Unit 2: Nervous system Flashcards
Function of the nervous system:
Main responsible for the control and regulation of the organism, together with the endocrine system
* Sensory
* Integrative: receiving and understanding information
* Effector: pathway that transmits the information from the control center into the effector organ
neurons: - 3
- Process and transmit the electric impulses
- They are the most important cell because they can fill the three responsibilities of the nervous system (sensory, integrative, effector)
- “Polar cell” → which ensures the transmission of the electric impulse one single direction
2 ways of understanding the nervous system:
- anotomical division:
seperates the central and peripheral nervous system - functional division:
* according to the direction of the information
Sensory / afferent: receive the information from peripheral receptors and carry the impulse to the CNS
Motor / efferent: carry the nervous impulse from the CNS to effector organs
- Somatic nerves: the target organ is the skeletal muscle. Controls voluntary and involuntary movements
- Autonomic nerves: the target organs are smooth muscle, cardiac muscle or glands (anything but skeletal muscles)
–> Sympathetic
–> Parasympathetic
label and define these parts of the neuron:
types of neurons:
- sensory neurons - afferent part of the NS. from receptors into the CNS
- interneurons - present only in CNS, connect neurons and form pathways
- motor neurons - Efferent part of the NS. from the CNS into target organ
label this
- Schwann cells
* Myelin production - Satellite cells
* Scaffolding in ganglia - axon
- neuron cell body
oligodendrocytes and microglia in the central nervous system:
- Oligodendrocytes
* Myelin production - Microglia
* Specialized immune cells
* Eliminate damaged cells and external pathogens
astrocytes and ependymal cells in the central nervous system:
- Astrocytes:
* name astro bc star shaped with lots of projections
* some projections will grab oxygen from the blood and give it to the muscles and with the other projections will grab the glucose from the blood and give to the neurons - Ependymal cells:
* Isolation of the nervous system from the fluid compartments of the CNS (ventricles with the cerebrospinal fluid)
* A source for nervous “stem cells” that can be differentiate in new neurons or glial cells
* Stem cells are cells that are not specialized to be any type of cells but have the ability to transform into any type of cell
The brain and spinal cord are protected by three levels of what
The brain and spinal cord are protected by three levels of tissues separating the spinal cord and the vertebra:
1. bones - cranium, vertebral column
2. meninges - pia matter, aranchoid, dura mater
3. fluids between layers - cerebrospinal fluid
how are the brain and spinal cord isolated
Brain and spinal cord are isolated by a system of membranous layers: the meninges
From outer to inner there are three meningeal membranes:
- Dura mater: fibrous tissue, very resistant. Outer layer lining the skull
- Arachnoid: thinner than the dura, contains blood vessels.
- Pia mater: inner and thinner layer, covers the nervous system and brain
spaces between the meninges
- Epidural space:
Between the bone and dura mater
Contains fat and connective tissue - Subdural space:
Between the dura and the arachnoid
Contains serous fluid (With proteins) - Subarachnoid space
Between the arachnoid and the pia mater
Contains CSF (cerebral spinal fluid)
ventrical system:
the four intercconected cavities in the brain that produced in plexuses
- they are all filled with cerebrospinal fluid
1 and 2: lateral ventricles
3 and 4: descendant ventricles
* third ventrical
* fourth ventricle
cerebrospinal fluid
- where is produced
- what is produced by
- purpose
- where does it absorb
- produced constantly in ventricles
- produced mostly by choroid plexuses, a vascular tissue located in the walls of the four ventricles (the components of the CSF are taken from the blood)
- purpose: constant circulation, fills the four ventricles and the central canal of the spinal cord, and draining to the subarachnoid space, where it surrounds the CNS
- From the subarachnoid space the CSF is reabsorbed into the venous blood in certain areas of the arachnoid membrane: arachnoid granulations or villi
Function: physical and chemical protection of the nervous tissue
- Regulates nutrient supply and waste collection
- Provides lubrication
- Provides mechanical support (cushioning) and regulates pressure (hydrocephalus)
blood brain barrier purpose
- Functioning barrier made of the endothelial cells of the brain capillaries (small blood vessels) and astrocytes, join together by tight junctions
- Capillaries in most areas of the brain are not permeable to prevent the entrance of dangerous substances from the blood: protective barrier
blood brain barrier purpose - 2
- Regulate which substances enter the CNS and protect if from toxic molecules: selective permeability
- Maintaining constant the composition of the extracellular environment surrounding neurons:
* Ensure the supply of energetic substrates (glucose, ketogenic bodies, lactate)
* Isolates neurons from pathogens and dangerous substances
* Some molecules (very small like alcohol or gasses, or some drugs) can avoid the BBB
* Some brains areas lack BBB:
–> Hypophysis: so it can release hormones into the blood flow
–> Vomit center in the brain stem to check for toxic substances in the blood
7 main areas presented in the adult CNS
- cerebrum
- diencephalon
- midbrain
- cerebellum
- pons
- medulla oblongata
- spinal cord
the brainstem - 4
contains: midbrain, pons, medula oblongata
- It is the most primitive area of the brain
- It develops between the diencephalon and the spinal cord
- White matter on the outside, nuclei and reticular formation on the inside
function of brainstem
- receiving and sending info to various areas both in the brain and the spinal cord
basic processes brianstem is involved in - 7
- Alertness
- Arousal and sleep regulation
- Coordination of breathing
- Heart rate control
- Muscle tone
- Blood pressure regulation
- Modulation of pain
medulla oblongata: parts and where it is
Most caudal part of the brainstem (transition with the spinal cord
parts:
1. Anterior/ventral part: pyramids (motor axons)
- Posterior/dorsal part: gracilis and cuneatus nuclei (sensory pathways)
- Lateral sides: olives - equilibrium
pons - 3
- Protrudes between the midbrain and the medulla oblongata. It is ventral to the cerebellum
- Mostly white matter: axons coming to and from the cerebellum (relay station)
- Few nuclei inside that participate in the control of breathing together with the medulla oblongata
midbrain parts
Ventral part: cerebral peduncles (white matter). Large bundles of axons (sensory and motor) that attach the cerebrum to the brainstem
Posterior part (tectum): corpora quadrigemina. Reflex centers for vision and hearing:
–> Superior colliculus (pair): involved in vision and eye movement
–> Inferior colliculus (pair): involved in the hearing pathway
what is the red nucleus and substantia ningra involved with
involved in motor coordination and involuntary movement
cerebellum - 4
- 2nd largest structure in brain
- where it is in the brain
- Involved in motor learning and precise movement
- White matter inside: arbor vitae (tree of life)
- Cerebellar peduncles, white matter that attaches the cerebellum to the brainstem
- Involved in motor learning and precise movement
diencephalon parts
thalamus
hypothalamus
epithalamus
diencephalon
thalamus - 2
- Relay station of sensory information
- Receives information from all sensory inputs (retina, ears, skin receptors…) and distributes it in the cerebral cortex
diencephalon
hypothalamus - 4
- Connected with all the brain areas
- Involves in homeostasis (temperature, hunger, water intake)
- Behaviour (limbic system, circadian system)
- Hormone secretion
diencephalon
epithalamus - 2
- Better known as the pineal gland
- Part of the endocrine and circadian system
table of parasympathetic and sympathetic activity
