CHAPTER 9 & GROWTH HORMONE

What are the three types of muscle tissue?

Skeletal, cardiac, and smooth muscle.

What is skeletal muscle?

Voluntary muscle attached to bones that produces movement.

What is cardiac muscle?

Involuntary muscle found in the heart.

What is smooth muscle?

Involuntary muscle found in the walls of hollow organs.

What are the four characteristics of muscle tissue?

Excitability, contractility, extensibility, and elasticity.

What is excitability?

The ability to respond to a stimulus.

What is contractility?

The ability to shorten and produce force.

What is extensibility?

The ability to stretch.

What is elasticity?

The ability to return to its original shape or length.

What is the sarcolemma?

The membrane surrounding a muscle fiber.

What is the sarcoplasm?

The cytoplasm of a muscle fiber.

What is a sarcomere?

The smallest contractile unit of muscle.

What are the two main contractile proteins?

Actin and myosin.

What is actin?

The thin filament in muscle.

What is myosin?

The thick filament in muscle.

What is the prefixes that refers to muscles?

myo, mys, sarco

What does the sarcoplasmic reticulum do?

Stores and releases calcium.

What do T tubules do?

Carry electrical impulses deep into the muscle fiber.

What does calcium do during muscle contraction?

Binds to troponin and allows myosin to bind to actin.

What does troponin do?

Binds calcium and helps move tropomyosin.

What does tropomyosin do?

Blocks myosin-binding sites on actin when the muscle is relaxed.

What is the sliding filament theory?

Actin slides past myosin, shortening the sarcomere.

What is a tendon?

Connective tissue that attaches muscle to bone.

What does the endomysium surround?

One muscle fiber.

What does the perimysium surround?

A bundle of muscle fibers called a fascicle.

What does the epimysium surround?

The entire muscle.

What is the neuromuscular junction?

The connection between a motor neuron and a skeletal muscle fiber.

What is acetylcholine (ACh)?

A neurotransmitter that stimulates skeletal muscle.

What does acetylcholinesterase do?

Breaks down acetylcholine.

What is ATP?

The molecule that provides energy for muscle activity.

What happens during muscle relaxation?

Calcium returns to the sarcoplasmic reticulum, allowing the muscle to relax.

What is a concentric contraction?

The muscle shortens while producing force.

What is an eccentric contraction?

The muscle lengthens while producing force.

What is an isometric contraction?

The muscle produces force without changing length.

What is an isotonic contraction?

The muscle changes length while producing force.

What is a motor unit?

One motor neuron and all the muscle fibers it controls.

What is a muscle twitch?

A muscle's response to one brief stimulus.

What is recruitment?

Activating more motor units to increase muscle force.

What are the three ways muscles produce ATP

Creatine phosphate, anaerobic glycolysis, and aerobic respiration.

What are slow oxidative fibers?

Muscle fibers that contract slowly and resist fatigue well.

What are fast glycolytic fibers?

Muscle fibers that contract quickly but fatigue relatively fast.

What is muscle fatigue?

A reduced ability of a muscle to produce force.

What is muscle hypertrophy?

An increase in muscle size.

What is muscular dystrophy?

A group of inherited diseases that damage muscle tissue.

What is peristalsis?

Muscle contractions that move substances through hollow organs.

What is muscle tone?

Continuous, slight muscle contraction that helps maintain posture.

What does hGH stand for?

Human growth hormone.

Where is growth hormone released from?

The anterior pituitary gland.

Which cells release growth hormone?

Somatotrophs.

What hormone stimulates growth hormone release?

Growth hormone-releasing hormone (GHRH).

Where is GHRH produced?

The hypothalamus.

What does IGF-1 stand for?

Insulin-like growth factor 1.

Which organ produces IGF-1 in response to growth hormone?

The liver, along with other tissues.

What is the growth hormone pathway?

Hypothalamus releases GHRH, anterior pituitary releases GH, and the liver and other tissues produce IGF-1.

What is one major function of growth hormone?

Supporting body growth and affecting metabolism.

What is lipolysis?

The breakdown of fat.

What is lipogenesis?

The formation of fat.

What does IGF-1 do in bone?

Stimulates cartilage cell growth and supports bone growth.

What does IGF-1 do in muscle?

Supports muscle cell development and amino acid uptake.

What are chondrocytes?

Cartilage cells.

What are myoblasts?

Cells involved in muscle development.

What is proliferation?

An increase in cell number.

What is differentiation?

The process by which cells develop specialized characteristics.

What is interstitial growth?

Growth from within a tissue.

What is appositional growth?

Growth by adding material to the surface of a tissue.

When does growth hormone normally peak?

During puberty.

What is pituitary dwarfism?

Too little growth hormone during childhood, resulting in reduced growth.

What is gigantism?

Too much growth hormone during childhood, before growth plates close.

What is acromegaly?

Too much growth hormone in adulthood, causing thickening of bones and other tissues.

What happens to growth hormone levels as people age?

They generally decline.

What may contribute to the age-related decline in growth hormone?

Increased somatostatin or decreased GHRH, according to the lecture.