Human Body 1 Flashcards - Weeks 1 to 5

Semester 1 Year 1 Revision

Define homeostasis.

The body’s ability to detect change, activate mechanisms that reverse it and maintain a stable internal environment within a normal range

What are the 3 aspects of the homeostasis control system?

The receptor, integrating center and effector

What does the receptor do?

Senses a change within the body

What does the integrating center do?

Processes information and decides on an appropriate response

What does the effector do?

Carries out the action that corrects the change

What is a negative feedback loop?

A self-correcting mechanism that maintains homeostasis. The body detects change and activates mechanisms to reverse it

What is a positive feedback loop?

A self-amplifying homeostasis mechanism where change leads to even greater change in the same direction (eg. labour contractions)

What are atoms?

The building blocks of matter with an equal number of protons, neutrons and electrons

What are molecules?

They are composed of at least 2 atoms

What is an anion?

Negatively charged (gains electrons)

What is a cation?

Positively charged (loses electrons)

What is a non polar molecule?

When electrons are shared equally

What is a polar molecule?

When electrons are shared unequally

What are inorganic compounds?

They have no carbon (eg. water and minerals)

What are organic compounds?

They contain carbon (eg. glucose) and are often complex macromolecules built from monomers

What are the 4 categories of organic compounds?

Carbohydrates, lipids, proteins and nucleotides

Describe carbohydrates as an organic compound.

Hydrophilic molecules that are a quick fuel source for energy production. The basic monomer is C6 H12 O6

Describe lipids as an organic compound.

Hydrophobic molecules (fatty acids, triglycerides, phospholipids or steroids)

Describe proteins as an organic compound.

Contains carbon, oxygen, hydrogen and nitrogen, and are a polymer of amino acids. There are 20 different amino acids held together by peptide bonds to create proteins (mostly hydrophilic)

Describe nucleotides as an organic compound.

Nucleic acids are a monomer of nucleotides. One nucleotide has a deoxyribose sugar, phosphate and a nitrogenous base (AGCT). In RNA, thymine (T) is replaced by uracil (U)

What is a hydrophilic molecule?

Water soluble molecules that must be positively or negatively charged (eg. Na+ or Cl-) or polar molecules (eg. glucose)

What are hydrophobic molecules?

Fat soluble molecules that cannot dissolve in water. They must be non-polar or neutral molecules because they aren’t attracted to water

What is a monosaccharide?

A monomer, like glucose, fructose or galactose

What is a disaccharide?

Two monomers, like sucrose (glucose + fructose)

What is a polysaccharide?

Polymers of glucose (like glycogen for energy storage)

What is a nutrient?

A chemical substance from food that provides ATP energy and building blocks to support life. Some non-essential nutrients can be made by the body

What is ATP?

Adenosine triphosphate - the body’s energy transfer molecule. It is made as needed and it stores energy gained from food breakdown

What are vitamins?

Micronutrients that contain carbon (organic) and are easily destroyed by heat, air, acid or mixing

What are minerals?

Micronutrients that don’t contain carbon (inorganic) and retain their chemical structure. Some are needed in smaller amounts but are still important as the body can’t function without them

What are cells?

The smallest living units in the body

What is the plasma membrane?

A phospholipid bilayer that separates the inside and outside of the cell. It contains lipids, proteins and microvilli to create a barrier, allow certain molecules in and out of the cell and increase surface area for absorption

What are cilia?

They can be non-motile (like an antenna) and motile, and they sweep substances across surfaces

What does the cytoplasm contain?

The cytoskeleton, organelles and cytosol

What is the endoplasmic reticulum?

A network of membranous channels and sacs within the cytoplasm. There is rough ER with ribosomes for protein synthesis and smooth ER without ribosomes that detoxify alcohol and drugs

What is the Golgi complex?

A membranous structure with flat membranous sacs called cisternae that form Golgi vesicles

What are lysosomes?

Enzymes that use water to break down and destroy things

What is the mitochondrion?

A double membraned organelle (inner membrane is folded to increase surface area) that synthesises ATP energy for the body

What is a centrosome?

Two short cylinders of centrioles that organise microtubules in mitosis

What is the cytoskeleton?

It maintains cell structure, support, strength and provides transport systems

What are the main steps in protein synthesis?

1. DNA is separated and transcribed into mRNA by the RNA polymerase

2. mRNA leaves the nucleus and goes to the ribosome

3. The ribosome reads the mRNA strand and translates it into different amino acids to create a protein

What is passive transport?

Where molecules move down the concentration gradient (high to low). It can be simple diffusion that occurs through the phospholipid bilayer or facilitated diffusion that occurs through a carrier or channel protein in the phospholipid bilayer

What is osmosis?

Simple diffusion of water across the phospholipid bilayer. Water concentration is determined by solute concentration, because they displace water (high water levels = low solute levels)

What is osmolarity?

It describes the concentration of solute in a solution. Water will move down the concentration gradient until concentration of solutes are equal on both sides of the phospholipid bilayer

What is tonicity and what are the 3 solutions?

The ability of a solution to cause a cell to shrink or swell.

• Hypotonic solutions = less solute and more water in the cell

• Isotonic solutions = equal solute and water concentration

• Hypertonic solutions = more solute and less water in the cell

What is active transport?

Where molecules move against the concentration gradient (low to high) which requires ATP energy. Solutes bind to a transport protein which changes its shape to release the solute on the other side of the phospholipid bilayer

* Vesicular transport - Large molecules are surrounded by a vesicle and merge with the phospholipid bilayer through exocytosis and endocytosis

What is interphase?

DNA replicates to make chromosomes for new cells.

46 chromosomes = 92 chromatids (held together at the centromere (middle of the chromosome x))

What is prophase?

Chromosomes are compacted, centrioles sprout spindles to push them to opposite ends of the cell. Some spindles attach to the chromosome’s centromere

What is metaphase?

Chromosomes are lined up in the middle of the cell by the spindles

What is anaphase?

Centromeres (middle of the chromosome x) split to separate chromatids to the opposite ends of the cell

What is telophase?

The nucleus is reformed and cytokinesis pinches the cytoplasm off completely to form two identical daughter cells

Which microorganisms are cellular?

• Bacteria (prokaryotic)

• Archaea (prokaryotic)

• Fungi (eukaryotic)

• Protists (eukaryotic)

• Helminths (eukaryotic)

Which microorganisms are acellular?

• Viruses

• Prions

What is epithelial tissue?

It lines and covers organs and makes up the skin’s surface

• No blood vessels, gets nutrients through diffusion from the connective tissue under it

• Glandular epithelium - cells that secrete products that diffuse into the blood, like insulin or into ducts and out to the surface, like sweat

What type of epithelium is found in the alveoli of the lungs, inner lining of blood vessels and serous membranes of the viscera?

Simple squamous epithelium

What is simple epithelium?

One layer of epithelial tissue that involves diffusion, osmosis, filtration, absorption or secretion

What is stratified epithelium?

Multiple layers of epithelial tissue which protects surfaces from abrasions and friction

What are the 3 shapes of tissue?

1. Squamous - flattened

2. Cuboidal - cube shaped

3. Columnar - column shaped

What is connective tissue and where is it commonly found?

Tissue that connects, supports, strengthens, protects, insulates, allows movement, and internal transportation and provides an energy source.

It is composed of an extracellular matrix that’s composed of a ground substance (with water, adhesion proteins, polysaccharides and protein fibers like collagen and elastic fibers)

* Found in bones, tendons, ligaments and padding like adipose (stores lipids and fat)

What are the types of connective tissue?

1. Dense tissue - More fibers than matrix. Strong rope-like structures like tendons, ligaments and the dermis.

2. Loose tissue - More matrix than fibers. Positions organs, blood vessels and nerves as it’s widely distributed and randomly arranged to allow space for swelling to occur if needed.

3. Adipose tissue - Adipocytes (set number at birth) accumulate triglycerides.

What are the functions of the integumentary system?

• Protection from pathogens or physical objects

• Temperature regulation (thermo-receptors)

• Sensation (ability to detect pressure and temperatures)

• Metabolic functions (photoproducts like Vitamin D)

• Blood reservoir (holds 5% of blood volume)

• Excretion (removes wastes through sweat)

Name the different types of cells in the epidermis.

• Keratinocytes (produces keratin - double helix structure)

• Dendritic cells (phagocytic, reports to the immune system)

• Tactile cells (touch receptors with sensory nerve endings)

• Stem cells (produces new keratinocytes to replace dead ones)

• Melanocytes (produces melanin, transfers it to keratinocytes to protect DNA from UV light to reduce risk of melanoma)

Name the order of the cell layers of the epidermis from the outermost layer to the innermost layer.

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum basale

What is the stratum corneum?

5 to 50 layers of very keratinized dead cells

What is the stratum lucidum?

A few rows of dead keratinocytes that are only present in high-friction areas like fingertips, palms and toes

What is the stratum granulosum?

3 to 5 layers of keratinocytes where organelles degenerate, cells flatten and die. They have granules that secrete a protein to bind keratin filaments together. Some granules also secrete a glycolipid that waterproofs it against water movement and nutrient diffusion

What is the stratum spinosum?

Stratified epithelium, keratinocytes and keratin fibers that are linked by desmosomes

What is the stratum basale?

Simple cuboidal epithelium that is attached to the dermis. New stem cells here will become new keratinocytes, and this process will accelerate if there is an injury

What is the dermis?

The main part of the skin holding the body together. it contains strong, flexible, connective tissue with mostly collagen and blood vessels

What is the papillary layer of the dermis?

The top dermis layer made of loose connective tissue with collagen and dermal papillae that interlock with the epidermis. The dermal papillae increase surface area for grip and have sites for pressure receptors and nerve endings

What is the reticular layer of the dermis?

The bottom dermis layer made up of dense, irregular connective tissue including fibroblasts, macrophages and deep pressure receptors

What is the hypodermis?

The third, subcutaneous layer of the skin that is made up of loose connective tissue with adipocytes to store body fat. It acts as a shock absorber, insulator and an overall energy source. Collagen fibers here are interwoven with the dermis fibers

Why is the hypodermis a good injection site?

The adipose in this layer slows down medication release, there is a good blood supply to the area (vascular), no nerve endings and no pain receptors in the area either

How is skin colour created?

Skin consists of haemoglobin (red), carotene in palms and soles of feet (yellow/orange) and melanin (melanocytes) in the forms of eumelanin (brown) and pheomelanin (reddish yellow)

• Melanin creates freckles, moles, age spots and more

• Skin colour depends on the environment (UV exposure levels)

Too much UV causes __ and too little UV light causes __?

1. Skin cancer

2. Vitamin D deficiencies

What are the integumentary system’s accessory organs and what are their functions?

1. Sebaceous glands - Oil glands that secrete sebum

2. Merocrine glands - Exocrine glands for evaporative cooling

3. Apocrine glands - Scent glands that open into hair follicles

4. Hair/hair follicles - Dead keratinized cells that stand when cold

5. Nails - Keratinized, hard derivatives of the stratum corneum

What are the 4 stages of a wound assessment?

1. Broken blood vessels bleed into the cut, delivering antibodies, clotting proteins, erythrocytes and leucocytes to the area

2. The blood clots and macrophages digest debris

3. The dermis is replaced with new fibroblasts, collagen and capillaries

4. The epidermis is replaced with new keratinocytes from the stratum basale stem cells

How is tissue repaired?

Through regeneration (replacement with the same cell types) or fibrosis (repair by dense connective tissue). The type that is used is determined by the type of tissue damaged and the severity of it

What are the functions of bone?

To support the body, protect organs and allow for movement (skeletal muscles pull on bone)

Where are blood cells produced?

In red bone marrow

What does yellow bone marrow do?

Provides storage for lipids and it is a source of hydrogen to make ATP energy

What is bone strength made of?

Minerals, electrolytes, calcium, phosphate and collagen

How many bones do infants and adults have?

Infants - 270 bones

Adults - 206 bones

What are short bones?

They are equal in length and width, designed to glide across one another (eg. carpals and tarsals)

What are long bones?

They are longer than they are wider, like rigid levers acted upon by muscles (eg. the femur)

What are flat bones?

Curved, but wide and thin bones that protect soft organs (eg. sternum)

What are irregular bones?

They don’t fit into a standard category (eg. pelvic bone)

What are bone markings?

Elevations, depressions, grooves, holes and tunnels that are attachment sites for muscles, ligaments and tendons, and openings for blood vessels and nerves

Describe the two types of bone tissue.

1. Outer compact bone - Smooth, solid, protective layer stopping bone marrow from seeping out. It’s an attachment site composed of cylindrical units called osteons

2. Inner spongy bone - Absorbs impact, strong but light, lattice of rods and plates called trabeculae

What is an osteon composed of?

4 to 20 hollow tubes (lamellae), with one placed outside the next around a blood vessel. The collagen of lamellae gives the bone its flexibility

What is spongy bone?

It is filled with trabeculae and spaces are filled with blood vessels and bone marrow. Nutrients and other things diffuse from the bone marrow into the bone tissue

What is the difference between the diaphysis and the epiphysis?

The diaphysis is the shaft/cylinder of bone and the epiphysis is the head of the bone that strengthens the joint and allows for ligaments and tendons to attach to it

Describe bone growth as you age.

Bone grows from the epiphyseal plate (growth plate). Hyaline cartilage grows and is then replaced with bone as you age and epiphyseal plates become calcified, creating the epiphyseal line

What does hyaline cartilage do?

It separates the epiphysis and the diaphysis and it covers the ends of bones and allows joints to move while being friction free

What are the two bone coverings/linings and what do they do?

1. Periosteum - Found around the outer compact bone made of dense connective tissue that attaches to ligaments and tendons. It is vascular and has nerves as well

2. Endosteum - It lines bone marrow cavities

Describe the bone formation process.

1. A collagen framework is laid down (ossification)

2. Minerals like calcium phosphate are deposited and crystallised (calcification). Bone is ideally 1/3 collagen and 2/3 minerals

3. This provides strength to resist compression and flexibility to resist tension and shattering

• If calcium is removed, the bone bends. If collagen is removed, the bone shatters

What are osteogenic cells?

Stem cells that differentiate into osteoblasts that are located on the bone side of the periosteum and endosteum, central canals and epiphyseal plates.

What are osteoblasts?

They are bone-producing cells that secrete collagen and other parts of the extracellular matrix to initiate calcification. When it is surrounded by the extracellular matrix, it becomes an osteocyte.

What is an osteocyte?

A mature bone cell that maintains bone tissue. Cells are connected by channels called canaliculi and exchanges are made through gap junctions

What are osteoclasts?

Bone-breaking cells on the bone side of periosteum or endosteum that are giant multinucleate cells. Lysosomes break collagen and hydrochloric acid dissolves minerals within the bone

What is osteoporosis and what does it affect?

Osteoporosis is when osteoclasts break down bone cells faster than they can be produced, and it mainly affects the articular hyaline cartilage