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Development,Aging & Disorders

Homeostatic Imbalances and Disorders

Ronald Aguilera and Ryan Roman

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General Development of Brain

During 3rd wk. of gestation, ectoderm thickens into Neural Plate. Neural groove (longitudinal) and Neural folds (raised edges)

are formed Folds meet to form Neural Tube Inside the neural tube is the Neural Crest, a mass of tissue

adjacent to neural tube Neural Crest eventually forms:

◦ Spinal and Cranial Nerves◦ Ganglia of Cranial Nerves◦ And much more

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General Development of Brain

3 layers of cells differentiate from walls of neural tube:◦ (Outer) Marginal Layer cells become white matter

◦ (Middle) Mantle Layer cells become gray mater

◦ (Inner) Ependymal Layer cells become lining of central canal

of spinal cord and ventricles of brain

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General Development of Brain

During 3rd to 4th wk. of embryonic development, neural tube develops into three Primary Brain Vesicles: ◦ Prosencephalon (Forebrain) ◦ Mesencephalon (Midbrain)◦ Rhombencephalon (Hindbrain)

During 5th wk. of development, Secondary Brain Vesicles develop◦ Prosencephalon -> Telencephalon

& Diencephalon◦ Rhombencephalon ->

Metencephalon & Myelencephalon Area of neural tube inferior to

myelencephalon becomes the Spinal Cord

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General Development of Brain

Telecephalon -> cerebral hemispheres (basal ganglia, lateral ventricles)

Diencephalon -> thalamus, hypothalamus, epithalamus Mesencephalon -> midbrain, cerebral aqueduct Metencephalon -> pons, cerebellum, and houses part of the 4th

ventricle Myelencephalon -> medulla oblongata, and houses the remainder of

4th ventricle

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Aging and the Nervous System

The older we get, the more the Nervous System gets weaker◦# of synaptic contacts declines◦Decrease in brain mass and nerve cells◦Decreased capacity for sending nerve impulses

Processing of info decreases Conduction velocity decreases Voluntary motor movement decreases Reflex times increase

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Cerebral Palsy

Neuromuscular disabilityInfants and toddlers affectedVoluntary muscles are poorly controlled or paralyzedCaused by brain damage either genetics or accidental2 out of every 1000 newborn affected

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Anencephaly

Cerebrum and part of brain are never developed Newborns are the ones affected Caused by neural folds fail to fuse rostrally (fuse towards the head) Victims in “vegetative state” meaning that mental life is nonexistent Victims usually pass away Approx 1 out of every 68,000 affected

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Spina bifida

Incomplete formation of vertebral arches along the lumbosacral region (lower back)

Children mainly affected (newborns) Spina bifida cystica: cyst protrudes from child’s back; can lead to: functionless spinal cord if not treated incontinence muscle paralysis renal failure urinary tract infection Spina bifida occulta: least serious form with only one or a few vertebrae

and causes no neural problems

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Alzheimer’ Disease

Most common form of dementia (weakening of mind due to age) Mind literally deteriorates alongside the brain Causes not well understood Old people mainly affected 1 in 8 older Americans affected by AD Symptoms usually reveal during or after age 65: Confusion Mood Swings Trouble with language Long term memory loss

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QUIZ TIME!!!!!

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Which of the following is true about the aging of the nervous system?

A) there’re no ways to slow down the deterioration of the nervous system.

B) as you age, your brain and spinal cord lose nerve cells & weight

C) average human’s nervous system ages at the same rate

D) None of the Above

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Which are true about Alzheimer’s Disease?

A) It has a higher likelihood for older people during or after the age of 75

B) Symptoms are: aggression, memory loss, confusion etc.

C) It stays the same as it progressesD) All of the above

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All of the following are considered primary brain vesticles EXCEPT:

A) Rhombencephalon

B) Prosencephalon

C) Metencephalon

D) Mesencephalon

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Which of the following is false about anencephaly?

A) Victims are in the “vegetative state”B) caused by cerebrum and brain stem

never developingC) little mental capabilities existD) caused by neural folds failing to fuse

rostrally

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Spina Bifida Occulta is more serious than Spina Bifida Cystica

True

False