Human Bio Year 11 Sem 2

Australia Year 11 ATAR Human Biology Semester 2 Revision

What are the 3 types of muscles?

Skeletal, smooth, and cardiac muscles.

Function of skeletal muscles

They are responsible for voluntary movement. They are attached to the skeleton

What are smooth muscles?

They are involuntary muscles that are found in the walls of internal organs like the stomach and intestines.

What are cardiac muscles?

They are involuntary muscles that are found in the walls of the heart.

Extensibility vs Elasticity

Extensibility is the ability to be stretched and elasticity is the ability to return to the original length after being stretched

What connective tissue surrounds the entire muscle?

Epimysium

What are fascicles?

Bundles of muscle fibers surrounded by perimysium

What connective tissue surrounds a fascicle?

Perimysium

What is the Sliding Filament Theory?

It explains muscle contraction as the sliding of actin (thin) filaments over myosin (thick) filaments within the sarcomere.

Define sarcomere

The basic unit of a muscle's structure that helps it contract. It contains the proteins actin and myosin, which slide past each other to make the muscle shorten or contract.

What are the main proteins in the sliding filament theory?

Actin, myosin, troponin, and tropomyosin

What triggers muscle contraction?

A nerve impulse releases calcium ions, which bind to troponin and expose actin binding sites.

What happens when ATP is hydrolyzed in muscle contraction?

ATP is broken down into ADP, releasing energy that powers the myosin head movement.

What are antagonistic muscle pairs?

Muscle pairs where one contracts while the other relaxes to create movement.

What is an agonist muscle?

The main muscle responsible for a specific movement (prime mover).

What is a synergist muscle?

A muscle that helps the agonist by adding force or stabilizing a joint.

What are Z-Lines?

They are the boundaries that separate each sarcomere in a muscle fiber. They hold the thin filaments (actin) in place and move closer together during muscle contraction, helping the muscle shorten.

Are actin and myosin muscle fibers, myofibrils, or microfilaments?"

They are best classified as microfilaments

Why are synergist muscles important in movement?

They help the prime mover by stabilizing joints and preventing unwanted movements.

What is the diaphysis of a long bone?

The shaft or central part of a long bone, composed mainly of compact bone and containing the medullary cavity.

What are the epiphyses of a long bone?

The rounded ends of a long bone, composed mostly of spongy bone and covered with articular cartilage.

What is the periosteum and what is its function?

A dense connective tissue membrane covering the outer surface of bone, involved in protection, nourishment, and bone growth and repair.

What are osteons?

Cylindrical structures that make up compact bone, essentially acting as a building block for compact bones.

What are lamellae?

Rings of bone tissue that make up an osteon.

What are osteocytes?

Bone cells that live in small spaces called lacunae which maintain bone tissue.

What is spongy bone?

Bone with a web-like structure (trabeculae) filled with red marrow.

What do trabeculae do in spongy bone?

They provide support and help absorb shock by spreading out forces.

How is spongy bone different from compact bone?

Spongy bone is lighter and has open spaces and doesn’t have osteons, unlike compact bone

What is chondrin?

The firm, gel-like material in cartilage that gives it shape.

What do chondroblasts do?

They make and build new cartilage.

What are chondrocytes?

Cartilage cells that maintain and repair the cartilage matrix once formed

3 types of cartilage

Hyaline, Elastic, and Fibrocartilage

Hyaline Cartilage function

Reduces friction in joints and supports the body. An example is the nose.

Elastic Cartilage function

Maintains shape while allowing bending. An example is the outer ear.

Fibrocartilage function

Provides strong support and can withstand heavy tension. An example is the intervertebral discs of the spine.

What is the articular capsule in a synovial joint?

It is a double-layered capsule that encloses the joint cavity, providing stability and allowing movement.

What are the two layers of the articular capsule?

The outer fibrous capsule and the inner synovial membrane.

What is the role of the synovial membrane?

It produces synovial fluid, which lubricates and nourishes the joint.

How does synovial fluid benefit a synovial joint

It reduces friction, nourishes cartilage, and acts as a shock absorber.

What is the function of articular cartilage?

To cover bone ends, reduce friction, and absorb impact during movement.

What is the role of ligaments in synovial joints?

To connect bone to bone, providing joint stability and preventing excessive movement.

What does DNA stand for?

Deoxyribonucleic Acid.

What are the four nitrogenous bases in DNA?

Adenine. Thymine, Cytosine, and Guanine

What is a chromosome?

A tightly packed structure of DNA and proteins carrying genetic information.

What is the main function of chromatin?

To package DNA, protect it, and control gene activity.

What is the difference between autosomes and sex chromosomes?

Autosomes do not determine sex; sex chromosomes (XX or XY) do.

What enzyme unwinds DNA during replication?

Helicase.

What does semi-conservative replication mean?

Each new DNA molecule has one old strand and one new strand.

Why is the Y chromosome important?

It carries genes that trigger male development.