Human Physiology - The CNS Flashcards
(34 cards)
Gray matter:
unmyelinated cell bodies, dendrites and axons. In brain Gray matter is found in surface layers or in nuclei (internally, surrounded by white matter
White matter:
is dominated by myelinated axons running in tracts, to connect different areas
Where is Gray Matter found in the spinal cord?
In spinal cord Gray matter is found internally
Nuclei in white matter most likely belong to___________
Oligodendrocytes.
The brain and spinal cord are supported and protected by three layers of connective tissue;
dura mater, arachnoid membrane, pia mater.
a.k.a DAP
Blood vessels branching within these layers deliver oxygen and nutrients to neural tissues
The meninges is
the system of membranes which envelops the central nervous system.
Meningitis: viral or bacterial infection of the meninges
Dura Mater:
Layer of dense collagen directly under the bone. In between, in the spinal cord, the epidural space (site of injection of epidural anesthesia)
Arachnoid, contains
the arachnoid membrane, a squamous epithelia
Underneath is the subarachnoid space that contains cerebrospinal fluid
dAS
Pia mater,
a thin layer directly in contact with neural tissues
Choroid Plexuses
Cerebrospinal fluid (CSF) is secreted in membranes known as choroid plexuses in each brain ventricle. CSF circulates around the CNS and is reabsorbed in the arachnoid membrane.
Blood-Brain Barrier
Is a highly selective endothelial barrier that protects the brain against fluctuations (ions, hormones, neurotransmitters) in the body
Capillaries in brain have tight junctions (unlike normal capillaries), so everything moves via membrane transporters; SELECTIVITY
Cerebrospinal fluid may contain ___
Same Na concentration as plasma
Electrolyte concentration surrounding neurons is defined by___.
Choroid plexuses
Gray matter consists of
sensory and motor nuclei.
White matter consists of
tracts of axons carrying information from and to the brain
Draw the Gray Matter in the Spinal Cord and indicate
- Somatic Motor Nuclei
- Automomic Sensory Nuclei
- Somatic Sensory Nuclei
- Dorsal & Ventral Regions
- Visceral sensory nuclei
.
Reflexes
are rapid, automatic responses to specific stimuli coordinated within spinal cord
One reflex produces one motor response through interconnected sensory neurons, motor neurons, and interneurons
True
Reflex arc:
The wiring of a single reflex. Generally opposes original stimulus (negative feedback
Steps in a Neural Reflex
- Arrival of stimulus and activation of receptor (eg Heat from fire)
- Activation of asensory neuron (in Dorsal horn)
- Sensationrelayed to thebrain by axoncollaterals. Information processing in the CNS
- Activation of a motor neuron in ventral horn
- Response by effector (eg muscles to move away from source oh fire)
Brain Structure and Function.
SMOPMT
The Brain Stem: Medullaoblongata Pons Midbrain Thalamus The Diencephalon
The Brain Stem:
Composed of:
Medulla oblongata: transitional area.
Contains many ascending and descending tracts, that cross to the opposite site, so right brain controls left body.
Some nuclei also control involuntary functions such as blood pressure, breathing, swallowing and vomiting.
Pons: relay between cerebellum and cerebrum
Midbrain or mesencephalon: controls eye movement
The Diencephalon
Contains important centers for homeostasis.
Thalamus:
Receives sensory fibers (optic, ears, spinal cord). Relay and integration.
Hypothalamus:
Hunger, thirst and other homeostatic functions.
Controls endocrine functions through the autonomic nervous system
Pituitary gland and pineal gland.
Important endocrine glands (to study in later lectures)
The Hypothalamus
- Activates sympathetic nervous system.
- controls catecholamine release from the adrenal medulla during fight of flight.
- Maintains body temperature. (controls homeostasis)
