March 4, 2015 --> Cards 31-45 Flashcards Preview

BOARD: Biochemistry (Dental Decks) > March 4, 2015 --> Cards 31-45 > Flashcards

Flashcards in March 4, 2015 --> Cards 31-45 Deck (90):
1

Define the Cephalic phase of gastric secretion

-- AKA "the wake up call"
Sensations of thoughts about food are relayed to the brainstem where parasympathetic signals to the gastric mucosa are initiated.
- This directly stimulates gastric juice secretion and stimulates the release of gastrin, which prolongs and enhances the effect.

2

What is the Gastric phase of gastric secretion

--AKA "full steam ahead"
Presence of food, specifically the distension food triggers local and parasympathetic nervous reflexes that increase the secretion of gastric juice and gastrin (which further amplifies gastric juice secretion).
- Products of protein digestion can also trigger the gastrin mechanism

3

What is the Intestinal phase of gastric secretion

-- AKA "step on the brakes"
As food moves into the duodenum, the presence of fats, carbohydrates and acid stimulates hormonal and nervous reflexes that inhibit stomach activity.

4

In muscle contraction, as intracellular Ca2+ is increased, Ca2+ begins to bind to what?

Troponic C on the thin filaments, causing a conformation change in troponin that permits the interaction between actin and myosin

5

In muscle contraction, after calcium binds with troponin, what occurs?

Tropomyosin moves from its blocking position, permitting actin and myosin to interact.

6

Thick filaments are composed mainly of what protein? Thin filaments?

Thick: Myosin
Thin: Actin

7

What are the three sources of ATP to keep the ATP pool filled in muscle contraction

Creatine phosphate
Glycogen
Cellular respiration in mitochondria

8

Creatine phosphate + ADP ?

Creatine + ATP

9

T or F, Each muscle fiber is innervated by a single alpha-motor neuron. Each alpha-motor neuron innervates many muscles

False, Each alpha-motor neuron innervates many muscle fibers

10

What part of the muscle contracts when the motor neuron fires an action potential?

All of the fibers innervated by that motor neuron

11

In relation to muscles, what is the Size principle:

Motor units are recruited in order of the size of the motor unit. If only a small amount of tension is required to perform the movement, then only small motor units will be activated. If greater force is required, more and larger motor units will be recruited.

12

When a patient bites down rapidly on an unexpected hard surface while chewing, the cessation of motor unit recruitment in the jaw closing muscles is caused by what?

Periodontal mechanoreceptors

13

Define Fractionation?

Means that it is not necessary to activate all of the motor units in a muscle

14

What is the junction between the terminal of a motor neuron and a muscle fiber?

It is a neuromuscular junction

15

When an action potential arrives at a neuromuscular junction, what happens?

1. Calcium ions enter the nerve terminal, causing the release of acetylcholine from synaptic vesicles within the motor neuron.
2. Acetylcholine then binds to the nicotinic cholinergic receptors in the muscle fiber plasma membrane.
3. Depolarization occurs which triggers an action potential.
4. This action potential triggers the release of calcium ions from the sarcoplasmic reticulum.
5. This leads to crossbridge formation between actin and myosin.

16

Fast-twitch fibers are for what? Slow-twitch?

Fast: Rapid, powerful actions
Slow: Prolonged activity

17

Compare Myoglobin content vs Glycogen content in Fast and Slow twitch muscles

Fast:
- High Glycogen content
- Low Myoglobin content

Slow:
- Low Glycogen content
- High Myoglobin content

18

Compare Mitochondria and Capillaries in Fast and Slow twitch muscles

Fast:
- Few mitochondria
- Few capillaries

Slow:
- Many mitochondria
- Many capillaries

**Oxidative capacity is related to 1) # of capillaries, 2) myoglobin content, 3) # of mitochondria

19

Compare Oxidative capacity and Enzymes for anaerobic glycolysis for Fast and Slow twitch muscles:

Fast:
- Low oxidative capacity
- High amount of enzymes for anaerobic glycolysis

Slow:
- High oxidative capacity
- Low amount of enzymes for anaerobic glycolysis

20

Which of the muscle fibers are characterized by having High Myosin-ATPase activity, Fast/High Speed/Intensity of contraction and a low resistance to fatigue?

Fast twitch muscle fibers

21

Oxidative capacity is related to what 3 things?

1. # of capillaries
2. Myoglobin content
3. # of mitochondria

***If the muscle fiber has high numbers of these, it is most likely a slow twitch fiber

22

Muscle tone is "fine-tuned" by what 2 sensory organs:

1. Muscle spindle (measures muscle length)
2. Golgi tendon organ (measures muscle tension)

23

What sensory organs activate and inhibit the alpha motor neuron?

Muscle spindle activates
Golgi tendon organ inhibits

24

Name the 3 components of the Muscle spindle

1. Specialized muscle fibers (Intrafusal fibers)
2. Sensory terminals (group Ia and II afferents)
3. Motor terminals (gamma motor (efferent) neurons)

25

Golgi tendon organ is innervated by what?

By a single-group Ib sensory (afferent) fiber

26

T or F, The muscle spindle is a small, highly differentiated part of muscle tissue located within the bell of muscles and runs perpendicular with the main muscle fibers

False, parallel

27

Describe location of annulospiral endings

They are wrapped around specialized muscle fibers that belong to the muscle spindle (intrafusal fibers) and are quite separate from the fibers that make up the bulk of the muscle (extrafusal fibers)

28

Motor neurons can be further classified as what?

Alpha or gamma motor neurons

29

Describe what Alpha motor neurons and gamma motor neurons individually innervate or how their roles are different

Alpha --> innervate and stimulate skeletal muscle
Gamma --> innervate the muscle spindle

30

T or F, the muscle spindle depolarizes in response to stretching

True

31

What is the process that triggers contraction of the muscle

1. Muscle is stretch, so is the muscle spindle
2. Muscle spindle depolarizes and sends action potentials to the spinal cord where it synapses with a motor neuron
3. This triggers the stretch reflex, causing the muscle to contract

32

Basic function of muscle spindle

To convey information to the CNS concerning muscle length and tension

33

The sensory receptors serving the stretch reflex are classified as what?

Proprioceptors

34

Stretch reflex:
- # of synapses
- Stimulus
- Afferent fibers
- Response

- Monosynaptic
- Muscle is stretched
- Ia
- Contraction of the muscle

35

Golgi tendon reflex:
- # of synapses
- Stimulus
- Afferent fibers
- Response

- Disynaptic
- Muscle contracts
- Ib
- Relaxation of the muscle

36

Flexor-withdrawal reflex (after touching hot stove):
- # of synapses
- Stimulus
- Afferent fibers
- Response

- Polysnaptic
- Pain
- II, III, & IV
- Ipsilateral flexion, contralateral extension

37

T or F, Golgi tendon organs depolarize in response to muscle stretch but inhibit the motor neuron, causing the muscle to relax

True

38

What is the reflex arc?

A simple neural pathway connecting receptors to an effector.

39

Most reflex have what six basic elements?

1. Receptor
2. Sensory (afferent) neuron
3. Integration center (CNS)
4. Interneuron
5. Motor (efferent) neuron
6. Effector

40

What two important spinal reflexes influence the contraction of skeletal muscles?

1. Stretch reflex
2. Tendon reflex

41

Describe the tendon reflex

It is initated at receptors called neurotendinous organs (golgi tendon organs) that are sensitive to tension that occurs as a result of muscular contraction. This reflex stimulates the contracted muscle to relax

42

What is Reciprocal Inhibition

When the stretch reflex stimulates the stretched muscle to contract, antagonistic muscles that oppose the contraction are inhibited.

43

What is reciprocal innervation

The neuronal mechanism that causes reciprocal inhibition

44

Describe 3 main points about Extrafusal muscle fibers

1. Fibers that make up the bulk of the muscle
2. Innervated by alpha-motor neurons (efferent)
3. Provide the force for muscle contraction

45

Describe 2 main points about Intrafusal muscle fibers

1. Are encapsulated in sheaths to form muscle spindles
2. Innervated by gamma-motor neurons (efferent)

46

What are the two types of intrafusal fibers

1. Nuclear bag fibers
2. Nuclear chain fibers

47

Describe both Nuclear bag fibers and Nuclear chain fibers and how they differ

Nuclear bag fibers:
- Detect fast, dynamic changes in muscle length and tension
- Innervated by group Ia afferents - fastest in body

Nuclear chain fibers
- Detect static changes in muscle length and tension
- Innervated by slower group of II afferents as well as the group Ia afferents

48

A sensory (afferent) neron transmits afferent nerve impulses from where to what location?

From the receptor to the spinal cord

Receptor: peripheral ending of a sensory neuron

49

A motor (efferent) neuron transmits efferent nerve impulses from where to what location?

From integrating center (in spinal cord) to an effector (muscle cell)

50

Cell bodies in the anterior (ventral) horn transmit what impulses? What about the posterior (dorsal) horn?

Ventral --> motor impulses
Dorsal --> Sensory impulses

51

Axons of cells that run on the same side as their cell bodies of origin are referred to as what?

Ipsilateral

52

Axons of cells that run on the opposite side of their cell bodies of origin are referred to as what?

Contralateral

53

T or F, Sensory pathways are descending systems and motor pathways are ascending systems

False,
Sensory --> Ascending
Motor --> Descending

54

The white matter refers to those parts of the brain and spinal cord that are responsible for what?

Communication between the various gray matter regions and between the gray matter and rest of body.

55

Gray matter is where what is done? White matter is where what easily described as what?

Gray matter is where processing is done
White matter is the channels of communication

56

If an analogy were used to describe gray and white matter, what would be the CPU in a computer and what would be the printed circuit board that connects it to the other parts of the computer?

Gray matter --> CPU
White matter --> connects other parts of computer together

57

Which of the two types of matter (gray, white) is characterized by having bundles of axons each coated with a sheath of myelin?

White matter

58

Gray matter is characterized by what?

Masses of cell bodies and dendrites, each covered with synapses

59

In the spinal cord, the white matter is found where? Gray matter is found where? What about the brain?

Spinal cord:
- White matter is at surface
- Gray matter is inside

Brain:
- Gray matter is at surface
- White matter is inside

60

Basal ganglia location

- Located deep to the cerebral cortex

61

What is the function of the basal ganglia?

Control complex patterns of motor activity

62

T or F, Damage to the basal ganglia nuclei causes weakness and can cause dramatic motor abnormalities

False, Does not cause weakness but does cause dramatic motor abnormalities

63

What two diseases are associated with damage to the nuclei of the basal ganglia?

Parkinson's disease
Huntington's disease

64

What is the thalamus

A large ovoid collection of nuclei (grey matter) that relays all sensory stimuli as they ascend to the cerebral cortex

65

General function of thalamus

Sensory and motor relay to the cerebral cortex regulation of cortical activation and visual input

66

T or F, The hypothalamus is a distribution center that controls activity in specific regions of the cerebral cortex

False, the thalamus

67

Functions of Hypothalamus

Controls many homeostatic processes, which are often associated with autonomic nervous system.
- regulating body temperature
- Water balance
- GI activity
- Sleep
- Fear and rage
****Also regulates the release of the hormones of the pituitary gland

68

T or F, The hypothalamus is involved in many homeostatic processes as well as endocrine activity by regulating the release of the hormones of the pituitary gland.

True

69

Stimulation of the posterior hypothalamus by a reduction in core temperature will produce what?

Shivering!

70

Functions of Hippocampus

Consolidation of memories and in learning

71

The human forebrain is made up of what?

1. A pair of cerebral hemispheres called the telencephalon
2. A group of structures located deep within the cerebrum that make up the diencephalon (central core of brain)

72

Main structures of the hindbrain (rhombencephalon)

1. Cerebellum
2. Pons
3. Medulla oblongata

73

Describe the location of the Cerebellum and its functions

Location: Large brain mass lying posterior to the pons and medulla and inferior to the posterior part of the cerebrum.
Functions: Motor coordination, motor learning and equilibrium

74

Describe the location of the pons and its functions

Location: Connects cerebellum with the cerebrum and links the midbrain to the medulla oblongata
Functions: Respiratory/urinary control, control of eye movement and facial sensation/motor control

75

What CN nerve is associated with the PONS

CN V

76

Functions of Medulla oblongata

Cardiovascular and respiratory control, auditory and vestibular input and brainstem reflexes

77

What CN are associated with Medulla

CN IX, X and XII

78

What CN are associated with the junction of pons and medulla

CN VI, VII and VIII

79

Brainstem consists of what 3 things?

Midbrain
Pons
Medulla oblongata

80

What is the limbic system?

A primitive brain area deep within the temporal lobe.
Functions: Initiates basic drives (hunger, aggression, sexual arousal and emotional feelings). Also screens all sensory messages traveling to the cerebral cortex

81

Which part of the brain initates basic drives like hunger, aggression, emotional feelings and sexual arousal

The limbic system

82

Describe the frontal lobe

Contains the primary motor (movement) area and influences personality, judgment, abstract reasoning social behavior and language expression

83

Describe the temporal lobe

Controls hearing, language comprehension, storage and recall of memories

84

Describe the parietal lobe

Interprets and integrates sensations of: pain, temperature and touch -- particularly in regards to size, shape, distance and texture; important for awareness of body shape

85

Describe the occipital lobe

Functions mainly to interpret visual stimuli

86

What is the corpus callosum

A mass of nerve fibers connecting the hemispheres of the cerebrum

87

Which blood vessels is surrounded by the thickest layer of muscle?

Arteries

88

Which veins are the only veins that contain oxygenated blood?

Pulmonary and umbilical veins

89

T or F, The amount of blood that flows through the capillaries per minute is not equal to the amount of blood that flows through the aorta per minute

False, equal

90

Which blood vessels regulate the flow of blood into capillaries?

Arterioles