pump is working
Step 1: An action potential is triggered when the threshold potential is reached.
Step 2:
- start off by opening sodium gated channels, NOT potassium, which is still closed
- Voltage-gated Na+ channels open when the threshold potential is reached.
- Na+ move down [gradient] and rush into the axon
- high to low concentration for Na+
- Membrane is depolarized
- membrane potential difference is now
+40 mV.
(more positive charges inside cell)
- +40mV is the max voltage the inside of the neuron can reach
Step 3:
- Voltage-gated Na+ channels close due to change in membrane potential (Caused by Na+ moving into the cell)
- Voltage-gated K+ channels open at this voltage (+40mV)
- K+ move down [gradient] and exit the axon (cell)
- membrane becomes hyperpolarized to -90 mV (Due to K+ leaving)
- below -70mV is hyperpolarize
- The job of the sodium potassium pump is to move K back into the cell, and Na back out of the cell in preparation for the next action potential
- sodium ligand gated channels are closed
- potassium ligand gated channels are open
- this allows the inside of cell to be more negative
Step 4:
- then, voltage-gated potassium channels are closed when -90mV is hit
- both channels are now closed
- primary active transport now happens to get it back to -70mV
- since potassium and sodium are in the opposite place of where they should be, the pump helps them to go back to normal
- Na-K pump and naturally occurring diffusion restore resting membrane potential of -70 mV
- The membrane is now repolarized once the Na-K pump restores pre-action potential concentrations
- refractory period: the period between -90mV to -70mV, after an action-potential
- the membrane cannot be restimulated during a few seconds
Action potentials as they move down an axon.
They cannot move upstream because of the refractory period.
a) An action potential is caused by a certain stimulus. Na+ rushes in the cell while K+ rushes out
b) The sodium-potassium pump fixes this, and moves K+ back into the cell and Na+ back out of the cell until the next stimuli triggers another action potential. (The sodium potassium pump is always running due to leaky K+ channels in the membrane)
Membrane potential
When a membrane has a charge imbalance, it has potential energy
- charge imbalance, also called electric chemical gradient, makes potential energy. This energy can be used to allow a electric impulse to move through a neuron
When the value drops below the equilibrium value, the membrane is considered polarized
This rest potential is created mainly by the sodium-potassium pump (voltage gated). This pump is usually at the end to reset everything to allow another action/potential to happen
As well as large negative proteins and leaky ion channels
Refractory Period
- time after an action potential occurs where the membrane cannot be stimulated again (milliseconds)
-occurs after hyperpolarization (-90mV to -70mV) - Action potentials continue down length of axon until it reaches the end to initiates response at the next cell
- the period between -90mV to -70mV, after an action-potential
- the membrane cannot be restimulated during a few seconds
Myelinated Nerve Impulse
- super fast signal
- Myelinated neurons have exposed areas on axons
- Called Nodes of Ranvier
- nodes contain Na+ channels for action potentials to occur
- Action potentials “jump” from node to node, don’t have to occur along the entire axon
- helps to repolarize a lot quicker
ECF = extracellular fluid (any fluid outside of the cell body itself)
The action potential does not need to travel along the entire axon membrane, it ‘jumps’ over the myelin sheaths to each set of Na+ gates
Neuron Communication
Neurons eventually end at the axon
The action potential is passed on to the next neuron or the muscle cell across a synapse
Synapse: a junction between 2 neurons or between a neuron and an exon terminal/effector (muscle or gland)
A neurotransmitter is a chemical messenger secreted by neurons to carry a neural signal from one neuron to another, or from a neuron to an effector (muscle or gland).
- Travel across the synapse in 0.5-1ms to reach dendrites of postsynaptic cell
- The neurotransmitter will bind a receptor protein on the postsynaptic cell causing depolarization to occur
- Synapses are usually neuron-neuron, but neurons can also synapse with muscle cells.
- neuromuscular junctions
Adrenaline
fight or flight neurotransmitter
- fight/flight/freeze
Noradrenaline
concentration neurotransmitter
- released WITH adrenaline
- overproduction linked to high blood pressure, anxiety, and insomnia.
- Deficiency linked to hunger cravings and exhaustion.
- also called norepinephrine
Glutamate
memory neurotransmitter
- found mostly in nuts
Acetylcholine
Learning neurotransmitter
Dopamine
Pleasure neurotransmitter
- excess leads to schizophrenia
- deficiency linked to Parkinson’s disease
Serotonin
mood neurotransmitter
- deficiency linked to depression or anxiety
Gaba
calming neurotransmitter
- sleep
- melatonin has lots of GABA
endorphins
euphoria neurotransmitter
- deficiency linked to increased risk of alcoholism
Excitatory Effect
- Opening of Na+ channels causes depolarization of post-synaptic neuron (allows Na+ into cell)
- NTs bind to the post-synaptic neuron.
- initiation of a new action potential in post-synaptic neuron due to depolarization (Na+ rushes into the cell making it more positive)
- calcium is important because it creates the vesicles that hold the neurotransmitters so that they can pass through the synaptic-cleft to the next neuron. Extocytosis
Inhibitory Effect
- Opening of K+ channels causes hyperpolarization of post-synaptic neuron (leaks K+ out of the cell)
- Some cells will react to NT binding by hyperpolarizing instead of depolarizing. (K+ rushes out of the cell, making it more negative)
- inhibitory effect: brings membrane potential farther from the action potential threshold
- makes an action potential less likely
- Depends on particular receptor/cell type – the same NT can be excitatory at some synapses, while inhibitory at others
Common neurotransmitters
Dopamine - affects control of body movements, linked to sensation of pleasure
Serotonin - temperature & sensory perception, mood control
Endorphins - euphoric, natural painkillers, emotional areas of brain
Norepinephrine – used by the brain and some autonomic neurons
- all of these can cause an action-potential to happen because they are stimulus
- when released across the synapse to the next neuron, they make it fire or shut it off
These have either excitatory or inhibitory effects on the postsynaptic membrane. - Excitatory molecules, like acetylcholine, cause action potentials by opening sodium channels, causing depolarization.
- Inhibitory molecules cause potassium channels to open, causing hyperpolarization, GABA
White Matter
- Contains myelinated axon tracts that connect different areas of grey matter in the brain and spinal cord (Myelin causes white appearance)
- transmits nerve signals
- makes up 60% of the brain’s volume
The Spinal Cord
- Extends out of the skull from the brain and downward through a canal within the backbone.
- Sensory and motor nerves are found within
- It’s the primary reflex centre (fast responses)
- The tissues are protected by cerebrospinal fluid, soft layer tissues, and the spinal column (vertebrae).
- Injury to the spinal cord can result in paralysis.
- involved in the reflex arc
- no integration or thought process here
Grey Matter
- mainly composed of cell bodies, dendrites and synapses (unmyelinated)
- signals are generated and processed
- makes up the other 40% of brains volume (uses most of the total oxygen and gases that goes to the brain)
The Brain
- Estimated at 100 billion cells
- complex centre that maintains homeostasis
- protected by the skull and the meninges
- blood-brain barrier-
- Three layers of tissue, called the meninges, surround and protect the brain and spinal cord.
The Blood-Brain Barrier
Formed by glial cells and blood vessels
Separates blood from CNS and selectively controls the entrance of substances into the brain from the blood.
Brain requires a constant supply of O2 and glucose (Why?)
- Both can cross the blood-brain barrier through special transport mechanisms.
Lipid-soluble substances (caffeine, nicotine, alcohol) have rapid effects on brain function because they are able to pass directly through the barrier.
Constant supply of oxygen and glucose are required for cellular respiration. The brain uses a lot of ATP in signal transmission, and these are needed to carry this out. (mitochondria are located in the cell body of the neuron - allows for on site ATP production and fast use)
Cerebrospinal Fluid
- Dense, clear liquid derived from blood plasma, found in the ventricles of the brain, in the central canal of the spinal cord, and in association with the meninges
- They transport hormones, white blood cells, and nutrients across the blood-brain barrier to the cells of the brain and spinal cord.
- Also acts as a shock absorber to cushion the brain.
Cerebrum
Each half of the cerebrum consists of an internal mass of white matter and a thin outer covering of grey matter called the cerebral cortex.
The cerebral cortex is responsible for language, memory, personality, conscious thought, and other activities associated with thinking and feeling.
The left and right half of the cerebrum are called cerebrum hemispheres.
Corpus callosum
bundle of white matter that joins the two cerebral hemispheres of the cerebrum, of the brain; sends messages from one cerebral hemisphere to the other, telling each half of the brain what the other half is doing.
The Somatic System
Controls voluntary movement of skeletal muscles.
Its neurons service the head, trunk, and limbs.
The somatic system includes:
- 12 pairs of cranial nerves
- 31 pairs of spinal nerves (all myelinated)
The Autonomic System
Controls involuntary glandular secretions and the functions of smooth and cardiac muscle
Maintains homeostasis by adjusting the body to variations in the external and internal environments
Controlled by hypothalamus and medulla oblongata
further divided into the sympathetic and parasympathetic systems.
The Parasympathetic Nervous System
- part of autonomic system
- activated when the body is calm and at rest
- acts to conserve energy and is often referred to as the “rest-and-digest” response.
- uses the neurotransmitter acetylcholine to control responses (reduced heart rate, reduced blood pressure, and increased digestion).
- Both branches of the autonomic system work in opposition to balance reactions and maintain homeostasis.
Frontal lobe
- top front of brain
- general motor association area
- primary motor area
- frontal association area (planning, personality)
- Broca’s area (expressing language)
The Sympathetic Nervous System
- part of autonomic system
- Typically activated in stressful situations and is often referred to as the “fight-or-flight-or-freeze” response.
- The Amygdala electrically signals the hypothalamus, the hypothalamus signals the pituitary gland via hormones, the pituitary gland signals the adrenal glands (via hormones) to release epinephrine and norepinephrine
- excitatory neurotransmitters that activate the stress response (increased heart rate, breathing rate, increased blood pressure to increase the amount of O2 and glucose to muscles, and decreased digestion).
- Meditation may reduce the activity of
the sympathetic nervous system.
Occipital lobe
- back of brain
- visual association area
- primary visual cortex (visual input)
Parietal lobe
- top of brain
- primary somatosensory area
- taste
- general sensory association area
Temporal lobe
- both sides of brain (left and right)
- smell
- auditory area (hearing input)
- auditory association area
- facial recognition area (on inner side of cortex)
- Wernicke’s area (understanding language)
pituitary gland
- connected to hypothalamus
- sends information to the rest of the body
- controlled by hypothalamus
- main gland that controls a lot of the homeostasis within body.
afferent system
primary neurons that receive information from our sensory system
- found in PNS
- send information to CNS
- CNS integrates a response through reflex, spine or brain
- Sends back response through the efferent system
- autonomic or involuntary control
Schwann cells
- made up of glial cells
- type of glial cell
- line themselves on the axon and insulate it
- axon is the most important part of a neuron because it does the transferring of communication signals
what refers to the maintenance of the body’s internal environment at a constant level?
homeostasis
Mylanation
- using Schwann cells to insulate axon
- parkinsons disease: when mylanation starts to degrade. This leads to loss of motor function which is why it’s hard to move. Axons will eventually also start to degrade
caffeine
- freely enters through the blood-brain barrier
- unregulated drug
- can stunt growth
- proven to cause drug-like symptoms
- the first thing it affects is the brain
- this is why it affects mood
- can have withdrawal symptoms
which division of the nervous system controls the senses of touch, taste, sight, sound, and smell?
a. motor division of the central nervous system
b. motor division of the peripheral nervous system
c. parasympathetic division of the autonomic system
d. somatic division of the central nervous system
e. somatic division of the peripheral nervous system
e. somatic division of the peripheral nervous system
The generation of a nerve impulse begins with a slight leakage of sodium ions through sodium channels in the neuron. This results in a change in the membrane potential, which, in turn, causes more sodium channels to open which creates the action potential. Which is this an example of?
a. a negative feedback system
b. a positive feedback system
c. the integumentary system
d. the endocrine system
e. a regulatory system
b. a positive feedback system
Which is responsible for carrying impulses from the external sensory receptors to the CNS as well s carrying motor commands to the skeletal muscles?
a. parasympathetic system
b. somatic nervous system
c. sympathetic system
d. central nervous system
e. autonomic nervous system
b. somatic nervous system
Which are the main neurotransmitters of the sympathetic nervous system and the parasympathetic nervous system, respectively?
a. dopamine and serotonin
b. dopamine and norepinephrine
c. serotonin and acetylcholine
d. endorphins and norepinephrine
e. norepinephrine and acetylcholine
e. norepinephrine and acetylcholine
Which lobe of the cerebral cortex is responsible for understanding speech and retrieving visual and verbal memories?
a. temporal lobe
b. parietal lobe
c. occipital lobe
d. frontal lobe
e. motor lobe
a. temporal lobe
Which of the following statements about the parasympathetic nervous system is false?
a. the PNS releases acetylcholine
b. the PNS lowers blood pressure
c. the PNS decreases breathing rate
d. the PNS slows heart rate
e. The PNS decreases intestinal activity
e. The PNS decreases intestinal activity
