Presentation 19: CNS

Question 1

Ependyma

Answer 1

Central canal of spinal chord, lined with ependymal cells (a specific epithelium)

Question 2

Grey matter

Answer 2

Less myelinated neurons (less insulation)

In spinal cord made up of dorsal horn (sensory neurons) and ventral horn (motor neurons)

Question 3

White matter

Answer 3

Contains more myelin (insulation)

In spinal chord made up of ascending (bring info to brain) and descending (bring info everywhere else) tracts

Question 4

Reflex arc

Answer 4

Interneurons confined to spinal cord, involved in sending sensory signals straight to motor without going to the brain

Question 5

Neurocoel

Answer 5

Hollow cavities in the brain filled with cerebro-spinal fluid which acts as a cushion and a medium of exchange

Cerebral hemispheres = lateral ventricles
Thalamus = third ventricle
Midbrain = aqueduct
Metencephalon = upper part of 4th ventricle
Myelencephalon = lower part of 4th ventricle

Question 6

General components of the brain

Answer 6

Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)

Question 7

Prosencephalon

Answer 7

The forebrain
- composed of Telencephalon (cerebral hemisphere) and Diencephalon (thalamus, epithalamus, and hypothalamus)
- enlarged in birds and mammals which reflects more complex behaviors and more efficient muscle control

Question 8

Mesencephalon

Answer 8

Midbrain
- just the mesencephalon, composed of tectum (roof, sensory function) and tegmentum (floor, motor function)
- impulses go up at cranial nerves 3-4
- contains auditory and optic lobes
- neurocoel = cerebral aqueduct

Question 9

Telencephalon

Answer 9

Part of forebrain
Cerebral hemispheres
- neurocoel = lateral ventricle
- contains olfactory bulbs, tracts, and lobes
- higher vertebrates have sulci (grooves) and gyri (ridges)

Question 10

Diencephalon

Answer 10

Part of forebrain
Thalamus
- Includes epithalamus (roof), thalamus (main part), hypothalamus (floor and walls)
- neurocoel = 3rd ventricle

Question 11

Tela choroidea

Answer 11

thin membrane that lines the brain cavity and projects into brain as choroid plexus

Question 12

Choroid plexus

Answer 12

projection of tela choroidea into brain cavity. Produces cerebro-spinal fluid which cushions the brain and acts as a medium of exchange

Question 13

Rhombencephalon

Answer 13

Hindbrain
- split into the metencephalon (cerebellum + pons) and myelencephalon (medulla oblongata)
- Neurocoel = 4th ventricle

Question 14

Metencephalon

Answer 14

Part of hindbrain
Made up of cerebellum and pons
- ventrally have pyramidal tracts that connect to corticospinal tracts
- neurocoel = upper part of 4th ventricle
- roof = cerebellum (dorsal outgrowth, most prominent)

Question 15

Myelencephalon

Answer 15

Most post. part of hindbrain
Composed up of medulla oblongata
- neurocoel = lower part of 4th ventricle

Question 16

Medulla oblongata

Answer 16

Primary component of myelencephalon
- transition from brain to medulla of spinal cord
- assoc. w/ cranial nerves 7-12
- has distinctive nuclei assoc. w/ sense organs

Question 17

What are the 3 functions of the medulla oblongata?

Answer 17

1. cluster of nuclei assoc. w/ cranial nerves
2. major root of info from body to brain through ascending/descending tracts
3. clusters of soma for visceral, auditory, and proprioceptive receptors (things you don’t control)

Question 18

What are the 2 main functions of the cerebellum

Answer 18

1. process all sensory input
2. maintain equilibrium w/ input from inner ear to myelencephalon

Question 19

Pons

Answer 19

Part of metencephalon
Connects cerebellum to cerebral cortex
- most prominent in mammals

Question 20

Cerebellum

Answer 20

Dorsal outgrowth of metencephalon
- roof of 4th ventricle along with choroid plexus
- larger in birds/mammals but reduced in fishes

Question 21

Tectum

Answer 21

Roof of mesencephalon
- Sensory function
- contain optic lobes which receive input from retinas
- contain auditory lobes, posterior optic lobes, and cochlea
- specialized into superior and inferior colliculi

Question 22

Tegmentum

Answer 22

Floor of Mesencephalon
- Motor function
- primary place for cross of ascending and descending tracts

Question 23

Epithalamus

Answer 23

Roof of diencephalon
- associated w/ pineal organ (photoreceptor in lampreys, endocrine organ in higher vertebrates)

Question 24

Optic lobes

Answer 24

Part of tectum (except in mammals - telencephalon)
- receives visual input from retina

Question 25

Cerebral aqueduct

Answer 25

Very large in anamniotes (fishes/amphibians/etc.), smaller in amniotes (birds/mammals/reptiles) Connects cavities of the 3rd and 4th ventricles

Question 26

Thalamus

Answer 26

Main part of diencephalon - paired mass of nuclei forming dorsal walls get info for coordination center and receive all sensory impulses from spinal cord, midbrain, and hindbrain and sends that info to cerebral cortex - split into ventral and dorsal sections (dorsal part is the important one)

Question 27

hypothalamus

Answer 27

make up floor and ventrolateral walls of diencephalon - nuclei that regulate appetite, sexual activity, temperature, water balance, and behavior (homeostasis) - activity is enhanced by hormones released during breeding season

Question 28

Cerebral cortex/hemispheres

Answer 28

pair of extended lobes of telencephalon - Surface of cerebral cortex is folded to increase area forming sulci (grooves) and gyri (ridges)

Question 29

Sulcus

Answer 29

grooves formed by folding of cerebral cortex to increase area

Question 30

Gyrus

Answer 30

Ridges formed by folding of cerebral cortex to increase area

Question 31

How are nervous tissues divided

Answer 31

Into Pallium and paleostriatum - pallium divided into archipallium and paleopalleum)

Question 32

Pallium

Answer 32

Type of nervous tissue - Divided into archipallium and paleopalleum - forms roof of ventricle

Question 33

Paleostriatum

Answer 33

forms floor of the ventricle and a type of nervous tissue

Question 34

What is the diversity of nervous tissues between fish, amphibia, amniota, and mammalia?

Answer 34

Fish: the entire cerebral hemispheres are made of paleostratium Amphibia: oflactory and motor nuclei mostly located in the telencephelon Amniota: Add neostriatum (new layer of tissue from paleostriatum) which allows for coordination of skeletal muscle Mammalia: Paleopalleum and neostriatum reduced into the basal ganglia at the base of telencephalon - expanded pallium called neopallium which = brain cortex made of grey matter - have gyri and sulci - have corpus callosum which connects cerebral hemispheres

Question 35

Corpus callosum

Answer 35

Connects two cerebral hemispheres in mammals - integrates both sensory and motor info that then responds as actions