Physiol Exam 2: Chps. 10-12 + Labs 05-06 Flashcards
(119 cards)
1
Q
Describe the functions of sensory receptors
A
• Perceptions created by brain
• Sensory receptors respond (to stimuli), generate & propagate APs
1. Respond to a particular modality (form) of stimuli (internal or external)
— Different neural pathway & synaptic connections
2. Transduce (change) different forms of energy (stimuli) into APs → CNS for perception/understanding
2
Q
Define the following terminology: tonic receptor, phasic receptor, sensory adaptation
A
Tonic receptors: Maintain firing of AP during stimulation (Slow adapting); as long stimulus is present
* EX: pain
Phasic receptors: Burst of AP firing but quickly fades (Fast adapting)
— Sensory adaptation: If stimuli constant, sensory receptor ceases to respond
* EX: hot tub (starts off hot, then body adapts)
3
Q
Describe generator potentials & their effect on action potentials
A
- Stimulus at sensory endings of sensory receptor
- Lead to local (signal), graded changes in membrane potential (generator potential)
- If it reaches threshold, generator potentials lead to AP
4
Q
Define receptive fields & describe the relationship between area and density of sensory receptors. How does this apply to the back and legs, and fingertips?
A
Receptive field: Refers to area of skin around each sensory receptor
* Area varies INVERSELY with density of sensory receptors; more sensory receptors = each receptor is responsible for small area and vice versa
- Back & legs = FEWER number sensory receptors with LARGER receptive fields
- Fingertips = LARGER number sensory receptors with SMALLER receptive fields
* Greater sensory acuity = sharpness of sensation for fingertips
5
Q
Describe the purpose of the two-point threshold
A
- Two-point touch threshold: Minimum distance between 2 pts of touch perceived as 2 pts
- Threshold indicates TACTILE ACUITY
- Test: Used to detect approximate size of receptive field for light touch
- Calipers touch skin at same time
6
Q
Describe the relationship between a region’s two-point touch threshold & its representation on the sensory homunculus
A
Areas with smaller two-point touch threshold will have greater representation at the brain
7
Q
Describe the purpose of lateral inhibition
A
Lateral inhibition: sharpens the sensation by inhibiting interneurons
* When blunt object touches skin, central area stimulated more than lateral fields
* Result: Brain perceives 1 sharp touch
* Ex: Hearing, Vision, Smell
8
Q
Memorize the details for the neural pathways for somatesthetic sensations
A
Sensations from proprioceptors (body position) & cutaneous receptors (found in skin) relayed to brain in three neurons:
- 1st order neuron: large, myelinated nerve fibers
* Receptor → SC or medulla oblongata; ipsilaterally
- 2nd order neuron: up & decussate to reach thalamus (gateway to cerebral cortex)
- 3rd order neuron: (at the thalamus) project to postcentral gyrus
9
Q
Define referred pain
A
Referred pain: visceral pain mistaken for somatic pain
* Possibly due to visceral & somatic sensory neurons synapsing on SAME interneuron
10
Q
Identify the components that form the vestibular apparatus
A
Vestibular Apparatus (2 parts)
1. Three semicircular ducts
2. Otolith organs (Utricle and saccule)
11
Q
Distinguish endolymph from perilymph
A
- Endolymph - inner fluid with higher [K+] than other fluids
- Perilymph - surrounding outer fluid with normal [ion]
12
Q
Describe the information provided by the frequency of action potentials in the hair cells of the vestibular apparatus
A
Frequency of APs = gives info about direction of movements
Stimulated:
Stereocilia bend TOWARD kinocilium→ K+ channels open → depol. → release MORE chemical messenger → more AP’s in vestibular n. (CNVIII)
Inhibited:
Stereocilia bend AWAY from kinocilium→ hyperpol.→
release less chemical messengers → less AP’s in vestibular n. (CNVIII)
13
Q
Name the cranial nerve (and number) involved in equilibrium & name the 2 locations in the brain that receives the information from the cranial nerve
A
Vestibulocochlear nerve (CN VIII)
1. Cerebellum
2. Vestibular nuclei of medulla oblongata
14
Q
Name the type of information that the utricle vs. saccule vs. all 3 semicircular ducts together vs. each individual semicircular duct detect(s)
A
- Utricle: for detecting horizontal acceleration
- Saccule: for detecting vertical acceleration
- Semicircular ducts: detecting rotational acceleration
1. Anterior semicircular duct: detects sagittal rotational acceleration
2. Posterior semicircular duct: detects coronal rotational acceleration
3. Lateral semicircular duct: detects horizontal rotational acceleration
15
Q
Distinguish vestibular nystagmus from vertigo
A
Vestibular nystagmus: involuntary oscillations of the eye
Vertigo: the loss of equilibrium
16
Q
Memorize the sequence of structures & spaces of the ear that sound waves travel through to be detected at the spiral organ for low sound waves and high sound waves
A
- Auricle/Pinna
- External acoustic meatus
- Tympanic membrane
- Malleus
- Incus
- Stapes
- Oval window
- Perilymph of scala vestibuli
- LOW sound waves
- Apex of helicotremma then returns to base via scala tympani
- Round window and sound dies
OR
9. HIGH sound waves
10. Vestibular memebrane
11. Cochlear duct/Scala media (with endolymph)
12. Basilar membrane (to scala tympani)
17
Q
Distinguish the location on the basilar membrane where high vs. low vs. moderate pitch sounds are detected
A
- Base for high pitch/frequency
- Apex for low pitch/frequency
- Middle for pitches/frequencies in between
18
Q
Describe the process of how vibrations in the perilymph of the scala vestibuli lead to the generation of action potentials in the sensory neuron of cranial nerve VIII
A
As basilar membrane moves towards tectorial membrane, K+ channels open → depol. in inner hair cell → release glutamate → depol. in sensory neuron of CNVIII → AP’s
19
Q
Describe how louder sounds are detected & how they influence action potential generation
A
Louder sounds
* Causes GREATER bending of basilar membrane & stereocilia →↑ chemical messenger → ↑ generator potentials in sensory neuron →↑ number of APs
20
Q
Memorize the entire pathway (4) that information about SOUND travels through after leaving the spiral organ of the cochlea
A
- Sensory neuron in CN VIII
- Inferior colliculus: for auditory reflexes
- Medial geniculate body of thalamus
- (Temporal lobe) Primary auditory cortex and auditory association area: to interpret
21
Q
Distinguish the function of the inferior colliculus vs. primary auditory cortex vs. auditory association area
A
Inferior colliculus: for auditory reflexes (turning our head to hear that sound)
Primary auditory cortex: to interpret
Auditory association area: to interpret
22
Q
Define tonotopic organization
A
Tonotopic organizations: Different regions of the ear represent different pitches
23
Q
Distinguish sensorineural hearing loss from conductive hearing loss
A
Sensorineural hearing loss: Impaired AP’s from cochlea to auditory cortex
- Impairs SOME pitches to others
- Solution - Cochlear implants
Conductive hearing loss: Impaired SOUND WAVES from outer and middle ear to oval window
- Impairs ALL sound frequencies
- Solution: Hearing aids
24
Q
Memorize the sequence of structures, substance & spaces of the eye that light waves travel through to be detected at the retina
A
- Cornea
- Aqueous humor of anterior cavity
- Pupil
- Lens
- Vitreous humor or vitreous chamber
- Retina
25
How is image projected onto each retina? Distinguish the portions of the visual field that focus on the left half vs. right half of each retina
- Image projected onto each retina is INVERTED and REVERSED
- Cornea and lens:
— Focus R-half of field of vision onto L-half of each retina = L eye temporal (lateral) half & R eye nasal (medial) half
— Focus L-half of field of vision onto R-half of each retina = L eye medial half & R eye lateral half
26
Name the cells & structures that the retina consists of
* Retinal pigment epithelium
* Photoreceptors (rods and cones)
* Bipolar cells and ganglion cells
27
Distinguish the direction of incoming light from the direction of neural activity
Incoming light:
Cornea ➡ Aqueous humor of anterior cavity ➡ Pupil ➡ Lens ➡ Vitreous humor of posterior cavity ➡ Retina (ganglion cells, bipolar cells, photocreceptors) ➡ Choroid
Neural activity:
Photoreceptors ➡ Bipolar cells ➡ Ganglion cells ➡ Optic nerve ➡ Optic chiasma ➡ Optic tract...
➡ (Some;30%) Superior colliculi
OR
➡ (Most;70%)Thalamus ➡ Optic radiations ➡ Primary visual cortex ➡Visual association area
28
Memorize the details of the bleaching reaction
* Once light enters eyes, rods activated during the bleaching reaction
* Light absorbed by rhodopsin @ outer segment
* CIS-retinal (while attached to opsin) becomes TRANS-retinal (free)
* Trans-retinal splits from opsin
- Changes rod’s ion permeability → NO generator potential = neurotransmitters can't be released
29
Memorize the details of the interactions among retinal cells in the dark
In the DARK:
* Rods & cones: Na+ channels in their cell membrane OPEN → Na+ in (called DARK CURRENT) → Slight depol. (excited)
* → Rod cells release inhibitory neurotransmitters → IPSP in bipolar cells → No neurotransmitters from bipolar cell to ganglion cell, so NO AP’s in ganglion cell
30
Memorize the details of the interactions among retinal cells when there is light
When there is LIGHT:
* Rods & cones: Na+ channels in their cell membrane CLOSE → LESS Na+ in = LESS dark current → Hyperpol. (inhibited)
* → no inhibitory neurotransmitters released→
Bipolar cells free to release excitatory neurotransmitters
→EPSP in ganglion cell→ AP’s in optic n. (ganglion cell's axon)
31
Name the specific structure that forms the optic nerve
Ganglion cell's axon
32
Describe the steps involved in producing the dark current
In the DARK, cGMP keeps Na + channels open by binding to it → Na in → dark current
33
Describe how light causes the stopping of the dark current
When there is light, trans-retinal formed & leaves opsin, opsin changes shape
- Opsin's G protein is released and activates an enzyme (Phosphodiesterase), which turns cGMP into GMP, CLOSING Na+ channels
34
Name the photoreceptor cell that the fovea centralis contains & describe the 2 consequences of having this type of cell here
Contains ONLY CONES
1. Greatest visual acuity
2. Poorest sensitivity to low light
35
Memorize the entire pathway that information about light travels through after leaving the optic nerve
Optic chiasma
- Some decussate (medial side) @ optic chiasma vs. others stay ipsilateral (lateral side)
→ Optic tract
36
Distinguish the function of the superior colliculus vs. primary visual cortex vs. visual association area
* Superior colliculus: For visual reflexes; "Where is it?"
— SOME from optic tract (~30%) ; turn our head for what we see
* Primary visual cortex: Makes us aware that we are looking something
* Visual association area: To interpret; "What is it?"
37
Define accommodation
Accommodation: Ability of eye to keep images focused on retina as distance between eyes & the object varies
38
Describe the details of accommodation when a person focuses on a distant vs. close object (focus on the ciliary muscle, tension on suspensory ligaments & lens convexity)
Distant (≥ 20 ft)
1. Ciliary m. relax
2. Causes tension on suspensory ligaments
3. Pulls on lens & makes it least convex (thinner)
Close:
1. Ciliary m. contract (NOT constrict)
2. Reduces tension on suspensory ligaments
3. Lens most convex (thicker)
39
Describe the pupillary reflex vs. when the eye is in dim light (focus on the iris muscles & division of the autonomic nervous system involved in each)
Pupillary reflex AKA consensual light reflex: shine light into 1 eye, both pupils constrict
- Coordinated by superior colliculi of midbrain
- From oculomotor nerve, synapse on ciliary ganglion, with postganglionic PARASYMPATHETIC axon = circular smooth m. constrict
Eye in dim light:
- From superior cervical ganglion to the postganglionic SYMPATHETIC axon = radial smooth m. dilates
40
Describe the purpose of proprioceptors & name 2 examples of proprioceptors
Purpose of proprioceptors: provide continuous sensory feedback (helps control skeletal muscle movements)
- EX: Golgi tendon organs and muscle spindles
41
Distinguish the function of Golgi tendon organs from muscle spindles
Golgi tendon organs: monitor tension on tendons
Muscle spindles: monitor muscle length
42
Distinguish alpha motor neurons from gamma motor neurons in terms of control (voluntary vs. Involuntary), muscle fiber type innervated & relative speed
Alpha (α) motor neuron
* Voluntary
* Innervate extrafusal fibers
* Relatively faster speed
Gamma (γ) motor neuron
* Involuntary
* Innervate intrafusal fibers
* Relatively slower speed
43
Name the initial precursor molecule used to synthesize all steroid hormones & identify the chemical nature of that precursor molecule (polar or non-polar)
Cholesterol; non-polar
44
Distinguish the 3 types of hormone interactions (& if applicable, their subtypes) & recognize examples of each type/subtype
1. Antagonistic effect: action of 1 hormone opposes effects of another hormone
- EX: Insulin (synthesis) vs glucose (breakdown of adipose tissue)
2. Permissive effect: 1st hormone enhances responsiveness of target organ to 2nd hormone or ↑ activity of 2nd hormone
- Ex: Prior exposure to estrogen causes ↑ # receptors for progesterone (uterus) = stronger response
3. Synergistic effect: ≥ 2 hormones work together
a. Additive: alone, each hormone produces response; but together→ greater effect
- EX: Epinephrine and Norepinephrine on HR
b. Complementary: each hormone produces different step in the target cell's response
- EX: Estrogen + Cortisol + Prolactin + Oxytocin on lactation
45
Name the 3 locations that remove hormones from the circulation
1. Target tissue
2. Liver
3. Kidneys
46
Describe the half-life for most hormones
Half-life: Time [hormone] in plasma reduced to 1⁄2
- Most: minutes to hours
47
Distinguish upregulation from downregulation
Upregulation: ↑ # receptors on target cells, leading to a STRONGER response
Downregulation: ↓ # receptors on target cells, leading to a WEAKER response
48
Name the 2 locations for receptors of non-polar hormones
Cytoplasm or nucleus
49
Memorize the names of several examples of hormones considered non-polar that are discussed in class
1. Steroid hormones (Progesterone, estrogen, testosterone, cortisol, aldosterone)
2. Thyroid hormone (T3, T4/Thyroxine)
3. NO
50
Describe the method used to transport non-polar hormones in the blood
Requires carrier protein
51
Describe the method used to move non-polar hormones with the cell.
Nuclear-hormone receptor, which makes its way to the nucleus and act as transcription factors to make mRNA
52
Name the form of thyroid hormone considered active
T3, Triiodothyronine
53
Describe the general events that result after a non-polar hormone & its receptor are bound to a DNA sequence
* Leads to gene transcription to make mRNA
* mRNA then gets translated (into a protein)
* Steroid hormone’s effects (~30 mins.)
54
Name the location for receptors of polar hormones
Cell membrane
55
Describe the 3 classes of 2nd messenger systems
A. Adenylate cyclase-cAMP
1. Hormone binds to its receptor protein on cell membrane
2. G-proteins subunits dissociate and one of the subunits go to a membrane protein/enzyme, adenylate cyclase
3. Adenylate cyclase is activated; breaks ATP into cyclic AMP and pyrophosphate
4. Cyclic AMP removes regulatory subunit from inactive protein kinase and activates protein kinase
5. Protein kinase adds phosphate to other proteins, leading to 1) activation of enzyme or 2) inactivation of protein enzyme
B. Phospholipase C-Ca2+
1. Hormone binds to its receptor protein on cell membrane
2. G-proteins subunits dissociate and one of the subunits go to a membrane protein/enzyme, Phospholipase C
3. Phospholipase C take a phospholipid from the cell membrane and turns it into 2 different molecules, DAG and IP3
— IP3 travels into cytoplasm to the smooth endoplasmic reticulum to help release Ca+ into the cytoplasm
4. Ca binds to calmodulin→
* Activates protein kinases
5. Protein kinase adds phosphate to other proteins, leading to 1) activation of enzyme or 2) inactivation of protein enzyme
C. Tyrosine kinase
1. Two half receptors form the insulin receptor (receptor and enzyme/tyrosine kinase), prior to insulin binding
2. Insulin binds to its receptor w/n cell membrane, causing autophosphorylation of receptor
3. Activates tyrosine kinase of receptor and will phosphorylate other signaling molecules in the cytoplasm...
4. Continues until the signaling molecules that are needed are activated to ultimately produce the effect of the insulin
— Glucose uptake and anabolic reactions
56
Name the 2 hormones released by the posterior pituitary & describe the function of each hormone
1. ADH: from supraoptic nucleus; water retention at kidneys
2. Oxytocin: from paraventricular nucleus; contract uterus & mammary gland
57
Name the 6 hormones released by the anterior pituitary & describe the function of each hormone and what does it target?
F.L.A.T. P.G.
1. ACTH (adrenocorticotropic hormone): stimulates secretion of glucocorticoids (coritsol)
- Targets: Adrenal cortex
2. TSH (thyroid-stimulating hormone): stimulates secretion of thyroid hormones
- Targets: Thyroid gland
3. GH (growth-hormone): Promotes protein synthesis and growth; lipolysis and increased blood glucose
- Targets: Most tissue
4. FSH (follicle-stimulating hormone): Promotes gamete production and stimulates estrogen production in females
- Targets: gonads
5. PRL (prolactin): Promotes milk production in lactating females; additional actions in other organs
- Targets: Mammary glands and other sex accessory organs
6. LH (Luteinizing hormone): Stimulates sex hormone secretion; ovulation and corpus luteum formation in females; stimulates testosterone secretion in males
- Target: Gonads
58
Describe the term “troph” as it relates to anterior pituitary hormones
hormones that "feed" the target cells
59
Name the 6 hormones released by the hypothalamus & describe the function of each hormone
1. Corticotropin-releasing hormone (CRH): Stimulates secretion of adrenocorticotropic hormone (ACTH)
2. Gonadotropin-releasing hormone (GnRH): Stimulates secretion of follicle-stimulating hormone (FSH) and (LH)
3. Prolactin-inhibiting hormone (PIH) - Dopamine: Inhibits prolactin secretion
4. Somatostatin AKA growth hormone inhibiting hormone: Inhibits secretion of growth hormone and TSH
5. Thyrotropin-releasing hormone (TRH): Stimulates secretion of thyroid stimulating hormone (TSH) and prolactin
6. Growth hormone releasing hormone (GHRH): Stimulates growth hormone secretion
60
Name the 2 major hormones released by the adrenal medulla & describe how the target cells at the medulla are stimulated to release these hormones
1. Epinephrine
2. Norepinephrine
- Stimulated by preganglionic sympathetic axons
61
Memorize the name of the 3 zones of the adrenal cortex & their specific order
1. Zona glomerulosa
2. Zona fasiculata
3. Zona reticularis
62
Describe corticosteroids
Hormones that are secreted by the adrenal cortex that are non-polar
63
Name the 1 hormone released by the zona glomerulosa of the adrenal cortex & describe the function of that hormone
Aldosterone; Mineralocorticoids
- Na+ and K+ balance in kidney
64
Name the 2 hormones released by the zona fasciculata as well as zona reticularis of the adrenal cortex
1. Cortisol; Glucocorticoids
- glucose metabolism
2. Androstenedione and DHEA; Sex steroids
- (types of sex steroids)
65
Distinguish mineralocorticoids from glucocorticoids & name 1 hormone for each category
Mineralocorticoids - Aldosterone
Glucocorticoids - Cortisol
66
Name the 2 hormones (& if applicable, variations) released by the thyroid gland (if applicable, including their alternative names) & describe the function of each hormone
1. T3 (Triiodothyronine) and T4 (Tetraiodothyronine/Thyroxine):
- Increase Basal Metabolic Rate (BMR); use O2 for energy
- Raises O2 consumption
- Calorigneic effect: increase heat production (from Na/K pump)
2. Calcitonin: lower blood Ca2+ levels
67
Name the chemical element needed to make thyroid hormone
Iodide
68
Define hypothyroidism
Hypothyroidism: Insufficient T3 and T4 secretion
69
Define goiter & describe how a goiter can develop with hypothyroidism
Goiter: abnormal growth of thyroid gland
— If iodide is inadequate, there's low amounts of T3 and T4 = low negative feedback
— Anterior pituitary will continue to secrete TSH excessively, causing the target cells at the thyroid to hypertrophy = producing a goiter
70
Name the 1 hormone released by the parathyroid gland
PTH (Parathyroid hormone): Increase plasma Ca2+ levels
71
Memorize the details of the negative feedback loop for regulating decreased plasma calcium
1. Stimulus - Decreased plasma Ca2+
2. Sensor - Parathyroids
3. Integrating center - Parathyroids
4. Effector - Parathyroid: secretes PTH
a. Kidneys: Stimulates reabsorption of Ca2+; Inhibits reabsorption of phosphate
→ 1,25 Dihydroxyvitamin D3 (Vitamin D): Stimulates intestinal absorption of Ca2+ and phosphate
b. Bones: Stimulates dissolution of CaPO4 crystals
5. Response: Increased plasma Ca2+
- Negative feedback occurs when there's excess
72
Name the 1 hormone released by the pancreatic alpha cell
Glucagon
73
Distinguish glycogenolysis vs. gluconeogenesis & name the hormone activating both processes
Glycogenolysis: breakdown glycogen @ liver
Gluconeogenesis: turn non-carbs into glucose @ liver
— Activated by glucagon
74
Name the 1 hormone released by the pancreatic beta cell
Insulin
75
Memorize the details of the 2 negative feedback loops for blood sugar regulation involving the 2 hormones discussed in this section
Decrease of Glucose in Plasma
1. Stimulus - Decrease of glucose in plasma
2. Sensor - Pancreatic islets (alpha cell and beta cell)
3. Integrating center - Pancreatic islets (alpha cell and beta cell)
4. Effector - Alpha cell - increase glucagon; increases glycogenolyisis and gluconeogenisis
Beta cell - decrease insulin; decrease cellular uptake of glucose
5. Response: Increase glucose in plasma
Increase of Glucose in Plasma
1. Stimulus - Increase of glucose in plasma
2. Sensor - Pancreatic islets (alpha cell and beta cell)
3. Integrating center - Pancreatic islets (alpha cell and beta cell)
4. Effector - Alpha cell - decrease glucagon
Beta cell - increase insulin; = increase cellular uptake and utilization of glucose
5. Response - Decrease glucose in plasma
76
Name the location of the insulin receptor
Cell membrane of liver, skeletal m., and adipose tissue
- Made up of two parts
- Functions as receptor and enzyme (tyrosine kinase)
77
Name the 1 hormone released by the pineal gland
Melatonin (via melanocytes)
78
Distinguish paracrine regulators from autocrine regulators
Paracrine regulators: target DIFFERENT cell type (nearby) in same organ
Autocrine regulators: target SAME cell and cell type in same organ
79
Memorize the details of the 3 negative feedback loops/axes discussed in this section:
Hypothalamus - Pituitary - Thyroid Axis
Hypothalamus - Pituitary - Thyroid Axis
Hypothalamus
↓Thyrotropin-releasing hormone (TRH)
Anterior Pituitary
↓Thyroid-stimulating hormone (TSH)
Thyroid
↓
Growth of thyroid
OR
Thyroxine (T4) and T3 → Target cells
- Negative feedback: some goes to hypothalamus to stop secreting TRH
- Negative feedback: some goes to anterior pituitary to stop responding to TRH
80
Memorize the details of the 3 negative feedback loops/axes discussed in this section:
Hypothalamus - Pituitary - Gonad Axis
Hypothalamus - Pituitary - Gonad Axis
Hypothalamus
↓Gonadotropin-releasing hormone (GnRH)
Anterior Pituitary
↓Gonadotropins (FSH of LH)
Gonads
↓ Sex steroid hormones (estrogens and androgens)
- Negative feedback: some goes to hypothalamus to stop secreting GnRH
- Negative feedback: some goes to anterior pituitary to stop responding to GnRH
Target cell (male reprod. system or bone cells)
81
Memorize the details of the 3 negative feedback loops/axes discussed in this section:
Hypothalamus - Pituitary - Adrenal Axis
Hypothalamus - Pituitary - Adrenal Axis; Stress
(Nonspecific stress) → Higher brain centers
↓
Hypothalamus
↓ Increase of CRH (Corticotropin-releasing hormone)
Anterior Pituitary
↓ Increase of ACTH (Adrenocorticotropic hormone)
Adrenal cortex
↓Cortisol
Target cells
OR
- Negative feedback: some goes to hypothalamus to stop secreting CRH
- Negative feedback: some goes to anterior pituitary to stop responding to ACTH
82
Describe muscle fibers, identify the specific type of neuron that innervates them & identify the type of control it is under (voluntary or involuntary)
* 1 muscle fiber = 1 muscle cell
* Somatic motor neuron (voluntary) innervates many muscle fibers
83
Describe transverse tubules
Transverse tubule (T- tubule): deep invaginations of the sarcolemma
84
Name the organelle & specific structure that is part of that organelle that stores & releases calcium in a skeletal muscle fiber
* Sarcoplasmic reticulum (SR): muscle fiber’s smooth ER
- Contains terminal cisternae: stores & releases Ca2+
85
Name the proteins that make up thick filaments vs. thin filaments
Thick filaments: contains myosin
Thin filaments: contains actin, troponin, tropomyosin
86
Distinguish I bands vs. A bands vs. H band
— I band: light bands
* End of 1 thick filament to the end of the next
* Contains actin, troponin & tropomyosin (thin filament)
— A band: dark bands
* Boundary of a thick filament
* Contains myosin
— H zone AKA H band
* Within A band, contains only thick filaments
87
Define excitation & memorize the details of excitation discussed in class
Excitation: process where AP in axon leads to AP in muscle fiber
1. Signal/AP travels down motor neuron axon to the terminal bouton
2. Voltage gated calcium channels activated
3. Calcium diffuses into cytoplasm
4. Synaptic vesicles containing ACh exocytosed
5. ACh diffuses on synaptic cleft and binds to nicotinic receptor proteins on motor end plate
6. Na+ diffuses into cytoplasm through nicotinic receptor
7. Excitation AKA End Plate Potential produced
8. Na+ diffuses into cytoplasm
9. Action potential produced on sarcolemma
88
Define excitation-contraction coupling & memorize the details of excitation-contraction coupling discussed in class
Excitation-Contraction coupling: events linking AP to activation of myofilaments (thick and thin filaments)
(9) Continuation from excitation...
10. Signals/AP travel down T-tubules to terminal cisternae of SR
11. Voltage gated calcium channels activate by AP, changing its shape, causing...
12. Calcium release channels on the terminal cisternae of SR open
13. Calcium diffuses into cytoplasm from Ca2+ release channels
89
Distinguish the difference between a relaxed muscle and contracting muscle
Relaxed muscle: Troponin-tropomyosin inhibit
- Tropomyosin blocks the myosin binding sites on actin
Contracting Muscle: Troponin-tropomyosin moved away
- Ca2+ binds to troponin, causing complex to move
90
Describe the sliding filament theory; and what must occur before the mysoin head bind to actin?
Sliding filament theory: Sliding of filaments (thick and thin) because of CROSS BRIDGES = Formed by myosin heads attaching to actin
- ATP → ADP + Pi MUST OCCUR before myosin head binds to actin
91
Memorize the details of the cross bridge cycle discussed in class
(13) Continuation from excitation-contraction coupling
14. Calcium binds to troponin
15. Myosin hydrolyses ATP into ADP + Pi
16. Cross bridge formed
17. Powerstroke (conformation change of mysoin head) when Pi released
18. Cross bridge broken when ADP released and a new ATP binds to the myosin head
92
Describe the effect contraction has on the A band, I band, H band, thick filament & thin filament
A bands: NO length change; (thick filaments NO length change)
I band: shortens; (thin filaments NO length change)
H band: shortens
93
Describe motor units
1 Motor unit = 1 somatic(/alpha) motor neuron + all muscle fibers it innervates
- Motor neuron controls multiple muscle fiber at same time
* 1 axon forms many collateral branches that go to many muscle fibers = contract as a unit (All or none)
* 1 terminal bouton on each muscle fiber
94
Distinguish small motor units from large motor units
* Smaller motor unit = finer neural control
* Larger motor units = greater strength
95
Describe recruitment
Recruitment: small (motor units) then large (motor units)
- asynchronous activation of motor units for muscle contraction
96
Distinguish type I fibers vs. type IIA fibers vs. type IIX fibers in terms of glycogen content, resistance to fatigue, capillaries, myoglobin content, energy system used (anaerobic fermentation and/or aerobic respiration), twitch rate & mitochondria
Glycogen content:
Type I - Low
Type IIA - Intermediate
Type IIX - High
Resistance to fatigue:
Type I - High
Type IIA - Intermediate
Type IIX - Low
Capillaries:
Type I - Many
Type IIA - Many
Type IIX - Few
Myoglobin content:
Type I - High
Type IIA - High
Type IIX - Low
Energy system used:
Type I - Aerobic respiration
Type IIA - Aerobic respiration
Type IIX - Anaerobic respiration
Twitch rate:
Type I - Slow
Type IIA - Faster
Type IIX - Fastest
Mitochondria:
Type I - Many
Type IIA - Large number
Type IIX - Few
97
Memorize the alternative names for type I vs. type IIA vs. type IIX
Type I - Slow oxidative fibers
Type IIA - Fast oxidative -glycolytic fibers
Type IIX - Fast glycolytic fibers
98
Describe the function of myoglobin in muscle fibers
Myoglobin: molecule that binds to O2 to supply oxygen to muscle
99
Distinguish skeletal muscle vs. smooth muscle vs. cardiac muscle in terms of sarcomeres (present or absent), calcium source(s), gap junctions (present or absent), receptor that calcium binds to
Skeletal muscles:
- Sarcomeres
- Ca2+ source: SR
- Ca2+ binds to troponin
- NO gap junctions
Smooth muscle:
- NO sarcomeres
- Ca2+ source: SR & ECF
- Ca2+ binds to calmodulin
- Gap junctions
Cardiac muscle:
- Sarcomeres (contains actin and myosin)
- Ca2+: SR and ECF
- Ca2+ binds to troponin
- Gap junction (w/n intercalated discs)
100
Distinguish isometric contractions vs. isotonic contractions vs. concentric contractions vs. eccentric contractions
Isometric contraction: “same length”
* Length of fibers = constant
* Load not moved
Isotonic contraction: “same tone”
* Force of contraction = constant
* Load moved
— Concentric contraction: occurs when the muscle shortens but has the same tension as it is shortening
— Eccentric contraction: force exerted on a muscle to stretch > force of muscle contraction
101
Explain the (4) possible reason for muscle fatigue
1. ↑ phosphate from CP (creatine phosphate; energy source) breakdown
2. ↓ ATP, especially near T-tubules & SR
3. Muscle glycogen (energy storage) depletion, somehow ↓ Ca2+ release from SR
4. ↑ ADP in cytoplasm → ↓ muscle shortening velocity during fatigue
102
Describe central fatigue
Central fatigue: muscle fatigue due to changes in CNS
103
Recognize organs/structures (7) based on histology images similar to those used in Turn In 05
- Pituitary gland
- Thyroid
- Parathyroid
- Adrenal glands
- Pancreas
- Testis
- Ovary
104
Name the cells synthesized in the seminiferous tubules
Seminiferous tubules - produces sperm
— Sustentacular/Sertoli cells: supporting cells that help provide nutrients and removal of wastes for the developing sperm
* ALSO produces inhibin, targeting the anterior pituitary to inhibit FSH secretion
105
Distinguish what produces, the target organ, and function for the following hormone: Inhibin (Testis)
Produced by - Sustentacular/Sertoli cells
Target organ - Anterior pituitary
Function - inhibits FSH (follicle-stimulating hormone) secretion
106
Distinguish what produces, the target organ, and function for the following hormone: Testosterone
Produced by - Interstitial cells/cells of Leydig
Target organ - Multiple organs (skeletal m., bone for growth, libido, testes)
Function - sperm production and male reproductive development
107
Distinguish what produces, the target organ, and function for the following hormone: Estradiol
Produced by - Granulosa cells and Corpus Luteum
Target organ - Many tissues
Function - regulates the ovarian and menstrual cycle and pregnancy, preparation of the mammary glands for lactation, and to cause female reproductive development and puberty
108
Distinguish what produces, the target organ, and function for the following hormone: Inhibin (Ovary; produced by Granulosa cells)
Produced by - Granulosa cells
Target organ - Anterior pituitary
Function - Inhibits FSH secretion
109
Distinguish what produces, the target organ, and function for the following hormone: Androstenedione (Androgen)
Produced by - Theca cells
Target organ - Granulosa cells
Function - make estradiol via aromatase
110
Distinguish what produces, the target organ, and function for the following hormone: Luteinizing
Produced by - Corpus luteum
Target organ - F: ovaries; M: testes
Function - F: cause ovulation and maintain the corpus luteum, producing progesterone; M: secrete testosterone
111
Distinguish what produces, the target organ, and function for the following hormone: Inhibin (Ovary; Produced by Corpus Luteum)
Produced by - Corpus luteum
Target organ - Uterus
Function - Inhibits the secretion of FSH
112
Draw the hypothalamic-pituitary-ovary axis as a mature follicle is produced (before ovulation), include the feedback loop and the relative amounts of each hormones (which you can depict showing up arrows for increase or down arrows for decrease):
Hypothalamus - Pituitary - Ovary Axis
Hypothalamus
↓Gonadotropin releasing hormone (GnRH) increase
Anterior Pituitary
↓LH/FSH increase
Ovary
↓Increase of progesterone and increase of estrogen
Uterus
OR (If no implantation happens then the amount of progesterone and estrogen will decrease)
- Negative feedback: some goes to hypothalamus to stop secreting GnRH
- Negative feedback: some goes to anterior pituitary to stop responding to GnRH
113
Recall all the 3 experiments conducted for lab 06
Experiment 1: Muscle Twitch, Incomplete Tetanus, Complete Tetanus, and Fatigue
Experiment 2: EMG for Recruitment and Fatigue
Experiment 3: Using a Weight for Fatigue
114
Distinguish muscle twitch vs. treppe vs. incomplete tetanus vs. complete tetanus
- Muscle twitch: consists of one cycle of contraction and relaxation and three phases (latent period, contraction period, relaxation period)
- Treppe: when a muscle contracts and FULLY relaxes and then is stimulated again, but this time the muscle tension of the contraction is stronger than the previous muscle contraction
- Incomplete tetanus: the muscle tension will increase even more since temporal summation occurs by increasing the frequency of the stimulus, BEFORE the muscle can fully relax
- Complete tetanus: a sustained contraction by increasing the frequency of the stimulus even more so that the muscle does not even have a chance to relax AT ALL
115
What does an EMG detect?
determine whether a nerve or muscle has issues, like whether you have a muscle disorder, or to see if the nerve conduction to the muscles is normal or not
116
What two ways help increase the force of contractions when doing this EMG experiment?
The activation of motor neurons (AKA recruitment) and the increase of frequency of AP of your neurons innervating your muscles (AKA temporal summation)
117
What type of fatigue did you experience first?Why does this occur?
Central fatigue: occurs when your brain tells you that you are fatigued to prevent you from damaging your muscles
118
What is the other type of fatigue you experience after the first?
Physiological fatigue: occurs when all the factors mentioned below occurs and the muscles can no longer contract
• The increase of extracellular K+, due to action potentials and end-plate potentials opening of voltage- gated K+ channels, decreasing the intracellular K+.
• Decrease in glycogen within the muscle, since glycogen is stored in the skeletal muscles and broken down into glucose by glycogenolysis so that more ATP can be produced.
• Decrease of Ca2+ being released by the sarcoplasmic reticulum, since more is being released than being pumped back into the sarcoplasmic reticulum, the amount of stored Ca2+ in the sarcoplasmic reticulum will become less and less.
• Increase in phosphates due to the breakdown of phosphocreatine, an energy source to store Pi to be used for ATP production.
• Increase of ADP or Pi, due to ATP being broken down by the myosin head’s ATPase.
• Decrease in pH due to the increase of lactic acid from anaerobic respiration, although this may not be a cause of fatigue but a result of fatigue.
119
Describe the mechanisms of equilibrium
* Hair cells within the macula of the vestibule (urticle and saccule) and crista ampullaris of the semicircular ducts are activated when their stereocilia within the otolithic membrane or cupula bends. The bending of the stereocilia will send nerve impulses to the...
* Vestibular branch of the vestibulocochlear nerve (cranial nerve VIII), which then sends information to both the...
— Cerebellum to help coordinate with our skeletal muscles for balance.
— Superior colliculi which has the oculomotor center to control eye movement by the oculomotor nerve (cranial nerve III) to the extrinsic eye muscles.
