Physiology Exam 1

What is the basic structural and functional units of life?

Cells

\
\-All living organisms are cellular in nature

What only has one cell?

amoebas,

\
\-Also known as unicellular

\-This is different from humans , animals and big plants which are known to have many cells (multicellular)

There are __ __to__ ______ cells in the human body

50, 100 trillion

What are the 3 main regions of a cell?

\-Plasma membrane

\-Cytoplasm

\-Nucleus

Plasma Membrane

is the outer thin flexible membrane of the cell which separates the intracellular from the extracellular compartments (fluid)

What is the plasma membrane made up of?

double layer of lipids such as phospholipids, cholesterol, and glycolipids, with which proteins are embedded.

What are the most abundant lipids?

Phospholipids

Phospholipids heads?

hydrophilic (water loving) so it lies in the intracellular and extracellular fluids. (can say inner and outer portion of the membrane)

Phospholipid tails ?

Hydrophobic (water hating) so it lies in the center of the plasma membrane

What are the two main proteins of the plasma membrane?

integral and peripheral.

What are integral proteins?

These are the most abundant proteins. Most lie in the membrane (extend entirely through the membrane (transmembrane)). Other proteins will protrude out from one side of the membrane and act as a receptor.

What are peripheral proteins?

The mostly lie on the cytoplasmic side. So they will support the cytoplasmic side of the membrane by a network of filaments (threadlike fiber )

What is glycocalyx?

Are an additional structure to proteins. It is a sugar covering, so it will cover the cell/coat the cell. so it functions cell-to cell binding and recognition.

Glycocalyx is made up of _____ __(sugars) that projects from the external surface of _______ or _________

\-carbohydrates

\-glycoproteins

\-glycolipids

What produces glycocalyx and what is an example of their function of cell to cell binding?

Produced by corneal epithelial cells, and helps bind mucins onto the corneal surface.

What are the three functions of the plasma membrane?

1\.) Serves as an external barrier against substances and external forces outside of the cell.

2\.) The membranes external facing proteins act as receptors (for hormones, neurotransmitters, etc) and in cell to cell recognition

3\.) Acts in transport of substances into or out of the cell. So this membrane is a selective permeable barrier which allows some substances to bass b/w the intercellular and extracellular fluids while preventing others.

What are 3 ways substances can move across the plasma membrane?

1\.) Passive Process

2\.) Active Process

3\.) Vesicular or bulk transport

Passive process

Substances can pass freely through the lipid bilayer down their concentration gradient meaning from an area of high concentration to an area of low concentration. This is why no energy (ATP) is required

Diffusion

Is an example of passive transport. This is movement of small, uncharged molecules like O2, Co2, and fat soluble molecules across the membrane (high conc to low conc)

Active process

Substances move against a concentration gradient, meaning they move from an area of high concentration from an area of low concentration. Energy (ATP) is required.

What type of molecules are used in active transport?

Large water-soluble or charged molecules, such as glucose, amino acids and ions. In which they are transported by carrier proteins which pump the molecules against their concentration gradient and it also involves integral proteins

Vesicular or bulk transport

Large particles and macromolecules pass through the membrane by this mechanism. There are generally two types of bulk transport: which are exocytosis and endocytosis

Exocytosis

How this works is membrane-lines cytoplasmic vesicles fuse with the plasma membrane and the plasma membrane can then release its contents to the OUTSIDE of the cell.

\-Example: ==mucus== and proteins secrations from the glands in the body.

vSNARES and tSNARES in exocytosis

vSNARES are proteins extending from the vesicle membrane, will go and bind to tSNAREs (t stands for target) which are extending from the plasma membrane. This then causes the lipid layers of the vesicles and cell membrane to join.

Endocytosis

\-Brings large molecules into the cell, through the initial infolding of the plasma membrane, This will them enclose the large molecules to form cytoplasmic (inside of the celI) vesicles.

\- ==CLATHRIN== protein is found in the cytoplasmic side of the infolding. This protein is responsible for the deforming the membrane to allow for the vesicle to pass through the membrane

What are the 3 types of endocytosis

\-phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Phagocytosis

\-cell eating,

\-Parts of the membrane form pseudopodes, this will flow around large molecules, such as bacteria and cellular debris and engulf it.

\-Now membranous vesicles called phagosomes are formed.

\-Phagosomes will fuse to lysosomes for the enzymatic breakdown of of the phagosomal contents.

\-White Blood cells have phagocytic activities

Pinocytosis

\-cell dinking, is fluid phase endocytosis

\-The small infolding of the plasma membrane surrounds a small quantity of extracellular fluid containing dissolved molecules.

\-An example of this is cells lining the small intestines in order to absorb nutrients

Receptor mediated endocytosis

\-Molecules such as insulin, other hormones, enzymes, and low density lipoproteins (LDL, are molecules that carry cholesterol in the blood to the body’s cells)

\-These molecules are brought into the cells by first attaching to a receptor on the membrane then the molecules are taken into the cells in a protein coated vesiclele.

\-The contents in the vesicle are released by the binding to lysosomes and the receptors are recycled back (put pack) tp the plasma membrane.

\-Viruses and some toxins use this mechanism to enter the cell.

Familial hypercholesterolemia

\-Recall that LDL, low density lipoproteins, are molecules that carry cholesterol in the blood to the body’s cells.

\-So in this inherited disease cells lack the receptors that bind to cholesterol that bind to LDLs

\-This will then cause cholesterol to not enter the cell and cholesterol then build up in the blood. Which cause hypercholesterolemia and atherosclerosis which leads to a stroke or myocardial infraction.

The Cytoplasm:

\-is the cellular \n region between the nucleus \n and plasma membrane.

\-It consist of cytosol, or cytoplasmic matrix which is a viscous fluid containing water, ions and enzymes, inclusions containing stored nutrients and pigments and organelles

\

Ribosomes (part of the cytoplasm)

\-are dark staining granules with no membrane.

\-are the site of protein production.

\-The consists of two subunits: which are the proteins and ribosomal RNA (rRNA, ribonucleic acid)

\-Free ribosomes make the proteins in cytosol.

\-Ribosomes attached to the surface of the rough ER make the proteins used for the cell membrane or these proteins are exported out of the cell.

\-Amino acids on the ribosomes are linked together to form protein, this process is called ^^translation^^. This process is dictated by DNA in the nucleus, and the instructions from the DNA or carried to the ribosomes by messengers called messenger RNA (mRNA)

Rough Endoplasmic Reticulum (Part of the cytoplasm)

Is a ribosomes-studded system (is made up ribosomes) of the membrane-walled envelopes in cytosol, called ^^cisternae^^.

\-Ribosomes on the rough ER make proteins which enter the cisternae and are secreted by the cell in the vesicles. Ribosomes also make the proteins of the cell membrane.

Smooth Endoplasmic Reticulum (part of the cytoplasm)

Is a network of membranous system of sacs and tubules in the cytosol. It has NO RIBSOMSOMES

\-It is involved in the synthesis of lipids and steroids. And conducts lipid metabolism and drug detoxification

Golgi Apparatus (part of the cytoplasm)

\-is a stack of 3-10 disc shaped envelopes or cisternae which are bound by the membrane.

\-Cisternae has a cis (convex/curve like the exterior of a circle) and a trans (concave/surface that curves like the inside of a circle) face

\-The function is to sort products of the Rough ER and packs them in membrane bound vesicles and sends them to their proper destination.

\-Secretory granules and lysosomes also arise from the Golgi apparatus

Mitochondria (part of the cytoplasm)

\-Are rod like organelles covered by two membranes in the cytoplasm.

\-The inner membrane is folded into projections called ^^cristae^^

\-Functions is being the main energy generator of the cell and are the main site of ATP synthesis.

Lysosomes (part of the cytoplasm)

\-Are spherical, membrane walled sacs containing digestive enzymes called ^^acid^^ ^^hydrolases^^

\-Lysosomoes are sites of intracellular digestion and they destroy (digest) deteriorated organelles a nd substances brought into the cells by vesicles.

\-Lysosomes fuse with phagosomes and empty their enzymes into phagosomes, breaking down their contents. So phagocytic cells have a lot of lysosomes

Tay-sachs disease

is an inherited disease. This is when infants lack specific enzymes in their lysosomes that are responsible for the break down of certain glycolipids. As a result, glycolipids accumulate in the cell membrane specifically on neurons. This results in mental retardation, blindness, spastic movements (muscle spasms) and death within 1.5 years from birth

Gauchers’s Disease

he lack of the glucocerebrosidase enzyme causes harmful substances to build up in \n the liver, spleen, bones, and bone marrow. The substances prevent cells and organs \n from working properly.

What are the 3 main types of Gaucher’s disease

1\.Type 1 disease is most common. It involves bone disease, anemia, an enlarged \n spleen and thrombocytopenia. Type I affects both children and adults.

\n 2.Type 2 disease usually begins in infancy with severe neurologic involvement. This \n form can lead to rapid, early death.

\n 3.Type 3 disease may cause liver, spleen, and brain problems. Patients may live into \n adulthood.

What are the symptoms of Gaucher’s disease

Bone pain and fractures \n Enlarged spleen \n Enlarged liver \n Lung disease \n Seizures

Peroxisomes (part of the cytoplasm)

\-Are membrane-walled, enzyme-containing sacs.

\n -They contain oxidase and catalase enzymes. \n Oxidases use oxygen to neutralize aggressively reactive substances called \n ^^free^^ ^^radicals^^, by converting them to hydrogen peroxide. \n Hydrogen peroxide, although reactive and dangerous, it is converted to oxygen and water by catalases which break down poisons like alcohol, phenol and \n formaldehydes that have entered the body.

\
\-Liver and kidney have many peroxisomes.

Cytoskeleton (this is part of the cells Skelton or the “bones” that help support the cell.

Is a network of rods running throughout the cytosol to support the cellular structure.

\n and generates movements of the cell.

What are the three types of cytoskeleton

Microtubules, microfilaments and intermediate filaments

Microtubules

Are cylindrical structures made of ^^tubulin proteins.^^

\-They radiate out from the \n centrosome region close to the nucleus (they come out of the centrosomes) . They give the cell its shape and they organize the distribution and transport of various organelles within the cytoplasm.

Microfilaments (actin filaments):

\-Are fine filaments of contractile protein called \n actin (they are made up of the protein actin).

\
\-They are labile.

\n -Actin interacts with another protein called ^^myosin^^, and generates contractile forces within the cell. It is involved in muscle contraction, and other types of cellular movements such as amoeboid movements and \n extension of pseudopods.

Intermediate \n filaments:

are tough insoluble and stable protein fibers which act to resist tension placed on the cell.

Centrosomes

is a spherical structure in the cytoplasm near the nucleus. It consists of an outer cloud of protein called: ^^matrix^^ and an inner pair of ^^centrioles^^.

\-Matrix protein is involved in the elongation \n of microtubules and mitotic spindle of \n microtubules radiates from it in dividing \n cells.

What are some impermanent (not permeant) Structures in the cytoplasm.

Lipids droplets, glycogen containing glycosomes.

Centrioles

are in the core of centrosome. These are paired cylindrical bodies perpendicular to one another

\-each composed of nine triplets of microtubules. \n They organize a microtubule network \n during mitosis to form the spindle and \n asters. They also form the bases of cilia and flagella

The nucleus:

\-Nucleus is the control center of the cell \n and contains genetic materials (DNA), \n which directs the cell’s activities by \n providing the instructions for protein \n synthesis. \n

\-Most cells have one nucleus in the center, \n some have multiple nuclei such as skeletal \n muscle. However, mature red blood cells \n have no nucleus (anucleate) at all.

What are the three main parts of the nucleus:

1- Nuclear envelope
2- Chromatin and chromosomes
3- Nucleoli

Nuclear Envelope

Surrounds the nucleus and has pores and \n is continuous with endoplasmic reticulum

Nucleolus:

\-a dark staining body within the nucleus. \n It contains parts of chromosomes and is the \n cell’s ribosome producing machine (has \n genes that code for rRNA).

Chromatin

\-granular thread-like material in the nucleus composed of DNA(Deoxyribonucleic acid) and histone proteins.

\-DNA constitute the genes (dna make up genes). \n genetic code is copied onto mRNA in a \n process called transcription.

Deoxyribonucleic acid (DNA):

\*DNA molecule in chromatin is a double helix chains of nucleotide molecules. \n \*Nucleotides consist of sugar, phosphate and \n one of four bases: thymine (T), adenine (A), \n cytosine (C) or guanine (G), which bind to \n hold the DNA helix together like a ladder.

\n \*DNA helix wraps around clusters of eight \n spherical proteins called ^^histones^^, which \n regulate gene expression and transcription.

\n \*Each cluster of DNA and histones is called \n a ^^nucleosome^^.

Chromosome

\*Chromosome contains a single, very long \n molecule of DNA. There are 46 chromosomes \n in a typical human cell. \n \*Chromatin is distributed in chromosomes. \n During cell division, the chromatin is highly \n coiled, making the chromosomes appear as \n thick rods.

The Cell Life Cycle:

The cell life cycle is a series of changes \n a cell experiences from the time it forms \n until it reproduces itself.

What are the two major periods of the cycle cycle?

1- Interphase, in which the cell grows
and carries on its usual activities,


2- Cell division (mitotic phase), during
this period, the cell divides into 2 cells.


\*Cell division is essential for growth and
repair of the body.

Interphase

Is the non-dividing phase of the cell cycle, \n cells maintain their life-sustaining activities \n and prepare for the next cell division. \n It consists of subphases G1, S and G2.

G1 (gap 1):

cells are active and grow vigorously and \n centrioles start to replicate.

S (synthetic) phase:

DNA replicates itself for the future two \n daughter cells having identical genetic \n material.

G2 (gap 2):

Enzymes needed for cell division are synthesized, centrioles finish replication and cell gets ready to divide.

What are the 4 stages of mitosis?

1- prophase
2- metaphase
3- anaphase
4- telophase

What occurs in prophase?

\*^^Asters^^ (stars) are formed; these are microtubule arrays, extending from the centrosome.

\n \*Chromosomes are formed from coiling and condensation of the chromatin threads. \n (each chromosome has 2 identical chromatin threads, now called chromatids; the chromatids are held together by centromere and a protein complex called cohesin.)

\n \*nucleoli disappear \*centriole pairs separate \*nuclear envelope fragments

\n \*microtubules disassemble and are newly assembled to form mitotic spindles which lengthen \n and push the centrioles farther apart to the poles of the cell (some of these spindles are attached to chromosomes and are called kinetochores; others are called polar spindles).

Metaphase:

\*Chromosomes cluster at the middle of the cell, \n to form a metaphase plate. \n \*Separase, an enzyme which cleaves \n cohesin, start to separates the chromatids.

Anaphase: (third phase)

\*the V-shaped chromatids are pulled apart \n by the kinetochore spindles to become the \n chromosomes of the daughter cells, and the \n polar spindles still push against each other \n to elongate the cell. \n This stage lasts for few minutes only.

Telophase: (fourth phase)

\*This phase is like prophase in reverse. \n \*chromosomes at the opposite sides of the cell \n uncoil and resume extension of the chromatin. \n \*nuclear envelope forms by rER. \n \*nucleoli appear.

Cytokinesis

For a short period, the cell has 2 nuclei until \n it is completely separated by the process of cytokinesis

What is meiosis

Meiosis is a specialized process of cell division that occurs only in the production of gametes. It consists of two divisions that result in the formation of four gametes, each containing half the number of chromosomes (23 single chromosomes) and half the \n amount of DNA (1N) found in normal somatic cells (46 single chromosomes, 2N).

What are the important events in meiosis 1

\*Synapsis: pairing of 46 homologous duplicated chromosomes.

\n \*Crossing over: large segments of DNA are exchanged.

\n Alignment: 46 homologous duplicated chromosomes align at the metaphase plate.

\n Disjunction: 46 homologous duplicated chromosomes separate from each other; centromeres do not split.

\n Cell division: two secondary gametocytes (23 duplicated chromosomes, 2N) are \n formed.

What occurs in meiosis II

Synapsis: absent

\n Crossing over: absent

\n Alignment: 23 duplicated chromosomes align at the metaphase plate.

\n Disjunction: 23 duplicated chromosomes separate to form 23 single chromosomes; centromeres split.

\n Cell division: four gametes (23 single chromosomes, 1N) are found.

What is aneuploidy and examples of it?

abnormal number of chromosomes, can be trisomy or monosomy

An example of aneuploidy: Down syndrome

An example of trisomy because there are 3 chromosomes on chromosome 21 '

\-Trisomy 21

Example of Aneuploidy: Klinefelter syndrome:

Another example of trisomy because there is an extra x chromosome

\-XXY

Example of aneuploidy is turner syndrome

This is an example monosomy because it is missing an x chromosome (XO)

Gametes

\-contain 23 single chromosomes (22 autosomes and 1 sex chromosome) and 1N amount of DNA.

\-Contain 23 chromosomes because you need a sperm and egg that come together to fertilize then you get 46 chromosomes

\-The term “haploid” is classically used to refer to a cell containing 23 single chromosomes.

\
\*Female gametes contain only the X sex chromosome. \n \*Male gametes contain either the X or Y sex chromosome; ^^therefore, the male \n gamete determines the genetic sex of the individual.^^

Aging

Aging is complex and may involve cell damage due to free radicals as a result \n of normal cell metabolism or cell injury due to radiation and chemical pollutants.

Mitochondrial theory of aging

involves a decrease of energy production by \n radical-damaged mitochondria which weakens and ages the cell.

\
\-Vitamins C and E \n act as antioxidants and prevent excessive production of free radicals.

\
\-The same is \n true with caloric intake restriction due to lowering the metabolic rate which slows \n aging.

Genetic theories of aging

proposes that aging is programmed into our genes \n (senescence: the process of deterioration with age).

Apoptosis (Programmed Cell Death)

Apoptosis is the method whereby cells are removed from tissues in an orderly fashion \n as a part of normal maintenance or during development.

\n Cells that undergo programmed cell death have several morphological features.

\-They include chromatin condensation, breaking up of the nucleus, and the plasma \n membrane. \n - The cell shrinks and is fragmented into membrane-enclosed fragments called \n ^^apoptotic bodies. \n ^^

The signals that induce apoptosis may occur through several mechanisms.

Certain cytokines, such as tumor necrosis factor (TNF), may also activate \n caspases that degrade regulatory and structural proteins in the nucleus and \n cytoplasm, leading to the morphological changes characteristic of apoptosis.

Defects in the process of programmed cell death (Apoptosis) contribute to many major diseases.

* Too much apoptosis causes extensive nerve cell loss in Alzheimer disease and
stroke.
* Insufficiency of apoptosis (lack of cell death) has been linked to cancer and other autoimmune disease.

Cancer

A cell mass which divides and multiplies abnormally; it is also called a ^^neoplasm^^. \n Neoplasms are classified as Benign or Malignant.

Benign neoplasm (cancer)

or tumor is a local mass, remains compacted, often encapsulated, grows \n slowly and seldom kills the host.

\
\-So does bot spread.

Malignant neoplasm or cancer

is a mass which is not-capsulated and grows rapidly. \n Cells here are immature and they invade their surrounding. \n These give metastasis (invading other tissues) by means of lymphatics and/or blood.

\
\-This one spreads

Oncogenes

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


1. Genetic accidents or viruses may lead to the formation of oncogenes.
2. Oncogenes dominate the normal alleles (proto-oncogenes), causing deregulation of cell
division, which leads to a cancerous state.
3. Bladder cancer and acute myelogenous leukemia are caused by occogenes.

Tissues

are collection of structurally similar cells with related function. The entire body is composed of only four major types of tissues.

What are the 4 major tissues

1. Muscle
2. Nervous
3. Epithelial
4. Connective tissues

Organs

Groupings of these four primary tissues into anatomical and functional units are called \n organs. \n Organs in turn, may be grouped together by common functions into systems.

Muscle tissue

contractile tissue of the body and is derived from the mesodermal layer of \n embryonic germ cells. It is classified as skeletal, cardiac, or smooth muscle, and its \n function is to produce force and cause motion, either locomotion or movement within \n internal organs.

Skeletal muscle

type of striated muscle, usually attached to the skeleton. \n Skeletal muscles are used to create movement, by applying force to bones and \n joints; via contraction.

\
Long striated cells with multiple nuclei

common location: In skeletal Muscles

Function: contraction of voluntary movement

Smooth muscle

found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, and blood \n vessels, and unlike skeletal muscle, smooth muscle is not under conscious control.

\
Long, striated, spindle-shaped cells, each with a single nucleus.

\
Common location: in hollow organs like the stomach

Function: propulsion of substances along internal passageways

Cardiac muscle

is also an "involuntary muscle" but is a specialized kind of muscle \n found only within the heart.

\
Branching, striated cells fused at plasma membranes.

Location: walls in the heart

Function is to pump blood in the circulatory system.

Nervous tissue

Nervous tissue is specialized \n to: \n react to stimuli and to conduct \n impulses to various organs in \n the body which bring about a \n response to the stimulus. \n \n ^^Nerve^^ ^^tissue^^ (as in the brain, \n spinal cord and peripheral nerves \n that branch throughout the body) \n are all made up of specialized \n nerve cells called neurons. \n ^^Neurons^^ are easily stimulated \n and transmit impulses very \n rapidly.

A nerve is made up of many nerve cell fibers (neurons) bound together by connective \n tissue. A sheath of dense connective tissue called what?

the epineurium surrounds the nerve

This sheath, the epineurium, penetrates the nerve to form what

the perineurium which surrounds bundles \n of nerve fibers. blood vessels of various sizes can be seen in the epineurium.

The endoneurium

which consists of a thin layer of loose connective tissue, \n surrounds the individual nerve fibers.

What are the functions of the epithelial tissue

1. Protection: Epithelial cells from the skin protect underlying tissue from
mechanical injury, harmful chemicals, invading bacteria and from excessive loss of
water.
2. Sensation Sensory stimuli: penetrate specialized epithelial cells. Specialized
epithelial tissue containing sensory nerve endings is found in the skin, eyes, ears,
nose and on the tongue.
3. Secretion In glands:, epithelial tissue is specialized to secrete specific chemical
substances such as enzymes, hormones.
4. Absorption: Certain epithelial cells lining the small intestine absorb nutrients
from the digestion of food.