Chapter 15: Chemical Control of the Brain and Behavior

Question 1

The Hypothalamus regulates body temperatures and blood compositions within a narrow range in response to a changing environment. What is this regulatory process called?

Answer 1

Homeostasis.

Question 2

The Hypothalamus controls the two lobes of the pituitary (Hypophyse). What are the two lobes of the pituitary called?

Answer 2

There is a posterior and an anterior pituitary.

Question 3

What are the substances called that are released into the blood by neurons?

Answer 3

Neurohormones

Question 4

Which are the largest of the hypothalamic neurosecretory cells?

Answer 4

Magnocellular neurosecretory cells.

Question 5

Into which Lobe of the pituitary do magnocellular neurosecretory cells extend axons into?

Answer 5

Magnocellular neurosecretory cells extend axons into the posterior lobe of the pituitary.

Question 6

Which neurohormones do magnocellular neurosecretory cells release into the bloodstream?

Answer 6

Oxytocin and Vasopressin.

Question 7

What does Vasopressing also called Antidiuretic Hormone ADH regulate?

Answer 7

Blood Volume and Salt concentration.

Question 8

Which enzyme does the liver release under conditions of lowered blood pressure? What does the enyme do?

Answer 8

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.

Question 9

By which part of the Telencephalon that lacks the blood-brain barrier is Angiotensin II detected?

Answer 9

By the subfornical organ which projects axons into the Hypothalamus.

Question 10

The Axons of the subfornical organ project into the Hypothalamus. Among other things, which Cells do they activate?

Answer 10

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.

Question 11

By which hypothalamic neurons is the anterior lobe controlled?

Answer 11

Parvocellular neurosecretory cells (perventricular area)

Question 12

How do the parvocellular neurosecretory cells communicate with their targets in the anterior lobe of the pituitary?

Answer 12

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.

Question 13

Which steroid hormone does the adrenal cortex produce?

Answer 13

Cortisol

Question 14

Out of which two parts does the adrenal glands consist?

Answer 14

A shell called adrenal cortex and a center called adrenal medulla.

Question 15

The adrenal cortex produces a steroid hormone called cortisol. What happens when it is released to the bloodstream?

Answer 15

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.

Question 16

Which cells that cotrol the adrenal cortex determine wether a stimulus is stressful or not as defined by the release of cortisol?

Answer 16

Parvocellular neurosecretory cells.

Question 17

Imaginge there is a stressfull stimulus like a big dog coming toward you barking. What happens starting at the parvocellular neurosecretory cells?

Answer 17

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.

Question 18

How come the cortisol production is to some extend self-regulatet?

Answer 18

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.

Question 19

Which part of the ANS is more responsible for fight or flight situations and which is more responsible for relaxed situations?

Answer 19

The Sympathetic division is more responsible for fight or flight.
The Parasympathetic ist more responsible for relaxed situation.

Question 20

Which single function does the Somatic Motor System have?

Answer 20

It innervates and commands skeletal muscle fibers.

Question 21

Which two systems constitute together the total output of the CNS?

Answer 21

ANS together with the somatic motor system.

Question 22

The somatic motor system innervates and commands skeletal muscle fibers. Which other innervated parts (tissue or organs) does the ANS have to command?

Answer 22

Every other

Question 23

Where are the cell bodies of the somatic lower motor neursons located? Where are the cell bodies of the autonomic lower motor neurons located?

Answer 23

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.

Question 24

What are neurons in the autonomic ganglia called? By which neurons are these neurons driven?

Answer 24

Postganglionic neurons.

Postganglionic neurons are driven by preganglionic neurons.

Question 25

Where do the cell bodies of preganglionic neurons lie?

Answer 25

Spinal cord and brain stem.

Question 26

Which different pathways do the somatic motor system and the ANS use to control their peripheral targets?

Answer 26

Somatic motor system: monosynaptic pathway

ANS: Disynaptic pathway

Question 27

The ANS innervates/regulates…:

Answer 27

secretory glands (salivary, sweat, tear..)
heart and blood vessels to control blood pressure and flow
bronchi of th the lungs to meet the oxygen demands of the body
regulates the digestive and metabolic functions of the liver, gastrointestinal tract and pancreas
regulates the function of the kidney, urinary bladder, large intestine and rectum
essential to sexual responses of the genitals and reproductive organs
interacts with the body’s immune system

Question 28

Behaviors related to the sympathetic division are summerized in he four FS which are…? The Parasympatheic related behaviors are more…?
What does it mean that the two division are reciprocal?

Answer 28

fight, flight, fright, sex

Parasympathetic: digestion, growth, immune response, energy storage.

When one is high the other one ist low.

Question 29

Name six Hormones of the Anterior Pituitary with their target and action.

Answer 29

Follicle-stimulating hormone FSH
Target: Gonads
Action: Ovulation, spermatogenesis

Luteinizing Hormone LH
Target: Gonads
Action: Ovarian, Sperm maturation

Thyroid-stimulating hormone (Thyrotopin) TSH
Target: Thyroid
Aciton: Thyroxin secretion which increases matbolic rate

Adrenocorticotropic hormone ACTH
Target: Adrenal Cortex
Action: Cortisol secretion

Growth Hormone GH
Target: All Cells
Action: Stimulation of protein synthesis

Prolactin
Target: Mammary Glands
Action: Growth and milk secretion

Question 30

Out of which two networks does the enteric division consist?

Answer 30

myentric plexus

submucous plexus

Question 31

What do diffuse modulatory systems have in common?

Answer 31

Core of each system has smalll set of neurons (several thousand)

Neurons of the diffuse system arise from the central core of the brain, most of them from the brain stem

Each neuron can influence many others

The synapses made by many of these systems release transmitter molecules into the extracellular fluid, so they can diffuse to many neurons rather than be confined ti the vicinity if the synaptic cleft

Question 32

Name four diffuse modulatory systems.

Answer 32

The noradrenergic locus coeruleus
The serotonergic raphe nuclei
The dopaminergic substantia nigra and ventral tegmental area
The cholinergic basal forebrain and brain stem complexes