A&P Exam 2 (Cell, Histology, Integumentary)

Plasma Membrane & phospholipid bilayer

acts as a gatekeeper, allowing only specific substances in or out;

Isolate, Regulate, Communicate

1 polar, hydrophilic head & 2 non-polar hydrophobic tails

Receptors (membrane protein)

binds external signaling molecules to trigger a specific cellular response (ex: binds hormones)

Enzymes

catalysts for a specific reaction in the body

Transporters

transports specific substances across the membrane (ex: channel and carrier proteins)

Ion channels

proteins with pores that allow water and dissolved ions to cross membrane

• Open - constantly open

• Gated channels - open and close in response to stimuli

Gated-channels

• Ligand (chemically) - regulated gates - open when stimulated by a chemical substance or neurotransmitter

• Voltage-regulated gates - open due to change in voltage

Glycoproteins

critical components for cell identification, structural support, and immune defense

Cell adhesion molecules (CAM)

protein binds one cell to another

Microvili

small folds that increase the surface area of the cell; found in cells lining the intestine

Mitochondria

produces ATP

Ribosomes

protein synthesis

Rough ER

studded w/ numerous ribosomes (sites of protein synthesis)

Smooth ER

synthesizes phospholipids and steroid hormones

Golgi apparatus/complex

Organizes, modifies, packages, sorts, and tags proteins from ER

Peroxisome (vesicle)

produced in the ER; detoxify alcohol and other drugs

Lysosome (vesicle)

contain digestive enzyme

Centrioles

responsible for forming mitotic spindle

Cilia

hair-like projections that line respiratory tract to move mucus

Flagella

allow movement of the cell

Nucleus

contains DNA, control center of the cell & begins protein synthesis

Chromatin

thread-like matter composed of DNA

Nucleoli

one or more in cell; where ribosomes are produced

Nuclear membrane/envelope

double layer that contains pores

Passive transport

substances move “down” the concentration gradient; little or no energy is required

1. Filtration

2. Diffusion

   1. Simple diffusion

   2. Facilitated diffusion

3. Osmosis

Active transport

all cells need to move some substances against their concentration gradient or move “uphill”; energy is required (ATP)

1. Ionic pumps

2. Vesicular transport

   1. Exocytosis

   2. Endocytosis

      1. Phagocytosis

      2. Pinocytosis

Filtration (passive transport)

Movement of water and small solutes across a membrane due to hydrostatic pressure (fluid pressure)

Diffusion (passive transport)

Movement of molecules from an area of higher concentration → lower concentration until they are evenly distributed.

Simple vs. facilitated diffusion?

Simple = directly through membrane, no protein
Facilitated = through a membrane protein
Both = high → low, no ATP

Osmosis (passive transport)

Water moves from an area of high water potential (low solute) to low water potential (high solute)

Sodium-potassium (ionic) pumps

moves sodium and potassium ions in opposite directions, each against its concentration gradient (3 Na+ out, 2 K+ in)

Vesicular transport

large particles or fluid droplets, substances are transported in vesicles

Exocytosis (vesicular transport)

moves material out of the cell

Endocytosis (vesicular transport)

moves molecules and liquids into the cell

Phagocytosis (Endocytosis)

“cell eating”; keeps tissues free of debris and infectious microorganisms

Pinocytosis (Endocytosis)

“cell drinking”; taking in droplets of ECF containing molecules useful in the cell

Tonicity

the measure of osmotic pressure gradient

What happens to a cell in a hypertonic solution?

Water leaves the cell → cell shrinks

What happens to a cell in a hypotonic solution?

Water enters the cell → cell swells

What happens to a cell in an isotonic solution?

Water moves equally in and out → cell stays the same size

What is the difference between chromatin and chromosomes?

Chromatin = loose DNA; Chromosomes = tightly coiled DNA

What is the function of DNA?

Stores the cell's genetic information/instructions.

What is the function of RNA?

Helps carry and use genetic instructions to make proteins.

What are DNA's base pairs?

A–T and C–G (apple tree, car garage)

What are RNA's base pairs?

A–U and C–G (aunts uncles, children grandparents)

What are the two steps of protein synthesis?

Transcription makes mRNA from DNA, then translation uses mRNA to build a protein

What is transcription?

The process of copying a section of DNA into mRNA. It occurs in the nucleus. The mRNA carries the genetic instructions from the DNA to a ribosome to be used to make a protein.

Remember: DNA → mRNA

What is translation?

The process of using the mRNA instructions to build a protein. It occurs at a ribosome. The ribosome reads mRNA in codons (3 bases at a time), while tRNA brings the correct amino acids that are joined together to make a protein.

Remember: mRNA → protein

What happens during prophase?

• DNA/chromatin condenses into visible chromosomes

• The nuclear envelope begins to break down

• Spindle fibers form and begin preparing to move the chromosomes

What happens during metaphase?

• Chromosomes line up in the middle of the cell

• Spindle fibers attach to the chromosomes

What happens during anaphase?

• Sister chromatids separate

• Spindle fibers pull the chromatids toward opposite ends of the cell

What happens during telophase?

• Chromosomes reach opposite ends of the cell

• Two new nuclear envelopes form

• Chromosomes begin to uncoil back into chromatin

• The cell prepares to divide into two cells

What are the details of epithelial tissue?

• Covers body surfaces & lines organs/cavities

• Avascular (no blood vessels)

• Functions: protection, absorption, filtration, secretion

Simple squamous — shape & location?

1 thin layer of flat cells. Found in alveoli of lungs, blood vessels, and kidney filtration areas.

Simple cuboidal — shape & location?

1 layer of cube-shaped cells; found in ducts of most endocrine and exocrine glands

Simple columnar — shape & location?

1 layer of tall cells

• non-ciliated: GI tract lining

• ciliated: lines trachea and fallopian tubes)

• pseudostratified: lines airways of upper respiratory tracts and ducts of most glands

Stratified squamous — shape & location?

Multiple layers; surface cells are flat

• stratified keratinized: epidermis of skin

• stratified non-keratinized: inside wet surfaces

Stratified cuboidal — shape & location?

Multiple layers of cube-shaped cells. Found in sweat gland ducts.

Stratified columnar — shape & location?

Multiple layers; surface cells are tall. Found in some larger ducts and parts of the reproductive tract.

What are exocrine glands?

Secrete out to the surface by a duct

Examples: sweat glands, salivary glands, digestive glands.

What are endocrine glands?

Release hormones directly into the blood; ductless.
Examples: thyroid, adrenal glands.

What are the 4 main categories of connective tissue?

Loose, dense, cartilage, and blood.

Areolar (loose) CT — where is it found?

surrounds most organs; subcutaneous skin

Adipose (loose) CT — where is it found?

subcutaneous skin; surrounding heart, kidneys

Reticular (loose) CT — where is it found?

supports liver, spleen, lymph nodes

Dense regular CT — where is it found?

Tendons and ligaments. Strong in one direction.

Dense irregular CT — where is it found?

Dermis of skin. Strong in many directions.

Cartilage

flexible and resilient; consists chondrocytes and surrounded by lacunae

Hyaline cartilage — where is it found?

Joints, nose, trachea, and ribs.

Elastic cartilage — where is it found?

External ear and epiglottis. Flexible.

Fibrocartilage — where is it found?

Intervertebral discs. Strong and absorbs shock.

Blood — what does it do and where is it found?

Transports oxygen, nutrients, wastes, and hormones. Found in blood vessels and the heart.

What are the 2 main cell types in nervous tissue?

Neurons and neuroglial (glial) cells.

What do neurons do?

Receive and transmit electrical signals.

What do neuroglial cells do?

Support, protect, nourish, and insulate neurons.

What are the 3 types of muscle tissue?

Skeletal, cardiac, and smooth.

Skeletal muscle — characteristics?

Striated, voluntary, many nuclei. Attached to bones.

Cardiac muscle — characteristics?

Striated, involuntary, usually 1 nucleus. Found only in the heart.

Smooth muscle — characteristics?

Non-striated, involuntary, 1 nucleus. Found in organs like the stomach, intestines, and blood vessels.

What is the general structure of the skin?

Epidermis, dermis, hypodermis

Epidermis is made out of?

keratinized stratified squamous epithelium

Dermis layers?

Consists of two layers:

• Papillary

• Reticular

What is the papillary layer in the dermis? What is it made of?

superficial layer; contains blood vessels to supply nutrients to epidermis and regulates temp; made of areolar connective tissue

What is the reticular layer in the dermis?

90% dense irregular connective tissue

Hypodermis what tissue is it made of?

not a part of the skin; adipose connective tissue (subcutaneous fat) (loose fibrous connective tissue)

What is body temperature regulation?

regulates body temp through sweat and adjust flow of blood in dermis

What is thermoregulation?

vasoconstriction/vasodilation

What is vasoconstriction?

Blood vessels narrow, reducing blood flow near the skin → less heat is lost / conserve heat (thermoregulation)

What is vasodilation?

Blood vessels widen, increasing blood flow near the skin → more heat is released / release heat (thermoregulation)

Skin protection

• Keratin: protects from microbes, abrasion, heat & chemicals

• Melanin: protects against UV light

• Sebum: prevents hair from drying out

• Lipids: reduce water loss & waterproof the skin

• Keratin + acid mantle: resist trauma & infection

What are the barrier functions of the skin?

• Water loss → waterproofing

• UV radiation → melanin

• Harmful chemicals → keratin & skin barrier

What are cutaneous sensations?

sensations in skin such as touch, warmth and coolness, and pain which can send a warning for tissue damage

Which two part of the body are best at detoxifying?

1. Liver

2. Skin

Excretion and absorption

small role in eliminating substances from the body through pores, excretion, and absorbing materials from the environment into the body

Synthesis of Vitamin D

when skin is exposed to UV radiation, this activates vitamin D which is then converted to a hormone calcitriol (active hormonal form of vitamin D3)

Transdermal absorption

administration of certain drugs via injections or adhesive patches

What is the epidermis?

superficial and thinner than dermis, composed of epithelial tissue

What tissue is the epidermis made of?

Stratified squamous epithelium

• non-keratinized (lines wet surfaces: mouth esophagus, vagina)

  • keratinized (epidermis of skin) - contains mostly dead cells

What are the 5 cells that make up the epidermis?

Some Kids Make Delicious Marshmallows

1. Stem cells

2. Keratinocytes

3. Melanocytes

4. Dendritic (Langerhans) cells

5. Merkel cells

What are stem cells in the epidermis?

mitotic dividing cells that give rise to keratinocytes

What are keratinocytes in the epidermis?

the main type of cell in the epidermis (90%), arranged in 4 of 5 layers, produce the protein keratin