Chapter 15: Chemical Control of the Brain and Behavior Flashcards
What does proper function require?
Restricted synaptic
communication
- Sits along wall of 3rd ventricle
- Connected by a stalk to the
pituitary - Two lobes: anterior and
posterior - Integrates somatic and visceral responses in accordance with the needs of the brain
- 3 F’s
Hypothalamus
- Regulates body temperature and blood composition within a narrow physiological range in response to external environment
- responds to a sensory stimulus with humoral,
visceromotor, and somatic motor responses
Homeostasis
In cold weather, how does homeostasis work?
- Adjusts balance of sympathetic and
parasympathetic outputs of the ANS - Ex: Constrict blood vessels to minimize peripheral blood flow
- Incites appropriate somatic motor
behavioral response - Ex: Shivering
- Stimulates or inhibits release of pituitary
hormones (humoral) - Conserve water within the body – release vasopressin
3 zones of the hpothalamus
lateral, medial, periventricular
____________ zone lies next to 3rd ventricle
Periventricular
Lateral and medial zones have connections with what?
brain stem and cortex
What contains the suprachiasmatic nucleus (SCN)?
Periventricular zone
Regulates circadian rhythms (biological clock)
Suprachiasmatic nucleus
Send axons to the stalk of the pituitary
Neurosecretory cells
Posterior pituitary is _______ ________.
brain tissue
- Largest secretory cells
- Extend axons down the stalk into posterior
pituitary - release two neurohormones into bloodstream.
Magnocellular neurosecretory cells
What two neurohormones that are released into bloodstream by Magnocellular neurosecretory cells?
- Oxytocin
- Vasopressin (ADH)
- “love hormone”
- Promotes social bonding, Lactation
Oxytocin
- Regulates blood volume and salt concentration
- ADH-containing neurons receive info about
these changes and release vasopressin - Acts directly on the kidney
- leads to water retention and reduced urine production
Vasopressin (ADH)
“Master gland” of the endocrine system
Anterior lobe
What controls the anterior pituitary gland?
parvocellular neurosecretory cells
- Do not extend axons all the way into the
anterior lobe—project to the median
eminence - Communicate via bloodstream
- Secrete hypophysiotropic hormones
- via a network of blood vessels: hypothalamo-pituitary portal
circulation - hypophysiotropic hormones bind to receptors on the surface of pituitary cells
-> Activation causes pituitary cells to secrete or stop secreting hormones
parvocellular neurosecretory cells
What do parvocellular neurosecretory cells do in response to stress? (first step)
secrete corticotropin-releasing hormone (CRH—aka: CRF) into portal circulation
second step in stress response
CRH travels to anterior pituitary and
stimulates the release of
adrenocorticotropic hormone (ACTH)
third step in stress response
ACTH enters general circulation»> travels to the adrenal cortex (in kidney)
* stimulates glucocorticoid (cortisol in primates: aka “stress hormone”)
release from adrenal cortex
* Cortisol inhibits CRH release (negative feedback via hippocampus)
- Part of the PNS
- Carried out without conscious control
- commands every other innervated tissue and organ in the body
-> Widespread actions instead of pinpoint accuracy - Sympathetic division: “fight or flight”
- Parasympathetic division: “rest and digest”
Autonomic Nervous System
Mobilizes the body for a short term emergency at the expense of processes that keep it healthy long-term
Sympathetic Division
Works calmly for long-term good
Parasympathetic Division
What type of neurons does the sympathetic and parasympathetic division have?
Preganglionic neurons