Lecture 4 NS Physio III Flashcards
What’s the function of the midbrain ?
Controls auditory and visual REFLEXES
Movement of eyes, head and neck in response to visual and auditory stimuli.
What comprises the brain stem?
Midbrain , pons, medulla
What is the function of the pons?
Functions with medulla to regulate breathing
Pontine respiratory centers controls rate and depth of breathing
Where in the midbrain does decussation occur ? What happens a a result of this?
Medulla Oblongata
The left portion of the brain will receive information from the right side of the body and control the right skeletal muscles
The medulla Oblongata houses vital reflex centers, what are they?
Respiratory ( drives breathing role)
Vasomotor(controls blood vessel diameter)
Cardiac center (modifies heart rate)
Medulla Oblongata also controls “other centers” other than vital centers, what are they?
Swallowing , Vomiting , Coughing
Sneezing
What is the overall function of the brain stem?
Controls life sustaining processes like breathing and circulation
If the entire brain cortex was damaged except the brain stem, what would happen?
The individual would be alive but unaware and they would have no conscious control
The hypothalamus is apart of the diancephalon superior to the midbrain and is extremely important. It regulates the ANS… Which regulates ..
Autonomic nervous system
Smooth, cardiac muscle and glands
T or f the hypothalamus regulates, the endocrine system, body temperature, food and water intake( via body fluid concentration)
True
The hypothalamus is part of the limbic system (along with the thalamus and the cerebrum) what is the limbic system responsible for?
It is “the emotional brain”
Basic emotions
Like rage and fear
The hypothalamus co-ordinates the reticular activating system (RAS)
The reticular formation is located in the brain stem, what is it’s function?
ALERTING
RAS Receives incoming sensory input for awakening
Alerting thalamus, cortex, hypothalamus and reticular formation
It also receives input from the visual system used to set daily rhythms
The hypothalamus receives sensory input from cutaneous receptors of nipples and external genetalia… Therefore it is involved with
Sexual arousal and associated behaviours
Damage of hypothalamus leads to
Loss of homeostasis
It has major homeostatic functions
The efferent nervous system is comprised of
A
B
A) the ANS ( cardiac, smooth, gland)
B) the Somatic NS skeletal muscle as effector)
Various levels of the brain involved
The ANS has 2 further subdivisions
They are
Sympathetic and parasympathetic
The SNS or sympathetic nervous system pathway from CNS to effector is
CNS (spinal nerves t1 - L2) to >preganglionic neuron to >ganglion > post ganglionic neuron to effector
What neurotransmitter is most commonly released via post ganglionic neuron of sympathetic ND
Norepinephrine NE
What NT is released between pre and post ganglionic neurons of SNS
ACh
The preganglionic neuron of SNS is said to be ______________
The post ganglionic is _________ or
Pre- Cholinergic (acetylcholine releasing)
Post- Adrenergic (NE)
What is the function of the sympathetic nervous system ?
Prepares the body for activity
Fight or flight
What breaks down norepinephrine and where?
Monoamine Oxidase (MAO) In PRESYNAPTIC NEURON
Another division on the ANS is the PSNS
What part of CNS is associated with it ?
CNS = sacral portion of spinal cord
>preganglionic neuron :; ACh postganglionic neuron ;; ACh
Pre ganglionic neurons of PSNS and SNS are both __________.
________ is broken down by _______ on receiving cell membrane.
Cholinergic
ACh broken down by acetylcholinesterase on receiving cell membrane or post synaptic membrane
What is the function of the PSNS ?
rest and digest “house keeping”
Most organs are innervated by ANS have both SNS and PSNS and the effects are usually opposite , give an example
Heart rate is excited by SNS and inhibited by PSNS
Or
Motility of the GI tract: excited by PSNS and inhibited by SNS
Effects of SNS on Pupil Heart GI tract Blood vessel Gland Genitals
Pupil: dilate Heart: increase HR GI: inhibit motility Blood vessels: vasoconstriction Glands: (sweat) increase secretion Genitals: ejaculation in male
Effects of PSNS on Pupil Heart GI tract Blood vessel Gland Genitals
Pupil: constricts
Heart: decrease HR
GI : increase motility
Bvessels: no innervation except p and clitoris
Glands: no innervation at all
Genitals: erection and lubricant of vagina
Describe higher order of ANS to it’s divisions SNS / PSNS
Cerebrum including limbic system To Hypothalamus To Medulla Oblongata To And To PSNS and SNS
Somatic nervous system
From CNS to _____ to effector (skeletal muscle)
Lower motor neuron
There are 3 types of movement, what are they?
Reflexes
Voluntary movement
Rhythmic
There are 2 types I reflexes what are they and describe them
A) spinal reflexes : least complex. Require sensory input (eg muscle spindle)
b) postural reflex: for balence and posture. Require sense input from proprioceptors (eyes ,inner ear)
Describe voluntary movement
Most complex
No external stimuli required
What is rhythmic movement
Walking or running
It is a complex of voluntary and reflex movement
Initiated and ended by cerebrum, but input from cerebrum not required once it has begun
Level 1 of motor control entails
Planning Move ? If yes what movement needed Plan sequence of muscle contractions Signals primary cortex Works with input from cerebellum
Level 2 of motor control
Signals directly to motor neurons
Down cortical spinal tract
For fine skilled movements
Level 3 of motor control
Brain stem nuclei
Decendin motor tracts to lower motor neurons = indirect tracts
Receive input from cortex, basal nuclei, cerebellum
Coordination of large muscle groups
Involved in posture and locomotion
Level 4 of motor control
Spinal cord contains cell body of lower motor neurons
Networks of neurons (central pattern generators CPGs) set rhythmic repeated movements (runningetc)
Requires cortical (cortex) input to begin or stop movement
Corticospinal tract is
Also pyrimidal tracts
Conducts impulses from brain to spinal cord
What are central pattern generators
Set rhythmic and repeated movements
Associated with level 4 motor control
Cerebellum has many roles in movement. One is planning and initiating movement… Where is the imput sent ?
Cortical areas
cerebellum stores planned movement and compares actual movement to the plan using sensory input (eg from proprioceptors) so that it may
Correct plan if necessary
Cerebellum maintains balence, controls eye movements, role in maintaining muscle tone… It also coordinates _____ movements and timing of contractions involving ___ or more joint
Voluntary
One or more
Basal nuclei along with cerebellum aid in
Planning movement and maintaining muscle tone
Basal nuclei suppresses unwanted movements
corticospinal pathway is a direct pathway descending to skeletal muscle from the cortex for
Fine precise movements
What are upper motor neurons
Part of the corticospinal pathway
Cell bodies that are located in motor areas of frontal cortex (primary motor cortex)
Axons move into spinal cord
what are lower motor neurons
Part of the corticospinal pathway
Cell bodies located in VENTRAL horn of spinal cord
What would happen if there was a destruction of upper motor neurons?
Reflex arc is present: get
A) spastic paralysis - increased muscle tone ( low level of contraction ) no atrophy
B) exaggerated reflexes eg. Patellar, Achilles, babinski
Describe babinski reflex
Normal : plantar flexion / all toes curl under
Babinski: extend big toe
If babies under 2 get sign > corticospinal tract is unmyelinated
Asses damage to NS
What happens when there is destruction of lower motor neurons
No reflex arc is present
A)Get flaccidity > decreased muscle tone
Muscle atrophy
B) no reflex action
Describe how polio elicits a no reflex action
Polio destroys cell bodies of ventral horn of spinal cord ( lower motor neurons ) > flaccid paralysis
Language areas in brain are located
In left cortex in most people
99 % of right handed people
67% of left handle people
For language, the cortex is responsible for
Concepts and ideas
Wernikes area located in
Broca’s area located in
Parietal and temporal for wernikes
Frontal for Broca’s
Broca’s area, wernickes area and basal nuclei form a
Single language implementation system that analyzes incoming and produces outgoing word sounds and grammatical structures
Damage to wernickes area produces
Inability to understand spoken or written words
Can speak but words are meaningless
Inappropriate or mixed up grammar
Damage to Broca’s Area elicits
Can understand language but cannot produce speech that is sensible
