Histophysiology Flashcards
Why can’t muscles regenerate?
They are post-mitotic cells
The active contraction of a muscle can be either:
Spontaneous or induced by a nerve impulse
Muscle types are divided into what:
Structure and Location
When muscles are classified by structure, what is the type of muscle that has nucleus in the center?
Smooth muscle
Where does striated muscle have its nuclei?
In the periphery
What are the 3 types of muscles that are classified by location?
Visceral, Vascular, and Skeletal
What is the main component of muscles
Fibers
What 2 parts make up the contractile skeleton of a muscle fiber?
Myofibrils and myofilaments
Myofilaments are made up of what two proteins?
Actin (thin) and Myosin (thick)
Are myofibrils acidophilic or basophilic?
Acidophilic
What are some characteristics of smooth muscle? (Shape, nucleus, contraction)
- Spindle shaped
- Nucleus in center
- mechanical and gap Jxn
- Contraction is prolonged w/ less energy req
What is the structural unit of striated muscle and what 3 parts make it up?
Sarcomere
A/I band and Z disk
In striated muscle, what specific structure stores Ca?
sER
What is the invagination of the sarcolemma in the sER called?
Transverse tubule
What is the first muscle to work in utero?
Cardiac muscle
What connects cardiac muscle to each other?
Intercalated disks (desmosomes and Nexus)
What are the two types of cardiac muscles?
Working and conducting
What fuses to form fibers in skeletal muscle during development?
Myoblasts
How does a skeletal muscle contract?
The myofibril contracts: myosin slides between actin filaments after Ca goes into the cytoplasm from the sER
What is the neurotransmitter that initiates the contraction of a skeletal muscle?
Acetylcholine
What process causes the influx of Ca into the cytoplasm?
Depolarization
What enzyme degrades a neurotransmitter to reestablish resting membrane potential in skeletal muscle?
Acetylcholinesterase
Where does stimulus transmission in skeletal muscle occur across?
The synaptic cleft
Smooth muscle has striations, true or false
False
Is skeletal muscle multinucleated?
Yes
What type of blood vessel connects Arteries and veins and exchanges nutrients?
Capillaries
Where do veins carry blood?
To the heart
List the 3 layers of blood vessels
T. Intima
T. Media
T. Adventitia
What structure of the T. Intima is only present in arteries?
Internal Elastic Lamina
What is the most prominent and thickest layer in arteries that is composed of smooth muscle and elastic CT ?
T. Media
In which layer of blood vessels are the vasa and Nervi vasorum located?
T. Adventitia
Dense irregular CT is usually found in which layer of blood vessels?
T. Adventitia
What is the borderline between the T. Media and Adventitia called?
External Elastic Lamina
What are the 3 classifications of arteries?
Elastic/Conducting
Muscular/Distributing
Arterioles
Which type of artery has a close/open lumen, a prominent IEL, and a thick T. Media?
Muscular/Distributing
Which artery is the largest with a prominent T. Media with elastic CT?
Elastic/Conducting = all directions/no stop
What are 2 characteristics of arterioles?
Smallest type of artery and have 1-3 smooth muscle layers
What regulates blood vessels?
Nervi vasorum (vascular nerves)
What are 2 differences veins have compared to arteries?
Larger lumen and irregular/flattened shape
What is the most prominent blood vessel layer in veins?
T. Adventitia
What structure do veins have that arteries don’t that helps allow blood move to the heart to decrease effort?
Valves
Which structure leads to capillary beds?
Arterioles
Blood flow through capillary beds is controlled by what?
Pre-capillary sphincters
Why can you live with only a percentage of your liver?
Because only 20-25% of capillary beds needs to work to exchange nutrients and gas
Is total volume in capillary beds greater or lesser than blood volume in body?
Greater
Capillaries are wide enough for how many RBCs to go through?
One
The walls of capillaries only have what vessel layer?
T. Intima
What are the 3 types of capillaries?
Continuos/Closed
Fenestrated
Sinusoidal
Where are continuos/closed capillaries found?
Brain, skin, lungs, muscle
What type of vesicles are in continuos capillaries that help bulk transfer? What direction do they transport?
Transcytotic and they are bidirectional
Does a fenestrated capillary have a complete or incomplete basement membrane?
Complete
How does bulk transfer occur in fenestrated capillaries?
Via fenestrae
In the kidney and intestine, one would find what type of capillary?
Fenestrated
Which capillary has an incomplete basement membrane and found in the liver and spleen?
Sinusoidal
What is the function of the Lymphatic Vascular System?
Drain excess tissue fluid (lymph) and return it to the cardiovascular system
What makes up the lymphatic vascular system?
Lymphatic Capillaries, Vessels, Collection Ducts
Lymphatic capillaries of the intestine develop from what structure?
Lacteals
Where are lymphatic capillaries not found?
Cartilage
What structure does a lymphatic vessel have similar to venues, but with more numbers?
Valves
Into what two parts does the peripheral nervous system divide into?
Afferent and Efferent
The efferent division carries information away from the CNS, what two types of neurons are present?
Somatic and Autonomic
Spinal nerves are separated into roots with axons, into which two parts?
Afferent = dorsal root
Efferent = ventral root
The axons of spinal nerves are surrounded by what?
Myelin Sheaths produced by Schwann cells
What is the outermost CT of peripheral nerves?
Epineurium
Fascicles are surrounded by what layer?
Perineurium
What are the non-insulated sites in the axon where 2 Schwann cells meet called ?
Nodes of Ranvier
Do myelinated axons require more or less energy?
More
Are sensory neurons myelinated or not?
Not myelinated
What are the collection of sensory neuron cell bodies called?
Dorsal root ganglions
What are the 5 types of Afferent sensory nerves found in the skin?
Free Nerve Endings, Merkel’s Cells, Meissner’s, Pacininian, and Ruffini
Where can you find Free Nerve Endings?
Epidermis
Where can you find Merkel’s cells?
Stratum básale
Which Afferent nerve of the skin is responsible for mechanotransduction, immunity and inflammation?
Merkel’s cell
Which sensory skin nerve is sensitive to light touch and is present in dermal papillae?
Meissner
What is the function of a Pacinian Corpuscle?
Pressure sensitivity and vibration in dermis
Ruffini sensory nerves are sensitive to touch and torque, where can we find them?
hairless skin, ligaments and tendons
Efferent Nerves are in contact with muscle fibers through a what?
Neuromuscular junction
Botilunus and curare toxins and succinylchloine (a short term muscle relaxant) can do what to a neuromuscular junction?
Block it
