Physiology exam 1 bare-bones

Plasma membrane

thin, flexible membrane of the cell, separates intracellular from extracellular compartment.

Integral proteins

most abundant, most extend entirely through the membrane (transmembrane), but some can protrude through one side, and can act as a receptor.

Integral proteins - CLINICAL

If there is a mutation to an integral protein and it changes the structure, it can lead to hormonal disorders (like type 2 diabetes)

Peripheral proteins

mainly on the cytoplasmic side by a network of filaments

Glycocalyx

short chain of carbohydrates (sugars) projected from the external surfaces of glycoproteins and glycolipids, used for cell-to-cell binding and recognition, produced by corneal epithelial surface cells.

Functions of the plasma membrane

1. Serves as an external cell barrier against substances and forces

2. Externally facing proteins act as receptors (hormones, neurotransmitters) and in cell-to-cell recognition

3. Transport of substances in and out of the cell (selectively permeable)

Passive transport

substances can pass freely through the lipid bilayer and down the concentration gradient, no ATP needed (more concentrated -> less).

Diffusion

small, uncharged molecules (O, CO2, fat soluble molecules).

Active transport

movement against the concentration gradient from low to high concentration, requires ATP, usually larger water-soluble or charged molecules transported by a pump and involve integral proteins

Vesicular transport

type of active process, passes large particles and macromolecules, two types: exocytosis and endocytosis

Exocytosis

Vessicles will fuse with the plasma membrane and release their contents to the outside of the cell. Releases contents from the cell into the blood.

Endocytosis

Brings large molecules into the cell by enclosing them and forming a cytoplasmic vesicle. Three types of endocytosis: phagocytosis, pinocytosis, and receptor mediated endocytosis. 

Phagocytosis (cell eating)

plasma membrane forms pseudopodes and englufs large molecules, leading to enzymatic breakdown of phagosomal contents

Pinocytosis (cell drinking)

small infolding of the plasma membrane surrounds a small amount of extracellular fluid containing dissolved molecules

Receptor mediated endocytosis

selective, specific molecules (insulin, hormones, enzymes, LDL) are brought into the cell by attaching to a receptor and being transported in a protein-coated vesicle

Receptor mediated endocytosis - CLINICAL

When the LDL receptor has a mutation and cholesterol cannot enter the cell (or ovaries or testicles, as cholesterol is the precursor to sex hormones), cholesterol increases in the blood

Familial Hypercholesterolemia

Inherited disease. Individuals lack the receptor that binds to cholesterol binding LDL. Cholesterol cannot enter the cell and builds up in the blood. This can cause hypercholesterolemia and atherosclerosis -> stroke or myocardial infarction.

Cytoplasm

Cellular region between the nucleus and plasma membrane

Ribosomes

Dark staining granule with no membrane, site of protein production

Rough ER

ribosome-studded system of membrane-walled envelopes in the cytosol, makes proteins

Smooth ER

Involved in the synthesis of lipids and steroids, lipid metabolism, and drug detoxification. 

Golgi Apparatus

Sorts the products of rER and packs them into membrane lined vesicles + transports them.

Mitochondria

Main energy generator of the cell and site of ATP production

Chemiosmosis

occurs in the inner membrane of the mitochondria using a proton gradient across a membrane to make ATP.

Lysosomes

Site of intracellular digestion for deteriorated organelles and substances brought into the cell via a vesicle. Fuse with the phagosome and empty their enzymes into the phagosome to break down the contents

Tay-Sachs disease

inhereted, infants lack the enzyme to break down certain glycolipids. Glycolipids accumulate in the cell membrane (on neurons), resulting in mental retardation, blindness, spastic movements, and death within 1.5 years of birth.

Gaucher’s Disease

Lack of glucocerebrosidase enzyme causes harmful substances to build up in the liver, spleen, bones, and bone marrow. Substances prevent cells from working properly. Three main types;

Type 1: most common, bone disease/anemia/enlarged spleen/thrombocytopenia, in children and adults.

Type 2: begins in infancy with severe neurological involvement, rapid+early death.

Type 3: Liver/spleen/brain problems, patients may live into adulthood. Symptoms vary on type but generally include bone pain/fractures, enlarged spleen + liver, lung disease, and seizures.

Peroxisomes

Membrane-walled, enzyme-containing sacs (oxidase and catalase) - both neutralize reactive oxygen species. Liver and kidney have many

Microtubules

gives the cell its shape and organizes the distribution and transport of various organelles within the cytoplasm.

Microfilaments

involved in muscle contractions and other types of cellular movement

Intermediate filaments

resist tension placed on the cell. 

Centrosome

spherical structure near the nucleus, has an outer cloud of protein (matrix) and an inner pair of centrioles. Matrix protein helps with elongation of microtubules and mitotic spindle of microtubules radiates from it in dividing cells.

Centrioles

They organize a microtubule network during mitosis to form the spindle and asters.

Nuclear envelope

Surrounds the nucleus, has pores and is continuous with the ER

Chromatin and chromosomes

chromatin is the thread-like material in the nucleus composed of DNA and histone proteins. Chromosomes contain a single, long piece of DNA (46 in a typical human cell) and has chromatin distributed throughout.

Nucleoli

contains parts of the chromosomes and is the cell’s ribosome producing center (code for rRNA)

DNA

DNA wraps around clusters of eight spherical proteins (histones) which regulate gene expression and transcription. Each cluster of DNA and histones is called a nucleosome. Zygote has 46 single chromosomes, half from mom and half from dad.

Interphase

cell grows and carries out its usual activities

Cell division (mitotic phase)

cell divides into 2, essential for growth and repair of the body. 

Interphase

1. G1 (gap 1): cells are active and grow vigorously, centrioles start to replicate.

2. S (synthetic): DNA replicates itself for two daughter cells with the same genetic material

3. G2 (gap 2): enzymes needed for cell division are synthesized, centrioles finish replication and the cell gets ready to divide.

Prophase

asters (stars) are formed (microtubule arrays that extend from the centrosome), chromosomes are formed (each chromosome has 2 identical chromatin threads called chromatids, chromatids are held together by a centromere and protein complex called cohesin), nucleoli disappear, centriole pairs separate, nuclear envelope fragments, microtubules disassemble and are newly assembled to form mitotic spindles (push centrioles to poles of the cell).

Metaphase

Chromosomes cluster at the center of the cell to form a metaphase plate, separase starts to separate the chromatids. All chromosomes in one line like a soldier.

Anaphase

V-shaped chromatids are pulled apart by kinetochore spindles, spindles push apart to elongate the cell.

Telophase

chromosomes uncoil and resume extension, nuclear evelope forms by the rER, nucleoli appear. Cells are then separated through cytokinesis. 

Meiosis 1

has large segments of DNA exchanged and the centromeres do NOT split. Results in 2 secondary gametocytes with 23 duplicated chromosomes and 2N DNA.

Meiosis 2

does not have crossing over but the centromeres DO split, resulting in 4 gametes with 23 single chromosomes and 1N DNA

Meiosis 2 - CLINICAL

Abnormal disjunction step in Meiosis 2 leads to genetic disorder - called aneuploidy. (ex. down syndrome - chromosome 21)

Aneuploidy

an abnormal number of chromosomes, can be trisomy and monosomy, Down syndrome is trisomy 21. Klinefelter syndrome (XXY). Turner syndrome (XO) is monosomy,

Gametes

Contain 23 single chromosomes and 1N DNA. Called a “haploid”

Aging

cell damage due to free radicals as a result of normal cell metabolism or cell injury due to radiation/chemical pollutants.

Mitochondrial theory of aging

decreased energy production by radical-damaged mitochondria which weakens and ages the cell

Genetic theory of aging

proposes aging is programmed into our genes.

Apoptosis

Method of cell removal where cells are removed from tissues in an orderly fashion as a part of normal maintenance or during development. Certain cytokines, like tumor necrosis factor (TNF), can activate capases 3 and 9 that degrade proteins in the nucleus and cytoplasm leading to the morphological characteristics of apoptosis.

Apoptosis - CLINICAL

too much apoptosis causes nerve damage and can lead to Alzhiemers and stroke, too little apoptosis linked to cancer and other autoimmune diseases.

Benign

remains compacted, often encapsulated, grows slowly, seldom kills the host.

Malignant

grows rapidly, immature cells invade their surroundings/surrounding cells, gives metastasis (invading of other tissue) through the blood or lymphatics.

Oncogenes

Oncogenes are the result of mutations of certain regulatory genes, called protooncogenes, which are normally supposed to stimulate/inhibit cell proliferation and development.

Oncogenes - CLINICAL

Oncogenes can cause bladder cancer and myelogenous leukemia

Muscle tissue

Produces force and causes motion, and can be skeletal, smooth, or cardiac

Skeletal muscle - applies force to bones and joints

Nervous tissue

specialized, reacts to stimuli and conducts impulses.

Epithelial tissue

Protection

Sensation sensory stimuli

Secretion in glands

Absorption

Excretion

Diffusion

Cleaning

Reduces friction

Pseudostratified with cilia

there is only one layer of cells but the position of the nuclei gives the impression that it is stratified

Simple squamous epithelia

line body cavities and capillaries to reduce friction, line the alveoli to facilitate gas exchange

Simple cuboidal epithelia

function is for secretion and absorption, found in glands and lining of kidney tubules, as well as in the ducts of the glands

Simple columnar epithelia

forms the lining of the stomach and intestines, some are specialized for sensory reception (nose, ears, and taste buds)

Pseudostratified columnar epithelia

found in ducts of large glands, ciliated variety lines the trachea. Function for secretion of mucous.

Stratified cuboidal epithelia

function to protect the ducts of sweat glands and the male urethra.

Stratified columnar epithelia

function to protect and secrete, small amounts in male urethra and in large ducts of some glands.

Stratified squamous epithelium

found in the vagina

Transitional epithelia

stretches readily and permits distension of urinary organ, lines the ureters, bladder, and part of the urethra. 

Exocrine glands

Exocrine are glands that retain ducts to body surfaces. Products of these cells collect in the duct of the gland and flow toward the surface to which the duct is in contact. Then they secrete their products onto body surfaces/cavities

Merocrine

cells form membrane-bound secretory vesicles internal to the cell. These are moved to the apical surface where vesicles coalesce with the membrane in the apical surface to release the product. Most glands release their products this way.

Apocrine

the apical portions of cells are pinched off and lost during the secretory process. This results in a secretory product that contains a variety of molecular components, including those of the membrane. Mammary glands release their products in this manner.

Holocrine

involves death of the cell. The secretory cell is released as it breaks apart, the contents of the cell become the secretory product. Results in most complex secretory product. Some sweat glands in the axillae, public areas, and around the ateoli of breasts release in this manner, sebaceous glands are this type too.

Endocrine gland

Referred to as ‘ductless’ glands. Their product is released across the cell membrane into interstitial spaces around the cells

Pancreas secretes

3 hormones - insulin, glucagon, and somatostatin

Tight junctions

they function to hold cells together, block movement of integral membrane proteins between apical and basolateral surfaces of the cell, preserve transcellular transport, and prevent passage of molecules and ions through space between cells.

Desmosomes

two disc-like plaques connected across intercellular space

Gap junctions

passageway between two adjacent cells, they let small molecules move directly between neighboring cells (act as channel for ions)

Marfan Syndrome

An autosomal dominant genetic disorder of the connective tissue characterized by disproportionately long limbs, long thin fingers, tall stature, and a predisposition to cardiovascular abnormalities (those affecting the heart valves and aorta). Has been linked to a defect in the gene on chromosome 15 which encodes a glycoprotein called fibrillin-1. Fibrillin is essential for the formation of the elastic fibers found in connective tissue.

Ehlers-Danlos Syndrome

Group of rare genetic disorders affecting humans and domestic animals caused by a defect in collagen synthesis (collagen 1 and 3). Looks like hyperextension - extreme elasticity of the skin and flexible joints.

Body Fluids

Extracellular space is a combination of blood vessels and interstitial space - collagen, polysaccharides, glycoproteins, and integrin

integrins

class of glycoproteins that extend from the cytoskeleton within a cell, through its plasma membrane, and into the extracellular matrix. By binding to components within the matrix, they serve as adhesion molecules between cells and extracellular matrix. 

Passive transport

net movement of molecules and ions across a membrane from higher to lower concentration that does not require metabolic energy.

Active transport

new movement across a membrane that occurs against a concentration gradient and requires ATP.

Primary active transport

occurs against an electrochemical gradient (uphill), requires direct input of metabolic energy (ATP), is carrier-mediated and exhibits stereospecificity, saturation, and competition.

Primary active transport - CLINICAL

Oversecretion of H+ into lumen of stomach leads to irritation of stomach = gastritis.

Secondary active transport

transport of two or more molecules is coupled, one of the solutes (usually Na+) is transported downhill and provides energy for the uphill transport of the other solute, metabolic energy is not provided directly

Secondary active transport - CLINICAL

Sodium (Na) can transport potassium (K), chloride (Cl-), amino acid, phosphate, glucose, calcium (Ca2+)

Simple diffusion

only form of transport that is not carrier-mediated, occurs down an electrochemical gradient (downhill), and does not require metabolic energy (passive)

Facilitated diffusion

occurs down an electrochemical gradient, similar to simple diffusion. Is passive as it doesn’t require metabolic energy, but is more rapid than simple diffusion. Carrier-mediated, so it has stereospecificity, saturation, and competition.

Facilitated diffusion - CLINICAL

Deficiency of insulin → hyperglycemia → type I diabetes

Osmolarity

the concentration of osmotically active particles in a solution. Two solutions with the same calculated osmolarity are isosmotic. If two solutions have different osmolarity, the solution with the higher osmolarity is hyperosmotic and the solution with the lower osmolarity is hyposmotic.

Osmosis

the flow of water across a semipermeable membrane from a solution with low solute concentration to a solution with high solute concentration.

Osmotic pressure

the OP increases when solute concentration increases, the higher to OP of a solution the greater the water flow into it. Water flows from hypotonic to the hypertonic solution

Cystic Fibrosis

CF is a result of a genetic defect, abnormal NaCl and water movement across wet epithelial membranes. Where these membranes line the pancreatic ductules and small respiratory airways, they produce a dense, viscous mucus that cannot be properly cleared, which can lead to pancreatic and pulmonary disorders. The genetic defect involves the glycoprotein CFTR (cystic fibrosis transmembrane conductance regulator) that normally exists in the cytoplasm of the cell and controls excretion of chloride from the cells into lumen of organs. Lumen osmotic pressure increases and lumen will absorb water and white blood cells (formation of mucus). Can cause death, pancreatitis, hormonal issues, diarrhea, dehydration, infertility in men.

Regulation of Blood Osmolarity

When a person is dehydrated, the blood is more concentrated as the total volume is reduced. This increase in blood osmolality and OP stimulate osmoreceptors, which are neurons in the hypothalamus - via CN 9 and 10. ADH acts on the kidneys to promote water retention, so a lower volume of more concentrated urine is excreted. Normal osmolarity in plasma is 280-303 milli-osmoles per kilogram. 

Edema

Water returns from tissue fluid to blood capillaries because the protein concentration of blood plasma is higher than that of tissue fluid. If a person has an abnormally low concentration of plasma proteins, excessive accumulation of fluid in the tissues will occur. Contributing factors: deficiency of proteins in blood (albumin), pregnancy, destruction of capillaries, lymphatic system disorders, cardiovascular/renal disorders, hypertension.

Hyperglycemia

In this case, glucose will be found in urine (glycosuria). This can come from the consumption of too much sugar or from inadequate action of the hormone insulin in the disease diabetes mellitus. (BG is over 120 mg/dl)

Hypoglycemia

When the plasma glucose concentration is abnormally low, it’s called hypoglycemia. (BG is below 50 mg/dl)