Podcast
Questions and Answers
What neurotransmitter is contained within the synaptic vesicles at the motor end plate?
What neurotransmitter is contained within the synaptic vesicles at the motor end plate?
- Serotonin
- Dopamine
- Norepinephrine
- Acetylcholine (correct)
What happens to muscle fibers if the nerve supply to skeletal muscle is cut?
What happens to muscle fibers if the nerve supply to skeletal muscle is cut?
- The muscle fibers will duplicate.
- The muscle fibers will hypertrophy.
- The muscle fibers will remain unchanged.
- The muscle fibers will atrophy. (correct)
What unique structure is found in the cardiac muscle fibers joining them together?
What unique structure is found in the cardiac muscle fibers joining them together?
- Axon terminals
- Intercalated discs (correct)
- Synaptic vesicles
- Sarcolemma folds
What structural feature increases surface area in the motor end plate?
What structural feature increases surface area in the motor end plate?
Why can't cardiac muscle regenerate?
Why can't cardiac muscle regenerate?
What is a key characteristic of cardiac muscle?
What is a key characteristic of cardiac muscle?
Which type of muscle is controlled by the autonomic nervous system?
Which type of muscle is controlled by the autonomic nervous system?
Why can't cardiac muscle regenerate?
Why can't cardiac muscle regenerate?
Where is smooth muscle typically found?
Where is smooth muscle typically found?
What structural feature is common in smooth muscle cells?
What structural feature is common in smooth muscle cells?
What are the two main components of the protoplasm?
What are the two main components of the protoplasm?
Which of the following is classified as a non-membranous organelle?
Which of the following is classified as a non-membranous organelle?
What is the role of cytoplasmic organelles?
What is the role of cytoplasmic organelles?
Which of the following is a component of the cytoplasm?
Which of the following is a component of the cytoplasm?
Which organelle is involved in the structural framework of the cell?
Which organelle is involved in the structural framework of the cell?
Cytoplasmic inclusions are described as being:
Cytoplasmic inclusions are described as being:
Which type of muscle tissue is voluntary and connected to bones for movement?
Which type of muscle tissue is voluntary and connected to bones for movement?
Which of the following is NOT a connective tissue layer of skeletal muscle?
Which of the following is NOT a connective tissue layer of skeletal muscle?
What is the function of the sarcoplasmic reticulum in a skeletal muscle cell?
What is the function of the sarcoplasmic reticulum in a skeletal muscle cell?
Skeletal muscle fibers are characterized by which of the following features?
Skeletal muscle fibers are characterized by which of the following features?
What are the main components of a myofibril within skeletal muscle fiber?
What are the main components of a myofibril within skeletal muscle fiber?
What type of tissue surrounds each individual muscle fiber in skeletal muscle?
What type of tissue surrounds each individual muscle fiber in skeletal muscle?
Where are macro vesicles usually found?
Where are macro vesicles usually found?
What is one function of the macro vesicles?
What is one function of the macro vesicles?
What can happen to macro vesicles after they contain formed substances?
What can happen to macro vesicles after they contain formed substances?
Which type of molecule is formed by adding carbohydrate fractions to proteins?
Which type of molecule is formed by adding carbohydrate fractions to proteins?
What are produced by the macro vesicles besides glycoproteins?
What are produced by the macro vesicles besides glycoproteins?
What are the main functions of mitochondria?
What are the main functions of mitochondria?
What does the mitochondrial matrix contain?
What does the mitochondrial matrix contain?
What is the significance of the mitochondrial inner membrane?
What is the significance of the mitochondrial inner membrane?
Which of the following stains is used for mitochondria?
Which of the following stains is used for mitochondria?
Which feature is unique to mitochondrial DNA compared to nuclear DNA?
Which feature is unique to mitochondrial DNA compared to nuclear DNA?
What is the size range of mitochondria?
What is the size range of mitochondria?
Where is the Golgi complex typically positioned in glandular cells?
Where is the Golgi complex typically positioned in glandular cells?
How many cisternae typically make up the Golgi complex?
How many cisternae typically make up the Golgi complex?
From where do the micro vesicles or transfer vesicles of the Golgi complex arise?
From where do the micro vesicles or transfer vesicles of the Golgi complex arise?
What is the function of the micro vesicles when they fuse with the immature face of the Golgi complex?
What is the function of the micro vesicles when they fuse with the immature face of the Golgi complex?
What is the concave face of the Golgi complex known as?
What is the concave face of the Golgi complex known as?
What variations can be found in the Golgi complex depending upon cell activity?
What variations can be found in the Golgi complex depending upon cell activity?
What is the average length of a sarcomere?
What is the average length of a sarcomere?
Which of the following is located in the center of the A band?
Which of the following is located in the center of the A band?
What comprises the thin myofilaments?
What comprises the thin myofilaments?
What is the function of intermediate filaments in muscle fibers?
What is the function of intermediate filaments in muscle fibers?
Which part of the sarcomere is formed only of actin filaments?
Which part of the sarcomere is formed only of actin filaments?
Where is the M line located within a sarcomere?
Where is the M line located within a sarcomere?
In which type of cells are smooth endoplasmic reticulum (SER) particularly abundant?
In which type of cells are smooth endoplasmic reticulum (SER) particularly abundant?
Which of the following is NOT a function of the smooth endoplasmic reticulum?
Which of the following is NOT a function of the smooth endoplasmic reticulum?
What role does the smooth endoplasmic reticulum play in muscle tissue?
What role does the smooth endoplasmic reticulum play in muscle tissue?
Which of the following compounds is synthesized by the smooth endoplasmic reticulum?
Which of the following compounds is synthesized by the smooth endoplasmic reticulum?
In which of the following processes is the smooth endoplasmic reticulum involved in liver cells?
In which of the following processes is the smooth endoplasmic reticulum involved in liver cells?
What is a primary function of the ribosomes on the rough endoplasmic reticulum?
What is a primary function of the ribosomes on the rough endoplasmic reticulum?
Which of the following is NOT a function of the rough endoplasmic reticulum?
Which of the following is NOT a function of the rough endoplasmic reticulum?
What gives the rough endoplasmic reticulum its rough appearance?
What gives the rough endoplasmic reticulum its rough appearance?
How does the rough endoplasmic reticulum protect the cytoplasm?
How does the rough endoplasmic reticulum protect the cytoplasm?
Which of the following is true about some membranes of the rough endoplasmic reticulum?
Which of the following is true about some membranes of the rough endoplasmic reticulum?
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Study Notes
Tissue Types and Functions
- Motor End Plate:
- Specialized region of contact between motor nerve fiber and muscle fiber
- Axon terminal contains numerous mitochondria and synaptic vesicles with acetylcholine (neurotransmitter)
- Synaptic cleft is the space between the axon terminal and muscle fiber
- Junctional folds are deep invaginations in the sarcolemma under the synaptic cleft to increase the surface area
- Muscle fibers depend on the nervous system for their integrity and function
- Denervation atrophy occurs if the nerve supply to skeletal muscle is cut
- Cardiac Muscle:
- Striated muscle of the heart
- Cardiac muscle fibers are joined to each other by intercalated discs forming branched muscle fibers
- Cardiac muscle has one or two nuclei centrally located and numerous mitochondria
- No stellate cells, so unable to regenerate
- Smooth Muscle:
- Non-striated and involuntary controlled by autonomic nervous system
- Found in wall of viscera, each muscle fiber is enclosed by thin basal lamina and fine network of reticular fibers
- Sarcolemma has numerous caveola, possibly having a role similar to that of striated muscle
Cytoplasm
- Gel-like fluid present between the plasma membrane and nucleus of the cell
- Three main components:
- Cytoplasmic organelles: involved in metabolism (e.g., mitochondria and endoplasmic reticulum)
- Cytoplasmic inclusions: small particles seen temporarily in the cytoplasm, may or may not be membrane-bound, metabolically inactive (e.g., lipid droplets, glycogen granules, pigment granules)
- Cytoskeletons: provide the structural framework to the cell
Organelles
- Membranous organelles:
- Rough endoplasmic reticulum
- Smooth endoplasmic reticulum
- Mitochondria
- Golgi apparatus
- Lysosome
- Peroxisome
- Non-membranous organelles:
- Ribosomes
- Cytoskeleton
- Microtubules
- Microfilaments
- Intermediate filaments
Muscle Types
- Muscular tissue:
- Specialized tissue for contractility to produce movement in the organ
- Divided into three types: skeletal muscle, smooth muscle, and cardiac muscle
- Skeletal muscle:
- Attached to bone for movement, voluntary controlled by motor and sensory fibers
- Formed of cylindrical muscle fibers with uniform thickness, doesn't branch
- Striated with multiple peripheral nuclei
- Connective tissue coat of the muscle:
- Epimysium: thick CT layer surrounds the whole muscle
- Perimysium: thin CT layer surrounds each individual muscle
- Endomysium: delicate CT surrounds each individual muscle fiber, consists of basal lamina synthesized by muscle fiber and reticular fibers and fibroblast
EM Structure of Skeletal Muscle
- Muscle filled with long striated myofibrils
- Myofibril is a bundle of myofilaments
- Two types of myofilaments: actin and myosin
- Muscle fibers are rich in mitochondria, SR (Sarcoplasmic reticulum), glycogen, myoglobin, Golgi complex
Sarcomere
- Structural and functional unit of a myofibril
- Formed by overlapping actin and myosin filaments
- Segment between two Z-lines, with an average length of 2.5µm
- Composed of a dark A band, which is intermediate between two light I bands
- A band is formed of myosin filaments with overlapping portions of actin filaments
- I band consists of actin filaments that do not overlap with myosin
- In the center of the A band, the H zone consists of only myosin
- H zone is bisected by the M line, the site of connection between myosin filaments
Mitochondria
- Ovoid-shaped structures, about 0.2-5µm in size, bound by a phospholipid bilayer membrane
- Outer membrane is smooth and encloses the entire organelle
- Inner membrane is folded to form cristae
- Matrix space is filled with mitochondrial matrix, containing matrix granules, rich in cations such as Ca and Mg
- Functions: cell respiration, absorption and secretion processes, protein synthesis, lipid metabolism, heat production, and calcium storage
Golgi Complex
- Present in nearly all cells, variable in position and size
- Consists of three components: flattened vesicles or cisternae, microvesicles or transfer vesicles, and macrovesicles or secretory vacuoles
- Functions: processing, modifying, and packaging of secretory products, addition of carbohydrate fractions to proteins, production of complex carbohydrates, mucoproteins, lipoproteins, and relatively pure proteins
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