Lecture 3: Neurophysiology Pt 2. Flashcards
Name the areas of the brain.
Cerebrum (forebrain)
Diencephalon (thymus, hypothalamus)
Cerebellum
Mesencephalon, Pons, Medulla, oblongata (brain stem)
What are the main tasks of the CNS?
-Receives continuous flow of info from out and inside body (ex thermoregulation always have receptors constantly going)
-Analyzes and interprets the info (makes sense of it)
-Sends commands to the body to maintain fxn of vital systems and organs and responds to external environment
TRUE OR FALSE: Meninges have 4 layers surrounding the brain and spinal cord
FALSE: The meninges have 3 layers surrounding the brain and spinal cord
- outer meninx = dura mater (thick, tough) supports the brain, inserted b/w cerebral hemispheres. Forms the venous sinus, collects most of the blood and cerebrospinal fluid from brain
-between these two layers is the sub-arachnoid space (filled with CSP) - Middle meninx = arachnoid
- Inner meninx = pia mater, tightly attached to the neural tissue, thinnest layer against neural tissue
How is cerebrospinal fluid (CSF) formed and what roles does it play in the CNS?
CSP is formed in the capillaries of specialized areas of the Pia mater (inner meninx) called the choroid plexus. Circulates from the brain’s ventricles down to the central canal of the spinal cord diffusing from the 4th ventricle to the subarachnoid space and circulates around the brain and the spinal cord. It drains into the venous sinus before entering blood circulation.
ROLES:
-Provides nutrients to the CNS (needs that constant supply of glucose)
-Protection (shock absorber)
-Ionic concentration ideal for optimum neural function (proper pH)
-Blood-CSF barrier: At choroid plexus, uptake of nutrients and drugs into CSF
What is allowed pasted the blood brain barrier?
No cells or proteins (too big), low amino acids, only lipid soluble substances (scubas gases) can diffuse.
Part of the cerebrum is the cerebral cortex, is that composed of white or grey matter? What is the purpose of this structure?
Grey matter.
Neural cell bodies are grey because they are unmyelinated, where as white matter is the axon which is myelinated.
Purpose: Acquired late in evolution, most superficial layer responsible for the conscious experience of sensory input. Site of high nervous association, marked by a high degree of educability. (learn & store info opposite to reflexes). Primary cortical areas have been mapped (mainly in humans)
Where is white matter located? What are the types of fibres involved?
Beneath the cortex: composed of myelinated nerve fibers includes:
-Association fibres share info between parts of the cortex
-Commissural fibres (connect right and left) between the two hemispheres
-Projection fibres (goes beyond cortex): connect cortex to other brain structures and spinal cord
Where is the basal nuclei located?
Deep within the cerebrum (close to the thalamus), paired nuclei composed of large pools of neurons. Control complex semi-voluntary movements such as walking, running, start it but then don’t have to think to continue. Works in conjunction with the cortex and cerebellum.
Why is the cerebellum sometimes referred to like an accessory brain?
Main role is to prevent distortion of intended movement (assisting the cerebrum) by receiving info regarding the status of the body, intended movement, and makes adjustments for a smooth completion. Corrective signals are sent via the thalamus to the cortex and spinal nuclei commanding muscles.
Not involved in consciousness and sensation but receives info from the inner ear (equilibrium), proprioceptive receptors (muscles, tendons, and joints) and cortex (visual and motor).
Where is the cerebellum well developed?
In animals requiring precise adjustment for locomotion (air, ground, water).
What part of the brain is known as the ‘midbrain’ and what parts are included?
Diencephalon: thalamus, epithalamus, and hypothalamus
Thalamus: relay station for sensory info, cerebellum and basal ganglia, and the cerebral cortex (grey matter/cell bodies bc high integration)
Epithalamus: contains olfactory correction centre and the pineal gland (sense of smell connecting with other sensory)
Hypothalamus: Controlling body functions
-Produces neuropeptides that control the anterior pituiary (process info then send neuropeptides to pituitary if problem to be fixed)
-Produces neurohormones related by the posterior pituitary
-Principal regulator of autonomic NS, with the brainstem, it is most important region for the control of homeostasis
TRUE OR FALSE: The brain stem has 4 main sections, and includes nuclei that given body function by reflexes, such as respiratory and cardio, and contains large amount of white matter?
BOTH:
TRUE: Includes nucei that gives body functions by reflex and contains large amount of white matter. And it mainly affected the respiratory and cardiovascular system.
FALSE: The brain stem has 3 major sections: Mesencephalon, Pons and Medulla Oblongata
What is the purpose of each part in the Brainstem?
Mesencephalon: Most mammals midbrain v small covered by cortex birds have well developed
-Visual reflex centre: receives visual info, controls eye movement (for focus)
-Auditory reflex centre: turn head for noise (automatically)
Pons and Medulla Oblongata:
-Contain center for postural reflexes (hopping, right, placing)
-Control reparatory movements
-Medulla oblongata crucial for control of: Heart active, BP, Relative distribution of blood to organs (towards the base of the brain)
How many pairs of crinal nerves do you have? Which ones are we focusing on and why?
12 pairs
- 1 (olfactory which is very short) and 2 (optic bringing info from retina to brain) are the only purely sensory nerves and remain in the brain
-3-12 all exit from the brain stem and innervate structures of the head and neck; most are both sensory and motor (mixed) When both sensory and motor neurons: PNS to brain sends info up AND brain to body which sends info down
-10 (vagus nerve) IS EXCPEPTION: most widely distributed nerve throughout the body (neck to abdomen)
The spinal cord contains what 5 regions?
- Cervical (neck)
- Thoracic (Chest)
- Lumbar (abdominal)
- Sacral (pelvic)
- Coccygeal (tail)
The number differs sometimes depending on species, most mammals have 7 cervical. But coccygeal can change depending on the size of the tail.
