Course Exam 3 Flashcards
What are the four principle function of the spinal cord?
1. Conduction - information sent up and down via electrical signals (between sensors, control center CNS and effectors
2. Neural Integration - Nerves receive information from multiple locations and they integrate
3. Locomotion - walking involves several muscles and neurons
4. Reflexes - integration- vital role in posture, motor control and response to pain
What are the regions the spinal chord is divided into?
cervical
thoracic
lumbar
sacral
In two areas the cord is a little thicker than eleswhere. What are these regions called?
In the inferior cervical region = cervical enlargement
lumbosacral region = lumbar enlargement
where does the cord taper to a point?
medullary cone (conus medullaris)
What is the bundle of nerve roots that occupy the vertebral cone from L2 to S5?
cauda equina
(resemblance of a horse’s tail)
Innervates the pelvic organs and lower limbs
What is the fiberous (3) membranes that enclose the spinal cord and brain called?
meninges
separate the soft tissue of the central nervous system from the bone of the vertebrae and skull
from superficial to deep, they are the dura mater, arachnoid mater and pia mater
What forms a loose-fitting sleeve around the spinal cord?
What is the sleeve called as well?
dura mater
- keeps other things separated from the spinal cord (Epidurals go into this outer dura mater)
dural sheath
What is the space between the sheath and vertebral bone called?
epidural space
occupied by bone vessels, adipose tissue, and loose connective tissue
location of the epidural anesthesia during childbirth
What consists of a highly vascular layer and a simple squamous epithelium that adhears to the inside of the dura, and a loose mesh of collagenous and elasic fibers
arachnoid mater
- does not preserve very well…
What gap is filled with cerebrospinal fluid (CSF)
subarachnoid space
What is inferior to the medullary cone, the subarachnoid space called? is occupied by the cauda equina and CSF
lumbar cistern
What is delicate, transparent membrane that closely follows the contours of the spinal cord
pia mater
What is relatively dull color because it contains little myelin - mainly neural cell bodies?
contains the somas, dendrites and proximal parts of the axons of neurons
The site of synaptic contact between neurons and therefore the site of all neural integration in the spinal cord
Gray matter
What is bright, pearly white appearance due to the abundance of myelin.
It is composed of bundles of axons, called tracts, that carry signals from one level of the CNS to another
White matter
What are two directional terms used in descriptions of CNS anatomy?
Name and describe
Rostral = “toward the nose”
caudal = “toward the tail”
What are the three major portions to divide the brain?
Cerebrum = 83% of brain’s volume and consists of a pair of half globes called the cerebral hemispheres
Cerebellum = occupies the posterior cranial fossa inferior to the cerebrum, separated from it by the transverse cerebral fissure
Brainstem = it is all of the brain except the cerebrum and cerebellum. Its major components, from rostral to caudal, are the diencephalon, midbrain, pons, and medulla oblangata
What is the thick folds that divide the brain?
What are the thick folds separated by with shallow grooves called?
Thick folds = gyri
Shallow grooves = sulci
What are the thick bundle of nerve fibers that are at the bottom of the fissure that connect the hemispheres?
corpus callosum
a prominent landmark for anatomical description with a distinctive C shape in sagittal section
What is the cerebellum separated by?
transverse cerebral fissure
What are the major components of the brainstem?
diencephalon, midbrain, pons, and medulla oblangata
What does the seat of the neurosomas, dendrites and synapses (gray matter) forming a surface layer called?
cortex
over the cerebrum and cerebellum, and deeper masses called nuclei surrounded by white matter
As in the spinal cord, white matter of the brain is composed of what?
tracts, or bundles of axons, which here connect one part of the brain to another and to the spinal cord
What does the nervous system develop from?
ectoderm, the outermost tissue layer of an embryo
When does the nervous system develop?
Within the first 3 weeks, a neural plate forms along the dorsal midline of the embryo and sinks into the tissues to form a neural groove, wich a raised neural fold along each side.
What occurs on day 26?
Creates a hollow channel called the neural tube. Following closure, the neural tube separates from the overlying ectoderm, sinks a little deeper, and grows lateral processes that later form motor nerve fibers
As the neural tube develops, some ectodermal cells that originally lay along the margin of the groove separate from the rest and form a longitudinal column on each side called this?
neural crest
give rise to the two inner meninges (arachnoid mater and pia mater); most of the peripheral nervous system, including the sensory and autonomic nerves and ganglia and schwann cells; and some other structures of the skeletal, integumentary, and endocrine systems
What are the neural tube exhibits three anterior dilations, or primary vesicles called?
forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon)
By the fifth week, it subdivides into five secondary vesicles. The forebrain divides into two of them, what are they?
telencephalon and diencephalon
By the fifth week, it subdivides into five secondary vesicles. The midbrain remains undivided and retains the name?
mesencephalon
By the fifth week, it subdivides into five secondary vesicles. The hindbrain divides into two of them, what are they?
metencephalon
myelencephalon
What are the three connective tissue membranes that envelope the brain?
meninges lie between the nervous tissue and bone made up from:
dura mater
arachnoid mater
pia mater
What is the function of the meninges (made of 3 layers)
Protect the brain and provide a structural framework for its arteries and veins
In the cranial cavity, the dura mater consists of two layers?
an outer periosteal layer equivalent to the periosteum of the cranial bones, and an inner meningeal layer
Only the meningeal layer continues into the vertebral canal, where it forms the dural sheath around the spinal cord
In some places, the two layers of dura are separated by?
dural sinuses, spaces that collect blood that has circulated through the brain
Two major, superficial ones are the superior sagittal sinus, found just under the cranium along the median line, and the transverse sinus, which runs horizonatally from the rear of the head toward each ear.
These sinuses meet like an inverted T at the back of the brain and ultimately empty into the internal jugular veins of the neck.
The brain has four internal chambers called?
ventricles
What is the largest and most rostral internal chamber of the brain
two lateral ventricles, which form an arc in each cerebral hemisphere
Through a tiny pore called the _________ _________, each lateral ventricle is connected to the _____ _____, a narrow median space inferior to the corpus callosum.
interventricular foramen
third ventricle
From here, a canal called the ____ _____ passes down the core of the midbrain and leads to the _____ _____, a small triangular chamber between the pons and cerebellum.
Cerebral aqueduct
fourth ventricle
Caudally, this space narrows and forms a _____ ______ that extends through the medulla oblongata into the spinal cord
central canal
on the floor or wall of each ventricle is a spongy mass of blood capillaries called?
choroid plexus
named for its histological resemblance to a fetal membrane called the chorion
What is the clear, colorless liquid that fills the ventricles and canals of the CNS and bathes its external surfac?
Cerebrospinal fluid (CSF)
Explain the movement of cerebrospinal fluid (CSF)
The brain produces ~500 ml of CSF/day, but the fluid is constantly reabsorbed at the same rate and only 100 - 160 mL is normally presented at one time.
~40% is formed in the subarachnoid space external to the brain, 30% by the general ependymal lining of the brain ventricles, and 30% by the choroid plexuses.
How is CSF produced and what does it compose of?
Begins with the filtration of blood plasma through the capillaries of the brain
Ependymal cells modify the filtrate as it passes through them, so the CSF has more sodium and chloride than blood plasma, but less potassium, calcium, and glucose and very little protein
What is the hydrocephalus?
The abnormal accumulation of CSF in the brain, usually resulting from a blockage in its route of flow and reabsorption. Such obstructions occur most commonly in the interventricular foramen, cerebral aqueduct, and apertures of the fourth ventricle. The accumulated CSF expands the ventricles and compresses the nervous tissue, with potentially fatal consequences. In a fetus or infant, it can cause the entire head to enlarge because the cranial bones are not yet fused. Good recovery can be achieved if a tube (shunt) is inserted to drain fluid from the ventricles into a vein of the neck.
CSF is reabsorbed by ______ _______, extensions of the arachnoid meninx shaped like little sprigs or cauliflower, protruding throug the dura mater into the superior sagittal sinus.
arachnoid granulations
CSF penetrates the walls of the granulations and mixes with blood in the sinus.
Cerebrospinal fluid sereves three main purposes
name and describe
- Buoyancy - Because the brain and CSF are similar in density, the brain neither sinks nor floats in the CSF. It hangs from delicate specialized fibroblasts of the arachnoid meninx. A human brain removed from the body weighs about 1,500 g, but when suspended in CSF its effective weight is only about 50 g.
- Protection
- Chemical stability
Despite its critical importance to the brain, blood is also a source of this?
antibodies, macrophages, bacterial toxins, and other potentially harmful agents
What protects the brain and strictly regulates what can get from the bloodstream into the tissue fluid of the brain
Brain barrier system
There are two poteintial points of entry that must be gaurded, what are they?
the blood capillaries throughout the brain tissue and the capillaries of the choroid plexuses
What type of protection is consists of tight junctions between the endothelial cells that form the capillary walls
blood-brain barrier (BBB)
What are the types of ascending tracts?
- Gracile Fasciculus
- Cuneate Fasciculus
- Spinothalamic
- Spinoreticular
- Spinocerebellar
‘Big Picture’
What makes up the peripheral nervous system?
Nerves and ganglia
‘Big Picture’
What makes up the central nervous system?
Tracts and centers
What is the main organization of the ascending tracts?
Neural pathway:
- first : stimulus to spinal cord - balance (afferent neurons)
- Second : spinal cord to thalamus
- Third : Thalamus to cortex (sense large changes)
Explain the Gracile Fasciculus
Ascending Tract
- Somatic pathway
- Carries sensations of trunk position and movement, deep touch, visceral pain and vibration
- Below T6 to the thalamus
gracile = “thin and skinny”
What structure is an ascending tract that does the following:
- cone shaped
- Carries sensations of movement, deep touch, visceral pain and vibration
- above T6 to the thalamus
Cuneate Fasciculus
- somatic pathway
(Recall, above T6 is the arms)
Explain the Spinothalamic
Ascending Tract
- Somatic pathway
- Carries sensations of light touch, itch, temperature, pain and pressure
- to the thalamus
- connects the spine and the thalamus
What carries senesations of pain from injury to the thalamus?
Spinoreticular
- Ascending tract
- Somatic pathway
- Recall: reticular = net like
Explain the spinocerebellar
Ascending Tract
- Somatic Pathway
- Carries information on muscle positions (proprioception) to the cerebellum
- No third order neuron, we do not have a sense of this, it just does it
Name the descending tracts
Muscles of the face are innervated in before spinal cord
Vast majority in cerebral cortex
- Corticospinal
- Tectospinal
- Reticulospinal
- Vestibulospinal
What is the organization of the descending tracts?
ALL SOMATIC
- Upper motor neuron - originates in the brain (most thin little slice in cerebral cortex = motor cortex)
- Lower motor neuron - innervates muscles as part of NMJ
- Synapse at grey horns
Explain the Corticospinal tract
Descending Tract
- Somatic pathway
- Fine control of limbs
- Pretty large areas, lots of axons due to lots of potential movements
- cortico = cerebral cortex and spine, then leaves by peripheral nerves
What is responsible for reflexive head movement
Tectospinal
- Descending tracts
- Somatic pathway
- Maintains head posture
Explain the Reticulospinal tract
Descending Tracts
- Somatic pathway
- Balance and posture, regulation of awareness of pain
- Can modify how much pain gets in
- Reticular = net like
What tract is responsible for balance and posture (lateral) and control of head position (medial)
Vestibulospinal
- Descending Tracts
Somatic Pathway
Explain where spinal nerves originate and what they do
- Originate at spinal cord and axons go to somewhere else
- Carry sensory input and motor output
- LOCATION, LOCATION, LOCATION
What is the region of skin innervated by sipinal nerves called?
Dermatomes
- can be used to locate spinal damage
- Knowing where the nerves run you can diagnose where the pain or injury is
- Above T6 = okay to move carms but paralized legs
What are the properties of reflexes, specifically somatic reflexes?
- Require stimulation
- Rapid (not many neurons involved)
- Involuntary (Cannot control them but can modify them consciously)
- Non-variable
Explain the reflex arc
Homeostatic feedback loop - sorta negative
- Stimulus
- Sensory neuron activation (afferent neuron)
- Integration by interneuron (s) - location in the CNS, not brain
- Motor neuron activation - Stimulus directly activates action to reach threshold potential
- Effector response - only activates if large enough stimulus
(recall: action potentials are non variable)
What is a proprioceptor?
Muscle Spindle - Neuromuscular structure goes to cerebellum (balance/equilibrium)
- Give information on muscle position
- Intrafusal fiber: (intera = inside) the muscles that are doing the actual work - inside skeletal muscles (general tightness of sensor) - between the fibers
- Afferent neurons monitor rate of change (primary) and length (secondary)
- receptors to the brain how quickly = primary; what the actual length is right now =secondary neurons
What are the primary motor neurons responsible for?
Monitor rate of change
what are secondary neurons responsible for?
monitoring length that the muscle is currently at
What are the two types of motor neurons?
- Alpha : extrafusal fibers (NMJ) : the ones that contract the muscles
- Gamma : intrafusal fibers : Stimulate the sensor that allows for the muscle to be tight
What are the types of somatic reflexes?
- Stretch reflex
- Withdrawl reflex
- Crossed Extensor Reflex
- Tendon Reflex
Explain the stretch Reflex
As a muscle is stretched, tone increases
- maintains posture and balance, stabilizes movement
- Can involve multiple neurons, or as little as two
1. Monosynaptic reflexes: patellar reflex :
knee jerk reaction
Primary nerve: how rapid change
(temperal summation)
2. Polysynaptic reflexes: Involve more than one neuron and take more time (withdrawl reflex and crossed extensor reflex)
Sensory (afferent) and motor neurons (efferent) involved
Explain the withdrawl reflex
Stimlated by painful stimuli
Reciprical inhibition:
- Coontraction of agonists
- Relaxation of antagonists: potassium gates or chloride channels inhibit the muscles
Not only stimulate muscles to allow for a concertric activity, but also inhibits the muscles that do the opposit
Explain the crossed extensor reflex
Painful stimulus to foot while walking
- One side contraction of agonist, relaxation of antagonists
- Reversed on the other side
Still have more than one neuron acting together, but still a pretty simple reflux
One pulls away, other prepares for that by locking everything down for balance
What makes up the Diencephalon?
Three critical structures of the Diencephalon
- Epithalamus
- Thalamus
- Hypothalamus
What is the function of the Diencephalon?
Integration of conscious and unconscious sensory information and motor commands
What makes up the Epithalamus?
What part of the brain is the Epithalamus in?
Includes pineal gland (melatonin secretion)
Choroid plexus, Major lining of 3rd ventricle
Located in the Diencephalon
What is the function of the Thalamus?
What is the location of the Thalamus in the brain?
Functions:
1. Filters and projects cerebral information (relay center) -decides if info is important to go on
2. Visual and auditory information to cortexes - optic and auditory nerves come in and project
3. Regulates consciousness - Damage = coma (lots of drugs impact this area)
4. Influences emotions - many think people with autism have issues with this area
Location in Brain:
Diencephalon
What are the major nuclei of the Thalamus?
Major Nuclei:
1. Anterior group : Part of the limbic system = area where we send info to cerebral cortex, color with emotion
2. Medial group: Emotional output to prefrontal cortex; awareness of emotions = projects sensory to frontal lobe
3. Ventral group: Projects somatic sensory info to somatosensory cortex; relays iinfo from cerebellum and basal nuclei to motor complex = localize where sensory is coming from, develop this as you grow
4. Lateral group: integration of sensory info and infuence of emotional state (see car = friend, relation)
5. Posterior group: two primary senses - visual and auditory
5.1. Lateral geniculate nucleus: projects visual info to the visual cortex
5.2. Medial geniculate nucleus: projects auditory info to auditory cortex
What are the three structures that make up the Diencephalon?
- Epithalamus
- Thalamus
- Hypothalamus
What is the function of the Hypothalamus?
What part of the brain is the Hypothalamus in?
“one ring” - to control them all… head quarters of Autonomic NS
Neurosecretory coordination - makes decision and send out hormones, endocrine and neural system
What does the Hypothalamus respond to?
- Neural stimuli : can change rate of action potentials
- Hormones : tropic hormones, cause other hormone systems to do their job
- Blood/CSF chemical stimuli : direct response to chemical stimulation
What are the major functions of the hypothalamus?
- Autonomic coordination (HR, BP) : viceral activity
- Neurosecretory functions (w/pituitary)
- Physiological drives (hunger, thirst)
- Memory (w/ limbic system)
- Regulation of body temperature
- Control of circadian rhythms : sleep rhythms
- Emotional behavior and sexual response
What makes up the Cerebrum?
- Gray matter
- White matter
- Basal Nuclei
- Cerebral cortex
Explain the function and makeup of the Gray matter in the cerebrum
- All the memories are right there
- Basal nuclei: unconscious coordination: athletics, walking, muscle memory
- Cerebral cortex: conscious awareness and intellectual functions : makes us uniquely consious learning individuals
Explain the white matter of the cerebrum
Neural wiring - relay information bypass (axons)
primary, secondary, tertiary…. primary attaches to muscles, etc
Explain the Basal Nuclei of the Cerebrum
- Process sensory information
- Direct control over subconscious movement
- Indirect control and modification of conscious movement (via motor cortex)
Explain the Cerebral Cortex of the Cerebrum
- Two functionally distinct hemispheres
- left receives info from and controls the right side of body
- coordinated by corpus callosum
- Specific areas control specific functions
- Motor and Sensory areas
- Association areas
Explain the Limbic System and it’s overall function
Coordinates information between cerebrum and diencephalon
how we integrate and color to remember the good things and do it again, remember the bad things
“colors/coats world with emotion”
Songs or associate with emotion
What are the individual functions of the Limbic system
- Establishes emotional states and drives
- Linking cerebrum (conscious) with brainstem (unconscious)
- Motivation and drive
- Coordinating memory storage and retrieval
- Amygdaloid body: emotion -> memory
- Hippocampus: memory storage and retrieval
- Neural activity
Where are Amygdaloid bodies located and what do they do?
Located in the Limbic System
Emotion -> memory
Where is the Hippocampus located and what does it do?
Located in the Limbic System
Memory storage and retrieval
What are the effectors of the Autonomic Nervous System?
- Smooth muscles
- Cardiac Muscles
- Glands
- Adipose Tissue
What are the visceral reflexes of the Autonomic Nervous System I
- Receptors:
- Bareceptors, chemoreceptors, thermoreceptors, etc
- Afferent (sensory) nerves
- Integration centers
- Efferent (motor) nerves
- Effectors
What are the Autonomic Divisions of the Autonomic Nervious System?
- Sympathetic :
- “Fight or Flight”
- Parasympathetic :
- “Resting and Digesting”
- Enteric :
- “The brain in your gut”
What are the Autonomic Pathways of the Autonomic Nervious System?
- Integrative center
- Preganglionic fiber
- Ganglion
- Post ganglionic fiber
- Varicosites
Explain the Funcational Anatomy of the Sympathetic Nervious System
Prepares somatic division for action = “Fight or Flight”
Neural and hormonal activity
Inhibitory and excitatory options
Explain the Sympathetic organisation
Preganglionic neurons branch from lateral gray horns of CNS
State and explain the three ganglionic neuron groups of the sympathetic nervous system
-
Sympathetic chain ganglia
- Innervates head and thoracic organs via sympathetic nerves
- Generally excitatory (heart rate, long dilation, etc)
- Innervate peripheral structures and glands via spinal nerves
-
Collateral ganglia
- Innervate abdominopelvic organs via splanchnic nerves
- Generally inhibitory (decreased digestion)
-
Adrenal Medullae
- Stimulate release of epinephrine and norepinephrine
- Sympathetic Anatomy
Explain the functional anatomy of the Parasympathetic Nervious System
- Visceral function and energy conservation =
- “Resting and Digesting”
- Fewer effectors, but more specific targeting than sympathetic
- Functional Anatomy:
- Preganglionic neurons in brain stem (cranial nerves) ans sacral segments
- Ganglionic neurons terminate near, or in, target organs
- Vagus nerve most significant
Explain the sympathetic activity
- “Normal” activity
- Targeted homeostatic mechanisms
- Eg: mobilization of energy stores, increased cardiac output, sweating, pupil dialation
- Targeted homeostatic mechanisms
- Sympathetic activation
- Activation of entire sympathetic system
- Crisis management
Explain the Parasympathetic Activity
- Pupil constriction
- Increased digestive activity - secretion and peristalsis
- Anabolic activity (eg. insulin release)
- “Bathroom” activities
- Reduced metabolic function: HR and respiration
- Sexual arousal
What are the Parasympathetic receptors for Autonomic Communication? (name)
- Cholinergic (NT: Acetylcholine)
- Nicotinic Receptors - Excitable polarized cells, direct effect
- Muscarinic - Indirectly effect the actifity in the cell
Explain the Cholinergic receptor
Parasympathetic receptor
- NT: Acetylcholine - it responds to acetylcholine = conformational change
What are Nicotinic Receptors?
Parasympathetic receptor
- Excitable polarized cells, direct effect
- Slightly negative causing them to become depolarized
- Ach binding ->
- Sodium channels opened ->
- Depolarization (excitatory!)
- E.g. All autonomic postganglionic neurons, adrenal medullae
Explain Muscarinic receptors
Parasympathetic receptor
- Indirectly effect the activity in the cell
- ACh binding ->
- G protein activation ->
- Activation / inhibition of effector cell activity via secondary messengers
- E.G. Increase gland secretion, Decreased cardiac muscle activity
- Most common type of post ganglionic to turn on switch
- eg. digestive system glands, heart slows down with injection
What are the types of sympathetic receptors?
“Fight or flight”
Adrenergic (NT: Norepinephrine (NE) and
epinephrine (E))
- Alpha receptors
- Beta receptors
What are the types of alpha receptors?
Sympathetic receptors = “Fight or flight”
- Alpha (a1) receptors: - Stimulate
- Alpha (a2) receptors: - Inhibitory
Explain Alpha (a1) Receptors
Sympathetic receptor
“Fight or flight”
- Bind to NE (‘normal’ sympathetic control or E
- Stimulate Ca 2+ release from the ER - second messenger
- Usually excitatory: e.g. contraction, secretion
- smooth muscle, face gets white when scared
Explain Alpha (a2) Receptors
Sympathetic Receptors “fight or flight”
Cellular gasoline
- Decrease cAMP levels
- Usually inhibitory: eg. digestive activity
Explain Beta (B) receptors and name the types
Bind to epinephrine and norepinephrine
Increase cAMP levels in target cells
Three types:
- Beta (B1) Receptor = Excitatory
- Beta (B2) Receptor = Inhibition of activity (smooth muscle)
- Beta (B3) receptor = Stimulates lipolysis of adipocytes
Explain Beta (B1) Receptors
Sympathetic Receptor “Fight or Flight”
Excitatory: eg Increase cardiac contraction
causes heart to beat faster and stronger
Explain Beta (B2) receptors
Sympathetic Receptors “Fight or Flight”
- Smooth muscle relaxation
- Inhibition of activity, decrease action of smooth muscle
- E.g. Respiratory smooth muscle relaxation
- -> vasodilation / bronchodilation
Explain Beta (B3) receptors
Sympathetic Receptor “fight or Flight”
Stimulates lipolysis in adiposcytes
function of sympathetic = free up reserves
break down adipose or fat tissue why spressed people are usually skinny
Explain the comparison between the SNS and ANS
- Lost of things the same = ACh common neurotransmitter
- Skeletal muscles = lower motor neurons (somatic nervous system)
- Preganglionic neuron and post ganglionic neuron, interacts with effector = cardiac muscle parasympathetic devision
- Main difference : smooth muscle sympathetic = uses norepinephrine
- glands in the sympathetic use ACh to turn on and epinephrine and norepinephrine to turn on
Explain the types of signals for the Autonomic communication
- Acetylcholine
- Norepinephrine and Epinephrine
Explain signal degradation
- Acetylcholine
- Acetylcholinesterase
- Works AMAZINGLY quick. Prevents continuous contraction, breaks down ACh
- Acetylcholinesterase
- Norepinephrine and Epineprhine
- Still works to break down, but takes a lot longer
- Monoamine oxidase (MOA)
- Breaks down norepinephrine (PTSD treatment)
- Catechol-O-methytrasferase (COMT)
- Breaks down norepinephrine, these that aren’t broken down in th eliver, takes long for the epinephrine to dial down
- Liver
- Monoamine oxidase (MOA)
- Still works to break down, but takes a lot longer
Explain dual innervation of autonomic communication
- Opposing (antagonistic) effects at effects - lots have both parasympathetic and sympathetic
- Present at most visceral organs
- Digestive trac, heart, lungs, eyes
- Autonomic tone
- Two controllable “gas/brake bedals” in operation at all times
- Half on/half off mode… allows for good control, evidence if you increase or decrease one you will see an impact in both up and down = rapid change is done
- Two controllable “gas/brake bedals” in operation at all times
- Single Innervation - light switch
- Sometimes only the PSNS or SNS control an effector
- eg. vasocontraction, reproductive activity (eg. blood vessels and sweat clands)
- Sometimes only the PSNS or SNS control an effector
- Autonomic Activity
What are the Autonomic Receptors?
- Baroreceptors - mechanoreceptors located in the carotid sinus and in the aortic arch. Their function is to sense pressure changes by responding to change in the tension of the arterial wall. The baroreflex mechanism is a fast response to changes in blood pressure.
- Chemoreceptors - specific for one molecule
What are the Autonomic Control Centers and what do they do?
- Cerebral Cortex
- Emotions can influence autonomic activity
- Fear, anxiety, arousal
- Hypothalamus
- Primary cortrol center of autonomic activity
- Hindbrain and Brain Stem
- Cardiovascular control
- Respiratory control
- Sweating, swallowing, bladder control, pupils, salivation and digestive secretion
- Spinal Cord
- Autonomic (Short) reflexes
- Micturation
- Defecation
- Sexual activity
What does the Thalamus do?
decides to send the signal or not based on the receptor
Explain the steps of signalling for an action
- Stimulus - have the ability to cause cells to become excitable = transduction
- Transduction (graded potential)
- Action potential - leads to a propagation will then get to the central nervous system
- Propagation (via labeled line)
- Sensation - Nervous system has been alerted to the stimulus leading to a perception
- Preception - what kind of pain or touch is it
What are the sensory cell types?
- Free nerve endings
- Neurons - excitable cells that can be depolarized (sense of touch)
- Receptor cell -> neurotransmitter -> neuron
- Transduction different stimuli
- Neurons in the integumentary system (skin) - pressure sensor or specialized cell - ears, eyes, nose…
Explain the Receptor potential
- Graded depolarization (or hyperpolarization) by stimulus
- May change rate of action potentials
- How do we turn analong info (on or off) to digital senses = rate of action potential
- Can detect the strength of the push is the pulses of action potentials
What are Receptor properties? - sensory receptors
- Modality - What type?
- Location - Where?
- Intensity - How strong?
- Duration - How long?
Explain the Modality receptor property - sensory receptors
- Modality - What type?
- Labeled line - similar to a wiring circuit to a building, one switch on or off… not born with it but do
- Neural pathway - learn in time
- Sensory receptor -> cerebral cortex
- Depends on the brain region stimulated
- Neural pathway - learn in time
- Receptor (afferent), spinal cord (2nd order), thalamus, cortex (3rd order)
- From source to the brain….
- Labeled line - similar to a wiring circuit to a building, one switch on or off… not born with it but do
Explain the Location receptor property? - sensory receptors
- Where?
- Receptive field - especially the case of touch
- Sensory projection
- Location perceived based on brain region
- Sensory homunculus
- Two-point discrimination
- Based on the relative number of receptive fields/skin area
- More fields = greater ability to localized stimulus
Explain the intensity receptor property? - sensory receptors
- How strong?
- Higher rate of APs
- Multiple neurons
- Various sensitivity
Explain the Duration receptor property? - sensory receptors
- How long?
- Sensory adaptation
- Phasic (fast-adapting) receptors
- Provide information on onset and/or intensity of stimulation, followed by adaptation
- Examples: thermoreceptors, tactile receptors, taste, and smell
- Tonic (slow-adapting) receptors
- Little (or NO) adaptation
- Examples: pain, muscle spindles, joint proprioceptors
- Little (or NO) adaptation
- Phasic (fast-adapting) receptors
What are the Receptor Types for sensory, name and describe? - sensory receptors
- Modality
- Thermoreceptors
- Photoreceptors
- Nociceptors
- Chemoreceptors
- Mechanoreceptors
- Osmoreceptors
- Stimulus Origin
- Exteroceptors
- Interoceptors
- Proprioceptors
- Receptor Distribution
- General (somatosensory) senses
- Special senses
What are the general senses receptor type?
- Free nerve endings (general)
- Root hair plexuses (hair movement)
- Tactile (Merkel’s) discs (light touch)
- Tactile (Meissner’s) corpuscles (light touch)
- Lamellated (Pacinian) corpuscles (deep pressure)
- Bulbous (Ruffini) corpuscles (skin distortion)
Name and describe the somatosensory Pathways
First- order neuron
- Sensory location -> Spinal cord (gray horns)
Second-order neuron
- Gray horn -> thalmus (after crossing over)
Third order neuron (if conscious awareness)
- Thalamus -> Sensory cortex
- CNS interneuron -> CNS interneuron
- Crossover (left sensory to right hemisphere)
What are the chemical senses?
- Gustation (taste)
- Olfaction (smell)
Explain the Gustation (taste) Anatomy
- Taste buds (epithelium + taste receptors)
- Fungiform papillae
- Circumvallate papillae
Explain the Gustation (taste) receptors
Sweet, salty, sour, bitter, umami
Explain the Gustation (taste) Physiology
- Sour (H+) and salt (Na+) pass through leak ion channels
- Others utilize G protein receptors (gustducins) and cAMP
Explain the Gustation (taste) Neural sensory pathways
VII (Facial)
IX (glossopharyngeal)
X (Vagus)
V (trigeminal)
Sensitive and capsaicin
Explain the Olfaction (smell) anatomy
- Olfactory epithelium
- Olfactory receptors
- Modified neurons
- 10-20 Million
- 2-4 k types
Explain the Olfaction (smell) physiology
- Odorant binding to specific G protein
- Adenylate cyclase activation
- ATP -> cAMP
- cAMP opens Na+ and Ca 2+ channels
- Depolarization -> action potentials
Explain the Olfaction (smell) integration
- Olfactory nerve (I) -> olfactory bulb
- Thalamus, hypothalamus and limbic system
- Olfacotry cortex
- Rapid, central adaptation
Explain the anatomy of the ear
- External ear
- Pinna, Acoustic canal, Tympanic membrane
- Middle ear
- Ossicles (malleus, incus, stapes)
- Transmit sound waves to cochlea
- Protection!
- Auditory tube
- Communicates with nasopharynx
- Ossicles (malleus, incus, stapes)
- Inner ear
- Cochlea
- Sound reception
- Organ of corti
- Outer hair cells - adjustment
- Inner hair cells - hearing
- Cochlea
Explain the principles of sound (auditory physiology)
- Principles of sound
- Waves moving through medium
- Frequency: distance between peaks
- Measured in Hertz (pitch)
- More distance = higher sound
- Measured in Hertz (pitch)
- Amplitude: energy of waves
- Measured in decibles
- Frequency: distance between peaks
- Transduced by number of hair cells distored = pitch and volume
- Waves moving through medium
Explain hearing physiology
- Hearing physiology
- Volume based on strength of distortion (# of hair cells)
- Pitch detected dur to location of distortion
- Flexibility of basilar membrane
- Regidity results in hearing loss
Explain hearing phisiology Transduction
Distortion cause K+ chanels to open or shut more than rest: change rate of action potientials
Banana salt…. K+ more on outside: cochlear branch of vestibulocochlear nerve
- Sound reaches tympanic membrane
- Ossicle displacement
- Pressure waves in perilymph - oval window from stapes
- Distortion of basilar membrane
- Depolarization due to mechanical distortion of hair cell membranes NT release
- Sent to brain via cochlear branch of the vestibulocochlear nerve
Pulse of action potentials go into the nerve
Explain the neural pathways
- Via cochlear nerve (VIII)
- Medulla
- Inferior colliculi
- Thalamus (MGN = mediate genicular nucleus, projects to auditory cortex)
- Auditory cortex
Explain the Equilibrium Anatomy and what it helps with
- Membranous labyrinth
- Semicircular canals
- Info on head rotation/position
- Saccule and utricle
- Info on gravitational position (acceleration and deceleration)
- Otolith (acceleration and deceleration)
- statoconia
- Info on gravitational position (acceleration and deceleration)
- Semicircular canals
Explain the Equilibrium physiology of the ear, including the neural pathways
- Hair cell deflection -> depolarization
- Neural pathways
- Via vestibular nerve (VIII)
- vestibular nuclei
- Multiple pathways
Explain the eye anatomy
- Retina
- Contains photoreceptors - special cells
- Rods and cones
- Fovea - highest concentration of cones
- Contains photoreceptors - special cells
- Lens
- Concentric transparent cells containing crystallin
- Distribution of rods and cones in retina
- Cones at fovea - fine details
- Rods at periphery
- Iris
- AN innervation
- Pupillary constriction - parasympathetic
- Pupillary dilation - sympathetic
- AN innervation
Explain the process of Image Formation
- Light relects off object and passes through lens
- Refracted to focal point - fovea
- Lens can distort to accommodate for object distance
- Flattening - far, compresses - close
- Lens can distort to accommodate for object distance
- Refracted to focal point - fovea
- Focus through ciliary muscle action
- Contraction and relaxation
- Image reversal - image in fovea upside down
- Brain compensates
Explain the cataract physical abnomality?
Cataracts: Loss of lens transparency
Explain the Astigmatism physical abnomality
Astigmatism: asymmetric lense curvature
Not perfectly circle
Explain the Myopia physical abnomality
Myopia: eyeball too deep
“nearsighted”
Can’t see things far away
- need light rays to be further back
Explain the Hyperopia physical abnomality?
Hyperopia: eyeball too shallow
“Farsighted”
- cant see things clearly up close
Need light rays to be converged more
Explain the visual spectrum
- Electromagnetic radiation
(380 - 750 nm wavelengths)
380 = violet
750 = red
Explain the visual receptor anatomy - segments
- Outer segment
- Discs
- Contain visual pigments
- Inner segment
- Synapses with bipolar neuron
- Goes into visual cortex and turns into actual image
- Discs
Explain the visual pigments
Rhodopsin - eventually structure you will see in rods = contains retinal and opsin
- Retinal +
- Changes shape becaue of the light energy
- Opsin
- Filter that can receive the different types of light, shape change
- excited by different wavelengths
- Different Opsin are excited a differerent way depending on the wavelength - not all or none
- Varies among rods and cones
Explaiin the Dark state action of Photoreception
Resting (dark) state
Dark state : NT release
- Permeable to incoming Na+ (Depolarized)
- cGMP ‘doorstop’
- “Dark current”
- Cell is depolarized
- NT release
- Bipolar cells inhibited
- Continuous neurotransmitter release, INHIBITORY to next cell
- Not sending information to the brain
- Bipolar cells inhibited
Explain the Active (light) state
NT release inhibition - Hyperpolarized
- Photons activate opsin - photon changes shape of retina
- Retinal changes shape - cis vs. trans (low to high energy)
- Opsin activates transducin (G protein)
- Transducin activates phosphodiesterase (PDE)
- cGMP -> GMP
- Na+ gates closed - no longer have Na going into the cell
- Hyperpolarization
- NT released inhibition
- Biopolar cells stimulated
- Inhibit the number of inhibitory Neurotransmitters
- Goes to visual cortex where the visual word is put together
Explain the recovery period of vision
Bleaching
- Rhodopsin is broken down and reassembled - Retinal is converted
- Time consuming and expensive! ATP
- Sight is a continuous regeneration of Opsin and Retinal
Explain color vision
Three cone types: Blue, Green, red
Based on the peak wavelengths they can transduce, less excitablility on each side
- Each detects _ 100 shades
- Color sensation depends upon which cones stimulated
- White: all cones
- Black: No cones
- Colors: Combos
- Tetrachromats - fourth gold cone
- artists
Explain the neural processing of vision
- Nerves corss at optic chiasma
- Information sent to
- Visual cortex in occipital region
- Brain stem (balance, etc)
- Pineal gland
- Circadian rhythm (night/day rhythms)
Explain field of vision
Depth perception
- Most of cones are in front, meaning more able to detect color, depth, details vs on outside of field of vision is very blurry
Different info coming in from each eye
Name and describe the secretion types of intracellular communication
- Direct - Open holes between each other = gap junctions, like a single cell kinda
- Synaptic - One cell interacts directly with another using a chemical (NT) -axon to receptor
- Paracrine - Releasing bodily fluid, but not affects across entire body and breakdown quickly
- Endocrine - Release bodily fluid into the blood stream and go everywhere, very cheep
Cost vs. speed
What works together with the pituitary gland?
Hypothalamus
Mutual control and coordination
Mostly with autonomic function, work together to create or release hormones
Explain the function and hormones of the Hyopthalamus
Produces more hormones than any other Endocrine organ
- Hypothalamic hormones (tropic hormones)
- Control release of anterior pituitary hormones
- Releasing (RH) and inhibiting hormones (IH)
- Ex. GHRH/somatostatin (GHIH), TRH (Thyroid releasing hormone), GnRH, CRH
- Hormone production (released by posterior pituitary)
- ADH and Oxytocin
- Neural control of adrenal hormone release (E and NE)
Linking the neurons and endocrine system
Explain the function and hormones of the Anterior Pituitary
Tropic hormones (regulate other endocrine organs or glands)
- TSH - stimulate release of thyroid hormones
- ACTH - stimulates release of adrenal cortex hormones
- Gonadotropins - FSH and LH (more later)
- Prolactin (PRL) - stimulates mammary gland development and milk production
- Growth hormone (GH) - stimulates cell division, frees up energy reserves
Explain the function and hormones of the Posterior Pituitary
Release of hormones synthesized by hypothalamus
-
Anti-diuretic hormone (ADH) - promotes water retention
- Physical release point for release of ADH and oxytocin
- Oxytocin (OT) - stimulates uterine contraction, milk release, seminal secretions, bonding and trust
Explain the function and hormones of the thyroid gland
- Follicular cells:
- Controlled by hypothalamus (TRH) and anterior pituitary (TSH)
- Thyroxine (T4)
- Triiodothyrine (T3)
- Increase metabolism/heat production
- Controlled by hypothalamus (TRH) and anterior pituitary (TSH)
- Parafollicular cells:
-
Calcitonin (CT)
- Decrease blood Ca2+ levels
- Inhibits osteoclast activity
- Increases Ca2+ excretion in kidneys
- antagonist to calcitonin is PTH
-
Calcitonin (CT)
Explain the function and hormones of the Parathyroid gland
-
Parathyroid hormone (PTH)
- Increases blood Ca2+ levels
- Stimulates osteoclast division
- Increases Ca2+ kidney reabsorption
- Stimulates calcitriol production (by kidneys)
- Increases Ca2+ absorption by GI tract
- Effectors: osteoclasts kidneys
- Increases blood Ca2+ levels
- Blood calcium homeostasis
Explain the feedback loop for blood calcium level
Feedback loop:
decreased blood calcium levels,
sensed by parathyroid gland,
PTH released,
Impacts osteoclasts and kidneys to increase blood calcium levels
Explain the hormones and function of the adrenal cortex
Corticosteroids
Helps regulate minaral balance = Na most important
-
Mineralocorticoids
- Target: kidneys
-
Aldosterone
- Promotes Na+ retention and K+ excretion in kidney
- Increases water retention
- Triggered by decrease in blood Na+ levels, BP, and blood volume
- As blood Na levels drop, BP increase
-
Glucocorticoids
- Stimulated by ACTH from pituitary
-
Cortisol, corticosterone
- Response to stress
- Increase blood glucose
- Increase lipolysis
- Immune system suppression
Explain the hormones and function of Adrenal Medulla
- Epinephrine and norepinephrine
“fight or flight” = sympathetic response
- Released controlled by hypothalamic sympathetic stimulation
- In response to stress
- Increase blood glucose
- Increase lipolysis
- Increase heart rate and contractile force
Norepinephrine = major neurotransmitter in the sympathetic nervous system
Free up energy for our muscles
Explain the hormone and function of the pineal gland
Secretes melatonin
- Increased production at night
- Regulation of circadian rhythm
- Antioxidant functions in nervous system
- Antioxidant helps to breakdown molecules as things get old
Pathway to our optic system
- Dark or eyes close the pineal gland produces melatonin
Explain the overall hormones and function of pancrease?
Endocrine and exocrine functions
Regulation of blood glucose
- Islets of Langerhans
- Alpha cells: glucagon
- Beta cells: insulin
- Delta cells: somatostatin
Explain the alpha cell function and use
Glucagon - Alpha cells
- In response to decreased blood glucose (<70 mg/dL)
- Stimulates:
- Breakdown of glucogen in liver and muscles
- Breakdown of triglycerides in adipose tissue
- Increases glucose production in liver
- Gluconeogenisis - make sugar from scratch (akins diet people, no carbs)
Glucose is the only thing the brain can use to feed it!!
Explain the beta cell function and use
Insulin - Beta cells
- In response to increase blood glucose (>110 mg/dL)
- Stimulates:
- Increase glucose uptake by cells, esp. muscle, liver and adipocytes
- All but kidneys and brain (not needed)
- Glucose -> glycogen in liver and skeletal muscle
- Increase triglyceride formation in adipose
- Increase glucose uptake by cells, esp. muscle, liver and adipocytes
Key to unlock to bring glucose into cells, not to break it down, NO ABSORPTION IF LACK OF INSULIN
Explain the hormone and function of the Gonads
Gonads: Ovaries and testes
- Under control of FSH and LH (and GnRH)
- Estrogen
- Androgens (e.g. testosterone)
- Progestins - only in females, not men
- More later!
- Target cells = FSH and LH (GnRH released from hypothalamus)
Explain the structure/types of hormones
Types:
- Monoamines
- Individual amino acid base structures (proteins, lipids)
- Peptides
- Proteins - amino acids bind to something on the cell membrane
- Steroid derivatives
- Lipids- move into cells and do actively internally
What are the hormone mechanisms?
- Membrane receptors (indirect)
- Alter enzyme activity
- Alter ion channel activity
- Bind to outside of cell and cause conformational change to active inside the cell (could increase permeability)
- Intracellular receptors (direct)
- Alter gene expression
- Steroid hormones = change actual proteins inside the cell
Explain the membrane receptors for hormones
Provide examples
- Hormone is first messenger
- Activates second messenger
- Often mediated by a G protein
Examples:
- cAMP concentration control
- Cellular gasoline, causes activity to go up
- How much produce depends on the hormone (second messenger)
- cAMP increase
- Enzyme activation
- Opening of ion channels
- cAMP decrease
- Enzyme inactivation
- Ca2+ control
- G protein stimulates release or intake
- Ca2+ is secondary messenger
- Binds to calmodulin
- Enzyme binding - structure that turns on activity/alter activity in cell
- Activation or deactivation
Explain the intracellular receptors for hormones (steroid)
Steroid hormones - testosterone, aldosterone
- Steroid hormones
- Alter DNA expression in nucleus
- Gene activation
- Example: thyroid hormones: Alter gene expression and ATP production
Explain the endocrin reflexes involved in hormones
How do we control if hormones are turned on or off = reflexes
- Humoral stimuli (chemical concentrations)
- Chemicals in blood that can very (sugar)
- Hormonal stimuli (tropic hormones)
- by other hormones
- Neural stimuli (adrenal hormones)
- Exhibit negative feedback
- Special = adrenal medulla turned on by nervous system NE, Epinepherone)
Explain stress and adaptation with hormone response
-
Alarm Phase - “fight or flight” response
- GLUCOSE BREAKDOWN
- Sympathetic stimulation of the adrenal medulla
- Mobilization of energy stores
- Increased BP
- In the long term, could result in lots of damage
-
Resistance Phase
- GLYCOGEN RESERVE BREAKDOWN, BAT BREAKDOWN
- Begin to run out of glycogen and glucose
- Depletion of glycogen stores
- ACTH release ->cortisol
- Stimulates lipolysis
- Decreased immune function
- GLYCOGEN RESERVE BREAKDOWN, BAT BREAKDOWN
-
Exhaustion Phase
- PROTEIN BREAKDOWN
- Fat reserves depleated
- Protein breakdown
- Homeostatic crisis
- Death
Where does the spinal cord arise from the medulla oblangata?
At the foramen magnum
The crossed ________ reflex is contralateral
extensor
Which of the following stimuli causes a muscle to reflexively contract?
a. Increased flaccidity
b. Increased elasticity
c. Increased stretch
D. Increased excitability
C. Increased stretch
A _________ is a tract of nerve fibers within column of the spinal cord.
fasciculus
T/F: The flexor reflex uses an ipsilateral reflex arc
true
What are the fold in the cerebellum called?
Folia
What does the blood barrier system (BBS) consist of?
Blood-CSF barrier
Blood-brain barrier
________ is the region of the brain responsible for equilibrium, motor coordination, and memory of learning motor skills
Cerebellum
What structures produce CSF?
Ependymal cells
Choroid plexus
CSF production begins with the filtration of blood plasma through capillaries in the brain. This filtrate is modified by the ependymal cells lining the ventricles in the brain
The blood-brain barrier is the barrier between the _________ and ______ fluid of the brain that is impermeable to many blood solutes
Bloodstream
tissue
The vasomoter center is located where?
medulla oblongata
The _______ ________ is a bundle of nerve fibers within the cerebral peduncles of the midbrain that connect the cerebrum to the pons and carry the corticospinal nerve tracts
cerebral crus
Where is the reticular formation located?
Throughout multiple levels of the brainstem
The posterior part of the midbrain, which includes the corpora quadrigemina, is called the ________
tectum
What are the main component of the cerebral peduncles?
Cerebral crus
Substantia nigra
Tegmentum
Which structures are involved with emotional feelings and memories?
Prefrontal cortex
Dienephalon
The _________ system is the part of the brain involved with emotion and learning
limbic
Sensory perception, thought, reasoning, judgment, learning, memory, imagination, and intuition are all examples of ________
cognition
Name the area of the limbic system also known as the memory forming center
Hippocampus
What are the types of brain waves?
Delta
Theta
Beta
Alpha
Which nerve controls movements of the eyeball, and upper eyelid as well as pupillary constriction and focusing?
Oculomotor (III)
Where does the optic nerve (II) terminate?
Thalamus , Midbrain
The ________ is part of the epithalamus and functions as a relay from the limbic system to the midbrain
habenula
Which structures are agreed upon by all sources as components of the limbic system?
Hippocampus
Amygdala
Cingulate gyrus
Which area of the brain functions to maintain thermal homeostasis?
Hypothalamus
Which region of cortex is responsible for the formation of spoken words?
Broca area
What are Dermatomes?
Regions of skin innervated by spinal nerves
can be used to locate spinal damage
What are somatic reflexes?
Reflexes of the skeletal muscle
