Exam Flashcards
3 places where single unit smooth muscle is found
- Digestive tract
- Urinary tract
- Reproductive tracts
3 places where multi-unit smooth muscle is found
- eye muscles
- blood vessels
- pili muscles (skin)
Describe the mechanism for excitation-contraction coupling in smooth muscle
Action potential or hormones can provide the rise in cytoplasmic Ca2+.
• Ca2+ binds to calmodulin
• The complex of Ca2+ and calmodulin together activates the enzyme MLCK (myosin
light chain kinase), which activates MLC (myosin light chain) via phosphorylation.
• This activates the cross-bridge.
List the 4 somatic and visceral sensations
- Touch
- Warm/cold
- Pain
- Body position
List the 5 special senses
- Taste
- Smell
- Hearing
- Vision
- Balance
What are the three methods of information input into the CNS? Give an example
- Direct (e.g. temperature sensing in hypothalamus)
- Endocrine (e.g. control of food intake)
- Nervous
What four types of information describe a sensory stimulus?
- Modality (type)
- Duration
- Intensity (frequency of AP firing)
- Location (of AP receptor)
Where in the muscle are the length receptors used for proprioception found?
Muscle spindle
Where in the muscle are the tension receptors used for proprioception found?
Golgi tendon organ
What receptor adapt slowly? Rapidly?
Slow - stretch receptors
Rapid - touch receptors
Describe the axons that nociceptors for fast/acute pain send signals through. What is the name for these fibres?
- Large, myelinated
- A fibres
Describe the axons that nociceptors for slow/chronic pain send signals through. What is the name for these fibres? Fast/slow conduction?
- Small, unmyelinated axons.
- B fibres.
- Slow conduction
Which of the following goes up and across? Which goes across and up?
- Somatic sensory – medial lemniscal (dorsal column)
- Somatic sensory– lateral spinothalamic (anterolateral)
- Up and across
2. Across and up
What is the Somatic sensory – medial lemniscal (dorsal column) pathway for?
- Fine touch and proprioception
What is the somatic sensory - lateral spinothalamic (anterolateral) pathway for?
- Pain
- Temperature
- Crude touch
What is the somatic motor – pyramidal (corticospinal) pathway for?
Precise movement (hands and feet)
In the withdrawal reflex, what happens ipsilaterally?
Interneurons and afferent neurons excite flexors, inhibit extensors.
In the withdrawal reflex, what happens contralaterally?
Interneurons and afferent neurons excite extensors, inhibit flexors.
(Stabilise)
Name the basal nuclei
- caudate nucleus
- amygdaloid
- lentiform nucleus
Where do sympathetic pre-ganglionic neurons emerge from the spinal
cord?
Thoracolumbar levels
Where do parasympathetic pre-ganglionic neurons emerge from the spinal cord?
Craniosacral levels
What is the neurotransmitter for a cholinergic neuron?
ACh
What is the NT for a adrenergic neuron?
NE
Are parasympathetic neurons cholinergic or adrenergic?
Cholinergic
Are sympathetic neurons cholinergic or adrenergic?
Can be both
What type of receptor is ionotropic? What is the effect?
Nicotinic cholinergic - excitatory
Where is adrenaline released from? How is this area innervated by the autonomic nervous system?
- Adrenal medulla
- Directly from first neuron in spinal cord (i.e. not via postganglionic neuron)
Name the CNS glia & their function
- Astrocytes: supply nutrients to neurons, ensheath blood capillaries, transmit info.
- Microglia: immune cells, engulf microorganisms and debris
- Ependymal cells: line fluid-filled spaces in brain and spinal cord, circulate CSF (cilia)
- Oligodendrocytes: form myelin sheath, support nerve fibres
What is the PNS glia? What’s its function?
- Schwann cells; form myelin sheet, support peripheral nerve fibres
What are the 3 morphological types of neuron?
- Multipolar
- Unipolar
- Bipolar
What are the 3 types of synapse?
- Axodendric
- Axosomatic
- Axoaxonic
Where in the spine do sympathetic nerves exit from?
Where do they synapse with the post-ganglionic neuron?
Thoracolumbar levels Sympathetic ganglion (short distance from spinal cord)
Where in the spine do parasympathetic nerves exit from?
Where do they synapse with the post-ganglionic neuron?
Craniosacral levels
In ganglion in/near effector organs (far from spinal cord)
What are the 4 structures associated with the spinal cord?
- Meningeal sack
- Conus medularis
- Filum terminale
- Cauda equina
Where does sensory info enter the spinal cord?
In dorsal roots
Where does motor info leave the spinal cord? (Somatic & autonomic)
Through ventral roots:
- somatic in ventral horns
- autonomic in lateral horns
Where do spinal nerves go once they leave the spinal column?
Break into two branches: dorsal and ventral rami
Ventral ramus communicates w/ sympathetic chain
Facial bones
- Zygomatic (x2)
- Maxillary (x2)
- Nasal (x2)
- Mandible
What are the 3 sutures of the skull? What bones do they separate?
- Coronal (frontal-parietal)
- Lambdoidal (parietal-occipital)
- Squamous (Temporal-parietal)
What is the name for the gaps substituting for sutures in infants?
Fontanelles
What are the 3 dural reflections?
- Falx cerebri (separates two hemispheres of cerebrum)
- Falx cerebelli (separates two hemispheres of the cerebellum)
- Tentorium cerebelli (separates cerebrum and cerebellum)
Circulation of the CSF in the ventricular system
Choroid plexus –> lateral ventricles –> third ventricle –> cerebral aqueduct –> fourth ventricle –> subarachnoid space
4 major sulci and fissures
- Central sulcus (divides frontal and parietal lobes)
- Parieto-occipital sulcus
- Lateral sulcus (perpendicular to central sulcus)
- Transverse fissure (gap b/w cerebrum & cerebellum)
2 major gyri
- Pre-central gyrus
2. Post-central gyrus
What are the two divisions of the motor cortex and how are they involved with voluntary movement?
- Pre-motor cortex: planning of movement
2. Primary motor cortex: execution of movement
What are the 4 major divisions of the brain and what structures do they include?
- Cerebrum
- Diencephalon: thalamus and hypothalamus
- Cerebellum
- Brainstem: Mid-brain, pons, medulla oblongata
Three types of white matter (tracts) in the brain
- Commissural tracts (side to side)
- Projection tacts (extend from motor cortex)
- Association tracts (same side)
Corticospinal tract:
- Controls?
- Where are cell bodies?
- Where does it cross over?
- Where does it synpase?
- Controls somatic motor neuron
- Cell bodies in primary motor cortex
- Cross in medulla
- Synapse in ventral horn of spinal cord
Simple somatic sensory pathway:
- Ascends in?
- Synapse in?
- Cross where?
- Second synapse?
- Terminates in?
- Ascends dorsal white columns
- Synapse in medulla
- Up and across
- Synapse in thalamus
- Ends in somatosensory cortex
What are the 5 nuclei that make up the basal ganglia?
- Caudate
- Putamen
- Globus pallidus
- Subthalamic nucleus
- substantia nigra
What are the concentrations of Na+ and K+ inside and outside the cell?
Inside: Na+ 12mM & K+ 150mM
Outside: Na+ 142mM & K+ 4mM
What does the sodium potassium pump move b/w the cell membrane?
2 K+ in
3 Na+ out
What are the 3 ways the synapse is switched off? Why does this occur?
Excess transmitter into cleft; removed by:
- Degradation by enzymes
- Reuptake into the bouton
- Reuptake into glia
Types of neurotransmitters (and excitatory or inhibitory)
- ACh; excitatory
- NE; inhibitory or excitatory
- Glutamate; excitatory
- GABA; inhibitory
Divergent networks
- Info from pre-synaptic cell diverges to activate 2+ post-synaptic neurons
- Allows a single signal to arrive at multiple brain regions
- Amplifies signal
Convergent networks
- Info from different brain regions converge to activate only 1 post-synaptic motorneuron (that excites a single muscle group)
- Allows redundancy
Function of the 3 types of muscle (skeletal, cardiac and smooth)
Cardiac - pump blood
Smooth - movement of fluids
Skeletal - generate heat, posture, movement
What are the thin and thick myofilaments?
Thin: actin, troponin, tropomysin
Thick: myosin, myosin heads
What is the mechanism for contraction? State the important parts of each step.
- Excitation: AP reaches bouton; Ca2+ entry; release of ACh; depolarisation of sarcolemma; initiation of AP
- Contraction: Ca2+ release from SR; cross bridge formation (actin and myosin); contraction
- Relaxation: Ca2+ reuptake; uncoupling of crossbridge
How long is the contraction for ATP? CP?
ATP: 2-4s
CP: approx. 20s
What are the 3 types of muscle fibres? Why are the coloured?
- Red; high myoglobin; high aerobic enzymes
- White; low myoglobin; low aerobic enzymes
- Intermediate; mixture; aerobic and anaerobic
Compare the muscle fibre types (in terms of rate of interaction w/ actin and force production)
- Red (Myosin type I): slow rate & slow force production & slow energy consumption
- White (Myosin type IIx): fast rate & fast force production & fast energy production
- Intermediate (Myosin type IIa); mixture
Difference b/w physiological fatigue and psychological fatigue
- Physiological: ATP depletion, buildup of by-products
- Psychological: feedback to brain producing sensation of fatigue
Structure of the 3 types of muscle
Cardiac: striated, intercalated discs, branched
Skeletal: striated, thin, cylindrical,
Smooth: non-striated (net)
Smooth muscle contraction
- AP or hormones provide Ca2+ rise
- Ca2+ binds to calmodulin
- Ca-calmodulin complex activates MLCK
- MLCK activates MLC which activates the crossbridge
Afferent pathway for touch and posture (dorsal column pathway):
- How many neurons in relay?
- Cross immediately or delayed?
- Starts and ends?
- 3 neurons
- Up and across
- Primary sensory neuron –> somatosensory ortex
Afferent pathway for pain (anterolateral pathway):
- How many neurons in relay?
- Cross immediately or delayed?
- Starts and ends?
- 3+ (can have interneurons)
- Across and up
- Primary sensory neuron –> somatosensory cortex
Somatic control (What does it control? Same pathway or different?)
- Control of skeletal muscle
- Reflex movements
- Precise, voluntary movements
- Autonomic movements
> All via a final common pathway
What two things occur simultaneously during a withdrawal reflex?
- Withdrawal from stimulus
2. Opposite side of body is activated to reverse the effect of withdrawal (stabilise)
Corticospinal pathway (pyramidal tract):
- Controls?
- How many neurons?
- Crosses over where?
- Starts and ends where?
- Fine control of the digits
- 2 neurons
- Crosses over at medulla
- Primary motor cortex –> effector
Somatic vs autonomic efferent pathway:
- how many neurons b/w CNS and effector
- what muscle does it innervate?
- excitatory or inhibitory?
- 1 (S) vs. 2 (A)
- Skeletal muscle (S) vs. Smooth muscle, cardiac muscle, glands (A)
- Excitatory (S) vs. excitatory or inhibitory (A)
Where do sympathetic and parasympathetic neurons emerge from (in the spinal cord)
Sympathetic: thoracolumbar levels
Parasympathetic: craniosacral levels
Ionotropic receptors
- receptors contain an ion channel
- nicotinic cholinergic (releases ACh)
- Depolarising and excitatory
Metabotropic
- receptors linked to intracellular messengers
- muscarinic cholinergic
- adrenergic (releases NE)
- excitatory or inhibitory
What are the major endocrine glands? (6 - not including reproductive)
- Hypothalamus
- Pituitary gland
- Thyroid gland
- Adrenal glands (2)
- Pancreas
Main steps for cellular response to water-soluble hormones
- Hormone binds to receptor in cell membrane
- Receptor activates associated protein
- Protein activates enzyme
- Second messenger produced
- Second protein activated
- second enzyme activated
- Enzyme converts substrate to product (cell’s response)
Main steps for cellular response to lipid-soluble hormones
- Hormone dissociates from carrier protein
- Diffuses through cell membrane
- Binds to receptor in cytoplasm
- Hormone-receptor complex acts as transcription factor
- New mRNA generated
- New protein generated
- Protein mediates specific response
Compare the storage of the two types of hormone
Water soluble: stored until required
Lipid soluble: Made as required (except for thyroid hormone)
Compare the fed state and fasting state
Fed state: anabolism, uptake of nutrients; synthesis/storage of glycogen, protein and fat
Fasting state: catabolism, breakdown of nutrients, breakdown of glycogen, protein and fat
What hormones maintain the blood glucose concentration? What is the reference range?
- Insulin (decreases) and glucagon (increases)
- 3.5-6mM
Type I diabetes:
- cause
- symptoms
- treatment
- diagnosis age
- Beta cells destroyed –> low/no insulin
- high blood glucose conc. (hyperglycaemia), glucose in urine (glycosuria), polydipsia, polyphagia, polyuria
- Insulin injections & trialling human/pig islet transplantation
- Young/childhood (usually)
Type II diabetes
- cause
- symptoms
- treatment
- diagnosis age
- Insulin resistant cells –> low insulin levels
- high blood glucose conc. (hyperglycaemia), glucose in urine (glycosuria), polydipsia, polyphagia, polyuria
- drugs promoting insulin release, exercise, sometimes insulin injections
- Used to be an adult disease, but more prevalent in kids
What can hyperglycaemia cause over time? (e.g. diseases)
- Atherosclerosis (can lead to heart attack, stroke)
- Blindness
- Nerve damage
- kidney disease
What happens when bg conc. decreases?
- Alpha cells secrete glucagon
- Liver cells: increase glycogenolysis, increase gluconeogenesis, increase ketone synthesis
- bg conc. increases
- negative feedback
- note: GH, adrenalin and cortisol also increase bg level
What happens when bg conc. increases?
- Beta cells secrete insulin
- Liver cells: decrease glycogenolysis, decrease gluconeogenesis, decrease ketone synthesis
- bg conc. decreases
- negative feedback
Posterior pituitary:
- What hormones does it release?
- What do these hormones do?
- How does it communicate w/ the hypothalamus?
- Releases ADH and oxytocin
- ADH stimulates water reabsorption, and oxytocin causes uterine muscles to contract during childbirth & stimulates milk release in breastfeeding
- Communicates via neurons
- Made in the hypothalamus and stored at the end of the neurons
Anterior pituitary:
- What hormones does it release?
- What do these hormones do?
- How does it communicate w/ the hypothalamus?
- Where are the hormones made?
- ACTH, GH, TSH
- GH promotes growth of muscle, bone and other tissues (stimulates cell division), ACTH stimulates the secretion of cortisol, TSH stimulates the secretion of TH
- Communicates via hormones (connected by blood vessels)
- Made in the anterior pituitary
What are the growth hormone disorders?
Dwarfism (deficiency) and gigantism (excess)
Adrenal glands:
- What (2) glands are they made up of?
Adrenal cortex and adrenal medulla
What is secreted by the middle and inner layer of the adrenal cortex?
What is secreted by the adrenal medulla?
Inner: androgens
Middle: cortisol
AM: mainly adrenalin
What are the effects of cortisol? What response is it released for?
Stress response:
- Increases blood glucose (via gluconeogenesis)
- Increases blood pressure
What is the pathway for cortisol secretion? (incl. stimulus)
- Stress or non-stress neural inputs
- Hypothalamus secretes CRH
- Anterior pituitary secretes ACTH
- Adrenal cortex secretes cortisol