Yuste C15: Emotions Flashcards
What are emotions
physiological responses of the body to a particular stressor — either positive or negative
What are feelings
feelings are the conscious cognitive flavor that accompanies emotions.
Emotions vs feelings
emotions are unconscious, and are generated sub-cortically, whereas feelings are conscious, and involve the cortex. However, physiological responses are often the same for different emotions and different feelings. All mixed up.
Are the autonomic and enteric systems technically still part of the motor system?
yes, as they can generate motricity and behavior. But they are also fundamentally involved in internal states; an independent part of the nervous system; probably evolutionary remnants of an ancient nervous system; resemble the nervous system of cnidarians in their ganglionic structure and also in their heavy use of neuromodulators and peptides.
Why do we say the autonomic nervous system is motor?
neurons from the brain stem or the spinal cord (“preganglionic” neurons) activate autonomic neurons in ganglia that are located throughout the body, and these “postganglionic” neurons activate effector cells in the body, such as smooth muscle cells, cardiac muscle cells, or gland cells, for example; these postganglionic neurons resemble “motor” neurons, except that they are located outside the spinal cord and don’t control skeletal muscle, but other types of muscle.
The autonomic nervous system relays brain commands to activate non-skeletal muscle cells and glands through an intermediate set of neurons located in ganglia throughout the body.
it activates or inactivates a body response; it also generates reflexes
How is the autonomic system divided?
the sympathetic and the parasympathetic systems
Autonomic nervous system specialised for what
To generate and orchestrate “fight or flight” (or “fight or fright”) responses: those are critical, life-threatening moments in the life of an animal where it needs to either fight an adversary or escape a predator.
The sympathetic system does “fight” and the parasympathetic “flight”.
How do you make sure you are efficient in the fight or fright/flight responses
engage different parts of the body. For example, if you are fighting you need to increase heart rate and blood pressure, to better oxygenate the muscles, stop digestion and circulation to non essential organs, inhibit salivation, widen your pupils to gather more light, widen your bronchia to get more oxygen, stimulate your liver to deliver more glucose, erect your hairs in your skin and increase sweating to dissipate more heat, etc.
if you want to escape, or, if you want to escape and go unnoticed by a predator (”fright response”), or if you want to recover after a fight and relax, you need to do pretty much the opposite with respect to all these body organs, and also stimulate digestion, to generate energy to replenish the lost reserves.
Autonomic system general
Mostly antagonistic. With the sympathetic branch involved in arousal, defence, and escape behaviors, and the parasympathetic in eating and procreation.
Sympathetic ganglia
located in rows parallel to the spinal cord, and innervate essentially every organ in the body, or the blood vessels that irrigate them.
Parasympathetic ganglia
are right next to the organs that they innervate, and they avoid the skin and skeletal muscle.
Sympathetic vs parasympathetic innervation
each organ or part of the body receives dual sympathetic and parasympathetic innervation. Their opposite functions are due to the different neurotransmitters they release: sympathetic axons mostly release norepinephrine (noradrenaline), whereas parasympathetic axons mostly release acetylcholine. And these transmitters, acting through adrenergic or muscarinic receptors, together with peptides like vasointestinal peptide (VIP), have opposite physiological effects
The autonomic system also generates reflexes
the baroreceptor reflex, which critically controls our blood pressure, raising it or lowering it as our posture changes and controlling the redistribution of blood.
Autonomic system reflexes vs spinal cord reflexes
whereas the spinal cord innervates skeletal muscle, the autonomic innervates smooth and cardiac muscle.
Baroreceptor reflex
Needed because of impact of postural changes etc on blood pressure. When you sit down or lie down, and blood pressure increases above a certain level, the baroreceptors send action potentials to the nucleus of the solitary tract in the brain stem, which activates a series of circuits which engages the parasympathetic system and disengages the sympathetic system, causing dilation of blood vessels, decreased cardiac output, and decreased blood pressure. When you stand up, your blood pressure drops, the baroreceptors stop firing and stop activating the brainstem, removing the inhibition on the sympathetic system, and that speeds up the heart and contracts the arteries to increase your blood pressure.
Baroreceptors
located in the carotid sinus (in the cranial artery)
and in the aortic arteries to monitor blood pressure,
and have stretch receptors that are activated by high
blood pressure, or inactivated if the blood pressure
falls below a particular level
Baroreceptor reflex and control theory
a set point of ideal blood pressure, a sensor that measures blood pressure and a negative feedback loop (high blood pressure decreases it, whereas low blood pressure increases it), and a “gain” that controls how strong this feedback loop is.
Enteric nervous sustem covers what
The digestive system; essentially disconnected from the rest of the nervous system; also known as the “visceral” nervous system.
How is the enteric nervous system built
built as a system of two parallel nerve nets, or plexuses, in the intestinal wall, one next to the intestinal mucosa and another one next to the muscle layer; like in cnidarians, the neurons are spread out, without forming ganglia, and are loaded with peptides.
What do the neurons of the enteric nervous system do
They control secretion from the mucosa, vasodilation or vasoconstriction of the blood supply, and also activate or inhibit the smooth muscle in the intestinal wall. ==> generate reflexes.
