HUMAN ANATOMY-4
Nervous system. Endocrine system.
General info
• There are 2 body systems, which maintain
internal coordination of trillions of cells:
nervous system and endocrine system.
• Nervous system sends electrical & chemical
messages to cells
• Endocrine system works by means of
hormones, secreted to the blood.
Nervous system – general info
• Nervous System (NS) consists of 2 types of
cells:
• cell of nervous tissue - NEURON &
• cell of connective tissue – GLIAL CELL.
• So the nervous system is the mixture of two
types of tissue, called neuroglia (p.164,
fig.5,24).
Neuron
• Neuron, apart from its common for majority
of other cells general cellular compartments,
has 2 types of extensions: DENDRIT & AXON.
• Dendrit – is a short and intensively branched
extension, which receives signals from other
cells.
• Axon – is the long (sometimes up to the 1 m
or more) extension, which sends outgoing
signals to the cells.
NEURON – physiologic properties
These characteristics allow neurons to
communicate.
• Exitibility – they response to environmental
stimuli
• Conductivity – produced electrosignals
propagate to various distances
• Secretion – nerve endings secret
neurotransmitters, that stimulates other cells.
NEURON – functional classes
(p.442, fig.12.3).
• – sensory (afferent) neurons, present within
organs to detect stimuli & send them to CNS
• – motor (efferent) neurons, send signals from
CNS to muscles & glands for action
• – interneurons, comprise 90% of all neurons,
present only in CNS.
Glial cell
• Glial cells occupy the most part of nervous
system
• Their major function is to support & protect
nervous cells.
• They resemble connective tissue cells and
don’t transmit signals for long distances.
Central & peripheral nervous systems
• Neuroglia comprises nervous system, which
consists of 2 departments:
• Central Nervous System (CNS) &
• Peripheral Nervous System (PNS) (p.440, fig.12.1).
CNS is presented by 2 subdivisions:
• BRAIN, located within the cranium, &
• SPINAL CORD (located within vertebral channel)
CNS & PNS – functional classification
• PNS consists of 2 subdivisions:
• SENSORY subdivision, which receives signals and
• MOTOR subdivision, which sends outgoing
signals.
• Each of this parts has visceral (involuntary) and
somatic (voluntary) parts.
• Besides that visceral motor subdivision is
comprised of SYMPATHETIC & PARASYMPATHETIC
compartments (p.441, fig. 12.2).
Autonomic nervous system
• The sympathetic division tends to arouse the
body for action, dominates at the daytime (&
inhibit digesition)
• The parasympathetic division tends to have
a calming effect , dominates at the nighttime
(& stimulate digestion)
• Common name for these divisions is
autonomic nervous system
SPINAL CORD (p.480, fig.13.1)
• Is a cylinder of nervous tissue, which spreads
from the brain upto the 1st lumbar vertebra
• Gives rise to 31 pairs of spinal nerves
Has 4 regions:
• cervical (C1 – C8),
• thoracal (T1 – T12),
• lumbar (L1 – L5) &
• sacral (S1 – S5)
BRAIN (p.513 fig.14.1)
• Consists of 3 major parts: cerebrum, cerebellum,
brainstem.
• Cerebrum is the highest center for control of body
functions & behavior
• Proportions of body parts on motor cortex of the brain
(p.542 fig.14.23).
•
• Cerebellum provides with balance & coordination
•
• Brainstem provides with breathing & heart beating
centers.
• 12 pairs of cranial nerves arise from the brainstem.