Chapter 15: Chemical Control of the Brain and Behavior Flashcards
(32 cards)
The Hypothalamus regulates body temperatures and blood compositions within a narrow range in response to a changing environment. What is this regulatory process called?
Homeostasis.
The Hypothalamus controls the two lobes of the pituitary (Hypophyse). What are the two lobes of the pituitary called?
There is a posterior and an anterior pituitary.
What are the substances called that are released into the blood by neurons?
Neurohormones
Which are the largest of the hypothalamic neurosecretory cells?
Magnocellular neurosecretory cells.
Into which Lobe of the pituitary do magnocellular neurosecretory cells extend axons into?
Magnocellular neurosecretory cells extend axons into the posterior lobe of the pituitary.
Which neurohormones do magnocellular neurosecretory cells release into the bloodstream?
Oxytocin and Vasopressin.
What does Vasopressing also called Antidiuretic Hormone ADH regulate?
Blood Volume and Salt concentration.
Which enzyme does the liver release under conditions of lowered blood pressure? What does the enyme do?
Renin. Renin breaks a protein released by the liver angiotensin into Angiotensin I which then breaks down further into Angiotensin II which then helps to increase blood pressure.
By which part of the Telencephalon that lacks the blood-brain barrier is Angiotensin II detected?
By the subfornical organ which projects axons into the Hypothalamus.
The Axons of the subfornical organ project into the Hypothalamus. Among other things, which Cells do they activate?
Vasopressin containing neurosecretory cells. In Addition the subfornical Organ activates cells in the lateral area of the Hypothalamus, somehow producing a strong thirst that motivats drinking behavior.
By which hypothalamic neurons is the anterior lobe controlled?
Parvocellular neurosecretory cells (perventricular area)
How do the parvocellular neurosecretory cells communicate with their targets in the anterior lobe of the pituitary?
They communicate with their targets via the bloodstream. The Neurons (parvocellular neurosecretory cells) release hypophysiotropic hormones into the hypothalamo-pituitary portal circulation. The hypophysiotropic hormones bind to receptors on the surface of pituitary cells causing these cell to either secrete or stop secreting hormones into the general bloodstream.
Which steroid hormone does the adrenal cortex produce?
Cortisol
Out of which two parts does the adrenal glands consist?
A shell called adrenal cortex and a center called adrenal medulla.
The adrenal cortex produces a steroid hormone called cortisol. What happens when it is released to the bloodstream?
Cortisol acts throughout the body to mobilize energy reserves and suppress the immune system, preparing us to carry on in the face of life’s various stresses.
Stimuli for the release of cortisol could be:
physiological stress like the loss of blood
positive emotional stimulation such as falling in love
psychological stress such as anxiety over an upcoming exam.
Which cells that cotrol the adrenal cortex determine wether a stimulus is stressful or not as defined by the release of cortisol?
Parvocellular neurosecretory cells.
Imaginge there is a stressfull stimulus like a big dog coming toward you barking. What happens starting at the parvocellular neurosecretory cells?
Parvocellular neurosecretory cells (Area: Periventricular Hypothalamus) release a peptide called corticotropin-releasing hormone CRH into the blood of the pituitary portal circulation. It travels down to the anterior pituitary where within 15 Seconds it stimulates the release of corticotropin or adrenocorticotropic hormone ACTH. ACTH enters the general circulation and travels to the adrenal cortex where, within gia few minutes ist stimulates cortisol release.
How come the cortisol production is to some extend self-regulatet?
Cortisol is lipophilic and is able to pass the blood-brain barrier. In the brain cortisol bind to specific receptors that lead to the inhibition of CRH corticotropin-releasing hormone.
Which part of the ANS is more responsible for fight or flight situations and which is more responsible for relaxed situations?
The Sympathetic division is more responsible for fight or flight.
The Parasympathetic ist more responsible for relaxed situation.
Which single function does the Somatic Motor System have?
It innervates and commands skeletal muscle fibers.
Which two systems constitute together the total output of the CNS?
ANS together with the somatic motor system.
The somatic motor system innervates and commands skeletal muscle fibers. Which other innervated parts (tissue or organs) does the ANS have to command?
Every other
Where are the cell bodies of the somatic lower motor neursons located? Where are the cell bodies of the autonomic lower motor neurons located?
Cell bodies of the somatic lower motor neurons lie within the CNS (Ventral horn of Spinal Cord of the brain stem).
Cell bodies of the autonomic lower motor neurons lie outside the CNS within cell clusters called Autonomic Ganglia.
What are neurons in the autonomic ganglia called? By which neurons are these neurons driven?
Postganglionic neurons.
Postganglionic neurons are driven by preganglionic neurons.
