Homeostasis and Stress Overview

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Questions and Answers

Which of the following best describes negative feedback mechanisms?

Regulatory processes that are independent of physiological parameters.

Responses that occur only during extreme physiological conditions.

Processes that reduce changes to maintain stability within a system. (correct)

Processes that amplify changes to drive a system away from its equilibrium.

Which directional term refers to a structure being located towards the front of the body?

Dorsal

Ventral (correct)

Medial

Inferior

In the context of blood glucose regulation, what role does negative feedback play?

Inhibits glucagon secretion during high glucose levels.

Stimulates glucose production when blood sugar is elevated.

Increases insulin release when glucose levels are high. (correct)

Lowers insulin release when glucose levels drop.

Which structural level of the hierarchy refers to a group of tissues that work together to perform specific functions?

Organ Signup and view all the answers

What is the primary function of positive feedback mechanisms during uterine contractions in labor?

To reinforce and amplify the contraction process until delivery. Signup and view all the answers

What is the primary function of a buffer in biological systems?

To resist changes in pH when acids or bases are added Signup and view all the answers

Which of the following describes the general chemical equation for cellular respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy Signup and view all the answers

In comparing glycolysis, the Krebs cycle, and the electron transport chain, which statement about energy production is accurate?

The Krebs cycle generates more ATP than glycolysis but less than the electron transport chain. Signup and view all the answers

How does anaerobic respiration differ from aerobic respiration in terms of energy efficiency?

Anaerobic respiration generates less ATP compared to aerobic respiration. Signup and view all the answers

Which location in the cell is primarily associated with the Krebs cycle?

Mitochondrial matrix Signup and view all the answers

What characterizes a hypertonic solution in relation to a cell?

The concentration of solutes in the solution is higher than inside the cell, causing water to flow out. Signup and view all the answers

Which membrane protein is primarily responsible for allowing specific ions to flow through the plasma membrane without the need for energy?

Gated ion channels Signup and view all the answers

What is the primary function of transcription in the process of protein synthesis?

To synthesize RNA from the DNA template. Signup and view all the answers

What is one characteristic that distinguishes connective tissue from other tissue types?

It often contains a large proportion of extracellular matrix. Signup and view all the answers

Which of the following best describes the role of cell-identity markers?

They help cells recognize each other and communicate. Signup and view all the answers

Which function of the skeletal system is primarily responsible for protecting vital organs?

Protection Signup and view all the answers

How do compact bone and spongy bone differ in their structural arrangement?

Compact bone has a solid structure with minimal spaces, while spongy bone contains trabeculae and is more porous. Signup and view all the answers

Which of the following correctly distinguishes between intramembranous and endochondral ossification?

Intramembranous ossification directly forms bone from mesenchymal tissue, whereas endochondral ossification involves a cartilage model. Signup and view all the answers

What type of joint is characterized by a joint cavity and movement in various directions?

Synovial joint Signup and view all the answers

What is the major difference between the axial and appendicular divisions of the skeletal system?

The axial skeleton supports the central axis of the body, while the appendicular skeleton includes the limbs and girdles. Signup and view all the answers

What is one function of the skeletal system?

Support and structure Signup and view all the answers

Which tissue types are found in bones and how are they arranged?

Cartilage, dense tissue, compact and spongy bone arranged in layers Signup and view all the answers

Which statement accurately distinguishes between intramembranous ossification and endochondral ossification?

Intramembranous ossification occurs in flat bones, while endochondral ossification occurs in long bones. Signup and view all the answers

Which of the following statements is true regarding synovial joints?

They contain articular cartilage and a joint cavity. Signup and view all the answers

What distinguishes the axial skeleton from the appendicular skeleton?

The axial skeleton consists of the skull, vertebral column, and ribs; appendicular includes the limbs and girdles. Signup and view all the answers

Which characteristic of muscle cells allows them to respond to stimuli?

Excitability Signup and view all the answers

What is the innermost connective tissue layer surrounding a muscle fiber called?

Endomysium Signup and view all the answers

Which term describes the connection point between a motor neuron and a muscle fiber?

Neuromuscular junction Signup and view all the answers

What is the function of acetylcholinesterase in the neuromuscular junction?

Breaks down acetylcholine Signup and view all the answers

Which energy source is utilized for short-term muscle contraction during intense activities?

Myokinase and creatine kinase Signup and view all the answers

Study Notes

Skeletal System

5 Major Functions of the Skeletal System

Support: Provides a structural framework for the body.
Protection: Encases vital organs (brain, lungs, heart).
Movement: Muscles attach to bones to produce movement at joints.
Blood Cell Production: Hematopoiesis occurs in bone marrow, producing blood cells.
Mineral Storage: Stores and releases calcium and phosphorus as needed by the body.

Bone Tissue Arrangement

Compact Bone: Arranged in osteons, cylindrical units with concentric layers (lamellae). This creates a strong and dense structure.
Spongy Bone: Composed of trabeculae, a network of bony struts. This creates a lightweight, porous structure supporting bone marrow.

Tissues Found in Bones

Cartilage: Covers articular surfaces of bones at joints, reducing friction.
Dense Connective Tissue: Forms ligaments and tendons, attaching bones to bones (ligaments) and muscles to bones (tendons); provides structural stability.
Compact Bone: Provides strength, found in shafts and coverings of bones.
Spongy Bone: Found in the interior of bones, with a lattice-like structure for support with less mass.

Ossification (Bone Development)

Intramembranous Ossification: Bone develops directly from mesenchymal (undifferentiated) connective tissue. This is common in flat bones (e.g., skull).
Endochondral Ossification: Bone develops by replacing hyaline cartilage models. This is typical for long bones.

Chemical Agents Affecting Bone Tissue

Calcium: Essential for bone strength; tightly regulated by hormonal mechanisms, preventing imbalances disrupting bone health.
- Hormonal Regulation:
  - Parathyroid Hormone (PTH): Increases blood calcium by increasing calcium reabsorption from bones and kidneys, and vitamin D increases calcium absorption in the gut.
  - Calcitonin: Lowers blood calcium by increasing calcium deposition into bones.
Other factors: Phosphorus and other minerals, overall growth, and development factors also affect bone tissue.

Types of Joints

Suture: Immovable fibrous joints, found in the skull.
Gomphosis: Immovable fibrous joints, like teeth in sockets.
Syndesmosis: Slightly movable fibrous joints.
Synchondrosis: Cartilaginous joint, slightly movable, typically temporary (e.g., rib attachment to sternum—costochondral junctions).
Symphysis: Cartilaginous joint, slightly movable, with fibrocartilaginous disc (e.g., pubic symphysis).
Synovial: Freely movable joints with synovial fluid, articular cartilage, ligaments, and accessory structures.

Structures in Synovial Joints

Synovial Membrane: Lines the joint capsule, secreting synovial fluid for lubrication.
Articular Cartilage: Covers articular surfaces of bones, reducing friction.
Ligament: Tough band of connective tissue, reinforcing the joint and restricting movement.
Accessory Structures:
- Meniscus: C-shaped pads of cartilage providing cushioning and stability within the joint.
- Bursae: Fluid-filled sacs that reduce friction between moving structures around a joint.
- Adipose Tissue: Pads found in and around joints further cushioning structures.

Divisions of the Skeletal System

Axial Skeleton: Forms the central axis of the body; includes the skull, vertebral column, and ribs.
Appendicular Skeleton: Includes the limbs and the pectoral (shoulder) and pelvic girdles.

Muscular System

5 Functions of Skeletal Muscle

Movement: Produces skeletal movement.
Maintain Posture: Maintains body position.
Stabilize Joints: Assists in stabilizing joints.
Generate Heat: Produces heat through contraction.
Guard Entrances/Exits: Controls passageways like the digestive system.

Characteristics of Muscle Cells

Excitability: Ability to respond to stimuli.
Contractility: Ability to shorten forcefully.
Extensibility: Ability to be stretched.
Elasticity: Ability to recoil to resting length.

General Structure of Skeletal Muscle

Endomysium: Connective tissue surrounding each muscle fiber.
Perimysium: Connective tissue surrounding fascicles (bundles of muscle fibers).
Fascicle: A bundle of muscle fibers.
Epimysium: Connective tissue surrounding the entire muscle.
Fasciae: Sheets of connective tissue surrounding groups of muscles.
Tendons: Connective tissue cords that attach muscle to bone.
Aponeurosis: Connective tissue sheet that attaches muscle to bone or other muscles.

Microanatomy of a Muscle Cell

Sarcoplasm: Cytoplasm of a muscle cell.
Glycogen: Stores energy for muscle contraction.
Myoglobin: Stores oxygen for muscle contraction.
Sarcolemma: Plasma membrane of a muscle cell.
Transverse Tubules (T-tubules): Invaginations of sarcolemma that allow for rapid signal transmission into the cell.
Sarcoplasmic Reticulum (SR): Specialized endoplasmic reticulum storing and releasing calcium ions. (Terminal Cisternae are enlargements of the SR).
Thick Filaments: Composed of myosin protein.
Myosin: Protein responsible for the movement of thick filaments.
Thin Filaments: Composed of actin, tropomyosin, and troponin proteins.
Actin: Protein that interacts with myosin for contraction.
Tropomyosin: Protein that blocks myosin binding sites on actin in a relaxed muscle.
Troponin: Protein that binds to tropomyosin and actin, regulating muscle contraction.
A Band: Region of sarcomere containing both thick and thin filaments.
H Band: Region of sarcomere containing only thick filaments.
I Band: Region of sarcomere containing only thin filaments.
Z Disc/Line: Separates adjacent sarcomeres.
Cross-Bridge: The connection between myosin heads and actin filaments during contraction.

Motor Unit

Motor Unit: A motor neuron and all the muscle fibers it controls.
Components:
- Motor neuron
- Muscle fibers
Neuromuscular Junction (NMJ):
- Synaptic Knob: Expanded end of the motor neuron.
- Synaptic Vesicles: Contain acetylcholine (Ach).
- Synaptic Cleft: Gap between the synaptic knob and muscle fiber.
- Junctional Folds: Invaginations of the muscle fiber's sarcolemma.
- Receptor Proteins: Respond to acetylcholine.
- Acetylcholine (ACh): Neurotransmitter that stimulates muscle contraction.
- Acetylcholinesterase (AChE): Enzyme that breaks down acetylcholine, terminating the signal.

Excitation-Contraction-Relaxation Coupling

Threshold Stimulus: Minimum stimulus required to cause a muscle contraction.
Latent Period: Delay between stimulus and the beginning of contraction.
Refractory Period: Time muscle cannot be stimulated again.

Energy Sources for Muscle Activity

Initial (Myokinase and Creatine Kinase): Immediate energy from stores of creatine phosphate.
Short-Term/Secondary: Anaerobic glycolysis, producing ATP and lactate.
Long-Term: Aerobic respiration, producing ATP from glucose or fatty acids.
Muscle Fatigue: Inability to maintain muscle tension.
Oxygen Debt: Amount of oxygen needed to return muscle to resting state after strenuous activity.

Specific Muscle Groups

Rotator Cuff: Supraspinatus, infraspinatus, subscapularis, teres minor
Quadriceps Femoris: Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
Hamstrings: Biceps femoris, semimembranosus, semitendinosus

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Description

This quiz covers the concepts of homeostasis and stress, emphasizing the body's ability to maintain internal balance amidst external changes. It also delves into negative feedback mechanisms involved in regulating blood pressure and glucose levels.