TIS

Chapter 5

Forebrain

 

I. INTRODUCTION

-- diencephalon: 2nd division of forebrain

1. Epithalamus:

2. Thalamus:

3. Hypothalamus:

4. Third Ventricle:

5. Part of the Pituitary Gland:

II. THIRD VENTRICLE

-- hypothalamus, thalamus, and epithalamus form its floor, walls and roof

III. EPITHALAMUS

A. Pineal Gland (Pineal Body): appears to regulate the body's clock

* produces melotonin

IV. THALAMUS

-- two oval masses of gray matter, covered w/white matter

-- Major function: relay point and processing center for all sensory impulses (except smell) running to cerebral cortex

V. HYPOTHALAMUS

-- Major function: serves as center for controlling autonomic (visceral, involuntary) activity and endocrine (hormonal) activity

-- specific functions:

1. Cardiovascular regulation:

2. Temperature Regulation:

3. Water and Electrolyte Balance:

* electrolyte: ions and molecules that carry an electric current

* ion: an atom that has a net positive or net negative charge

4. Hunger/Food Intake:

* consists of two centers:

a) hunger center

b) satiety center

5. Sleep-Wake Cycle:

6. Sexual Response:

* "sexual center"

7. Emotional Expression:

* feelings of emotion are expressed as visible physiological and physical changes

8. Endocrine Control:

* produces two hormones which are secreted by the posterior pituitary

* also produces hormones that regulate hormonal secretion of the anterior pituitary

VI. PITUITARY GLAND (HYPOPHYSIS)

-- hangs underneath the hypothalamus

* it is connected by the infundibulum

-- consists of two lobes:

1) adenohypophysis or anterior pituitary

* glandular epithelium

* synthesizes hormones

2) neurohypophysis or posterior pituitary

* axons from neuron cell bodies found in hypothalamus (neurosecretory cells)

I. INTRODUCTION

-- forebrain has two subdivisions:

1. diencephalon:

2. telencephalon: the cerebrum

* concerned w/higher brain fcts.

II. TELENCEPHALON

-- outer gray matter (cortex) and an inner white matter

-- Structure:

1. two cerebral hemispheres

2. hemispheres separated by a longitudinal fissure

3. connection between hemispheres: the corpus callosum

4. Cortex is highly convoluted

* raised area/elevation=gyrus

* depression or groove=sulcus

-- Lobes - 5 pairs:

1. Frontal:

* ends at the central sulcus

A. Broca's area: on left frontal

** motor functions involved w/speech

B. Precentral gyrus:

** primary motor area

** controls voluntary skeletal muscle movement

2. Parietal:

* ends anteriorly at central sulcus

* laterally ends at lateral sulcus

A. Postcentral gyrus:

** primary sensory area

B. Speech Comprehension Area("Wernicke's area")

3. Temporal:

* primary auditory area

* memories of auditory and visual experiences stored here

4. Occipital:

* receives/assembles visual info

* coordinates focusing of eyes

5. Insula: deep to the lateral sulcus

* memory

-- Basal Ganglia: paired masses of gray matter deep in cerebrum

III. RECEPTORS

-- Def: receptor = specialized dendritic ending of a sensory neuron. Converts a sensory stimulus to a nerve impulse.

-- 3 kinds, based on location:

1. Exteroceptors: near surface of body

* stimuli from outside environment

* ex: cutaneous receptors

* ex: special senses (sight, smell, taste, hearing, balance)

2. Visceroceptors: (enteroceptors)

* stretch receptors in smooth muscle of blood vessels and viscera

3. Proprioceptors: provides info about muscles, joints and tendons

IV. SPECIAL SENSES

A. Olfaction (smell):

* chemoreceptor (sense chemical stimuli)

* bipolar neurons make up olfactory epithelium in superior nasal cavity - they synapse w/ neurons in olfactory bulb

* odorant molecules must first be dissolved in fluid (mucus) before sense of smell can be stimulated

B. Gustation (taste):

* also a chemoreceptor: molecules must be dissolved in saliva

* specialized cells form taste buds

* taste buds are located on fungiform and circumvallate papillae, on tongue

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