Unit 2 Exam (Ch. 7, 11, 12) - Connect Flashcards
Encoding stimulus strength depends on which of the following? CHECK ALL THAT APPLY.
a. Different neurons have the same threshold of excitation.
b. The more strongly a neuron is stimulated, the less frequently it fires.
c. Different neurons have different thresholds of excitation.
d. The more strongly a neuron is stimulated, the more frequently it fires.
Different neurons have different thresholds of excitation.
The more strongly a neuron is stimulated, the more frequently it fires.
The bones of the skeleton provide structure to the body and serve as a __________ to hold up the body and maintain proper positioning of some organs.
support
The skull, pelvis, ribs, vertebral column, and sternum provide __________ to many delicate organs of the body by encasing them in hardened, shell-like or caged structures.
protection
The __________ of the entire skeleton or skeletal elements utilizes the anchoring of muscles to attachment sites on the bones, which then serve as levers.
movement
Minerals can be stored in the skeleton, which acts as a reservoir, storing or releasing minerals as needed to maintain ___________ throughout the body.
electrolyte balance
The storage or release of buffering compounds works to aid the body in __________ balance.
acid-base
Contained within the spongy sections of bones, red bone marrow is responsible for __________.
blood formation
Which of the following best describes osseous tissue?
a. A connective tissue with a hardened matrix that makes up bone
b. A connective tissue composed primarily of cartilage matrix and collagen
c. A connective tissue consisting of loosely arranged protein fibers
d. A connective tissue lacking fibers in the extracellular matrix
e. A hardened mineralized matrix devoid of living cells
A connective tissue with a hardened matrix that makes up bone
(osseous tissue = bone tissue)
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Vertebra =
Irregular Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Scapula =
Flat Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Capitate bone =
Short Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Craniam =
Flat Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Sphenoid Bone =
Irregular Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Ulna =
Long Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Talus =
Short Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Sternum =
Flat Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Femur =
Long Bone
Flat Bone, Irregular Bone, Short Bone, or Long Bone?
Radius =
Long Bone
LOOK AT IMAGE
Correctly label the following anatomical parts of a long bone.
word bank:
1. Diaphysis
2. Red bone marrow
3. Nutrient foramen
4. Marrow cavity
5. Periosteum
6. Epiphyseal line
7. Yellow bone marrow
8. Compact bone
9. Epiphysis
10. Articular Cartilage
11. Site of endosteum
Answer In Image
LOOK AT IMAGE
Correctly label the following anatomical parts of a long bone.
word bank:
1. Marrow cavity
2. Spongy bone
3. Compact bone
4. Epiphysis
5. Yellow bone marrow
6. Epiphyseal line
7. Site of endosteum
8. Articular Cartilage
9. Diaphysis
10. Red bone marrow
11. Periosteum
Answer In Image
LOOK AT IMAGE
Correctly label the following anatomical parts of a flat bone.
word bank:
1. Long bone
2. Trabeculae
3. Spongy bone
4. Compact Bone
5. Spicules
Answer In Image
Which osseous tissue is found on the surface of bones and composed of tightly arranged parallel osteons?
a. Compact
b. Spongy
c. Interstitial
d. Woven
e. Wolff’s
compact
Which bone cells produce the soft organic bone matrix?
a. Osteoblasts
b. Osteoclasts
c. Osteocytes
d. Chondrocytes
e. Osteoprogenitor cells
osteoblasts
Bone dissolving cells on bone surfaces are called __________.
osteoclasts
What is the calcium-phosphate salt deposited within bone called?
a. Hydroxyapatite
b. Calcitonin
c. Collagen
d. Calcitriol
e. Proteoglycan
hydroxyapatite
Is this found in the Organic portion or Inorganic portion of the bone?
Calcium carbonate =
inorganic
Is this found in the Organic portion or Inorganic portion of the bone?
Collagen =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Resists compressive forces =
inorganic
Is this found in the Organic portion or Inorganic portion of the bone?
Glycoproteins =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Resist tensile (pulling) forces =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Glycoaminoglycans =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Provides hardness =
inorganic
Is this found in the Organic portion or Inorganic portion of the bone?
Proteoglycans =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Provides flexibility =
organic
Is this found in the Organic portion or Inorganic portion of the bone?
Hydroxyapatite =
inorganic
LOOK AT IMAGE
Correctly label the following anatomical parts of osseous tissue.
word bank:
1. Collagen fibers
2. Central canal
3. Lacuna
4. Osteon
5. Circumferential lamellae
6. Periosteum
7. Perforating fibers
8. Concentric lamellae
9. Trabeculae
10. Perforating canal
Answer In Image
Compact bone or Spongy Bone?
Made up of osteons =
compact bone
Compact bone or Spongy Bone?
Gaps between ossified material are filled with marrow =
spongy bone
Compact bone or Spongy Bone?
Strong but light =
spongy bone
Compact bone or Spongy Bone?
Found in greater proportions in bone epiphyses =
spongy bone
Compact bone or Spongy Bone?
Visible, obvious, central canals =
compact bone
Compact bone or Spongy Bone?
Composed of trabeculae =
spongy bone
Compact bone or Spongy Bone?
Arranged along lines of force =
spongy bone
Compact bone or Spongy Bone?
Found in greater proportion in the bone diaphyses =
compact bone
Compact bone or Spongy Bone?
Also called dense bone =
compact bone
Compact bone or Spongy Bone?
Found in greater proportions in flat bones =
spongy bone
- The __________ are found deep in the diaphyses of long bones and are filled with yellow marrow in the adult.
marrow cavities
Located in the middle of osteons, the __________ contain the blood vessels and nervous supply of the compact bones.
central canals
Filled with __________, which are osteoblasts encased in matrix, __________ are found between layers of concentric lamellae.
osteocytes; lacunae
Osteocytes maintain contact with neighboring osteocytes in adjacent lamellae via dendrite-like extensions through __________.
canaliculi
LOOK AT IMAGE
Correctly label the following parts of the femur.
word bank:
1. Shaft
2. Osteons
3. Trabeculae of spongy bone
4. Lines of stress
5. Compact bone
6. Head
7. Metaphysis
8. Yellow bone marrow
Answer In Image
What is the function of red bone marrow?
a. Blood-cell production
b. Energy storage
c. Osteoid production
d. Long-bone growth
e. Blood-vessel growth
Order the following into the chronological order of intramembranous ossification:
a. Honeycomb of spongy bone developing periosteum
b. Deposition of osteoid tissue into embryonic mesenchyme
c. Filling up space to form compact bone at surfaces, leaving spongy bone in middle
d. Calcification of osteoid tissue and entrapment of osteocytes
Stage 1: Deposition of osteoid tissue into embryonic mesenchyme
Stage 2: Calcification of osteoid tissue and entrapment of osteocytes
Stage 3: Honeycomb of spongy bone developing periosteum
Stage 4: Filling up space to form compact bone at surfaces, leaving spongy bone in middle
The bones of the skull form by which type of ossification?
a. Intramembranous
b. Endochondral
c. Incomplete
d. Appositional
e. Interstitial
Intramembranous
Where does bone formation occur during endochondral ossification?
a. Hyaline cartilage model
b. Fibrous membranous sheet
c. Adipose tissue
d. Fibrocartilage model
e. Synovial membrane
Hyaline cartilage model
Which type of bone growth occurs within cartilage and results in bone elongation?
a. Interstitial
b. Appositional
c. Perichondrial
d. Epiphyseal
e. Endosteal
Interstitial
- Elongation of bones is accomplished via __________ growth.
interstitial
Growth in the epiphyseal plate adds to the __________ of a bone until the plate is depleted in early adulthood.
length
The __________ is a layer of hyaline cartilage with a metaphysis on each side.
epiphyseal plate
When the cartilage is depleted, the epiphyseal plates __________, and the bone can not grow longer.
close
The internal mark in the bone left behind by the closed epiphyseal plate is called the __________.
epiphyseal line
Mineralization is a process that extracts __________ and __________ from the blood plasma and deposits it into bone.
a. calcium; collagen
b. phosphate; collagen
c. calcium; sodium
d. phosphate; sodium
e. calcium; phosphate
calcium; phosphate
Which hormone inhibits osteoclasts and stimulates osteoblasts to lower blood calcium levels?
a. Calcitonin
b. Calcitriol
c. Parathyroid hormone
d. Insulin
e. Aldosterone
Calcitonin
Does this Increase of Decrease Blood Calcium?
Increased use of sunblock =
decrease
Does this Increase of Decrease Blood Calcium?
Increased urinary excretion of phosphate =
increase
Does this Increase of Decrease Blood Calcium?
Osteoblast activity =
decrease
Does this Increase of Decrease Blood Calcium?
Leaving at a northern latitude =
decrease
Does this Increase of Decrease Blood Calcium?
Increased bone resorption =
increase
Does this Increase of Decrease Blood Calcium?
Calcitriol =
increase
Does this Increase of Decrease Blood Calcium?
Parathyroid hormone =
increase
Does this Increase of Decrease Blood Calcium?
Calcitonin =
decrease
Does this Increase of Decrease Blood Calcium?
Osteoblast activity =
decrease
Does this Increase of Decrease Blood Calcium?
Inhibition of osteoblasts =
increase
When levels of blood calcium __________, parathyroid hormone is released from the parathyroid glands located on the posterior thyroid.
decrease
Parathyroid hormone causes an increase in the number of __________ and greater rates of bone resorption.
osteoclasts
In the kidney, parathyroid hormone will decrease the amount of calcium excreted by increasing __________ from the kidney tubules.
reabsorption
Parathyroid hormone increases the renal conversion of __________, which secondarily works to increase calcium levels in the blood.
calcidiol to calcitriol
Inhibition of __________ by parathyroid hormone occurs as a result of a decreased production of organic matrix.
osteoblasts
As a result of direct actions on the target cells of the bone and kidneys along with an indirect action on the small intestine (calcitriol), parathyroid hormone works to __________ blood calcium levels.
increase
The most active form of __________ is called calcitriol.
vitamin D
Osteoblast activity in children is stimulated by the hormone __________.
calcitonin
When blood calcium levels drop, glands embedded in the posterior thyroid secrete __________ hormone, which stimulates osteoclastic activity.
parathyroid
The hormone __________ influences both resorption and deposition of bone.
calcitriol
Vitamin D stimulates absorption of dietary calcium from the __________ system.
digestive
Any break in a bone is called a __________, and repair is done in stages by the body.
fracture
A __________ will form and will turn into granulation tissue at the site of injury.
hematoma
Depositions of collagen and fibrocartilage will then turn the tissue into a soft __________.
callus
__________ deposit a temporary bony collar around the fracture while ossification occurs.
osteoblasts
The process finishes with bone __________ converting spongy to compact bone.
remodeling
During the healing of a bone fracture, a hard callus is formed by __________.
a. osteoclasts
b. osteoblasts
c. osteocytes
d. fibroblasts
e. chondrocytes
osteoblasts
LOOK AT IMAGE
Place the following images into the correct order to represent the sequence of the steps of fracture healing.
Answer In Image
Muscles function in __________ of the head, neck, and limbs, as well as propulsion of the contents through the digestive tract.
movement
Muscles also function in __________ by preventing unwanted movement, as in maintaining posture.
stability
Using __________, or valves, muscles control the passage of contents from one body cavity, or lumen, to another.
sphincters
Since muscle contraction requires energy to do work, muscles help maintain our body __________.
heat
By absorbing a large share of one’s __________, muscles play an important role in blood-sugar control.
glucose
The ability to carry an electrical charge along the cell is called __________.
conductivity
Also known as responsiveness, __________ is a characteristic of all cells, though more highly developed in muscle and nerve cells.
excitability
Muscles can pull bones closer to one another and increase the motility of some organs. This is due to the property of __________.
contractility
Skeletal muscles can stretch up to three times their contracted length. This is called __________.
extensibility
Muscles can stretch and, when released, return to their original, shorter length. This property is referred to as __________.
elasticity
Because skeletal muscle is under the conscious control, it is said to be what?
a. Voluntary
b. Involuntary
c. Smooth
d. Visceral
e. Autonomic
voluntary
Which connective tissue layer bundles muscle fibers together into fascicles?
a. Epimysium
b. Perimysium
c. Endomysium
d. Peichondrium
e. Periosteum
perimysium
The connective tissue that surrounds each muscle fiber is called the __________.
endomysium
The specific name for a muscle fiber’s plasma membrane is the __________.
sarcolemma
Each myofibril is made of up of several __________.
myofilaments
Terminal cisterns are a structural feature of the organelle called the __________.
sarcoplasmic reticulum
In a muscle fiber, the __________ is adjacent to a terminal cistern, so the action potential can stimulate calcium ion channels.
T tubule
LOOK AT IMAGE
Correctly label the following parts of a skeletal muscle fiber.
word bank:
1. Sarcoplasmic reticulum
2. Muscle fiber
3. Openings into transverse tubules
4. Sarcoplasm
5. Sarcolemma
6. Transverse tubule
7. Nucleus
8. Mitochondria
9. Myofibril
10. Terminal cisterns
Answer In Image
LOOK AT IMAGE
Correctly label the following parts of a skeletal muscle fiber.
word bank:
1. Myofibril
2. Sarcolemma
3. Sarcoplasm
4. Myofilaments
5. Mitochondria
6. I band
7. Z disc
8. A band
9. Sarcoplasmic reticulum
10. Muscle fiber
Answer In Image
Thick Filaments, Thin Filaments, or Neither?
Actin =
thin filament
Thick Filaments, Thin Filaments, or Neither?
Tropomyosin =
thin filament
Thick Filaments, Thin Filaments, or Neither?
Myosin =
thick filament
Thick Filaments, Thin Filaments, or Neither?
Elastic Filament =
neither
Thick Filaments, Thin Filaments, or Neither?
Myosin heads =
thick filament
Thick Filaments, Thin Filaments, or Neither?
Dystrophin =
neither
Thick Filaments, Thin Filaments, or Neither?
Active sites =
thin filament
Thick Filaments, Thin Filaments, or Neither?
Troponin =
thin filament
LOOK AT IMAGE
Correctly label the anatomical features of thick and thin filaments.
word bank:
1. Thin filament
2. Z disc
8. Thick filament
9. Bare zone
10. H band
Answer In Image
A single __________ molecule consists of two intertwined polypeptides forming a twisted, filamentous tail and a double globular head.
myosin
A __________ filament consists of 200 - 500 myosin molecules bundled together with the heads projecting outward in a helical array.
thick
A thin filament consists of two intertwined chains of G actin molecules, smaller filamentous __________ molecules, and troponin.
tropomyosin
A region of overlap between the thin and thick myofilaments exists, and between each is a __________ zone.
bare
(bare zone = H band!)
LOOK AT IMAGE
Correctly label the following features of the muscle filament.
word bank:
1. Thin filament
2. Head
3. Thick filament
4. Actin
5. Tail
Answer In Image
LOOK AT IMAGE
Correctly label the anatomical features of the muscle filament.
word bank:
1. G actin
2. Thick filament
3. Myosin
4. Tropomyosin
5. Troponin complex
6. Thin filament
Answer In Image
LOOK AT IMAGE
Correctly label the different bands of a sarcomere.
word bank:
1. H band
2. I band
3. A band
4. Z disc
5. Sarcomere
6. M line
Answer In Image
Thick Filaments, Thin Filaments, or Both?
I band =
thin filament
Thick Filaments, Thin Filaments, or Neither?
H band =
thick filament
Thick Filaments, Thin Filaments, or Neither?
A band =
both
Thick Filaments, Thin Filaments, or Neither?
M line =
thick filament
Which of the following is/are a characteristic of skeletal muscle?
SELECT ALL THAT APPLY:
a. Overlapping thin and thick filaments
b. Striations
c. Overlapping myosin and actin proteins
d. Excitability
e. Involuntary
Overlapping thin and thick filaments, striations, overlapping myosin and actin proteins, and excitability!
LOOK AT IMAGE
Correctly label the anatomical features of a neuromuscular junction.
word bank:
1. Synaptic cleft
2. Nucleus
3. Postsynaptic membrane folds
4. Sarcolemma
5. Synaptic vesicles
6. Myofilaments
7. Mitochondria
8. Motor nerve fiber
9. Sarcoplasm
10. ACh receptor
Answer In Image
LOOK AT IMAGE
Correctly label the anatomical features of a neuromuscular junction.
word bank:
1. Basal lamina
2. Motor nerve fiber
3. Postsynaptic membrane folds
4. Synaptic vesicles
5. Axon terminal
6. ACh receptor
6. Synaptic cleft
7. Sarcolemma
Answer In Image
What is acetylcholine?
a. The neurotransmitter released at a neuromuscular junction
b. An autoimmune disorder where the immune system attacks ACh receptors
c. The name of the plasma membrane of a muscle fiber
d. The enzyme that removes the neurotransmitter in the neuromuscular junction
e. A chemical that blocks receptors on the motor end plate so they cannot be stimulated
The neurotransmitter released at a neuromuscular junction
An action potential reaches the axon terminal causing __________ to open.
voltage-gated Ca²⁺ channels
Stimulated by __________, acetylcholine is released into the synaptic cleft via __________.
calcium ions; exocytosis
Acetylcholine diffuses across the synaptic cleft before binding to its receptor, which is located on the __________.
motor end plate
Acetylcholine receptors function as __________.
ligand-gated ion channels
In response to acetylcholine binding, __________ move into the muscle fiber, causing the membrane potential to rise.
sodium ions
When the membrane potential reaches __________, an action potential spreads across the sarcolemma due to the opening of __________.
threshold; voltage-gated Na⁺ channels
True or False:
During excitation, the voltage fluctuation caused by K⁺ entering and Na⁺ leaving the cell through the sarcolemma is called the end-plate potential.
false
(The voltage fluctuation caused by Na⁺ entering the cell and K⁺ leaving the cell through the sarcolemma is referred to as the action potential, not the end-plate potential. The end-plate potential specifically refers to the depolarization of the motor end plate due to the binding of acetylcholine and the subsequent influx of sodium ions.)
What is the role of acetylcholinesterase?
a. It stimulates the motor end plate.
b. It breaks down ACh, ending muscle stimulation.
c. It is used by the muscle for energy.
d. It blocks ACh from binding to its receptor.
It acts as a kinase in cell-to-cell communication.
It breaks down ACh, ending muscle stimulation.
Place the events of excitation of a muscle fiber in order:
a. An action potential is generated in the adjacent sarcolemma.
b. Calcium ions enter the axon terminal through voltage-gated channels.
c. ACh is released into the synaptic cleft.
d. Na⁺ Na⁺ ions enter, and K⁺ K⁺ ions leave the cell, creating an end-plate potential.
e. ACh diffuses across the synpatic cleft and binds to receptors on the sarcolemma.
- Calcium ions enter the axon terminal through voltage-gated channels.
- ACh is released into the synaptic cleft.
- ACh diffuses across the synpatic cleft and binds to receptors on the sarcolemma.
- Na⁺ Na⁺ ions enter, and K⁺ K⁺ ions leave the cell, creating an end-plate potential.
- An action potential is generated in the adjacent sarcolemma.
Voltage sensitive proteins respond to the action potential that spreads down the __________.
T tubule
Voltage-gated __________ in the __________ open and release ions into the sarcoplasm.
calcium ion channels; terminal cisterns
These ions bind to __________, which forms a complex with __________.
troponin; tropomyosin
A conformational change in the __________ occurs, revealing active sites on the __________.
troponin-tropomyosin complex; actin filaments
The __________ bind to the active sites and form __________ between the thick and thin filaments.
myosin heads; cross-bridges
An action potential causes calcium ions to diffuse from the __________ into the __________.
a. sarcoplasmic reticulum; sarcolemma
b. sarcoplasmic reticulum; sarcoplasm
c. sarcoplasm; sarcoplasmic reticulum
d. sarcoplasm; sarcolemma
e. sarcolemma; sarcoplasm
sarcoplasmic reticulum; sarcoplasm
Which of the following best describes the role of Ca²⁺ in muscle contraction?
a. It binds to tropomyosin, moving troponin, so that myosin heads can bind to actin.
b. It binds to tropomyosin, moving troponin, so that actin heads can bind to myosin.
c. It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
d. It binds to troponin, moving tropomyosin, so that actin heads can bind to myosin.
e. It binds to actin, moving myosin, so that troponin can bind to tropomyosin.
It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
True or False:
An action potential causes depolarization of the T tubule membrane.
true
(An action potential causes depolarization of the T tubule membrane. This depolarization is essential for transmitting the electrical signal into the muscle fiber, leading to the release of calcium ions from the sarcoplasmic reticulum and ultimately initiating muscle contraction.)
True or False:
T tubules are invaginations of the sarcolemma of a muscle cell.
true
(T tubules (transverse tubules) are invaginations of the sarcolemma (the plasma membrane) of a muscle cell. They extend into the cell and help transmit the action potential deep into the muscle fiber, facilitating synchronized muscle contraction.)
During contraction of a muscle, calcium ions bind to the __________.
a. actin myofilament
b. troponin molecule
c. tropomyosin molecule
d. sarcoplasmic reticulum
e. sarcolemma
troponin molecule
The bond between the active site on actin and the myosin head is broken when an __________.
a. ATP molecule binds to the myosin head
b. ATP molecule binds to the actin molecule
c. ATP molecule breaks down on the myosin head
d. ATP molecule breaks down on the actin molecule
e. ADP molecule and a phosphate molecule bind to the myosin head
ATP molecule binds to the myosin head
True or False:
The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions and ATP are present.
true
(The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions and ATP are present. Calcium ions enable the binding of myosin heads to actin, and ATP provides the energy necessary for the myosin heads to pivot and pull the actin filaments, facilitating muscle contraction.)
True or False:
When cross-bridges form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.
true
(When cross-bridges form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament. This sliding mechanism is known as the sliding filament theory and is fundamental to muscle contraction.)
The step in which the muscle fiber develops tension and may shorten is called __________. It begins after the active site on actin is exposed.
contraction
The myosin head must have an __________ molecule bound to it to initiate the process.
ATP
The head extends toward the exposed __________ site on the thin filament.
active
A __________ is formed by the attachment of the myosin head to the thin filament.
cross-bridge
The myosin head pushes forward, moving the thin filament toward the M line. This is called the __________ stroke.
power
Once more ATP binds, myosin will release from the actin and hydrolyze another ATP. This is called the __________ stroke.
recovery
The __________ is described as two strands of actin molecules wrapped together.
a. thick filament
b. thin filament
c. elastic filament
d. troponin-tropomyosin complex
e. terminal cistern
thin filament
Which of the following happens as actin and myosin filaments slide past each other during muscle contraction?
a. Actin filaments shorten, while myosin filaments do not.
b. Myosin filaments shorten, while actin filaments do not.
c. Either actin or myosin filaments shorten, but not both at the same time.
d. Both actin and myosin filaments shorten.
e. Neither actin nor myosin filaments shorten.
Neither actin nor myosin filaments shorten.
Which of the following statements about the “heads” of the myosin molecules is true?
a. They form permanent links with actin filaments.
b. They can attach to different sites on the actin filament.
c. They straighten the myosin filaments.
d. They allow the myosin filaments to wrap around each other.
e. None of these are true statements.
They can attach to different sites on the actin filament.
True or False:
Each myosin protein has a globular head that extends outward from the myosin filament.
true
(Each myosin protein has a globular head that extends outward from the myosin filament. These heads play a crucial role in forming cross-bridges with actin filaments during muscle contraction.)
LOOK AT IMAGE:
Regarding the relaxation of a muscle fiber, determine which step each phrase is describing, in such a way that they accurately follow the sequence of events associated with muscle fiber relaxation.
a. Ion channels in the sarcolemma stop opening.
b. The myosin binding sites found on actin are again covered up by tropomyosin.
c. Exocytosis of neurotransmitter into synaptic cleft ceases.
4. Calcium ions are returned to storage within the muscle fiber.
- Exocytosis of neurotransmitter into synaptic cleft ceases.
→ This stops the stimulation of the muscle fiber. - Ion channels in the sarcolemma stop opening.
→ This leads to a cessation of the action potential and allows repolarization. - Calcium ions are returned to storage within the muscle fiber.
→ Calcium is pumped back into the sarcoplasmic reticulum. - The myosin binding sites found on actin are again covered up by tropomyosin.
→ This prevents myosin from binding to actin, leading to muscle relaxation.
Relaxation begins when nerve signals stop stimulating the synaptic knob and __________ release ceases.
acetylcholine
Acetylcholine dissociates from its __________ and is broken down enzymatically.
receptor
Active transport pumps in the SR move __________ ions back into the cisterns.
calcium
__________ moves back into position, blocking active sites, which prevents more contraction.
tropomyosin
If an appropriate force is applied, the __________ returns to its resting length.
muscle fiber
Rigor mortis occurs when there is an absence of __________, due to a lack of __________.
a. ATP; aerobic respiration
b. ATP; anaerobic respiration
c. CP; aerobic respiration
d. ADP; aerobic respiration
e. CP; anaerobic respiration
ATP; aerobic respiration
Contraction or No Contraction?
Active transport of Ca²⁺ into the sarcoplasmic reticulum =
no contraction
Contraction or No Contraction?
An inhibitor of voltage-gated Na⁺ channels =
no contraction
Contraction or No Contraction?
A mutation to tropomyosin that prevents it from binding to troponin =
no contraction
Contraction or No Contraction?
A mutation to tropomyosin that prevents it from binding actin =
contraction
Contraction or No Contraction?
Exposure of the active sites on the actin filament =
contraction
Contraction or No Contraction?
A mutation to troponin that prevents it from binding Ca²⁺ =
no contraction
Contraction or No Contraction?
Release of acetylcholine =
contraction
Contraction or No Contraction?
Presence of an organophosphate pepticide that inhibits acetylcholinesterase =
contraction
Contraction or No Contraction?
Opening of calcium ion channels in the terminal cisterns =
contraction
In a resting muscle fiber, a __________ is normally 2.0 to 2.5 micrometers long.
sarcomere
This is the optimum length for producing maximum __________ when the muscle contracts.
tension
If a muscle fiber is overly contracted, the __________ filaments butt against the Z discs.
thick
Conversely, if the muscle fiber is overly stretched, there is not enough overlap between the thick and __________ myofilaments.
thin
Therefore, if the thick and thin filaments do not overlap, very few __________ are formed.
cross-bridges
Latent Period, Contraction Phase, or Relaxation Phase:
Muscle tension decreases
relaxation phase
Latent Period, Contraction Phase, or Relaxation Phase:
Myofilaments slide over one another
contraction phase
Latent Period, Contraction Phase, or Relaxation Phase:
Depolarization occurs in the T tubule
latent period
Latent Period, Contraction Phase, or Relaxation Phase:
Excitation-contraction coupling
latent period
Latent Period, Contraction Phase, or Relaxation Phase:
Immediately follows stimulation of the muscle
latent period
Latent Period, Contraction Phase, or Relaxation Phase:
Internal but not external tension generated
latent period
Latent Period, Contraction Phase, or Relaxation Phase:
Ca²⁺ transported back into sarcoplasmic reticulum
relaxation phase
Latent Period, Contraction Phase, or Relaxation Phase:
Power stroke occurs
contraction phase
Latent Period, Contraction Phase, or Relaxation Phase:
Internal and external tension generated
contraction phase
Latent Period, Contraction Phase, or Relaxation Phase:
Sarcomeres shorten
contraction phase
Which of the following describes twitch summation?
a. A muscle fiber is under continuous stimulation, and contraction becomes unable to contract at all until it has rested.
b. Muscle fibers are able to contract and then completely relax before the next contraction.
c. Stimuli arrive at the muscle fiber so rapidly that there is no muscle relaxation between stimuli, resulting in a continuous contraction of the muscle fiber.
d. Stimuli arrive at the muscle fiber at such a rate that the muscle fiber is unable to completely relax between stimuli. Sequential contractions exhibit an equal contractive force that is greater than when the muscle fiber is allowed to rest completely.
e. A second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
A second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
Subthreshold stimuli produce no muscle __________.
contraction
When stimuli reach or exceed __________, they excite more motor units.
threshold
The more motor units that are excited, the __________ the contraction.
stronger
When multiple motor units are excited, it is called __________.
summation
When all nerve fibers are stimulated, an increase in stimulus strength will produce no __________ in muscle tension.
increase
What is a motor unit?
a. All of the muscle fibers innervated by a single motor axon.
b. A single bundle of fascicles.
c. A muscle unit within the epimysium.
d. All of the axons that innervate a muscle group.
e. All of the muscle fibers contained within a fascicle.
All of the muscle fibers innervated by a single motor axon.
Small motor unit or Large motor unit?
- Moving a piano =
- Playing a piano =
- Climbing stairs =
- Following words on a page with your eyes =
- Writing a note =
- Sitting upright =
- Moving a piano = LARGE motor unit
- Playing a piano = SMALL motor unit
- Climbing stairs = LARGE motor unit
- Following words on a page with your eyes = SMALL motor unit
- Writing a note = SMALL motor unit
- Sitting upright = LARGE motor unit
- precise movements = small motor unit!
- large movements = large motor unit!
With low-frequency stimulation, the muscle relaxes fully between contractions, resulting in __________ twitches per stimulus.
identical
As the frequency gets progressively higher, the muscle does not have time to __________ in between twitches. Each twitch rides “piggyback” on the previous one and generates __________ tension.
relax; higher
This pattern of stimuli causes a sustained fluttering contraction called __________.
incomplete tetanus
In a laboratory setting, an even higher stimulus frequency can cause the muscle to exhibit a state of continual contraction, called __________.
complete tetanus
Despite this pattern, the whole muscle contracts very smoothly because __________ function asynchronously, allowing some to relax while others contract.
motor units
Isotonic Contraction or Isometric contraction:
A mother lowers an infant into their crib.
isotonic contraction
Isotonic Contraction or Isometric contraction:
This begins when a weightlifter pulls on a barbell and ends the moment the barbell leaves the floor.
isometric contraction
Isotonic Contraction or Isometric contraction:
A person holds open a door for their date.
isometric contraction
Isotonic Contraction or Isometric contraction:
A sprinter leaves the starting block.
isotonic contraction
During a(n) __________ contraction, the muscle develops tension without changing in length.
isometric
Isometric contraction occurs at the __________ of a muscle contraction as well as during prolonged activities.
beginning
During isotonic contraction, the muscle shortens, even though the level of __________ is maintained.
tension
During isotonic contraction, a __________ can be moved.
load
The act of a muscle maintaining tension while it lengthens is called isotonic __________ contraction.
eccentric
During an isotonic eccentric contraction, a muscle is allowed to __________ without going limp.
lengthen
Which of the following describes slow-twitch fibers?
a. They have few mitochondria.
b. They have very little myoglobin.
c. They have a rich blood supply.
d. They have high levels of lactate.
e. They rely on anaerobic respiration.
They have a rich blood supply.
Fast Twitch Fiber or Slow Twitch Fiber:
Longer twitches =
SLOW twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Easily fatigued =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Few mitochondria =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Aerobic =
SLOW twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
More mitochondria =
SLOW twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Shorter twitches =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Low glycogen content =
SLOW twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Anaerobic =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
High glycogen content =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Low myoglobin content =
FAST twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
High myoglobin content =
SLOW twitch fiber
Fast Twitch Fiber or Slow Twitch Fiber:
Dunking a basketball =
FAST twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Marathon running =
SLOW twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Competitive diving =
FAST twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Running the 400-meter dash =
FAST twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Baseball pitching =
FAST twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Standing broad jump =
FAST twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Long distance swimming =
SLOW twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Long distance cycling =
SLOW twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Triathlon =
SLOW twitch fibers
Fast Twitch Fiber or Slow Twitch Fiber:
Shot put =
FAST twitch fibers
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Muscular density of blood capillaries =
Increases with AEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Long-term fatigue resistance =
Increases with AEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Mitochondrial density =
Increases with AEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Myofibril size and number =
Increases with ANAEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Blood volume and red blood cell count =
Increases with AEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Lactic acid processing =
Increases with ANAEROBIC exercise training!
Does the following: Increase with AEROBIC exercise training or with ANAEROBIC exercise training (glycolytic & phosphagen)?
Muscle size =
Increases with ANAEROBIC exercise training!
Which of the following is/are true regarding muscular strength and conditioning? CHECK ALL THAT APPLY.
a. Weight lifting does not increase the number of muscle fibers in a particular muscle exercised.
b. Swimming will increase the number of muscle fibers in a particular muscle exercised.
c. Blood capillary density will increase in slow-twitch fibers in response to training for a marathon.
d. Long-term resistance training will increase the number of myofibrils in a particular muscle exercised.
e. As muscle fibers become too large, mitosis causes them to divide into two.
Weight lifting does not increase the number of muscle fibers in a particular muscle exercised.
Blood capillary density will increase in slow-twitch fibers in response to training for a marathon.
Long-term resistance training will increase the number of myofibrils in a particular muscle exercised.
Cardiac muscle must function without the need for __________ control.
conscious (voluntary)
Cardiac muscle cannot be susceptible to __________.
fatigue
Cardiac muscle functions to expel blood from the heart __________.
chamber
Cardiac muscle cells are connected by __________ discs.
intercalated
Cardiac cells contract independently because they are __________.
autorhythmic
Which of the following describes cardiac muscle tissue?
a. Striated, uninucleate, branching
b. Striated, multinucleate, unbranched
c. Fusiform, striated, uninucleate
d. Nonstriated, uninucleate, branched
e. Nonstriated, multinucleate, unbranched
Striated, uninucleate, branching
Which of the following is/are true about the functions of cardiac muscle?
CHECK ALL THAT APPLY.
a. Cardiac muscle almost always utilizes aerobic respiration to obtain energy.
b. Cardiac muscle cells require nervous innervation for stimulation.
c. Cardiac muscle secures some of its calcium ions from the sarcoplasmic reticulum.
d. When the chambers are filled with blood, the myocytes utilize tight junctions to resist separation.
e. Autorhythmic cells allow the myocytes to contract consistently and regularly, efficiently pumping blood from the chambers.
Cardiac muscle almost always utilizes aerobic respiration to obtain energy.
Cardiac muscle secures some of its calcium ions from the sarcoplasmic reticulum.
Autorhythmic cells allow the myocytes to contract consistently and regularly, efficiently pumping blood from the chambers.
Which of the following describe smooth muscle tissue?
a. Uninucleate, nonstriated
b. Multinucleate, striated
c. Multinucleate, nonstriated
d. Uninucleate, striated
e. Anucleate, nonstriated
Uninucleate, nonstriated
Skeletal Muscle, Smooth Muscle, or Both?
Striated =
skeletal muscle
Skeletal Muscle, Smooth Muscle, or Both?
Contains thin filaments of actin =
BOTH skeletal & smooth muscle
Skeletal Muscle, Smooth Muscle, or Both?
Contains myofibrils =
skeletal muscle
Skeletal Muscle, Smooth Muscle, or Both?
Carbon dioxide levels in blood promote contraction =
smooth muscle
Skeletal Muscle, Smooth Muscle, or Both?
Ca²⁺ promotes contraction =
BOTH skeletal & smooth muscle
Skeletal Muscle, Smooth Muscle, or Both?
Contains T tubules =
skeletal muscle
Skeletal Muscle, Smooth Muscle, or Both?
May be autorhythmic =
smooth muscle
Skeletal Muscle, Smooth Muscle, or Both?
Multinucleate =
skeletal muscle
Skeletal Muscle, Smooth Muscle, or Both?
Dense bodies =
smooth muscle (contains dense bodies = structures that serve as attachment points for actin filaments)
What property of neurons allows them to respond to changes in the environment?
a. Excitability
b. Conductivity
c. Secretion
d. Permeability
e. Convergence
Excitability
Which term describes all neurons that carry signals towards the CNS?
a. Afferent
b. Efferent
c. Motor
d. Somatic
e. Visceral
Afferent
The visceral motor division of the PNS is also called the autonomic division. Which of the following are functions of this division? CHECK ALL THAT APPLY.
a. Controlling gland secretion
b. Accelerating or decreasing heartbeat
c. Stimulating or inhibiting digestion
d. Initiating contraction of skeletal muscles
Controlling gland secretion
Accelerating or decreasing heartbeat
Stimulating or inhibiting digestion
Which of the following is true of interneurons?
a. They carry signals to the central nervous system.
b. They are contained entirely within the CNS and carry signals from one neuron to another.
c. They carry signals from the CNS to muscles and glands.
d. They are specialized to detect stimuli such as light, heat, pressure, and chemicals.
e. They cannot process, store, and retrieve information and “make decisions” that determine how the body responds to stimuli.
They are contained entirely within the CNS and carry signals from one neuron to another.
What are the three general classes of neurons that correspond to the three major aspects of nervous system function? CHECK ALL THAT APPLY.
a. Motor neurons that send signals predominantly to muscle and gland cells
b. Schwann cells that envelop axons of the PNS
c. Interneurons that lie between, and interconnect the incoming sensory pathways and the outgoing motor pathways of the CNS
d. Sensory neurons that are specialized to detect stimuli such as light, heat, pressure, and chemicals and transmit information about them to the CNS
e. Ependymal cells that produce cerebral spinal fluid
Motor neurons that send signals predominantly to muscle and gland cells
Interneurons that lie between, and interconnect the incoming sensory pathways and the outgoing motor pathways of the CNS
Sensory neurons that are specialized to detect stimuli such as light, heat, pressure, and chemicals and transmit information about them to the CNS
About 90% of the neurons in the nervous system are __________ neurons.
a. sensory
b. motor
c. afferent
d. efferent
e. inter-
inter- (interneurons)
Correctly label the following anatomical features of a neuron.
word bank:
1. Axon
2. Axon terminals
3. Internode
4. Nucleus
5. Nucleolus
6. Myelin Sheath
7. Node of Ranvier
8. Dendrites
9. Cell Body
Answers In Image
Correctly label the following anatomical features of a neuron.
word bank:
1. Axon collateral
2. Axon terminal
3. Internode
4. Initial segment
5. Axon Hillock
6. Dendrite
7. Trigger zone
8. Myelin sheath
9. Schwann cell
Answers In Image
axon collateral - branch coming off of axon
Correctly label the following anatomical features of a neuron.
word bank:
1. Neurolemma
2. Schwann cell nucleus
3. Myelin sheath
4. Axon
5. Axon Hillock
Answers In Image
Most metabolic and regulatory functions in a neuron happen where?
a. The axon
b. The cell body
c. The dendrites
d. The axon hillock
e. The Schwann cell
The cell body
What is(are) the fundamental physiological properties that enable nerve cells to communicate with other cells?
a. The ability to respond to environmental changes
b. The ability to produce electrical signals that are quickly conducted to other cells at distant locations
c. The ability to secrete a chemical that will stimulate the next cell when an electrical signal reaches the end of an axon
d. The ability to respond to environmental changes and the ability to produce electrical signals that are quickly conducted to other cells at distant locations
e. The ability to respond to environmental changes, the ability to produce electrical signals that are quickly conducted to other cells at distant locations, and the ability to secrete a chemical that will stimulate the next cell when an electrical signal reaches the end of an axon
The ability to respond to environmental changes, the ability to produce electrical signals that are quickly conducted to other cells at distant locations, and the ability to secrete a chemical that will stimulate the next cell when an electrical signal reaches the end of an axon
What is the primary site on a neuron for receiving signals from other neurons?
a. The axon terminals
b. The axons
c. The axon collaterals
d. The cell bodies
e. The dendrites
The dendrites
Neurons are classified structurally according to the number of processes extending from the cell body. Match each classification to its description.
- Anaxonic neurons =
- Bipolar neurons =
- Multipolar neurons =
- Unipolar neurons =
options:
a. One axon; Multiple dendrites
b. One axon; One dendrite
c. A single process
d. No axon; Multiple dendrites
- Anaxonic neurons = No axon; Multiple dendrites
- Bipolar neurons = One axon; One dendrite
- Multipolar neurons = One axon; Multiple dendrites
- Unipolar neurons = A single process
TRUE OR FALSE:
In the brain, neurons are more abundant than neuroglia.
FALSE
In the brain, neuroglia (glial cells) are more abundant than neurons. Neuroglia outnumber neurons by a significant ratio, typically estimated to be about 10 to 1, and they play essential roles in supporting, protecting, and maintaining the function of neurons.
Correctly label the following anatomical features of the neuroglia.
word bank:
1. Astrocyte
2. Capillary
3. Ependymal cell
4. Oligodendrocyte
5. Microglia
6. Myelinated axon
7. Neurons
Answers In Image
Ciliated cells resembling epithelium: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Ependymal Cells
Multi-functioning cells involved with neurogenesis, scar formation, etc.: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Astrocytes
Insulate neurons and enhance the rate of transmission in the PNS: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Schwann Cells
Produce and circulate CSF: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Ependymal Cells
Form the myelin sheath in the CNS: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Oligodendrocytes
Surround and insulate cells of the PNS and found around the somas: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Satellite Cells
Macrophages of the CNS: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Microglia
Form the myelin sheath in the PNS: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Schwann Cells
Most abundant CNS glial cells: __________
options:
a. Oligodendrocytes
b. Ependymal Cells
c. Astrocytes
d. Microglia
e. Schwann Cells
f. Satellite Cells
Astrocytes
Which types of glial cells are found in the central nervous system? CHECK ALL THAT APPLY.
a. Oligodendrocytes
b. Ependymal cells
c. Microglia
d. Astrocytes
e. Schwann cells
f. Satellite cells
Oligodendrocytes, Ependymal cells, Microglia, and Astrocytes
TRUE OR FALSE:
In the PNS, unmyelinated axons are enveloped in Schwann cells.
TRUE
In the peripheral nervous system (PNS), unmyelinated axons are indeed enveloped in Schwann cells. These cells provide support and protection for the axons, even though they do not form a myelin sheath around them as they do for myelinated axons.
Which cells form myelin sheaths in the spinal cord?
a. Schwann cells
b. Astrocytes
c. Satellite cells
d. Oligodendrocytes
e. Microglia
Oligodendrocytes
TRUE OR FALSE:
The Schwann cell’s plasma membrane spirals repeatedly around the unmyelinated axon as it does in a myelin sheath.
FALSE
In unmyelinated axons, the Schwann cell does not spiral repeatedly around the axon as it does in a myelin sheath. Instead, the axon is simply enclosed by the Schwann cell without multiple layers.
Why is myelin important? CHECK ALL THAT APPLY.
a. It forms extensions called perivascular feet, which contact the blood capillaries and stimulate them to form a tight seal called the blood–brain barrier.
b. It speeds up signal conduction in the axon.
c. It produces cerebrospinal fluid.
d. It is formed to assist in the regeneration of damaged axons.
e. It insulates the axon.
It speeds up signal conduction in the axon.
It is formed to assist in the regeneration of damaged axons.
It insulates the axon.
Choose the correct statement about myelin.
a. It is best not to give children under two years of age a low-fat diet because myelin formation requires lipids.
b. It is formed by oligodendrocytes in the peripheral nervous system and Schwann cells in the central nervous system.
c. It is about 80% protein and 20% lipid.
d. The myelin sheath is segmented, and the gaps between the segments are called internodes.
e. Multiple sclerosis results from the abnormal accumulation of a glycolipid called GM2 (ganglioside) in the myelin sheath.
It is best not to give children under two years of age a low-fat diet because myelin formation requires lipids.
TRUE OR FALSE:
Unmyelinated axons in the PNS are enveloped in Schwann cells.
TRUE
Conduction of a nerve impulse would be the fastest in which of the following?
a. A large diameter myelinated axon
b. A small diameter myelinated axon
c. A large unmyelinated axon
d. A small unmyelinated axon
e. A small axon with multiple Schwann cells
A large diameter myelinated axon
A damaged __________ axon may regenerate if its cell body is intact and some neurilemma remains.
PNS
When an axon is cut, the axon distal to the injury __________ survive.
cannot
Near the site of injury, the basal lamina and the neurilemma form a __________ tube.
regeneration
The tube guides the growing sprout back to the original target cells, reestablishing __________ contact.
synaptic
When contact is established, the __________ shrinks, and reinnervated muscle fibers regrow.
cell body
When can a damaged peripheral axon regenerate?
a. When its cell body is intact
b. When the axon distal to the injury survives
c. When at least some neurolemma remains
d. When its cell body is intact and the axon distal to the injury survives
e. When its cell body is intact and at least some neurolemma remains
When its cell body is intact and at least some neurolemma remains
The resting membrane potential is created as a result of a greater net flow of positive charges from the __________.
ICF to the ECF
Though potassium ions and sodium ions both leak through the membrane at rest, there is a greater flow of __________ ions out of the cell.
potassium
The diffusion of sodium and potassium across the membrane is driven at all times by the __________.
electrochemical gradient
In order to maintain the electrochemical gradients for sodium and potassium, ATPase pumps move these ions __________ their respective gradients.
against
The resting membrane potential is negative due to which of the following?
a. Electrolytes are equally distributed between the extracellular fluid on the outside of the plasma membrane and the intracellular fluid on the inside.
b. There are more negatively charged particles on the outside of the membrane than on the inside.
c. There are more negatively charged particles on the inside of the membrane than on the outside.
d. The sodium-potassium pump adds more cations to the cell than it takes out.
There are more negatively charged particles on the inside of the membrane than on the outside.
Local potentials are __________, whereas action potentials are __________.
a. irreversible; reversible
b. self-propagating; local
c. graded; all or none
d. nondecremental; decremental
e. produced by voltage-regulated channels; produced by gated channels
graded; all or none
An inhibitory local potential causes which of the following?
a. Depolarization of the plasma membrane
b. Hyperpolarization of the plasma membrane
c. Repolarization of the plasma membrane
d. Neutralization of the plasma membrane
e. Drifting of the membrane potential toward the resting membrane potential
Hyperpolarization of the plasma membrane
Requires reaching threshold: __________
options:
a. Action Potential
b. Local Potential
c. Both
Action Potential
Voltage-regulated potassium channels: __________
options:
a. Action Potential
b. Local Potential
c. Both
Voltage-regulated potassium channels: __________
options:
a. Action Potential
b. Local Potential
c. Both
Action Potential
Important for transmission over long distances: __________
options:
a. Action Potential
b. Local Potential
c. Both
Action Potential
Rate of transmission increases with myelination: __________
options:
a. Action Potential
b. Local Potential
c. Both
Action Potential
Sodium-potassium ATPase pumps re-establish RMP (Resting Membrane Potential): __________
options:
a. Action Potential
b. Local Potential
c. Both
Both
Voltage-regulated sodium channels: __________
options:
a. Action Potential
b. Local Potential
c. Both
Action Potential
Decremental: __________
options:
a. Action Potential
b. Local Potential
c. Both
Local Potential
Reversible: __________
options:
a. Action Potential
b. Local Potential
c. Both
Local Potential
Causes summation: __________
options:
a. Action Potential
b. Local Potential
c. Both
Local Potential
Ligand-regulated sodium channels: __________
options:
a. Action Potential
b. Local Potential
c. Both
Local Potential
Where do most local potentials form in a neuron?
a. The dendrites
b. The cell bodies
c. The axon hillock
d. The trigger zone
e. The Schwann cells
The dendrites
Place these events into the order in which they occur during a single action potential:
a. Local potential depolarizes membrane.
b. Hyperpolarization
c. Depolarization spike
d. Repolarization
e. Threshold is reached.
- Local potential depolarizes membrane.
- Threshold is reached.
- Depolarization spike
- Repolarization
- Hyperpolarization
At resting membrane potential, which of the following statements about the voltage-gated sodium ion channels is true?
a. Activation gates are closed, and inactivation gates are open.
b. Activation gates are open, and inactivation gates are closed.
c. Activation and inactivation gates are open.
d. Activation and inactivation gates are closed.
e. Activation and inactivation gates alternate between open and closed.
Activation gates are closed, and inactivation gates are open.
TRUE OR FALSE:
The voltage-gated potassium channels close before the membrane potential is brought back to its resting level.
FALSE
Potassium channels stay open longer than Na+ channels, so slightly more K+ leaves the cell than the amount of Na+ that entered. Therefore, the membrane voltage drops to 1 or 2 mV more negative than the original RMP, producing a negative overshoot called hyperpolarization. The relative refractory period lasts until hyperpolarization ends. During this period, K+ channels are still open.
Why does depolarization occur?
a. Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
b. The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
c. The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
d. More sodium ions diffuse into the cell than potassium ions diffuse out of it.
e. The inactivation gates of the voltage-gated sodium ion channels begin to open, and the diffusion of sodium ions decreases.
More sodium ions diffuse into the cell than potassium ions diffuse out of it.
Why does repolarization occur?
a. Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
b. The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
c. The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
d. More sodium ions diffuse into the cell than potassium ions diffuse out of it.
e. The inactivation gates of the voltage-gated sodium ion channels begin to open, and the diffusion of sodium ions decreases.
Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
Why does hyperpolarization occur?
a. Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
b. The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
c. The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
d. More sodium ions diffuse into the cell than potassium ions diffuse out of it.
e. The inactivation gates of the voltage-gated sodium ion channels begin to open, and the diffusion of sodium ions decreases.
The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
TRUE OR FALSE:
After the passage of the action potential, the sodium-potassium pump re-establishes the resting membrane potential.
TRUE
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
At threshold voltage-gated Na⁺ channels open quickly.
options: A, B, C, D, or E
B
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
Potential across the membrane is becoming less negative.
options: A, B, C, D, or E
A
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
Voltage-regulated K⁺ channels open.
options: A, B, C, D, or E
C
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
Na⁺ arrive at the axon hillock and depolarize the membrane at that point.
options: A, B, C, D, or E
A
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
Hyperpolarization.
options: A, B, C, D, or E
D
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
-70 mV.
options: A, B, C, D, or E
E
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
-55 mV.
options: A, B, C, D, or E
B
LOOK AT IMAGE: Place each of the following labels in the proper position on the curve where each of the indicated items would occur.
Resting membrane potential.
options: A, B, C, D, or E
E
Place the following structures in the order that an electrical impulse would travel beginning with the post-synaptic membrane.
a. Soma
b. Internode
c. Axon Hillock
d. Dendrites
e. Terminal arborization
f. Node of Ranvier
g. Axon Terminals
- DENDRITES - The impulse begins at the dendrites, where it receives signals from other neurons at the post-synaptic membrane.
- SOMA - The signal is then transmitted to the soma (cell body), where it is processed.
- AXON HILLOCK - If the signal is strong enough, it reaches the axon hillock, where an action potential is initiated.
- INTERNODE - The impulse travels along the axon through the internodes (myelinated sections).
- NODE OF RANVIER - The action potential jumps from one node of Ranvier to the next, allowing for faster transmission (saltatory conduction).
INTERNODE (AGAIN) - After passing through the node, the impulse continues down the next internode.
- TERMINAL ARBORIZATION - The impulse reaches the terminal arborization, the branching structure at the end of the axon.
- AXON TERMINALS - Finally, the impulse arrives at the axon terminals, where neurotransmitters are released to communicate with other neurons or target cells.
During the absolute refractory period which of the following is true?
a. If a neuron reaches threshold, the action potential goes to completion.
b. The neuron fires at its maximum voltage if a stimulus depolarizes the neuron to threshold.
c. The signal grows weaker with distance.
d. It is possible to trigger a new action potential, but only with an unusually strong stimulus.
e. No stimulus of any strength will trigger a new action potential.
No stimulus of any strength will trigger a new action potential.
During the relative refractory period, the membrane is hyperpolarized and a larger incoming stimulus is required to trigger an action potential. How does this affect the response properties of a sensory neuron?
a. Higher stimulus intensity will increase the rate at which the sensory neuron fires action potentials.
b. Lower stimulus intensity will increase the rate at which the sensory neuron fires action potentials.
c. Higher stimulus intensity will cause the sensory neuron to fire larger (higher amplitude) action potentials.
d. Higher stimulus intensity will cause the sensory neuron to fire smaller (lower amplitude) action potentials.
e. Lower stimulus intensity will cause the sensory neuron to fire narrower (shorter duration) action potentials.
Higher stimulus intensity will increase the rate at which the sensory neuron fires action potentials.
An unmyelinated axon has voltage-gated ion gates along its entire ___________.
length
An action potential at the ___________ zone causes sodium to diffuse into the cell.
This results in membrane ___________.
trigger; depolarization
The depolarization causes a __________ that excites the entire membrane.
repetition
This continues until the traveling signal reaches the end of the __________.
axon
What would be the best explanation for why myelinated axons conduct signals faster than unmyelinated axons?
a. There are no sodium channels in unmyelinated axons.
b. Myelinated axons contain more sodium ions.
c. Myelinated axons have more sodium-potassium pumps in their membranes.
d. Active transport of sodium and potassium is faster in myelinated axons.
e. Electrical signals spread faster through insulated (myelinated) regions of axon.
Electrical signals spread faster through insulated (myelinated) regions of axon.
