Physiology II Exam II Dr. A Review

Question 0

What are the types of cells associated with the spinal cord and what are their functions?

Answer 0

Sensory (afferent neurons)
Anterior motor neurons (Alpha motor): give rise to A alpha (Aa) fibers
Interneurons: 30x more than Aa neurons, small and excitable, responsible for most of spinal cord integrative functions
Renshaw cells: receive collaterals from alpha motor neurons, inhibitory signals to surrounding motor neurons, results in lateral inhibition

Question 1

What is the integrative center for motor pathways? Where is most of motor activity initiated?

Answer 1

Spinal cord

Question 2

What is the function of the muscle spindle?

Answer 2

Detects changes in muscle length
Central region has no contractile fibers; functions as a sensory receptor
Stretching of central region of intrafusal fiber stimulates sensory fibers
Stimulation of sensory fibers results from lengthening of entire muscle which results in contraction of ends of intrafusal fibers

Question 3

What are the sensory and motor fibers involved in muscle spindle actions?

Answer 3

Muscle spindle has 3-12 intrafusal fibers and are innervated by small gamma motor neurons
Sensory fibers originate from central region: Ia primary fibers form auunolspiral ending, 17um, 70-120m/sec; II secondary fibers are 8 um so transmit slower

Question 4

What are the three main components of the cerebral cortex that affect motor functions?

Answer 4

Primary motor cortex (Broadman’s Area 4)
Premotor cortex (Area 6)
Supplementary motor Area (6)

Question 5

What is the function of the primary motor cortex?

Answer 5

Signals motor neurons to contract skeletal muscle fibers
Signals via the corticospinal (pyramidal tract)
Execution of commands is preceded by extensive processing by cerebellum and basal nuclei

Question 6

What is the function of Premotor cortex?

Answer 6

Plans movement based on sensory and visual cues
Signals generated here cause more complex patterns of movement than the discrete pattern generated by primary motor cortex; anterior part of premotor cortex develops a motor image of the total muscle movement that is to be performed
Image in posterior motor cortex excites each successive pattern of muscle activity required to achieve image
Posterior motor cortex sends signals to: primary motor cortex–>basal nuclei and thalamus–>primary motor cortex

Question 7

What is the function of the supplementary motor area?

Answer 7

Retrieves and coordinates memorized motor sequences

Question 8

What is one of the major differences between sensory and motor pathways in terms of neurons involved?

Answer 8

Motor system pathway only uses 2 neurons (Upper and Lower motor neurons) whereas sensory pathways uses 3 but this doesn’t take into consideraation the interneurons (association neurons) between upper and lower motor neurons

Question 9

What is the generalized motor pathway?

Answer 9

Descending pathway with 2 motor neurons: upper motor neurons and lower motor neurons but doesn’t take into consideration the association neurons between upper and lower motor neurons

Question 10

What tracts make up the descending pathways?

Answer 10

1. Corticospinal tract and corticobulbar tract (Pyramidal system)
2. Rubrospinal tracts, vestibulospinal tracts, reticulospinal tracts (Extrapyramidal system)
   * extrapyramidal includes descending motor tracts that do NOT pass through medullary pyramids or corticobulbar tracts
   Corticospinal is split in lateral and anterior corticospinal

Question 11

How are cells in the motor cortex organized?

Answer 11

Vertical columns; each column has 6 distinct layers

Question 12

What are the general characteristics of the pyramidal system (corticospinal tract and corticobulbar tracts)?

Answer 12

Start with upper motor neurons which originate in the motor cortices
75-85% decussate in pyramids and form the lateral corticospinal tracts
Remainder decussate near synapse with lower motor neurons and form anterior corticospinal tracts
Most synapse with association neurons in spinal cord central gray

Question 13

______ is made up of corticospinal fibers that have crossed in the medulla and supply all levels of the spinal cord

Answer 13

Lateral corticospinal tract

Question 14

______ is made up of uncrossed corticospinal fibers that cross near level of synapse with LMNs and supply neck and upper limbs

Answer 14

Anterior corticospinal tract

Question 15

Where do the corticospinal tracts originate? What is the pathway?

Answer 15

Originates in primary motor cortex, premotor cortex or somatosensory area
Pathway: Site of origin–>internal capsule–>medullary pyramids in lower medulla–>LATERAL column of spinal tract
Some fibers do not cross but continue down ipsilaterally in ventral corticospinal tract
Other fibers in from cortex pass into caudate nucleus and putamen, pass to red nucleus, pass to reticular sustance and vestibular nuclei, and large numbers of fibers pass to pontine nuclei

Question 16

What are the functions of the ccorticospinal tract?

Answer 16

Adds speed and agility to conscious movements–especially movements of hand
Provides high degree of motor control (movement of individual fingers)

Question 17

Corticobulbar tract

Answer 17

innervates head
Most fibers terminate in reticular formation near cranial nerve nuclei
Association neurons leave reticular formation and synapse in cranial nerve nuclei and synapse with lower motor neurons

Question 18

Rubrospinal Tract

Answer 18

Extrapyramidal
Begins in red nucleus, decussates in midbrain, descends in lateral funiculus (column), function is closely related to cerebellar function
Lesions result in impairment of distal arm and hand movement, intention tremors (similar to cerebellar lesions)

Question 19

Vestibulospinal Tract

Answer 19

Extrapyramidal
Orginates in vestibular nuclei-receives input from vestibular nerve CN 8
Descends in anterior funiculus column
Synapses with LMNs to extensor muscles-primary involved in maintaining upright posture

Question 20

Reticulospinal tract

Answer 20

Extrapyramidal
Orginates in various regions of reticular formation
descends in anterior portion of lateral funiculus
Thought to mediate larger movements of trunk or fine movements of upper limbs

Question 21

What are the components of the vestibular apparatus?

Answer 21

Urticle: Macula on horizontal plane which determines orientation of head when head is upright
Saccule: Macula on vertical plane which signals orientation of head when person is lying down
Semicircular canals

Question 22

What is the role of calcium carbonate crystals needed for balance and equilibrium reception?

Answer 22

Each macula is covered by gelatinous layer that has many embeded calcium carbonate crystals (statoconia); macula contains 1000s of hair cells which project cilia into gelatinous layer; weight of statoconia bends cilia in direction of gravitational pull

Question 23

Macula

Answer 23

Has 50-70 small cilia (stereocilia), has 1 large cilium (kinocilium) off set to one side; tips of stereocilia are connected together and to kinocilium; bending of cilia opens 100s of cation channels causing receptor membrane depolarization; bending of cilia in opposite direction closes channels and hyperpolarizes receptor membrane; hair cells oriented such that bending the head in different directions causes different groups of hair cells to depolarize

Question 24

Semicircular canals

Answer 24

When head is bent forward 30 degrees lateral ducts are horizontal, anterior ducts are in vertical planes projecting forward and 45 degrees outward posterior ducts are in vertical planes projecting backward and 45 degrees outward

Question 25

Ampulla

Answer 25

Enlargement at one end of each duct Filled along with duct with endolymph Crista ampullaris: Small crest within each ampulla Cupula: loose mass of gelatinous tissue on top of crista

Question 26

How are semicircular canals related to equilibrium and balance

Answer 26

When head rotates in any direction, inertia of fluid in one or more semicircular canals stays stationary while semicircular canal rotates with head; fluid flows from duct through ampulla and causes cupula to bend to one side Hundreds of hair cells within each cupula detect this bending and send signals via vestibular nerve

Question 27

Tonic rate of discharge graph: What happens when you begin rotation, what happens when you stop rotation? How do hair cells respond when a semicircular canal is stimulated by onset and then stopping of rotation

Answer 27

Tonic level of discharge=100 impulses per second (0-20 sec) When you begin rotation, the impulses per second jumps up to 400 impulses per second (rapid, sudden increase) During rotation, impulses per second rapidly decreases back to 100 impulses per second, and then once rotation has stopped, impulses per second goes down to zero.

Question 28

Anotomical Organization of the Cerebellum

Answer 28

Two hemispheres separated by vermis--each hemisphere divided into intermediate and lateral zone 3 lobes in cerebellum anterior to posterior: Anterior, Posterior, Flocculonodular (vestibular system)

Question 29

What is the oldest part of the cerebellum evolutionarily?

Answer 29

Flocculonodular lobe

Question 30

Vermis vs Intermediate zone vs. Lateral zone

Answer 30

Vermis: controls muscle movements of axial body, neck, shoulders, hips Intermediate zone: controls distal part of upper and lower limbs, hands, feet, fingers and toes Lateral zone: associated with cerebral cortex with planning sequential motor movements

Question 31

Intracerebellar nuclei: Which ones involved in trunk ataxia, which ones in extremity?

Answer 31

Dentate, emboliform, globose--lesions cause extremity ataxia; these fibers project to red nucleus and are related to limb musculature and fine manipulative movements Fastigial nuclei--lesions cause trunk ataxia; fibers project to reticular formation and vestibular nuclei and are related to postural activity and limb movements via reticulospinal and vestibulospinal tracts

Question 32

What is the relationship of the cerebellum to other major parts of brain stem like reticular formation and vestibular nuclei?

Answer 32

?

Question 33

What is the only output from the cerebellar cortex?

Answer 33

Purkinje cells

Question 34

What are the afferent tracts to cerebellum?

Answer 34

Corticopontocerebellar Vestibulocerebellar: ends in flocculonodular Reticulocerebellar: ends in vermis Spinocerebellar: dorsal and ventral, 120m/sec All of these above tracts form mossy fibers that end on granule cells (+) Olivocerebellar

Question 35

What are the efferent tracts of the cerebellum?

Answer 35

Cerebelloreticular Cerebellothalamocortical Cerebellorubral Cerebellovestibular

Question 36

Putamen circuit

Answer 36

For subconscious execution of learned patterns of movement Cerebral cortex-->globus pallidus-->thalamic relay nuclei (ventroanterior and ventrolateral nuclei)-->primary motor cortex (and premotor/ supplementary) BYPASSES CAUDATE NUCLEUS

Question 37

Caudate circuit (Look at circuit diagrams--direct vs. indirect!!)

Answer 37

``` For cognitive planning of sequential and parallel motor patterns Cerebral cortex (premotor, supp, somatosensory)-->caudate nucleus-->globus pallidus (internal)-->thalamic relay nuclei (ventroanterior & ventrolateral)-->premotor and supplementary motor cortex ```

Question 38

1. Dopamine (inhibitory) is the NT going between___ and ___ 2. GABA (inhibitory) is the NT going between ___ and ___ 3. Acetylchoine is the NT between ____and ___ 4. Multiple pathways from brain stem use ___ ___ and___ 5. What NT is excitatory and is involved in multiple pathways?

Answer 38

1. substantia nigra-->caudate nucleus and putamen 2. Caudate nucleus and putamen-->globus pallidus and substantia nigra 3. cortex-->caudate nucleus and putamen 4. Norepinephrine, serotonin (inhibitory), encephalin 5. Glutamate

Question 39

Parkinsons vs. Huntington's symptoms

Answer 39

Parkinsons: rigidity of much of musculature, involuntary tremors even at rest, difficulty in initiating movement (akinesia), postural instability, dysphagia, speech disorders, gait disturbance, fatigue Huntingtons: flicking movement of individual muscles, progressive severe distortional movements of entire body, severe dementia, motor dysfunctions

Question 40

Pathology of Parkinson's vs. Huntington's in relation to basal nuclei

Answer 40

Parkinson results from lesions in substantia nigra; destruction of pars compacta of substantia nigra that sends dopaminergic fibers to caudate nucleus and putamen Huntington is caused lesions in putamen (chorea)--loss of most of cell bodies of GABA secreting neurons of caudate nucleus and putamen and of Ach neurons in other parts of the brain

Question 41

What is the difference between conduction, convection and radiation?

Answer 41

Conduction: Kinetic energy of the molecules of skin transferred to air if air is colder than skin Convection: Removal of heat from body by convection air currents Radiation: Loss in the form of infrared heat rays radiated by all objects not at absolute zero; if temp of body is greater than ambient temp, more heat is radiated from the body than to the body

Question 42

What are the functions of the hypothalamus and the pre-optic area in terms of controlling heat?

Answer 42

Anterior hypothalmic pre-optic area and pro-optic area are principal areas of the brain affect body temperature. Anterior pre-optic area contains both heat sensitive and cold sensitive neurons. Heat sensitive neurons increase firing rate 2-10x in response to 10degree increase in body temp. Cold sensitive neurons increase firing rate when temp falls. Heating the pre-optic area causes dilation of skin blood vessels over entire body, profuse sweating over entire body, inhibition of excess heat production

Question 43

Set point for thermal control: 1. What is the critical body core temp? 2. How does this core temp relate to heat loss and heat production? 3. What is the set-point of the temp control mechanism?

Answer 43

1. 37.1 C (98.8 F) 2. Heat loss is greater at temp above 37.1, and heat production is greater at temp below this temp 3. Set point=level at which sweating begins or shivering begins in order to return to critical core body temp

Question 44

Set-point for thermal control 4. What is the feedback gain (and how is it calculated) of the temp control system and how does it compare to that of other biological control systems? 5. What are physiological mechanisms that alter the critical set point?

Answer 44

4. (change in env temp/change in body core tmep)-1.0=(28/1)-1=27 5. Mechanisms that alter set point: skin temperature changes

Question 45

What is the role of the thyroid gland in controlling heat production?

Answer 45

Increased thyroxine output increases the rate of cellular metabolism and therefore increases heat production

Question 46

How is the chemical composition of sweat different if you're sweating profusely vs. insensibly?

Answer 46

Precursor secretion: composition is similar to that of plasma without protiens: Na--142 mEq/L and Cl---104 mEq/L Rapid/strong stimulation of sweat glands: Large amounts of precursor secretion formed, ducts reabsorb only about half the sodium chloride and concentrations of sodium and chloride ions are about 50-60 mEq/L and little water is reabsorbed

Question 47

Layers of gut tube from outer to inner

Answer 47

Serosa, Longitudinal smooth muscle layer, myenteric plexus (of Auerbach), Circular smooth muscle layer, Meissner's plexus (submucosal plexus), mucosa

Question 48

Inhibitory effect of enterogastric nervous reflexes:

Answer 48

Reflexes occur directly from duodenum through enteric nervous system of gut wall Reflexes occur through extrinsic nerves that go to prevertebral ganglia and then back through inhibitory sympathetic nerve fibers to stomach Reflexes may occur via vagus nerves back to brainstem

Question 49

Interstitial cells of cajal are associated with what function?

Answer 49

Pacemaker activity for smooth muscle cells

Question 50

Voluntary stage of swallowing ends at what location?

Answer 50

Pharynx

Question 51

What is the sequence of layers making up the gut wall from inside (lumen) towards outside?

Answer 51

Mucosa, lamina propria, submucosa, circular muscle layer

Question 52

The submucosal (meissners) plexus is primarily responsible for regulating intestinal smooth muscle. True or False?

Answer 52

False. There are 2 plexuses: Myenteric plexus and Meissner's. Myenteric controls regulation of intestinal smooth muscle. Meissners is closer to mucosa.

Question 53

In the smooth musculature of the gut wall spike waves occur automatically when the resting membrane potential of the smooth muscle becomes more positive than about -40mV. True or False?

Answer 53

TRUE Could be phrased a diff way--know -40mV.

Question 54

Pancreatic Secretions

Answer 54

Digestive enzymes for proteins: trypsin, chymotrypsin and carboxypeptidase; trypsin inhibitor secreted by glandular cells; necessary to prevent action of trypsin on pancreatic tissues themselves Digestive enzymes for carbs: pancreatic amylase Digestive enzymes for fat: pancreatic lipase, cholestrol esterase, phospholipase Bicarbonate ions: HCO3- and Na+ are actively transported into duct lumen; hydrogen ions are exchanged for sodium ions

Question 55

Hormonal factors that control feedback from the duodenum

Answer 55

CCK is the most potent; other possible inhibitors include secretin and GIP

Question 56

Motor functions of the stomach

Answer 56

Storage of large amounts of food Mixing food with gastric secretions (Mixing occurs in upper stomach wall every 15-20 sec) and move toward antrum; mixing waves replaced by peristaltic waves that drive food toward pylorus; thickness of circular muscle layer in pylorus is 50-100% greater than elsewhere in stomach (pyloric sphincter) Slow emptying of chyme into SI: stretching of stomach wall due to increased food volume promotes increased emptying of stomach due to local myenteric reflexes in wall

Question 57

Regulation of pancreatic secretion

Answer 57

Acid from stomach releases secretin from wall of duodenum; fats and amino acids cause release of CCK Secretin and CCK absorbed into blood stream Vagal stimulation releases enzymes into acini Secretin causes copious secretion of pancreatic fluid and bicarbonate; CCK causes secretion of enzymes

Question 58

Nerve mechanisms for controlling gastric secretion

Answer 58

Gastic secretions: Chief cells Pepsinogen is stimulated by Ach from vagus nerves (parasympathetic and enteric nervous system) or gastric enteric nervous plexus--response to acid in stomach

Question 59

Parasympathetic regulation of salivary system (3 different levels of feedback pathways)

Answer 59

1. 3 main groups of salivary glands: parotid, submandibular and sublingual glands which have similar innervation pattern. 2. There are 2 main cranial nerves involved in this. In parotid gland, we have glossopharyngeal and facial nerve. Facial nerve has portion that is passing through the middle ear (called chordae tympani); 3. motor innervation to submandibular and sublingual gland is via the facial nerve. Motor innervation to parotid gland is via glossopharyngeal nerve. Both come from the superior and inferior salivatory nuclei--superior goes to submandibular and sublingual; the inferior goes to parotid. Glossopharyngeal activity also comes from tongue (sensory neurons) and they end up in tractus solitarius and have feedback to motor nucleus to salivary glands so when food hits tongue, it sets up feedback loop to cause saliva to flow. Because this is parasympathetic, facial and glossopharyngeal are cranial nerves that carry parasympathetic functions. We have ganglia (submandibular ganglia for submandibular and sublingual gland and the otic gland for parotid gland)--these represent the area synapse between the pre-ganglionic fiber and the post ganglionic fibers

Question 60

How does glucose and other sugars get into cells? What keeps them in cells? What happens to them once they are in cells?

Answer 60

Transport of glucose into cells can occur via sodium-glucose co transport or via facilitated transport Presence of insulin increases glucose transport x10 Phosphorylation of glucose prevents diffusion out of cell Phosphorylation can be reversed in liver, renal and intestinal cells

Question 61

Role of phosphorylase and phosphatase in metabolic pathways

Answer 61

?

Question 62

1. Role of CO2 fiven off in pathway? | 2. Oxidative phosphorylation and hydrogen ions

Answer 62

1. ? 2. Hydrogen removed in pairs; one member becomes hydrogen ion, the other combines with NAD+-->NADH Fate of electrons removed from H ions=enter ETC--important for energy calculations

Question 63

Pentose Phosphate Pathway: what does it do? Where does it occur?

Answer 63

Cyclical pathway where one molecule of glucose is metabolized for each revolution of cycle--for every 6 glucose that enter, five are resynthesized Pathway used for synthesis of fats and other substances H generated from this pathway are bound to NADP+ instead of NAD+ Occurs in the cytosol NADP+ (as NADPH) but not NAD+ can be used in synthesis of fats from carbs In liver excess glucose is broken down by PPP producing excess NADPH which converts Acetyl coA into FA chains (glucose is preferentially stored as glycogen until liver and muscle cells are saturated; excess glucose converted to fat stored in fat cells)

Question 64

What are the differences between Pentose Phosphate pathway and the Krebs cycle?

Answer 64

?

Question 65

Chemiosmotic mechanism in mitochondria

Answer 65

e- pass through chain, releasing lots of energy-->energy used to pump H ions from inner matrix into outer chamber between inner and outer membranes-->high conc of H+ in chamber-->strong neg potential in inner matrix-->H+ flow from high to low conc->Energy from H+ used by ATPase to convert ADP to ATP-->For every 2 e- through ETC, 3 ATP made-->2 H+ pairs from krebs cycle enter ETC later and provide energy for 2ATP per pair-->

Question 66

Know enzymes secretion and functions!!

Answer 66

Study!

Question 67

What is the driving force for oxidative phosphorylation?

Answer 67

Hydrogen ions in inter-membrane space creates concentration gradient that drives the formation of ATP

Question 68

Energy physics of ATP and ADP

Answer 68

ATP-->ADP+Pi=-7300 under lab conditions? but -12000 in real conditions of the body?

Question 69

Know how parietal cells and chief cells operate and the pumps they have in their cell membranes Chief cells:

Answer 69

Chief cells secrete pepsinogen, a proteolytic enzyme and is active at pH 1.8-3.5; its release is stimulated by Ach from vagus nerve or gastric enteric nervous plexus and responds to acid in stomach; chief cells also secrete intrinsic factor

Question 70

Know how parietal cells and chief cells operate and the pumps they have in their cell membranes Parietal cells

Answer 70

Parietal cells produce HCl Dissociation of water inside cell into H+ and OH- H ion is pumped out of cell in exchange for K+ K+ leaks outside the cell but is transported back in via H+-K+ ATPase pump Na+ is reabsorbed into cell due to Na+-K+ basolateral pump OH- +CO2-->HCO3- which is exchanged for Cl- ions Cl- ions are secreted through chloride channels into canaliculi