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Flashcards in hypothalmus Deck (29):
1

function of hypothalamus

- Homeostasis

- maintenance of the body's internal environment within normal physiological parameters

- carries out the function through interconnections with areas of the brain related to emtions, Sleep/awakenings, hormones and autonomic activity

- MONITORS blood glucose levels, blood osmolarity, body temperature and various hormone levels

2

blood supply to hypothalamus

- Perforating branches of circle of willis

3

Boundaries of hypothalamus

- Superior = hypothalamic sulcus

- anterior = lamina terminalis

- posterior = midbrain (interpeduncular fossa)

- inferior = optic chiasma, tuber cinereum, mammillary bodies

4

overview of hypothalamus

- hypothalamus is nodal point of interconnecting structures relating to autonomic, endocrine, emotional and somatic functions

- ALL FUNCTIONS relate to MAINTAINING homeostasis

--> stable internal environment, including temperature, hydration, glucose and monitoring hormone levels

5

describe the major INPUTS

- cerebrum = thoughts and decision

- Limbic system = organizes appropriate behavioral responses associated with basic drives, "feeling", motivation

- Retina = light information (amount/duration of day/night)

- Branstem and spinal cord = info from viscera

- Intrinsic neurons = monitoring blood temp, osmolarity, hormone levels, glucose concentration

6

describe major outputs

- To brainstem and spinal cord = influences viscera, especially AUTONOMIC FUNCTION

--> VII, IX, X, T1-L2, S2-4

- To PITUITARY = produces secretions (hormones and releasing factors)

7

Suprachiasmatic nucleus

- RECEIVES: light information from retina via RETINOHYPOTHALAMIC TRACT (retinosuprachiasmatic)

- NUCLEUS contains MELATONIN RECEPTORS

- Pineal secretes melatonin varying with light levels

- melatonin helps SET and SYNCHRONIZE the "clock"

- NUCLEUS CORRDINATES SLEEP/WAKEFULNESS CYCLES in the RETICULAR FOMRATION and other CIRCADIAN RHYTHMS

8

Mammillary bodies (nuclei)

- PROCESSES EMOTIONAL INFORMATION

- INPUT: from hippocampus and amygdala (largest INPUT pathway is FORNIX)

- OUTPUT: mammillothalamic, mammillotegmental tracts

- HYPOTHALAMUS TRIGGERS APPROPRIATE VISCERAL RESPONSES:

--> brainstem parasympathetic nuclei (VII, IX, X)

--> spinal cord sympathetic and parasympathetic segments (T1-L2, S2-S4)

9

Why is memory so important to hypothalamic function

REMEMBERING AND LEARNING

- location of food sources increases chances of feeding

- location of water sources increases changes of maintaining hydration

- location of and tactics for avoiding predators increases chances of long-term survival

- location of warmer climate associated with changing daylight length triggers migration for survival

- location and status of receptivity of potential mates increases chances for procreation

10

describe the autonomic control and integration of hypothalamus

- INPUT: Ascending visceral info from internal organs (pain, empty stomach, drysness in mouth, enviornmental factors) and limbic system (emotional info)

- OUTPUT:  Parasympathetic and sympathetic

- Fibers from various nuclei converge on PARAVENTRICULAR NUCLEUS and then via dorsal longitudinal fasciculas and mammillotegmental tracts to brainstem and spinal cord

11

describe Parasympathetic control and integration of hypothalamus

- Nuclei = PREOPTIC and ANTERIOR

- Response = pupillary constriction, increased salivation, decreased BP and HR, increased GI peristalsis

12

describe sympathetic control and integration of hypothalamus

- Nuclei = POSTERIOR and LATERAL

- RESPONSE = pupillary dilation, decreased salivation, INCREASED HR and BP, decreased GI peristalsis, VASOCONSTRICTION

13

Anterior hypothalamus function in thermostat

-  NUCLEI: Preoptic and anterior nuclei initiate HEAT LOSS

- VISCERAL RESPONSE: Sweating and vasodilation

- decreased motor activity

- BEHAVIOR: seek cooler environment, fan yourself

- ASPIRIN causes antipyretic (fever reducing) effect by acting DIRECTLY on HYPOTHALAMUS

14

Posterior hypothalmus function in thermostat

- NUCLEI: posterior nuclei activate heat production

- VASOCONSTRICTION

- increased muscular activity (including shivering)

- TH increases metabolic heat production

- BEHAVIOR: put on more clothes

15

describe the hypothalmus function of regulating food intact

- LATERAL NUCLEUS = Stimulation INDUCES eating, "feeding or hunger" center

- VENTROMEDIAL NUCLEUS = stimulation INHIBITS eating, "satiety" center

16

Osmoreceptors

- Monitor the concentration/hydration of blood

- Stimulation of the lateral hypothalamus (zona incerta) STIMULATES DRINKING

17

Glucoreceptors

- monitor glucose levels

- Affects feeding and satiety centers

18

describe hormonal control of Posterior pituitary

- hypothalamus synthesizes and releases the hormones of posterior pituitary (neurohypophysis)

- Nuclei: supraoptic and paraventricular

- Pathway: hypothalamo(supraoptico)hypophyseal tract

- Hormones:

--> ADH(antidiuretic hormone, vasopressin) = water conservation, increase blood pressure

--> oxytocin = uterus contractions, milk let down

- Intrinsic osmoreceptors sense and TRIGGER ADH to CONSERVE water

19

What is the result of damage to posterior pituitary

- INTERRUPT SYNTHESIS OF ADH leading to copious URINE FORMATION and CONSTANT THIRST

--> called DIABETES INSIPIDUS (tasteless)

- Blood and urine sugar levels are within normal limits

20

describe the hormonal control of anterior pituitary

- hypothalamus produces releasing factors that STIMULATE or INHIBIT release of hormoens from anterior pituitary (adenohypophysis)

- NUCLEI = ARCUATE, medial preoptic, preoptic, PERIVENTRICULAR nuclei

- Pathway: tuberohypophysial (-infundibular) tract then vascular, hypothalmo-hypphyseal portal system to adenohypophysis (anterior pituitary)

- Hormones: affect BODY GROWTH, thyroid secretion, gonadal function, adrenocortical secretion and mammary gland secretion

21

describe visceral response to CONSCIOUS THOUGHT

- thoughts, feelings, emotions can elicit:

- SYMPATHETIC RESPONSE = sweating and blanching, accelerated HR, constipation, increased or decreased frequency of urination when WORRIED OR SCARRED

- PARASYMPATHETIC RESPONSE = sexual dysfunction when depressed

- INTERRUPTION of NORMAL CYCLING OF gonadotrophic hormones = skipped or delayed menstration with worry or depression

22

describe Somatic response to CONSCIOUS and unconscious thoughts

- Slouching and moving slowly when depressed (Limbic)

- quick, agitated movements when STRESSED or ANXIOUS

- thoughts and emotions DRIVE facial movements appropriate to those thoughts and emotions

--> sad face, happy face, frightened face

23

describe the clinical correlation of direct connections between frontal lobs and hypothalmus

- Stroke victums can still move otherwise paralyzed muscles with EMOTIONAL RESPONSE

--> ex: smiling at a joke (duchenne smile)

- The muscles are ONLY PARALYZED for VOLUNTARY MOVEMENT (pyramid pathway, corticonuclear, is interrupted)

- pathway from cerebrum to hypothalamus takes DIFFERENT ROUTE (not well defined

24

function of suprachiasmatic

- circadian cycles, the clock

25

mammillary function

- processing emotional info

26

anterior and posterior nucleus

- regulate body temp

27

Ventromedial, lateral

satiety and feeding

28

supraoptic, paraventricular

- produce hormones in posterior pituitary

29

preoptic, medial preoptic, arcuate, periventricular

- release or inhibit hormones in anterior pituitary