Cardiac + Neuro - Part 1 Flashcards
What is the gross structure of the heart?
4 chambers:
- R atrium
- R ventricle
- L atrium
- L ventricle
What is the basic path of blood flow?
- r atrium -> right ventricle -> Lungs -> left atrium -> left ventricle -> body -> repeat
- blood from body is O2 POOR, blood from lungs is O2 RICH
What are the three layers of the heart?
Endocardium, myocardium, epicardium, **parietal pericardium
What are the 3 types of cardiac cells?
- working myocardium cells, pacemaker cells, conduction cells
Where is the SA node located?
Right atrium of the heart
Where are purkinje fibers located? What is their purpose?
The left and right ventricles. Conduct impulses to myocardium cells
Where are some features of working myocardial cells (myocardium)?
- both atrial and ventricular muscle
- striated muscle specialized for contraction and impulse conduction
What are some features of pacemaker cells?
- exhibit rhythmical electrical discharge in the form of action potentials
- self-excitatory
Cells that conduct action potentials through the heart, providing a excitatory system that controls rhythmically beating are _________.
Conduction cells
T/F: Cardiac muscle is not striated, is involuntary, and uninucleated
False; Cardiac muscle is striated
Cardiac muscle fibers are connected via
Intercalated disks
T/F: Cardiac muscle is a morphological syncytium, while skeletal muscle is a functional syncytium
False; Cardiac muscle is a functional syncytium, meaning it is not fused into a single fiber but is electrically connected via intercalated disks
What is a intercalated disk?
- A dark, dense cross-band located in the end of each myocardial cell that is continuous with the sarcolemma and contains gap junctions and desmosomes
T/F: pacemaker cells have a fast depolarization phase compared to atrial and ventricular cells
False; slow depolarization phase (lack phase 0)
What purpose do funny sodium channels (If or f channels) serve?
- Pacemaker Na channels, close during AP and open spontaneously when AP is finished, let Na into cell pushing MP up
After the spontaneous opening of the funny sodium channels, Na enters the cell and pushes the MP towards the threshold, at which point f channels close and __________ channels open, letting ____ into the cell, speeding the final approach to threshold
- Fast calcium channels (T-type), Ca2+
The ion that is mostly responsible for the AP in pacemaker cell is
- Calcium
After the threshold is reached, ________________ open and allow more ____ into the cell and depolarizes the membrane
-Slow calcium channels (L-type), Ca2+
____________ occurs after cleaving of L-type Ca2+ channels and opening of K+ channels
- Repolarization
What happens in the yellow phase?
- Fast Ca2+ channels open
What happens at the green spot?
K+ channels close and If / funny sodium channels open
What happens during the blue phase?
- Ca2+ channels close, K+ channels open, K+ exits the cell and the cell repolarizes
T/F: Myocardium AP has a rapid depolarization followed by a rapid repolarization
False; rapid depolarization followed by a plateau phase and abrupt repolarization
The myocardium action potential is caused by the opening of 2 types of channels, ___________ and ____________.
- Fast sodium (lets Na+ rapidly influx and depolarize) and L-type calcium (aka slow calcium or Ca-Na channels)
What ions contribute to the plateau phase in myocardium AP?
- Ca2+ and K+
- Ca2+ channels open, letting calcium in
- fast K+ channels close, reducing efflux 5 fold, preventing early return to resting level
Describe the phases of myocardium action potential
- Depolarization (fast Na+ channels open)
- Initial repolarization (fast Na+ channels close, fast K+ channels open)
- Plateau (slow L-type Ca2+ channels open, fast K+ channels close)
- Rapid repolarization (slow L-type Ca 2+ channels close, slow K+ channels open)
- Resting membrane potential (~90 mV)
The plateau phase is most of the ______________, when the cell is _________ by new stimulus
- Absolute refractory period, unexcitable
The plateau phase is a physiological mechanism that allows?
- Sufficient time for the ventricles of the heart to empty and refill before the next contraction
Atrial cells have shorter action potentials than ventricular cells. Atrial slow Ca+ channels stay ________ shorter than ventricular cells, and atrial potassium channels stay _______ for a shorter time.
- open, closed
What is excitation-contraction coupling dependent on in cardiac muscle?
- Ca2+ from extracellular fluid (T-tubules directly communicate w/ ECF)
What does calcium bind to, leading to cross-bridge formation?
Troponin
What are the main sources of energy for cardiac muscle contraction?
- Oxidative metabolism of fatty acids
- mitochondria make up 40% of cytoplasm volume in cardiac cells
- has numerous lipid droplets containing triglycerides
- only 10-30% of energy comes from glucose/lactate
Cardiac cells stop contracting after
- 30 seconds of O2 deprivation
What are the subdivisions of the nervous system?
- Central nervous system and peripheral nervous system
What does the central nervous system consist of?
- Brain and spinal cord
What is the function of the brain? The spinal cord?
- Brain
- receives and processes sensory information, initiates responses, store memories, generates thoughts and emotions
- Spinal cord
- conducts signals to and from the brain, controls reflex actions
What are the major divisions of the peripheral nervous system?
- Sensory division (afferent - signals TO CNS) and motor division (efferent - signals FROM CNS)
** they sound the SAME (sensory afferent motor efferent)
What are the major divisions of the sensory division and their functions?
- VISCERAL sensory division
- provide info about internal organs (visceral receptors and sensory organs)
- SOMATIC sensory division
- provide info about position, touch, pressure, pain and temperature (somatic receptors and sensory neurons)
What are the major divisions of the motor divisions and their functions?
- VISCERAL motor division
- provide autonomic regulation of smooth muscle, cardiac muscle, glands, and adipose tissue (involuntary control)
- SOMATIC motor division
- controls skeletal muscle contractions (voluntary control)
The sympathetic and parasympathetic divisions of the PNS are subdivisions of the:
- Visceral motor division
What are functions of the somatic sensory system?
- general: temperature, touch, noxious stimuli, spinal nerves, cranial nerve V
- special: vision, hearing
What are functions of the visceral sensory system?
- general: organ content, distinction, chemicals, spinal nerve branches, cranial nerves vi, in, x
- special: taste, olfaction
What are functions of the proprioception sensory system?
- general: muscle and joint movement, spinal nerves, cranial nerve V
- special: vestibular system cranial nerve viii
What are functions of the somatic motor system?
- general: striated skeletal muscle, spinal nerves, cranial nerves 3-7 + 9-12
What are functions of the visceral motor system?
- general: smooth and cardiac muscle, and glands
sympathetic: spinal nerves, splanchnic cells
parasympathetic: sacral, spinal nerves, cranial nerves iii, vii, ix, x
How do nerve impulses travel throughout the body?
- PNS receptor > afferent neuron > CNS interneuron (spinal cord) > efferent neuron > effector organ (muscle or gland)
What is the major functional unit of the NS?
- Neurons
- nerve cells specialized in info processing
- do not divide after reaching maturity
What are the 7 parts that make up a neuron?
- dendrites (info-receiving area of cell membrane)
- cell body, soma, or pericaryon (contains organelles)
- axon (info-carrying extension of cell membrane)
- axon hillock or trigger zone (axon origin, transmit information)
- presynaptic terminal (end of axon, transmit information)
- myelin sheath (increases speed of transfer **required in large neurons)
- nodes of ranvier (gaps in insulating myelin sheath)
What feature allows neurons to communicate?
- Synapses - specialized contact areas w/ other neurons, muscle fibers, or glands.
What is a myelin sheath?
- a very modified plasma embrace that is wrapped around the axon in a spiral fashion, is a electrical insulator, and allows for saltatory conduction of impulses
- conduction velocity of myelinated fibers is proportional to the diameter!
- aka they conserve space
What is the structure of a neuron?
What is saltatory conduction?
The “jumping” of AP from node to node, able to occur much more rapidly due to myelin
What are Schwann cells?
- PNS cells from which the myelin sheath originates, spiral wrap around the axon
What are classifications of neurons according to structure?
- multipolar - most common, 1 axon and many dendrites; length an arrangement vary
- bipolar - 2 processes; 1 axon and 1 dendrite
- pseudo-unipolar - single stem process that bifurcates to form 2 processes; one to the PNS and one to the CNS
- unipolar - “real” unipolar; in insects
What are some features of interneurons/association neurons?
- found in the CNS, connect motor and sensory neurons, and are usually multipolar or bipolar.
Multipolar neurons that send info from the CNS to muscle and glands are:
- motor neurons/efferent neurons
What are the types of glial cells and what system are they part of?
- CNS (microglial cells, astrocytes, oligodendrocytes, ependymal cells)
- PNS (schwann cells)
What are features of neuroglia or glial cells?
- smaller than neurons
- no axons/dendrites, fill empty space in the NS, more numerous than neurons, have dividing capacity
- do not produce APs
- do not participate directly in synaptic interactions + electrical signaling
What roles do glial cells perform in the nervous system?
- production of myelin sheaths
- modulate growth of developing or damaged neurons
- buffer extracellular concentrations of potassium + neurotransmitters
- participate in formation of contacts between neurons (synapses)
- participate in certain immune responses of the nervous system
The brains immune cells, which act as macrophages, release NO to prevent viral replication, protect the brain against injury/infection and help destroy unnecessary synapses are:
- microglia
Star-shaped cells w/ numerous long-cell processes, that make up 50% of the glial cell population in the CNS are?
- astrocytes
The glial cell that provides structural and metabolic support for neurons and helps maintain a neurons working environment is a?
- astrocyte
In what ways do astrocytes provide structural and metabolic support?
- form outer/inner glial limiting membranes of CNS, release neurotrophic factors important for neuronal survival, help elongate axons/dendrites, and participate in the repair process following tissue injury
How do astrocytes maintain a neurons working environment?
- control levels of neurotransmitters around synapses, control ion concentration, provide metabolic support, and modulate communication
What glial cell provides support to axons of neurons in the CNS via numerous processes that extend to neighboring axons to form myelin ?
- oligdendrocytes
What glial cell covers ventricles of the brain, central canal of the CNS and the choroid plexus; and is involved in creating cerebrospinal fluid?
- ependymal cells
What glial cell forms internodes of the myelin sheath and provides support to axons of the PNS?
- Schwann cells or “neurolemmocytes”
What are the 7 major regions of the CNS?
- spinal cord
- medulla (oblongata)
- pons
- midbrain/mesencephalon
- cerebellum
- diencephalon (thalamus + hypothalamus)
- telencephalon/cerebrum
What are the 5 major functional regions of the brain?
- cerebrum
- cerebellum
- thalamus
- hypothalamus
- brainstem (midbrain + pons + medulla)
What functional area of the brain is separated into L+R hemispheres and plays a role in experiencing sensation and initiating voluntary movement
- cerebrum/telencephalon
Gyrus and sulcus form on the brain due to:
- cerebral cortex (grey matter) growing faster than the underlying white matter during development
Cerebral cortex or grey matter is composed of _________ and functions to:
- 6 layers of nerve cell bodies (soma) and their processes
- involved in detailed sensory perception, voluntary movement, and learning/intelligent behavior
What are the regions of the brain and what systems are linked with them?
- parietal: somatosensory area (ex: pain)
- frontal: motor area
- temporal: auditory and vestibular systems
- olfactory: olfactory
- occipital: visual
What do the different regions of the cerebral cortex correspond to?
- layers i, ii, iii : intracortical association functions
- layer iv: most incoming signals
- layer v: to brainstem + spinal cord
- layer v, vi: most output signals
- layer vi: fibers to thalamus
What gives rise to the motor fibers that descend to the CNS?
- motor cortex/primary motor area
The corticospinal tract or pyramidal area are ___________, an consist of _________, _________, and _________.
- a pair of descending motor tracts on the ventral medulla whose fibers originate in the cerebral cortex and go to the spinal cord
- primary motor area (muscle activation)
- premotor frontal cortex (plan sequence of events)
- supplementary motor cortex (preparatory orientation of body to execute a task)
Areas involved with integration and interpretation of information, aka learning + intelligent behavior, are:
- association areas
Myelinated axons which connect cerebral cortex with other brain regions are _______, and are divided into ________, __________, and ________.
- white matter
- projection fibers (leave white matter and terminate in basal nuclei/brainstem/or spinal cord, or originate in thalamus and terminate in cerebral cortex)
- association fibers (connect regions of the cerebral cortex within one hemisphere)
- commissural fibers (connect vortices from L + R hemispheres, ex: corpus callosum)
A ___________ is a place where fibers cross and connect the two cerebral hemispheres
- commissure/decussation
-ex: corpus callosum: white matter in the brain connecting the two hemispheres, allowing for exchange of information between both hemispheres necessary to work as a functional unit
A cluster of neurons cell bodies (grey matter) in the CNS located deep in the cerebral hemispheres and brainstem are:
- basal nuclei/basal ganglia
What projects output via thalamus into the supplementary + premotor cortices, sends output directly to the brainstem, is an accessory motor system that helps execute the initiation + control of movement, and has inhbitory output?
- basal nuclei
A motor system becomes active when _____________
- the inhibitory effect of the basal nuclei is released
What are the locations of the basal nuclei?
- in the brain: caudate nucleus, lentiform nucleus, amygdaloid body, claustrum
What functional region is important in synchronizing muscle activity, and controlling equilibrium and eye movement
- cerebellum
- receives sensory information from skin, joints, muscles, vestibular system, and visual system and uses it to coordinate complex skeletal muscle activity, providing smooth coordinated movement.
If the cerebellum is damaged, what will result?
- loss of spatial accuracy and smooth execution of movements and equilibrium
What functional region of the brain is a large nucleus that extends into each cerebral hemisphere and pre-processes most information reaching the cerebral cortex?
- thalamus
What are functions of the thalamus?
- gatekeeper to cerebral cortex
- integrates and processes signals from sensory system and non-sensory areas
- essential for consciousness, attention, and alertness
What is a circuit related to behavior, emotions, arousal, and memory?
- limbic system
What are some features of the limbic system?
- found at the limbus (border) between cerebrum and thalamus
- comprised of structures that interact with diverse areas of the nervous system
- involved in how we behave emotionally and socially
- related to instinctual behaviors and memories
- related with autonomic nervous system (emotions affect visceral functions)
What functional region is the center of homeostasis, a place of neurological and endocrine connection, and secretes releasing and inhibitory hormones that control anterior pituitary secretion?
- hypothalamus
What is the hypothalamus responsible for?
- the four F’s: fighting, fleeing, feeding, and fucking
- coordinates andenopophysis, hr, bp, body temp, water balance, food intake, circadian rhythm, gonadol function, and emotions
What hormones does the hypothalamus secrete?
- thyrotropin releasing hormone, TRH
- corticotropin releasing hormone, CRH
- gonadtrophin releasing hormone, GnRH
- growth hormone inhibiting hormone, somatostatin, GHIH
- prolactin inhibiting hormone, PIH
