Flashcards in March 4, 2015 --> Cards 31-45 Deck (90):
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.
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
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.
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
In muscle contraction, after calcium binds with troponin, what occurs?
Tropomyosin moves from its blocking position, permitting actin and myosin to interact.
Thick filaments are composed mainly of what protein? Thin filaments?
What are the three sources of ATP to keep the ATP pool filled in muscle contraction
Cellular respiration in mitochondria
Creatine phosphate + ADP ?
Creatine + ATP
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
What part of the muscle contracts when the motor neuron fires an action potential?
All of the fibers innervated by that motor neuron
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.
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?
Means that it is not necessary to activate all of the motor units in a muscle
What is the junction between the terminal of a motor neuron and a muscle fiber?
It is a neuromuscular junction
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.
Fast-twitch fibers are for what? Slow-twitch?
Fast: Rapid, powerful actions
Slow: Prolonged activity
Compare Myoglobin content vs Glycogen content in Fast and Slow twitch muscles
- High Glycogen content
- Low Myoglobin content
- Low Glycogen content
- High Myoglobin content
Compare Mitochondria and Capillaries in Fast and Slow twitch muscles
- Few mitochondria
- Few capillaries
- Many mitochondria
- Many capillaries
**Oxidative capacity is related to 1) # of capillaries, 2) myoglobin content, 3) # of mitochondria
Compare Oxidative capacity and Enzymes for anaerobic glycolysis for Fast and Slow twitch muscles:
- Low oxidative capacity
- High amount of enzymes for anaerobic glycolysis
- High oxidative capacity
- Low amount of enzymes for anaerobic glycolysis
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
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
Muscle tone is "fine-tuned" by what 2 sensory organs:
1. Muscle spindle (measures muscle length)
2. Golgi tendon organ (measures muscle tension)
What sensory organs activate and inhibit the alpha motor neuron?
Muscle spindle activates
Golgi tendon organ inhibits
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)
Golgi tendon organ is innervated by what?
By a single-group Ib sensory (afferent) fiber
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
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)
Motor neurons can be further classified as what?
Alpha or gamma motor neurons
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
T or F, the muscle spindle depolarizes in response to stretching
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
Basic function of muscle spindle
To convey information to the CNS concerning muscle length and tension
The sensory receptors serving the stretch reflex are classified as what?
- # of synapses
- Afferent fibers
- Muscle is stretched
- Contraction of the muscle
Golgi tendon reflex:
- # of synapses
- Afferent fibers
- Muscle contracts
- Relaxation of the muscle
Flexor-withdrawal reflex (after touching hot stove):
- # of synapses
- Afferent fibers
- II, III, & IV
- Ipsilateral flexion, contralateral extension
T or F, Golgi tendon organs depolarize in response to muscle stretch but inhibit the motor neuron, causing the muscle to relax
What is the reflex arc?
A simple neural pathway connecting receptors to an effector.
Most reflex have what six basic elements?
2. Sensory (afferent) neuron
3. Integration center (CNS)
5. Motor (efferent) neuron
What two important spinal reflexes influence the contraction of skeletal muscles?
1. Stretch reflex
2. Tendon reflex
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
What is Reciprocal Inhibition
When the stretch reflex stimulates the stretched muscle to contract, antagonistic muscles that oppose the contraction are inhibited.
What is reciprocal innervation
The neuronal mechanism that causes reciprocal inhibition
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
Describe 2 main points about Intrafusal muscle fibers
1. Are encapsulated in sheaths to form muscle spindles
2. Innervated by gamma-motor neurons (efferent)
What are the two types of intrafusal fibers
1. Nuclear bag fibers
2. Nuclear chain fibers
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
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
A motor (efferent) neuron transmits efferent nerve impulses from where to what location?
From integrating center (in spinal cord) to an effector (muscle cell)
Cell bodies in the anterior (ventral) horn transmit what impulses? What about the posterior (dorsal) horn?
Ventral --> motor impulses
Dorsal --> Sensory impulses
Axons of cells that run on the same side as their cell bodies of origin are referred to as what?
Axons of cells that run on the opposite side of their cell bodies of origin are referred to as what?
T or F, Sensory pathways are descending systems and motor pathways are ascending systems
Sensory --> Ascending
Motor --> Descending
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.
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
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
Which of the two types of matter (gray, white) is characterized by having bundles of axons each coated with a sheath of myelin?
Gray matter is characterized by what?
Masses of cell bodies and dendrites, each covered with synapses
In the spinal cord, the white matter is found where? Gray matter is found where? What about the brain?
- White matter is at surface
- Gray matter is inside
- Gray matter is at surface
- White matter is inside
Basal ganglia location
- Located deep to the cerebral cortex
What is the function of the basal ganglia?
Control complex patterns of motor activity
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
What two diseases are associated with damage to the nuclei of the basal ganglia?
What is the thalamus
A large ovoid collection of nuclei (grey matter) that relays all sensory stimuli as they ascend to the cerebral cortex
General function of thalamus
Sensory and motor relay to the cerebral cortex regulation of cortical activation and visual input
T or F, The hypothalamus is a distribution center that controls activity in specific regions of the cerebral cortex
False, the thalamus
Functions of Hypothalamus
Controls many homeostatic processes, which are often associated with autonomic nervous system.
- regulating body temperature
- Water balance
- GI activity
- Fear and rage
****Also regulates the release of the hormones of the pituitary gland
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.
Stimulation of the posterior hypothalamus by a reduction in core temperature will produce what?
Functions of Hippocampus
Consolidation of memories and in learning
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)
Main structures of the hindbrain (rhombencephalon)
3. Medulla oblongata
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
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
What CN nerve is associated with the PONS
Functions of Medulla oblongata
Cardiovascular and respiratory control, auditory and vestibular input and brainstem reflexes
What CN are associated with Medulla
CN IX, X and XII
What CN are associated with the junction of pons and medulla
CN VI, VII and VIII
Brainstem consists of what 3 things?
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
Which part of the brain initates basic drives like hunger, aggression, emotional feelings and sexual arousal
The limbic system
Describe the frontal lobe
Contains the primary motor (movement) area and influences personality, judgment, abstract reasoning social behavior and language expression
Describe the temporal lobe
Controls hearing, language comprehension, storage and recall of memories
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
Describe the occipital lobe
Functions mainly to interpret visual stimuli
What is the corpus callosum
A mass of nerve fibers connecting the hemispheres of the cerebrum
Which blood vessels is surrounded by the thickest layer of muscle?
Which veins are the only veins that contain oxygenated blood?
Pulmonary and umbilical veins
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