19 A Nervous System Flashcards
sensory and motor fibers carry impulses to and from CNS; most common type of nerve
Mixed
carry impulses from CNS
Motor (efferent)
carry impulse to the CNS
Sensory (afferent)
tough fibrous sheath around a nerve
Epineurium
coarse connective tissue that bundles NERVE fibers into fascicles
Perineurium
loose connective tissue that surrounds axons (part of the nerve cell)
Endoneurium
cordlike organ of the PNS consisting of peripheral axons enclosed by connective tissue
Nerve
sensitive to pain-causing stimuli
Nociceptors
respond to chemicals (e.g., smell, taste, changes in blood chemistry)
Chemoreceptors
respond to light energy (e.g., retina)
Photoreceptors
sensitive to changes in temperature
Thermoreceptors
respond to touch, pressure, vibration, stretch, and itch
Mechanoreceptors
all neural structures outside the brain and spinal cord
Includes sensory receptors, peripheral nerves, associated ganglia, and motor endings
Provides links to and from the external environment
Peripheral Nervous System (PNS)
control rate and depth of breathing
Respiratory centers
adjusts force and rate of heart contraction
Cardiovascular control center
Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial)
Contains nuclei of the reticular formation
Maintains resting breathing
Pons
relay nuclei for some descending motor pathways
Red nucleus
secretes dopamine
Substantia nigra
auditory relay centers
Inferior colliculi
visual reflex centers
Superior colliculi
four domelike protrusions of the dorsal midbrain
Corpora quadrigemina
Nuclei that control cranial nerves III (oculomotor) and IV (trochlear)
Midbrain Nuclei
Consists of three regions –
1. Midbrain
2. Pons
3. Medulla oblongata
Similar to spinal cord but contains embedded nuclei
Controls automatic behaviors necessary for survival (breathing and heart rate)
Provides the pathway for tracts between higher and lower brain centers
Associated with 10 of the 12 pairs of cranial nerves
Brain Stem
Endocrine gland called the _________________
Stores many hormones produced by the hypothalmus
Master Gland
Endocrine Functions of the Hypothalamus
Releasing hormones control secretion of hormones by the anterior pituitary
The supraoptic and paraventricular nuclei produce ADH and oxytocin
Hypothalamic Function
Controls mechanisms needed to maintain normal body temperature
Acts like a secretary at an office. It takes in all sensory information, filters out things that are not needed and directs the impulse to where it should go.
Thalamus
Thalamus
Contains four groups of nuclei
anterior, ventral, dorsal, and posterior
a structure that secretes cerebral spinal fluid (CSF)
Choroid plexus
a hormone involved with sleep regulation, sleep-wake cycles, and mood
Melatonin
extends from the posterior border and secretes melatonin
Pineal gland
Most dorsal portion of the diencephalon; forms roof of the third ventricle
Epithalamus
Central core of the forebrain
Consists of three paired structures
1. Epithalamus and Thalamus
2. Hypothalamus
3. Pituitary Gland
Diencephalon
enter the hemispheres from lower brain or cord centers
Projection fibers
connect different parts of the same hemisphere
Association fibers
connect corresponding gray areas of the two hemispheres
Commissures
Plays a role in language and problem solving
Recognizes and predicts sequences of events
Figuring out Rubic cube happens here
Cerebellar Cognitive Function
receives impulses of the intent to initiate
Cerebellum
calculates the best way to perform a movement
Cerebellar cortex
connect the cerebellum to the medulla
Inferior peduncles
connect the cerebellum to the pons
Middle peduncles
connect the cerebellum to the midbrain
Superior peduncles
Three paired fiber tracts that connect the cerebellum to the brain stem
All fibers in the cerebellum are ipsilateral
Cerebellar Peduncles
distinctive treelike pattern of the cerebellar white matter (dendrites and axons)
Arbor vitae
Located dorsal to the pons and medulla
Protrudes under the occipital lobes of the cerebrum
Makes up 11% of the brain’s mass
Provides precise timing and appropriate patterns of skeletal muscle contraction (driving, typing, playing guitar, throwing a ball ect.)
Cerebellar activity occurs subconsciously
Two bilaterally symmetrical hemispheres connected medially by the vermis
The Cerebellum
separates the frontal and parietal lobes
Central sulcus
Deep sulci divide the hemispheres into five lobes
1.Frontal
2. Parietal
3. Temporal
4. Occipital
5. Insula
grooves between Gyri
-Pleural- Sulci
Sulcus
look like macaroni
- Pleural-Gyri
Gyrus
Form the superior part of the brain and make up 83% of its mass
Contain ridges (gyri) and shallow grooves (sulci)
Contain deep grooves called fissures
Are separated by the longitudinal fissure
Have three basic regions:
1. Cortex-Outer surface containing mainly grey matter (bodies(soma)) nerve cell
2. (White matter (nerve cell processes)
3. Basal nuclei clusters of nerve cell bodies with specific functions (Relay stations)
Cerebral Hemispheres
Composed of four parts
1. Cerebrum
2. Cerebellum
3. Diencephalon
a. Thalmus
b. Hypothalmus
c. Pituitary Gland
4. Brain Stem
a. Mid Brain
b. Pons
c. Medulla Oblongata
Surface anatomy includes cerebral hemispheres, cerebellum, and brain stem
The Brain
Due to blockage of drainage of CSF usually a result of a brain tumor or severe head trauma.
Can result in headaches and brain damage or death.
Treatment is to remove the blockage if possible or place a shunt into the ventricles running it into a neck vein.
Hydrocephalus
Deep meninx composed of delicate connective tissue that clings tightly to the brain
Pia Mater
The middle meninx, which forms a loose brain covering
It is separated from the dura mater by the subdural space
Beneath the arachnoid is a wide subarachnoid space filled with CSF and large blood vessels
Arachnoid villi protrude superiorly and permit CSF to be absorbed into venous blood
Arachnoid Mater
horizontal dural fold extends into the transverse fissure that forms a tent over the cerebellum. It separates the cerebrum and cerebellum.
Tentorium cerebelli
sagittal fold that runs along the vermis of the cerebellum
Falx cerebelli
sagittal fold that dips into the longitudinal fissure between the two cerebral hemisphere. It attaches to the Crista Galli of the ethmoid bone
Falx cerebri
Means “tough mother”
Leathery, strong meninx (singular for meninges) composed of two fibrous connective tissue layers.
a. Periosteal Layer-is connected to the periosteum of the cranial bones.
b. Meningeal layer- forms true external covering of the brain. Forms the dural sheath of the spinal cord.
In certain areas these two layers separate and form dural sinuses which collect venous blood from the brain and drains it into the the internal jugular veins
Dura Mater
forms true external covering of the brain. Forms the dural sheath of the spinal cord.
Meningeal layer
is connected to the periosteum of the cranial bones.
Periosteal Layer
Functions of the meninges
- Cover and protect the CNS
- Protect blood vessels and enclose venous sinuses
- Contain cerebrospinal fluid (CSF)
- Form partitions within the skull and keeps brain from bouncing around the skull.
Three connective tissue membranes lie external to the CNS
A. Dura mater
B. Arachnoid mater
C. Pia mater
Cranial Bones
- Frontal
- Parietals
- Occipital
- Temporals
- Sphenoid
- Ethmoid
shields the brain from harmful substances.
Blood-brain barrier
The brain is protected by
- Bone- Cranial bones
- Meninges:
a. Dura Mater
b. Arachnoid Mater
c. Pia Mater - Cerebral spinal Fluid (CSF)
- Blood-brain barrier
