BIO MED TERM 2 NERVE CELL + BRAIN Flashcards
Nuron =
Neuroglia =
Nuron = Nerve cell
Neuroglia = Supporting nerve cell
Skeletal muscle characteristics :
Excitability and Irritability - able to be stimulated
Contractions
Extensibility - shorter or longer
Elasticity - ability to come back to original length and shape
NEUROGLIA OR GLIAL CELLS
They protect the neurons and aid their function
They bind neurons together and provide a supportive
framework for the nervous tissue
They function as an insulation
Controls the chemical environment of the nervous tissue
Epimysium
Dense connective tissue covering the entire muscle
Each muscle is made of bundles of fascicles, parallel to each
other
Perimysium
Fibrous connective tissue covering each fascicle
Each fascicle is made up of bundles of muscle cells (muscle
fibres), parallel to each other.
Endomysium
Fine sheath of connective tissue covering each muscle
cell
Sarcolemma
Cell membrane of muscle cell.
Each muscle cell can have one or more nucleus.
just beneath the sarcolemma.
Sarcoplasm
Cytoplasm of muscle cell
It is rich in mitochondria and glycogen.
Myoglobin - unique oxygen binding protein that
stores oxygen within the sarcoplasm.
Myofibrils
Myofibrils
Each muscle cell is made up of myofibrils
Muscle filaments
Muscle proteins
Each myofibril is made up of muscle filaments
They alternate to form the dark and light bands
Each muscle filament is made up of muscle protein
Myosin or Actin
what is above and under the Sacrolemma?
the Sacrolemma is under the Endomysium of the muscle fibre and inside the Sacrolemma are microfibril, inside microfibril are 2 protiens of MYOSIN AND ACTIN
A segment of myofibril is :
Sacromere - each has actin and myosin
Aponeurosis
sheet like coverings attaches
two muscles.
Afferent nerves
Sensory :
Carry impulses towards the CNS from receptors all over the body
Efferent
Motor :
Carry impulses AWAY rom the CNS to the effector organs (muscles and glands)
CNS
Brain and Spinal cord
– occupy dorsal body cavity
– Integrating and
communicating centre
– Interprets incoming sensory information and dictates motor
responses based on past experience, reflexes and current
conditions
Peripheral Nervous System (PNS)
Outside the CNS; Consists of nerves that extend from the brain and
spinal cord.
Cranial nerves :
carry impulses to and from the brain
ii.
Spinal nerves:
carry impulses to and from the spinal cord
– Serves as communicating lines that link all parts of the body to
the CNS
Peripheral Nervous System consits of two types
Somatic nervous system – impulses from and to voluntary
muscles
a. Sensory (afferent) nerves
* Carry impulses from the skin, voluntary skeletal muscles and
joints to the brain.
b. Motor (afferent) nerves
* Carries impulses from the CNS to the voluntary skeletal muscles.
Autonomic nervous system – impulses from and to involuntary
muscles
a. Sympathetic
a. Increasing (arousing) effect on activity.
b. Parasympathetic
a. Decreasing (calming) effect on activity.
Nerves form cord like structures which can have 2 forms
- Bundles of axons that travel together in the PNS
* Covered by connective tissue (epi, peri and
endoneurium)
* Peripheral nerves - Bundle of axons that travel together in the CNS
* Have no connective tissue covering
* Tracts
Neuron (Nerve cell)
Composed of:
fun fact:
- Cell body
- Axon
- Dendrites
Permanent cells (do not under go mitosis) and they have a
high metabolic rate.
5 Main structures of a Nuron
Mitochondrion
Dendrite
Myelin sheath
Schwann cell
Axon terminal
- Contains the nucleus and nucleolus
- Has no centrioles (amitotic)
- Has an axon hillock
- Cone shaped area where the axon arises
NERVE CELL BODY (SOMA)
- Contains the nucleus and nucleolus
- Has no centrioles (amitotic)
- Has an axon hillock
- Cone shaped area where the axon arises
Dendrites
Short, tapering and branched processes
ii. They are the receiving or input regions of the neuron
iii. They convey incoming messages to the cell body / soma
Axons
i. They are slender processes arising from the axon hillock
ii. There is only one axon per neuron.
iii. The ends of the axon forms branched terminals with knob-like
structures – axon terminals.
iv. Chemical substances called neurotransmitters are stored in
vesicles in the axon terminals
Myelin Sheath
- White, segmented sheath around most long axons
- Composed of phospholipids
- Formed by supporting cells / neuroglial cells:
- Schwann cells in the PNS
- Oligodendrocytes in the CNS
- Myelin sheath is formed by the Schwann cells wrapping around the
axon. - Adjacent Schwann cells do not touch each other and the gap is called
node of Ranvier.
Functions of myelin sheath:
Protect the axon.
ii. Electrically insulate the nerve fibres from one another.
iii. Increases the speed of transmission of nerve impulse.
Properties of the neuron
- Irritability – highly excitable tissue
* Capable of generating a nerve impulse (action
potential) when irritated or stimulated e.g. touch to the
skin - Conductivity – transmit impulse along the entire length of
the nerve fibre
* Allows communication with other neurons, muscles
and glands.
Anaxonic neuron
Nerves found only in the CNS
Meninges –
s – membranes covering the brain
* Dura mater – outermost tough fibrous covering
* Arachnoid mater – middle vascular covering
* Pia mater – inner most delicate membranous covering
Arachnoid Mater
Middle layer with web-like extensions
- Separated from the dura mater by the subdural space
- Subarachnoid space – between the arachnoid mater and
the pia mater, contains cerebrospinal fluid and blood
vessels. - Arachnoid villi protrude into the superior sagittal sinus and
permit CSF reabsorption.
- Arachnoid villi
- Arachnoid villi protrude into the superior sagittal sinus and
permit CSF reabsorption.
- Subarachnoid space –
- Subarachnoid space – between the arachnoid mater and
the pia mater, contains cerebrospinal fluid and blood
vessels.
Pia Mater
- Layer of delicate vascularized connective tissue that clings tightly to
the brain.
Dura Mater
Strongest meninges
* Consists of:
* Two layers of fibrous connective tissue (around the
brain)
* Separates to form dural sinuses
* Dural septa limit excessive movement of the brain
* Falx cerebri—in the longitudinal fissure; attached to
crista galli.
* Falx cerebelli—along the vermis of the cerebellum. * Tentorium cerebelli—horizontal dural fold over
cerebellum and in the transverse fissure
Cerebrospinal Fluid (CSF)
Fluid present within the cavities of the brain or spinal cord and in the
subarachnoid space.
* Secreted by the choroid plexus (network of blood vessels) in the
cavity of the brain.
* Drained into the large thin-walled veins, dural sinuses in the
duramater.
Function of CSF
function:
* Floats (buoyancy) the brain so it does not get crushed under its own
weight.
* Cushions the CNS from blows and trauma to the head.
* Helps nourish the nervous tissue.
* Carries chemical signals.
