5.2: Brain Development, Protection, Blood Supply

How does the nervous system develop

The encephalon Development

• Encephalon develops from the neural tube of an embryo at 4 weeks

• becomes brain + spinal cord

What are the encephalon parts

• Proscencephalon (forebrain)

• Mesencephalon (Midbrain)

• Rhombencephalon (Hindbrain)

What does the Prosencephalon become?

• Telencephalon (lobes, basal ganglia, white matter)

• Diencephalon (thalamus, hypothalamus, pituitary gland, optic tract)

What does the Mesencephalon (Midbrain) become

Stays as midbrain (auditory and visual processing)

What does the Rhombencephalon (Hindbrain) become

• metencephalon (pons and cerebellum)

• Myelencephalon (medulla)

The forebrain consists of

• Cerebrum

• Thalamus

• Hypothalamus

• Pituitary gland

The cerebrum helps with

• thought, learning, speech, reading, writing, emotions, muscle functions

The thalamus helps with

• All sensory info other than smell

• Sleep, wakefulness, consciousness, learning & memory

The Hypothalamus helps with

• Homeostasis

• Releases chemical messages to pituitary

• Emotional response, body temp, heart rate, hunger/thirst, sexual behavior

The pituitary gland helps with

• secreting hormones for growth, metabolism, reproduction

The Hindbrain is made up of

• pons

• Medulla oblong tea

• Cerebellum

The pons helps with

• message station between cerebrum, cerebellum, and spinal cord

• Eye + body movement, sleep, arousal

• Part of brain stem

The medulla oblongata helps with

• control for heart and lungs

• Unconscious acts (breathing, swallowing, circulation)

• Part of brain stem

• Where spinal cord enters skull

The Cerebellum helps with

• coordination and regulates muscle activity

Whats the cerebrum?

The upper most part of the brain (80%)

• consists of

1. meninges (meninges lining)

2. cerebrospinal fluid (CSF)

2. ventricles

What do the meningeal lining (meninges) do

• maintains brains position in fluid suspension

• Prevents damage from sudden movement/trauma

What are the layers of the meninges

1. Dura Matter: two tough outer laters that adhere to bone

2. Arachnoid matter: spider like layer where blood vessels pass

3. Pia Matter: inner covering where major arteries/veins get blood flow

What does Cerebrospinal Fluid do

Provides nutrient delivery and waste removal

What do the ventricles do?

Open spaces that keep the brain afloat (buoyant) and cushioned

• 4 ventricles: (2 lateral, 3rd, 4th)

• Each ventrical has choroid plexi that produce CSF (cerebral spinal fluid)

What does the Cerebrovascular system do?

Carries blood to and from the brain to heart by

• Artieries: transport oxygen & nutrient blood to brain

• Veinous system/Veins: removes deoxygenated blood away from brain to heart

Function of cerebral arteries

• Cerebral arteries: provide blood in anterior, middle, and posterior cerebrum

• Carotid Artries: circulates blood from heart (Internal = brain, external = face/neck)

• vertebral arteries: circulate blood from heart to back of neck

• Basilar artery: forms two vertebral arteries that join @ skull base. Carries blood to cerebellum, brainstem, & occipital lobes

Circle of Willis

Joining of two internal carotid and basilar artery

• keeps blood circulating constant in case of cerebrovasular accident

• Equalizes pressure