Fatima Failsal Flashcards
How much % of body mass does skeletal muscle make up
40%
What is the stimulus for skeletal muscle contraction
Changing calcium ion concentration
What are the divisions of muscle fascilus 4
Muscle fibre
Myofibril
Myofilament
What is the region between 2 z lines
Sarcomere
What is the light band
Actin and myosin don’t overlap
What is the dark band
Actin and myosin overlap
What is the z line
Centre of each light band
What is the H zone
Centre of each dark band where only myosin present
What is the role of tropomyosin
To block actin myosin binding sites of actin at rest, held in place by troponin
What do globular heads of myosin bind to
Actin and ATP
What is the action of actin and myosin
4
1 calcium binding to troponin causes conformational changes which expose binding sites of actin
2 myosin head forms bond with actin filament called actin myosin cross bridges
3 myosin heads flex in unison pulling actin filament along myosin filament
4 myosin head detaches from actin using ATP and returns to original position
What happens during stimulation of the sarcolemma
5
1 action potential reaches synaptic knob of motor neurone
2 calcium ion channels stimulated to open so calcium floods into neurone through voltage gated channels
3 acetylcholine is released into neuromuscular junction by exocytosis
4 acetylcholine binds to nicotinic acetylcholine receptors on sarcolemma which are ligand gated receptors opening sodium ion channels
5 sodium diffuses into sarcoplasm causing depolarisation and action potential
What happens during stimulation of the sarcoplasm
7
1 AP in sarcolemma travels down Ttubules to sarcoplasmic reticulum
2 calcium ions are released from SR into sarcoplasm
3 calcium ions bind to troponin so tropomyosin pulled away from myosin binding sites of actin and myosin heads bond to form cross bridges
4 myosin head flexes and pulls actin filament along
5 ATP binds to myosin head causing it to release
6 after AP calcium reuptaken into SR by active transport
7 tropomyosin restored
What are the roles of ATP in skeletal muscle
3
Active transport of calcium into SR
Returning of myosin head to resting position
Myosin power stroke
Define extrafusal contractile fibres
Fibres that generate force of contraction
Define intrafusal contractile fibres
Sensory fibres that monitor change in muscle length, they can contract but don’t contribute much to contraction force
What are the types of muscle propreoceprors
3
Muscle spindles
Golgi tendon organs
Joint and skin sensors
What do muscle spindles do
What do they cause
In skeletal muscle monitor muscle length to prevent over stretching, with intrafusal fibres deep and extrafusal fibres surrounding
Cause contraction when triggered to prevent over stretching
Where are golgi tendon organs located
What do they consist of
What do they detect
What do they trigger
Located at junction between skeletal muscle and tendon
Connective tissue capsule filled with collagen fibres interwoven with sensory nerve endings
Detect muscle tension to prevent over contraction, during contraction collagen fibres pulled tight which compresses nerve endings and opens mechanosensitive channels to increase firing of inhibitory neurones in spinal chord
Cause relaxation to prevent over stretching
What do joint and skin receptors do
Detect how hard skin being stretched over joint to provide info like grip force
What happens during knee jerk reflex
Hitting patella tendon stimulated muscle spindles propreoceptors which send out 1 sensory signal
2 motor signals are related causing contraction of quad and relaxation of hamstring
What happens during golgi tendon reflex
Golgi tendon organ responds to muscle tension
Interneurones stimulated and alpha motor input inhibited
Muscle inhibited and antagonistic muscle activated to aid fine movement
What happens during the flexion reflex
Nocioceptors send signals to spinal chord and alpha motor neurones cause contraction of flexors with inhibition if antagonistic muscle to cause withdrawal
How many muscle pairs are involved in swallowing
25 pairs in pharynx, larynx and oesophagus
What is the overveiw of swallowing
Stimulation of pharyngeal mucosa
Impulses sent via cranial nerves 5, 9 and 10 to nucleus tractus solitarius in brainstem
Signals receive input from higher centres and interact with other brainstem nuclei
Motor signals sent to pharyngeal and laryngeal muscles by cranial nerve 10 and upper cerviacle nerves C1-3
What are the phases of swallowing
3
Oral phase
Pharyngeal phase
Oesophageal phase
What happens during the oral phase of swallowing
Voluntary phase
Chewing, bolus formation, bolus pushed to pharynx by tongue, tongue to palatial surface, bolus propelled backward
What happens during the pharyngeal phase of swallowing
Sensory input goes to nucleus of tractus solitarius which receives input from nucleus ambigus (swallowing centre) in brainstem which coordinates the swallowing response
Response involves inhibition of respiration, elevation of soft palate, glottis closing, elevation of larynx, adduction of vocal chords, contraction of aryepiglottic muscle to pull epiglottis over laryngeal opening, pharyngo oesophageal sphincter opening
What is the fringe benefit of the pharyngeal phase
Activation of pharyngeal muscles pull open Eustachian tubes which reduces pressure in eardrum
What happens do oesophageal phase of swallowing
Peristalsis propels food towards stomach and gastro oesophageal sphincter opens and food passes through into stomach
What is dysphagia
Sensation of food or liquid sticking in oesophagus during swallowing
What is the process of sneezing
6
Irritation of receptors in nasal mucosa Deep inspiration Glottis closes Uvula and soft palate depressed Diaphragm contracts against closed glottis Glottis opens and pressure released
What is the process of coughing
6
Mechano and chemoreceptors stimulated and signals sent via inferior laryngeal nerve
Signals reach higher centres and brainstem
Signals sent to inspire 2-2.5l of air via vagus and phrenic nerve
Glottis closes
Abdominal muscles contract to increase intrathoracic pressure
Glottis opens and pressure released
What is a laryngospasm
Spasmodic contraction of larynx causing glottic closure to prevent aspiration
What happens do prodromal phase of vomiting
Sympathetic over activity
What are the stages of vomiting
Nausea
Reaching
Emesis
What happens during gagging
3
Pharyngeal stimulation
Signals to vomiting area of brain
Simultaneous contraction against closed glottis
What muscles constrict during gagging
Pharyngeal constrictor Inspiratory muscles Diaphragm Muscles of anterior abdominal wall Smooth muscle of stomach wall
What happens during emesis 2
Relaxation of gastro oesophageal sphincter
Closure of epiglottis
What allows humans to speak 3
Low position of larynx in neck
Velopharyngeal mechanism
Highly developed brain
The TMJ is synovial, what does this mean?
Bones of joint joined with fibrous joint capsule, joint has synovial cavities containing synovial fluid
The TMJ is ginglymoarthroidal, what does this mean?
Both a ginglymus joint with hinge movement and an arthrodial joint with sliding movements
What type of cartilage is the articular disk of TMJ made of
Fibrocartilage
What are the layers of the articular surface of condyle and what are they made of
4
Calcified cartilage
Fibrocartilagenous layer
Cell rich layer
Superficial articular surface
What are the differences between cartilage and fibrocartilage
3
Cartilage made of type 2 collagen, fibro type 1
Cartilage has no cell contacts, fibro has cell connections
Cartilage has pericellular matrix, fibro doesn’t
What is the role of articular joint capsule
Attaches condyle to temporal bone and holds in synovial fluid
What does stylomandibular ligament do
Limits excessive protrusion
What does sphenomandibular ligament do
Supports rotation of mandible
What does temporomandibular ligament do
Goes over top of capsule from articular eminence of temporal bone to lateral surface condyle neck to prevent excess posterior movement of TMJ
What innervates TMJ
Auricular temporal branch of mandibular nerve
What muscles are in the infra temporal fossa
3
Temporalis
Lateral pterygoid
Medial pterygoid
Which nerves are in the infra temporal fossa
3
Otic ganglion
Mandibular
Chorda tympani
What ligament is within infra temporal fossa
Sphenomandibular
What are the properties of the articular disc
4
Non innervated
Posterior, intermediate, anterior regions
Superior head of lateral pterygoid inserts into anterior part
Condyle in contact with intermediate part
What is the difference between the superior and inferior lamina of bilaminar zone
What is between the zones
Superior elastic
Inferior non elastic
Loose connective tissue
What are the properties of the bilaminar zone of TMJ
2
Highly vascular
Innervated
How much does the TMJ move
40-70 mm
What are the 2 stages of jaw opening
Rotation- hinge movement, inferior joint cavity, first 20mm
Translation- gliding movement, superior joint cavity, condyle and disk slide onto articular eminence
Define ageusia
Inability to taste
Define hypoguesia
Decreased ability to taste
Define dysgeusia
Distorted ability to taste
Define cacogeusia
Sensation of bad taste in absence of stimuli
Define anosmia Hyposmia Dysosmia Parosmia Phantosmia Agnosia
Inability to detect odour
Decreased ability to detect odour
Distorted identification of smell
Altered perception of smell in presence of certain odour
Perception of smell without odour present
Inability to contrast or classify odours
Which papillae house taste buds
Circumvalate
Foliate
Fungiform
How many cells are in a taste bud
50-80
What are type 1 cells
What do they detect
What do they do
Glial like
Salty
Degrade and absorb neurotransmitter
What are type 2 cells
What do they taste
What is a key part of their structure
Receptor cells
Bitter umami sweet
Microvilli
What are type 3 cells
What do they taste
What do they do
Presynaptic cells
Sour
Form synaptic junctions with nerves and receive input from receptor cells (2)
What are the afferent pathways of taste cells
4
Chorda tympani to nervus intermedius
Greater superficial petrosal to nervus intermedius
Glossopharyngeal
Vagus
What is the diameter of the olfactory mucosa and what does it contain
3cm
Olfactory neurones and oderant receptors
How many types of olfactory receptors
What type of receptors are olfactory receptors
1000
G protein coupled receptors
What are turbinates
Structures that direct inspired air toward olfactory epithelium, also called conchae
What are the cell types in olfactory epithelium
4
Olfactory receptor cells
Supporting cells
Basal cells
Brush cells
What is the role of olfactory receptor cells
Detects odourants
Where are supporting cells located
What are the types of supporting cell and what do they do
Apical layer of pseudostratified cilliated columnar epithelium
Sustentacular cells provide metabolic and physical support
Microvillar cells express cKIT cell surface protein
What are the basal cells, where are they located, what do they do
Stem cells
Basal lamina
Smdifferentiate into receptor or supporting cells
What are brush cells
What do they do
Microvilli bearing cells which transduce general sensation to trigeminal nerve
