Nervous System (6) Flashcards
1
Q
The NERVOUS SYSTEM (2)
A
- The nervous system is the body’s way of gathering information, storing it, and responding to it.
- Main role is to assemble information about conditions EXTERNAL and INTERNAL to the body.
→ Analyze this information
→ Initiate responses that may be necessary to satisfy certain needs.
2
Q
The BRAIN (3)
A
- Control center or “computer” of the body.
- Incapable of performing physical tasks therefore it sends commands to other parts of the body to perform them.
- 6 main parts: Cerebrum, cerebellum, brain stem, diencephalon, limbic system, and the reticular activation system.
3
Q
Properties of the CEREBRUM (3)
A
- Largest part of the brain
- Contains nerve centers that control sensory and motor activities.
- Can be divided into two halves or “hemispheres”
→ Each hemisphere is divided into 4 lobes named after the bone they lie over.
→ Frontal lobe, temporal lobe, parietal lobe, occipital lobe.
4
Q
Properties of the CEREBELLUM (3)
A
- Second largest region.
- Lies behind and below the cerebrum.
- Main function is to coordinate muscle movement and control balance.
5
Q
Properties of the BRAIN STEM (3)
A
- Below cerebrum and in front of the cerebellum.
- Links the cerebrum with the spinal cord.
- Houses brain centers responsible for automatic functions, postural control, muscle tone, and eye movement.
6
Q
Properties of the DIENCEPHALON (3)
A
- Consists of the thalamus and hypothalamus.
- THALAMUS: Relays most sensory stimuli to the cerebral cortex.
- HYPOTHALAMUS: Controls body temperature, appetite, emotions and various automatic functions.
7
Q
Properties of the LIMBIC SYSTEM (1)
A
- Composed of a collection of structures that regulate basic drives.
→ i.e Hunger, aggression, emotional drives.
8
Q
Properties of the RETICULAR ACTIVATING SYSTEM (4)
A
- Network of neurons.
- Fans out through the cerebral cortex.
- Directs information to appropriate centers for interpretation.
- Crucial for maintaining consciousness.
9
Q
What is the PERIPHERAL NERVOUS SYSTEM? (3)
A
- Carries information in and out of the CNS using 2 different kinds of nerves:
- MOTOR NERVES - aka efferent (outwards) nerves carry information from the CNS to the body’s organs.
- SENSORY NERVES - aka afferent (inwards) nerves carry information from sensory receptors to the CNS.
10
Q
Explain the AUTOMATIC NERVOUS SYSTEM (3)
A
- Subsystem of the PNS
- Controls involuntary actions (i.e heartbeat)
- Comprised of two branches that act as opposing systems:
→ SYMPATHETIC SYSTEM
→ PARASYMPATHETIC SYSTEM
11
Q
Explain the SYMPATHETIC SYSTEM (2)
A
- Causes localized bodily adjustments to occur (i.e sweating)
- Prepares the body for emergencies
→ Involves release of adrenaline, increase heart rate, widening blood vessels and “fight for flight” response.
12
Q
Explain the PARASYMPATHETIC SYSTEM (1)
A
- Helps the body return to normal after it has been altered by the sympathetic system.
→ Sympathetic system will increase heart rate, parasympathetic system will decrease heart rate to bring it back to its resting state.
13
Q
Explain the SOMATIC NERVOUS SYSTEM (4)
A
- Responsible for our awareness of the external environment.
- Through this system, the PNS receives and processes information from receptors in the skin, voluntary, muscles, tendons and joints.
- Gives sensation of touch, pain, heat, cold balance, body position and muscle action.
- Handles the muscles in our extremities which allows us to move.
14
Q
Introduction to the REFLEX ARC (3)
A
- Reflexes are an automatic and rapid response to a particular situation.
- If the command center for the reflex is located in the brain, it is called CEREBRAL REFLEX.
- If the command center of the reflex is located in the spinal cord, it is called SPINAL REFLEX.
15
Q
What are AUTONOMIC REFLEXES? (3)
A
- Controlled by the autonomic division of the nervous system.
- Involve activation of smooth and cardiac muscles (involuntary muscles).
- Regulates bodily functions such as digestion, elimination, blood pressure, salivation and sweating.
16
Q
What are SOMATIC REFLEXES? (1)
A
- Involve stimulation of skeletal muscles
voluntary muscles
17
Q
Explain the REFLEX ARC (1) (5 steps)
A
The name given to the pathways along which the initial stimulus and corresponding response (message)
- RECEPTOR: Receives the initial stimulus i.e load noise.
- SENSORY NERVE (afferent nerve): carries the impulse to the spinal cord or brain.
- INTERMEDIATE NERVE FIBRE: Interprets the signal and issues an appropriate response.
- MOTOR NERVE (efferent nerve): carries the response message from the spinal cord to the muscle or organ.
- EFFECTOR ORGAN: Carries out the response i.e skeletal muscle moves hand away from danger.
18
Q
What are PROPRIOCEPTORS? (3)
A
- Specialized receptors found in tendons, muscles and joints.
- Provides sensory information about the state of muscle contraction, the position of limbs and body posture and balance.
- This feedback is provided primarily by afferent (sensory) input from two sensory receptors:
→ Golgi tendon organs (GTO)
→ Muscle spindles
19
Q
What are GOLGI TENDON ORGANS (5)
A
- Sensory receptors that terminate where tendons join the muscle fibers.
- Since they are aligned with the muscle, any stretching of the muscle also stretches the GTO.
- The job of GTO is to detect increased tension exerted in the tendon.
- When a change in tension is detected, an impulse is sent along AFFERENT (sensory) neurons to the CNS.
- The EFFERENT (motor) neurons transmit an impulse causing the muscle to relax, thus preventing injury.
20
Q
What are MUSCLE SPINDLES (3)
A
- Lies parallel to the muscle fiber.
- Send constant signals to the spinal cord.
- Helps maintain muscle tension and tone (standing posture)
→ Unlike GTO, they are sensitive to change in length, not tension.
21
Q
Explain the STRETCH REFLEX (2)
A
- Simplest spinal reflex.
2. Depends only on the single connection between primary afferent fibers (sensory) and motor neurons of the same muscle.
22
Q
STEPS to the stretch reflex (5)
A
- The receptor (patellar ligament/ quadriceps groups) senses the act of the hammer against the patellar ligament through the MUSCLE SPINDLE (due to change in length).
- Message is transmitted along the afferent (sensory) nerve axon to the spinal cord.
- The afferent nerve synapses with the efferent pathway (motor nerve) at the intermediate nerve fiber.
- An impulse is transmitted along the efferent pathways (motor neurons) to the muscle.
- The motor units of the quadriceps contract to accommodate additional stretch and prevent injury.
23
Q
What is RECIPROCAL INHIBITION? (2)
A
- During a reflex, the opposing muscle group is simultaneously stimulated.
- In a knee-jerk reflex the quadriceps contract to extend the knee while the hamstrings are inhibited in a slightly delayed response (they do not flex)
24
Q
What are POLYSYNAPTIC REFLEXES? (2)
A
- With other spinal reflexes, one or more interneurons lie between the primary sensory fibers and the motor neurons.
- the more interactions involved, the more complex and slow the reflex.
25
What is the WITHDRAWAL REFLEX? (3)
1. The withdrawal of a body part from a painful stimulus (body is in danger).
2. Reflex action involves transferring the impulse from a sensory neuron to a motor neuron through a connecting interneuron in the spinal cord.
3. Extremely rapid, the brain doesn't have time to interpret information.
26
What is REFLEX TESTING? (3)
1. Important medical diagnostic tool.
2. Weakm exaggerated or absent reflex response may indicate problems with portions of the nervous system.
3. Can help determine the exact area of spinal injury.
27
Explain SPINAL CORD INJURIES (3)
1. When the spinal cord receives a severe impact damage to the spine, it can affect its ability to send impulses to body parts.
2. When there is a serious injury to the spinal cord, the nerves about the injury keep working.
3. The nerves below the injury may or may not still function.
28
What is PARAPLEGIA? (1)
1. The injury prevents the use of the legs but NOT the arms (injury on the spinal cord, after the neck).
29
What is QUADRAPLEGIA? (1)
1. The injury prevents movement in both the arms and legs (injury at the beginning of the spinal cord).
30
What is the REHABILITATION process (3)
1. Involves extensive physiotherapy (maybe surgery).
2. Counselling to help the person and their family deal with the new situation.
3. May be able to regain mobility in damaged limbs (after swelling has gone down).
31
Head injuries - CONCUSSIONS (3)
1. Much more common than spinal cord injuries.
2. CONCUSSIONS result from a blow to the head, literally shaking the brain within the skull.
→ Often involves injury to the nerve fibers.
→ Can be mild or severe.
→ Brain cells become abnormal and do not function properly.
3. Second direct or indirect impact can cause dangerous changes in the brain's blood supply.
→ Leads to rapid swelling leading to coma or death.
32
Vertebral Column and the Spinal Cord (4)
1. Main pathway for information connecting the brain and peripheral nervous system.
2. Spinal cord runs through the vertebrae.
→ Starts from the base of the brain stem and travels down to the second lumbar vertebra.
→ Spinal nerves carry sensory information towards the CNS and motor commands away from the CNS.
