Chapter 11 Flashcards
The neurotransmitter released by postganglionic PARASYMPATHETIC neurons is usually what? The receptors that bind the neurotransmitter at the synapse are of a specific type referred to as what kind of receptors?
Neurotransmitter released - ACh
Receptors - muscarinic
The neurotransmitter released by postganglionic SYMPATHETIC neurons is usually what? The receptors that bind the neurotransmitter at the synapse are of a specific type referred to as what kind of receptors?
Neurotransmitter released - norepinephrine
Receptors - adrenergic
List the important effectors that receive sympathetic innervation but NOT parasympathetic.
- Most blood vessels
- myocardium
- adrenal medulla
- sweat glands
- kidney
There are numerous differences between the ANS and Somatic nervous Systems. Describe as many as you can.
- Somatic controls skeletal muscles; ANS controls cardiac muscle, smooth muscle, and glands.
- Somatic is voluntary; ANS is involuntary
- All somatic motor neurons release ACh; ANS - All sympathetic and parasympathetic preganglionic neurons release ACh and most sympathetic postganglionic neurons release norepinephrine while most parasympathetic postganglionic neurons release ACh
- Somatic - one neuron pathway; ANS - usually a two neuron pathway
Many organs are innervated by both divisions of the ANS, but there are a number of exceptions. List each exception, state which division does the innervation, and describe the general effect that division of the ANS has on the target organ. (excitation/inhibition or - and +)
The sympathetic division only innervates:
- Most blood vessels - causes vasoconstriction
- myocardium - increases the force of contraction
- Adrenal medulla - release of epi/norepi
- Sweat glands - excitatory-sweat
- Kidney - release renin
The term that describes the opposite effects that the sympathetic and parasympathetic have on the SA node is what?
Antagonistic
List the parts of the brain that serve as the major ANS control centers.
Medulla and Pons
Define the term “reflex”
Involuntary response to a stimulus
The ANS generally exhibits “divergence.” Explain what this means. Which division diverges more?
Divergence is when the axon of a presynaptic neuron branches, and its collaterals (branches) synapse on multiple target neurons.
The sympathetic division diverges more.
The ANS neuron whose axon exits the CNS is called the what?
Preganglionic
The ANS neuron that innervates the target is called the what?
postganglionic
The cranial nerve which carries nearly all parasympathetic axons is the what? It exits the CNS from the where?
Vagus X
Exits from the Medulla Oblongata through the jugular foramen
The adrenal medulla secretes what?
epinephrine and norepinephrine
Describe the effects of the sympathetic nervous system on the liver. Explain how this effect is critical during a sympathetic response.
The liver is stimulated to release glucose into the bloodstream providing more energy that will be ready to power the muscles in case it is needed.
Describe the effects of the sympathetic nervous system on adipocytes. Explain how this effect is critical during a sympathetic response.
Breaks down adipose tissue to be used as energy
Describe the function of the muscle spindle apparatus.
Sends info about muscle stretch/length to the CNS and involved in reflexes.
Explain the importance of muscle spindle reflexes. Describe a specific scenario or describe an example where this type of reflex is important.
Muscle spindles stimulate reflexively a muscle contraction to prevent overstretching and muscle fiber damage; also important in maintaining normal muscle tone.
ex. A person standing upright begins to lean to one side. The postural muscles that are closely connected to the vertebral column on the side will stretch. Because of this, stretch receptors in those muscles contract to correct posture.
What does EMG stand for? What does an EMG measure?
EMG - Electromyography
Measures the electrical activity associated with depolarization and contraction of skeletal muscle motor units.
List the seven components of a muscle spindle reflex arc. Describe the role of each.
- Stimulus - stretch
- Sensor - muscle spindles detect stretch/length change
- Sensory neuron - carries sensory info to CNS
- Integrating center - processes info and determines course of action
- Motor neuron - delivers action potentials to effector
- Target effector - carries out action
- Response
For specific muscle spindle reflexes (knee, biceps, and triceps jerk) know the peripheral nerve and muscle involved.
knee - quadriceps muscle, Nerve???
biceps - biceps brachii, musculocutaneous nerve
triceps - triceps brachii, radial nerve
What are the “sticky conductive pads” placed on the skin called during an EMG?
electrodes
Define fatigue as it applies to muscle physiology.
inability of a muscle to generate max force.
Explain what an isometric contraction is.
a contraction that generates force without changing the length of the muscle.
Explain what an isotonic contraction is.
a contraction that generates force by changing the length of the muscle
