APK2100c exam 1

Membrane lipids come in three varieties: glycolipids

account for approx. 5% of membrane lipids. These lipids are amphipathic molecules with sugar molecules attached to the phosphate group (glyco means sugar). Glycolipids are only found on the outer surface of the membrane--surface that faces the extracellular fluid. since they face the extracellular fluid they play an important role in cellular recognition, adhesion, and growth and development.

Membrane lipids come in three varieties: cholesterol

accounts for approx. 20% or membrane lipids but only found in the plasma membranes of animal cells. Cholesterol molecules can be found among the hydrophobic tails of the bilayer. They play in important role in maintaining the structural integrity of the bilayer, that is they ensure that the bilayer is not too fluid.

organelles- ribosomes

are the site of protein synthesis. ribo derives from the fact that ribosomes contain RNA. ribosomes are located in a number of places throughout the cell, including the rough endoplasmic reticulum, free ribosomes in the cytosol, and mitochondria.

epithelial cells- simple columnar epithelial tissue (wont present this cell with cilia)

consists of a single layer of cells that are taller than they are wide. the most prevalent place where this kind of epithelium can be found is in the lining of the gastrointestinal tract. note that the nuclei of columnar cells are usually closer to the basal surface of the cell than to the middle. confused w pseudostratified columnar epithelial tissue but if there is cilia it is pseudostratified columnar epithelial tissue

connective tissue fibers- reticular fibers

smallest fibers, which appear delicate but cluster into networks that make them relatively strong. their primary function is support. (women's pantyhose)

location of ribosomes-free ribosomes in the cytosol

some ribosomes are scattered throughout the cytosol and float freely

the cytoskeleton consists of three kinds of fibers: intermediate filaments

support cell shape and help to fix organelles in place. they are thicker than microfilaments but thinner than microtubules. intermediate filaments act as the cell's internal scaffolding, helping anchor the nucleus and other organelles in place. they also maintain rigidity and resist tension, so they are responsible for the maintenance of cell shape, and they help cells attach to one another

endocrine system

taught w the nervous system

organelles- peroxisomes

term broken down to mean "peroxide bodies." they are responsible for removing toxic wastes by using special enzymes. oxidase breaks down free radicals, which are byproducts from other reactions in the cell that may be harmful. this process results in the release of hydrogen peroxide. catalase breaks down the hydrogen peroxide to protect the cell. high concentrations of peroxisomes are found in the liver and kidneys.

selective permeability

membrane permeable to some substances but not to others

stratified epithelial tissue

more than a single layer of cells

three types of endocytosis- phagocytosis

(cellular eating) occurs when the cell reaches out with armlike structures called pseudopods and engulfs a particle, forming a vesicle called a phagosome. This vacuole then fuses with a lysosome, and the hydrolytic enzymes in the lysosome digest the food

three types of endocytosis- pinocytosis

(cellular drinking) occurs when the cell engulfs a drop of extracellular fluid to access the solutes in that fluid. these vesicles are typically smaller than the vesicles formed by phagocytosis

connective tissue- loose connective tissue proper- adipose loose connective tissue proper

-adipose loose connective tissue proper- is readily identifiable because it has large vacuoles with lipid droplets. These vacuoles grow, causing the cells to hypertrophy. they also push the nucleus to the side of the cell. (the lipid droplet is an example of an inclusion, a temporary structure found in some cells. previously, we discussed glycogen as another type of inclusion for sugar storage.) dont mix up w simple squamous epithelial tissue to tell the difference adipose loose connective tissue proper has the nuclei of the cells at the sides of the cells not the middle.

connective tissue- loose connective tissue proper- areolar loose connective tissue proper

-areloar loose connective tissue proper- consists of a network of all three types of fibers forming a random, loose network. its the most abundant type of connective tissue in the body. it underlies almost every type of epithelium. reticular lamina of basement membrane contain reticular fibers and reticular fibers are present in areolar loose connective tissue proper.

connective tissue- dense connective tissue proper- dense irregular connective tissue proper

-dense irregular connective tissue proper- has a similar composition as regular dense connective tissue proper, but the fibers are much more haphazard and not as nicely organized. whereas regular dense connective tissue proper is resistant to stretching along one plane, dense irregular connective tissue proper is resistant to stretching along many planes. for ex, dense irregular connective tissue proper in the skin allows you to pinch the skin from many directions and not deform it. likewise, dense irregular connective tissue proper in the joint capsule allows you to rotate your arm around and stretch in many directions without causing damage.

connective tissue- dense connective tissue proper- dense regular connective tissue proper

-dense regular connective tissue proper- consists of lots of collagen fibers stacked on top of one another, running in the same direction. recall that collagen fibers give the tissue tensile strength. as a result, this kind of connective tissue forms tendons (which attach muscle to bone) and ligaments (which attach bone to bone)

connective tissue- cartilage- elastic cartilage

-elastic cartilage- similar to hyaline cartilage, except it has elastin fibers as well. the presence of these fibers make it easy to distinguish this kind of cartilage from hyaline cartilage. this kind of cartilage is found in the pinna of the ear and in the epiglottis (the flap that covers the trachea, preventing food from entering)

connective tissue- dense connective tissue proper- elastic dense connective tissue proper

-elastic dense connective tissue proper- consists primarily of elastic fibers. this tissue allows for the extension and simultaneous recoiling of an organ. we therefore find this tissue in hollow organs that must have the ability to recoil, such as the upper bronchioles of the lungs or the aorta. the aorta has to be able to accommodate the stretching force created by the inflow of blood from the heart. it must then recoil in order to propel blood into the arteries. dont confuse w epithelial tissue. common mistake bc this kind of tissue is often found in the walls of hollow organs, so images often show the lumen of the organ, which appears to be a free space characteristic of epithelial tissue.

distinguishing epithelial tissue from other types of tissue

-epithelial tissue always has a free apical side -epithelial tissue is highly packed, with very little extracellular matrix

connective tissue- cartilage- fibrocartilage

-fibrocartilage- consists of many layers of highly condensed collagen fibers, making this tissue relatively hard. the main functions of fibrocartilage is shock absorption. this tissue makes up the menisci of the knee (which prevent the femur from crushing the top of the tibia) and it also makes up the cartilaginous discs between the vertebrae. confused w dense regular connective tissue proper bc both have highly dense networks of collagen fiber. key distinguishing feature is that the cells of fibrocartilage are rounder and exist within lacunae.

connective tissue- cartilage- hyaline cartilage

-hyaline cartilage- a very "glassy" looking tissue that consists of a small number of cells and an extracellular matrix with many small collagen fibrils (not fibers). this is a relatively firm, strong type of cartilage that is still relatively flexible. it is found in locations that need some hardness for protection and support but also some flexibility for movement. for ex, the costal cartilages are bars of hyaline cartilage that extend beyond the ribs and protect the lungs. these bars must be strong enough to effectively protect the lungs but flexible enough to allow the lungs to expand. before bones become bones they are hyaline cartilage. during development, hyaline cartilage is replaced by bone. however, some cartilage remains after the bone is formed. for ex, the smooth, glossy part at the end of a chicken wing bone is hyaline cartilage.

nervous tissue- neuroglia

-neuroglia- sometimes called glial cells, support cells for the neurons. they are typically very small, so you can usually only see their nuclei in images at a magnification that shows neurons as well.

nervous tissue- neurons

-neurons- the basic kind of nervous cell. the cell body is called a soma. this is where the nucleus and most of the organelles are found. off of the soma are a number of projections, including a single axon (which carries electrical information away from the soma) and many dendrites (which bring electrical information to the soma) you can think of the dendrites as the cell's "sensory feelers"

connective tissue- loose connective tissue proper- reticular loose connective tissue proper

-reticular loose connective tissue proper- contains many reticular fibers that stain dark and appear as extremely dark fibers under magnification. makes up the internal contents of soft organs like the spleen or lymph nodes.

covering and lining membranes- serous membrane

-serous membranes- line the closed cavities, including the pleural, pericardial, and peritoneal cavities. the highly slippery serous fluid on this membrane makes it wet. serous membranes are made of simple, squamous epithelial tissue. the visceral part of the serous membrane makes contact with the body organ, while the parietal part makes contact with the body wall.

muscle tissue- skeletal muscle

-skeletal muscle- skeletal myocytes or skeletal muscle cells are among the longest cells, often running the entire length of a muscle. they are long and cylindrical, like a column. they are also striated, or striped, and their stripes are perpendicular to the long axis of the cell. an unusual characteristic of skeletal myocytes is that they have multiple nuclei. this is because during the development of skeletal myocytes, multiple cells fuse together to form one large cell. multiple nuclei are retained to maintain adequate control over the cell, which can grow to be very long. skeletal muscle is involved in body movements. it typically attaches bone to bone, but it can also attach bone to the skin. for ex, the muscles in the face attach the bones in the face to the outer skin. skeletal muscle is involved in both voluntary and involuntary movement produced by skeletal muscles. the nuclei of skeletal myocytes are placed peripherally in the cell, like adipose loose connective tissue proper. in this case, the nuclei are pushed to the side of the cell by the protein fibers that cause the striated appearance.

muscle tissue- smooth muscle

-smooth muscle- smooth myoctes or smooth muscle cells are not striated. smooth muscle consists of cells that arrange into sheets. these cells are spindle shaped and have nuclei in the center. their major function is to proper things along internal passageways. for ex, smooth muscle moves food along the digestive tract, urine out of the bladder, and babies out of the uterus. dont confuse w stratified squamous epithelial tissue. although smooth muscles may appear to be tightly packed, flattened, and elongated like stratified squamous epithelial cells, you can distinguish the two because smooth muscle will not have free apical surface or a basement membrane, but stratified squamous epithelial tissue will. another key feature of smooth muscle cells is that they have cigar-shaped nuclei, which can be very long. *when deciding whether an image is of epithelium or something else, always look for a free apical surface

integumentary system- functions of the skin

-thermoregulation- covers the entire body so has a lot of surface area for radiating heat. moreover the evaporation of sweat from the skin cools the body down. the body can alter blood flow to the skin in order to either conserve or lose heat. in cold environments, blood flow to the skin is constricted so that the vital organs and the core of the body remain warm. in warm environments, blood flow to the skin is increased so that heat loss can occur and the body can maintain a constant internal temperature. -protection: the skin acts as a physical barrier that separates the internal body from the external environment. keratin in the skin protects against abrasion, microbes, chemicals and heat lamellar granules in the skin prevent water from entering or exiting the skin sebum prevents the skin from drying out and cracking and it also kills bacteria melanin protects the body from harmful ultraviolet radiation langerhans cells play a role in immunity, phagocytosing bacteria and other antigens -excretion and absorption- excretion involves the elimination of substances, and absorption involves taking in materials from the external environment (those who drink alcohol smell of alcohol bc body is secreting the toxic substance out) -synthesis of vitamin D- UV (from sun or tanning booth) triggers the skin to produce a molecule that will eventually be turned into vitamin D. vitamin D is essential because it is necessary for the absorption of calcium. calcium is used in a number of different metabolic pathways and physiological functions, so its proper absorption is important -cutaneous sensation-sensory organs in our skin help us feel things. its a protective mechanism because pain is an indicator that something is not right.

integumentary system- the skin- the epidermis- thick skin

-thick skin- covers the feet, fingertips and palm--the areas of the body where friction and mechanical abrasion are common. this kind of skin consists of the four layers present in thin skin plus an additional layer: the stratum lucidum. there are no hair follicles in thick skin *no hair follicles on thick skin bc hair follicles are typically associated w oil glands. thick skin is in areas where we grip things so we want to avoid oily surfaces there.

integumentary system- the skin- the epidermis- thin skin

-thin skin- covers most of the body and consists of four epidermal layers. this kind of skin covers areas of the body where there is very little friction or mechanical abrasion. hair is present in this type of skin.

Hierarchy of Structural Organization:

Chemical level, cellular level, tissue level, organ level, organ system level, organismal level

organelles- endoplasmic reticulum

a network of flattened sacs or tubules that extend from the nuclear envelope. the endoplasmic reticulum comes in two forms: rough ER (studded w ribosomes and closest to the nucleus) and smooth ER (does not have ribosomes). rough ER is involved in protein synthesis, while smooth ER is involved in lipid metabolism and the synthesis of fatty acids and steroids. a specialized endoplasmic reticulum called sarcoplasmic reticulum is used for calcium storage in muscle cells. (Reticulum means network)

cytoskeleton

a network of microtubules, microfilaments and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical and transport functions. we tend to think of the cytoskeleton as being the "scaffolding" of the cell. this network of fibers gives cells their three dimensional shape, and also assists in the transport of organelles. the cytoskeleton consists of three kinds of fibers: microfilaments, intermediate filaments, and microtubules

pseudostratified columnar epithelial tissue

a single layer of columnar cells that have nuclei that are arranged in such a way that it looks like more than one layer.

Membrane transport (3 methods) - vesicular transport

a vesicle is a piece of plasma membrane that has pinched off, enclosing the material inside of it. vesicles are only found inside cells. protein transporters are only effective for moving small molecules across a membrane. larger molecules that are too large or too charged to make it through a membrane must be moved in and out of the cell through vesicular transport--specifically, endocytosis and exocytosis. note that vesicular transport is a form of active transport, meaning it requires energy

accessory organs (epithelial derivatives)- oil and sweat glands

all of the glands of the skin are exocrine glands, meaning that they secrete their products into a system of ducts that lead to the body surface. two kinds of glands found in the skin are as follows: -subcutaneous glands-are glands that produce an oily substance called sebum. they are found in high abundance on the face and scalp, but they are found everywhere on the body except the soles of the feet and the palms of the hands. they are commonly found connected to hair follicles; they deposit sebum on hairs, and the sebum moves up the follicle and out to the body's surface. sebum serves a number of purposes, which include collecting dirt, protecting against brittle skin or hair, impeding bacterial growth, and making the hair and skin shiny and oily. if sebum accumulates in a duct of a sebaceous gland, acne can result. increased sebum leads to acne, it is hormone triggered explaining why teenagers are prone to acne. -sweat glands- are glands that secrete sweat, which consists of water that contains salts and various other substances. sweat glands can be classified into two groups: eccrine sweat glands- exist on the palms of hands, soles of the feet, and forehead. they produce "true sweat" into ducts that open directly onto the surface of the skin. this serves to cool the skin when the water evaporates. apocrine sweat glands- can only be found in the anal, genital, and axillary areas (such as the armpits). these glands produce "milky sweat" that is more viscous and odorous than the sweat that eccrine glands produce. the sweat contains chemicals that neutralize harmful bacteria. the interaction of this sweat and the bacteria produces what we call body odor. *eccrine glands are far more abundant than apocrine glands. eccrine glands-true sweat onto skin aprocrine glands-milky sweat onto hair follicles

basic components of all tissue

all tissues consist of a cellular component (cells working together for a common purpose) and an extracellular component (the extracellular matrix). the extracellular matrix is the component that gives a tissue its consistency. for example, differences in the makeup of the extracellular matrix make blood liquid, fat squishy, and bone hard. the extracellular matrix is made up of a fluid component (the interstitial fluid) and a solid component (sugars, fibers, proteins, amino acids, ions, and "other stuff"). for example the extracellular matrix in bones consists of many collagen fibers with crystallized (hard) minerals. this gives bones their hard texture. likewise, blood has a lot of plasma (which is mostly water), so the blood is liquid.

three types of cell junctions- desmosomes

also called anchoring junctions. they use a zipper-like interaction between transmembrane proteins called linker proteins to prevent cells from being separated by force. anchoring junctions are commonly found in places where the tissue is often under a lot of physical stress. examples include the skin an the heart. the skin and the heart do not tear easily, although they are frequently stretched, because of a high concentration of anchoring junctions between the cells.

serous membranes

also called serosa, are smooth membranes that are not open to the outside environment and do not produce mucus. Found in the abdominopelvic cavity and thoracic cavity. They secrete serous fluid, which is an oily fluid that adds lubrication and promotes easy movement. Serous membranes have two layers -visceral layer-the layer that makes contact with the organ it covers (viscera means organ). It contains cells that directly touch the outside of the organ. -parietal layer- layer that contacts the wall of the cavity. (pariet means wall) Serous membranes can be found surrounding the heart, each lung, and many abdominal organs

intro to the integumentary system

an organ system which consists of skin (integument) and several accessory organs. the skin, which is the largest organ in the body, consists of a collection of many tissues working together for a common function. the accessory organs include hair, nails, and oil and sweat glands, which are al epithelial derivatives

integumentary system- the skin- the dermis- cleavage lines

are less-dense regions of collagen in the reticular dermis that correspond with the orientation of the collagen fibers. they are invisible in most places of the body, but they play an important role in surgery. surgeons cut along the same axis of the cleavage line in order to promote wound healing without scarring or deformation after the surgery. incisions made parallel to cleavage lines heal better and promote less scarring.

cell junctions

are mechanisms for getting cells to stick together. cell junctions serve a number of purposes including: -protection- epithelial tissue plays an important role in protecting the body. as a result, it is important that it remains together as one solid sheet of cells rather than a porous collection of loosely attached cells. -connection- epithelial tissue does not receive nutrients directly from the blood because it is avascular. therefore, it must rely on nutrients from nearby cells and tissues, and those nutrients must have some way to be transferred directly from one cell to another. as we will see, this occurs through gap junctions. *the cell junctions covered are a result from the fusion of transmembrane proteins

the cytoskeleton consists of three kinds of fibers: microfilaments

are solid rods made up of a protein called actin. these fibers have the smallest diameters among the fibers that make up the cytoskeleton and are usually located near the cell's edge. they play a role in movement and mechanical support, and they contribute to the formation of microvilli-fingerlike projections on the outside of the cell. they are nonmotile (projections of the plasma membrane, they are not structures that "poke out") the role of the microvilli is to increase the surface area of the cell, increasing the cell''s diffusional capacity and the rate of diffusion. a highly absorptive cell needs as much surface area as possible to take materials in as quickly as possible. likewise, a cell that secretes a lot of material needs as much surface area as possible for secretion.

cytoplasm (3 component)- organelles

are specialized cellular structures that have specific functions.

organelles- mitochondria

called the "powerhouse" of the cell because they are the site of oxidative metabolism, also known as cellular respiration. it is here that the cell converts the energy stored in the bonds of organic molecules to ATP through redox reactions. for this reason, cells that are very physiologically active and thus require a lot of energy (like cardiac muscles) have a lot of mitochondria, and their mitochondria tend to be larger than average. when an animal needs a heightened amount of energy, mitochondria levels might rise, as mitochondria can reproduce independently of the cell. mitochondria have a double membrane. the smooth outer membrane is quite porous, and it takes in partially digested molecules that have been broken down in the cytosol. the inner membrane is highly folded, with fold called cristae. the inner membrane divides the mitochondrion into the intermembrane space and the mitochondrial matrix. enzymes embedded in the mitochondrial matrix play a major role in cellular respiration. the folding of the inner membrane increases the surface area, which promotes more efficient cellular respiration and the creation of a greater amount of ATP

muscle tissue- cardiac muscle

cardiac myocytes, or cardiac muscle cells, are striated and have only one nucleus. they are also shorter and more branched than skeletal myocytes. the cellular junctions between cardiac myocytes contain intercalated discs, which have many gap junctions and desmosomes (anchoring junctions). these intercalated discs are high in protein (as proteins are involved in forming cellular junctions), so they stain dark in histological images. gap junctions- between cardiac myocytes allow for electrical and metabolic coupling by facilitating the movement of nutrients and ions between cardiac muscle cells. desmosomes- (anchoring junctions)- between myoctyes allow the cardiac muscle to resist tearing. when your heart fills up with blood, the muscle must be able to stretch without pulling apart. desmosomes ensure that this is the case.

four major categories of connective tissue- cartilage

cells- chondrocytes and chondroblasts (in growing cartilage) matrix- gel-like ground substance with collagen and elastic fibers features-chondrocytes inside lacunae; cushions body structures and resists compression cartilage consists of cells called chondrocytes, which arise from chondroblasts. the key distinguishing feature of cartilage is that chondrocytes almost always exist inside small spaces call lacunae. (lacunae are also present in bone tissue, but you can readily distinguish cartilage from bone tissue). in pictures chondrocytes appear to be surrounded by a border of empty space or a "bubble." the bubbles are the lacunae. (key for recognizing cartilage is to look for cell in lacunae.) there are three types of cartilage: -hyaline cartilage- a very "glassy" looking tissue that consists of a small number of cells and an extracellular matrix with many small collagen fibrils (not fibers). this is a relatively firm, strong type of cartilage that is still relatively flexible. it is found in locations that need some hardness for protection and support but also some flexibility for movement. for ex, the costal cartilages are bars of hyaline cartilage that extend beyond the ribs and protect the lungs. these bars must be strong enough to effectively protect the lungs but flexible enough to allow the lungs to expand. before bones become bones they are hyaline cartilage. during development, hyaline cartilage is replaced by bone. however, some cartilage remains after the bone is formed. for ex, the smooth, glossy part at the end of a chicken wing bone is hyaline cartilage. -elastic cartilage- similar to hyaline cartilage, except it has elastin fibers as well. the presence of these fibers make it easy to distinguish this kind of cartilage from hyaline cartilage. this kind of cartilage is found in the pinna of the ear and in the epiglottis (the flap that covers the trachea, preventing food from entering) -fibrocartilage- consists of many layers of highly condensed collagen fibers, making this tissue relatively hard. the main functions of fibrocartilage is shock absorption. this tissue makes up the menisci of the knee (which prevent the femur from crushing the top of the tibia) and it also makes up the cartilaginous discs between the vertebrae. confused w dense regular connective tissue proper bc both have highly dense networks of collagen fiber. key distinguishing feature is that the cells of fibrocartilage are rounder and exist within lacunae.

four major categories of connective tissue- connective tissue proper

cells- fibrocytes, fibroblasts, defense cells, fat cells matrix- gel-like ground substance with all three fiber types (elastic, collagen, and reticular) features- lots of fiber in extracellular matrix; resists tension and functions as binding tissue consists of fibrocytes, which derive from fibroblasts. the distinguishing feature of this kind of connective tissue is that it has a lot of fibers in the extracellular matrix. 2 groups of connective tissue proper are loose connective tissue proper and dense connective tissue proper. loose connective tissue proper- consists of fibers that are loosely connected with one another in a rather haphazard network. there are 3 kinds of loose connective tissue proper which are: -areloar loose connective tissue proper- consists of a network of all three types of fibers forming a random, loose network. its the most abundant type of connective tissue in the body. it underlies almost every type of epithelium. reticular lamina of basement membrane contain reticular fibers and reticular fibers are present in areolar loose connective tissue proper. -adipose loose connective tissue proper- is readily identifiable because it has large vacuoles with lipid droplets. These vacuoles grow, causing the cells to hypertrophy. they also push the nucleus to the side of the cell. (the lipid droplet is an example of an inclusion, a temporary structure found in some cells. previously, we discussed glycogen as another type of inclusion for sugar storage.) dont mix up w simple squamous epithelial tissue to tell the difference adipose loose connective tissue proper has the nuclei of the cells at the sides of the cells not the middle. -reticular loose connective tissue proper- contains many reticular fibers that stain dark and appear as extremely dark fibers under magnification. makes up the internal contents of soft organs like the spleen or lymph nodes. dense connective tissue proper consists of a dense network of fibers that are closely connected in a regular, orderly network. 3 kinds of dense connective tissue proper are: -dense regular connective tissue proper- consists of lots of collagen fibers stacked on top of one another, running in the same direction. recall that collagen fibers give the tissue tensile strength. as a result, this kind of connective tissue forms tendons (which attach muscle to bone) and ligaments (which attach bone to bone) -dense irregular connective tissue proper- has a similar composition as regular dense connective tissue proper, but the fibers are much more haphazard and not as nicely organized. whereas regular dense connective tissue proper is resistant to stretching along one plane, dense irregular connective tissue proper is resistant to stretching along many planes. for ex, dense irregular connective tissue proper in the skin allows you to pinch the skin from many directions and not deform it. likewise, dense irregular connective tissue proper in the joint capsule allows you to rotate your arm around and stretch in many directions without causing damage. -elastic dense connective tissue proper- consists primarily of elastic fibers. this tissue allows for the extension and simultaneous recoiling of an organ. we therefore find this tissue in hollow organs that must have the ability to recoil, such as the upper bronchioles of the lungs or the aorta. the aorta has to be able to accommodate the stretching force created by the inflow of blood from the heart. it must then recoil in order to propel blood into the arteries. dont confuse w epithelial tissue. common mistake bc this kind of tissue is often found in the walls of hollow organs, so images often show the lumen of the organ, which appears to be a free space characteristic of epithelial tissue.

four major categories of connective tissue- blood

cells- hematopoietic cells matrix- plasma; no fibers features- consists of RBC's and WBC's in a fluid (plasma), found within blood vessels. This fluid tissue carries substances (O2, CO2, wastes, nutrients, hormones) to and from tissues consists of red blood cells (erythrocytes) and white blood cells (leukocytes) in a fluid matrix called plasma. it exists within blood vessels. only need to know what a red blood cell looks like. a red blood cell also called an erythrocyte has a bioconcave shape, meaning that it has a dimple on both sides. (donut whose center is not completely hollowed out). the bioconcave shape of a red blood cell increases its surface area, which is important because red blood cells carry oxygen. the shape also allows the red blood cell to fold so that it can get through extremely narrow capillaries without causing a blockage. interestingly, red blood cells travel through the thinnest capillaries in single-file fashion. red blood cells carry hemoglobin which is responsible for transporting oxygen. much like the keratin in skin cells, the hemoglobin in red blood cells essentially takes the cells over and kills them. this is not a problem however, because the body continuously produces new red blood cells in the bone marrow.

four major categories of connective tissue- bone (osseous tissue)

cells- osteocytes and osteoblasts matrix- ground substance (calcified and hardened with inorganic salts), and collagen fibers features- osteons consist of a central canal surrounded by lamellae (in compact osseous tissue). Hard tissue functions in support and resists tension and compression. connective tissue bc like all types of connective tissue their cells arise from embryonic mesenchyme. osseous tissue or bone comes in two types: -trabecular osseous tissue- a very spongy tissue. this tissue is easy to identify bc it looks like a sponge under a microscope. -compact osseous tissue- consists of a number of individual units called osteons each of which consists of a central canal surrounded by several concentric rings called lamellae (compared to tie dye) bone is a hard type of tissue that consists of osteocytes that exist in lacunae. the bone is highly vascularized, meaning it is supplied with blood from blood vessels.

superficial/deep

close to the surface/far from the surface

epithelial cells- simple cuboidal epithelial tissue

consist of a single layer of cube-shaped or hexagon-shaped cells. this kind of tissue often forms the ducts or secretory portions of glands. it can also be found on the ovary surface and in the kidney tubules.

covering and lining membranes

consist of epithelium and connective tissue. 3 types of membranes can be found in the human body. -mucous membranes- line the open cavities and organs, including the tubes of the digestive, respiratory, and urinary systems. the mucous on this membrane makes it wet. -serous membranes- line the closed cavities, including the pleural, pericardial, and peritoneal cavities. the highly slippery serous fluid on this membrane makes it wet. serous membranes are made of simple, squamous epithelial tissue. the visceral part of the serous membrane makes contact with the body organ, while the parietal part makes contact with the body wall. -cutaneous membrane- i.e the skin. covers the body's exterior surface. unlike the mucous and serous membranes, this membrane is dry. (body's only dry membrane)

epithelial cells- pseudostratified columnar epithelial tissue

consists of a single layer of columnar cells that have nuclei that are arranged in such a way that it appears to be more than one layer (pseudo means false). in reality all of the cells have contact with the basement membrane, although it may not appear to be so. (if the tissue were stratified only one layer would have contact w the basement membrane). ciliated pseudostratified columnar epithelial tissue often contains goblet cells, which secrete mucus. this makes sense, because cilia are required to move mucus. this kind of tissue is common in areas where mucus is secreted and needs to be moved, such as the lining of the trachea. * image of ciliated columnar epithelial cells will be of pseudostratified columnar epithelial tissue

epithelial cells- stratified squamous epithelial tissue

consists of multiple layers of cells whose apical layer consists of flat cells. there are two types: keratinized and non keratinized stratified squamous epithelial tissue. keratinized stratified squamous epithelial tissue- forms your dry membrane also known as your skin non keratinized stratified squamous epithelial tissue- lines places such as the mouth, the esophagus, and the vagina. they can be distinguished from each other bc keratinized tissue does not have nuclei at the apical end because the keratin has built up in the cell, killing it. like all kinds of stratified epithelial tissues, stratified squamous epithelial tissue serves a protective function. as a result, you will find this kind of tissue in areas of the body that have contact with something that could cause mechanical damage to the body, such as the mouth, vagina, and esophagus.

muscle tissue

consists of myocytes or "muscle cells" (myo refers to muscles). 3 types: cardiac myocytes, skeletal myocytes, and smooth myocytes. all 3 muscle types can be involuntarily controlled but only skeletal muscle can be under voluntary control -skeletal muscle- skeletal myocytes or skeletal muscle cells are among the longest cells, often running the entire length of a muscle. they are long and cylindrical, like a column. they are also striated, or striped, and their stripes are perpendicular to the long axis of the cell. an unusual characteristic of skeletal myocytes is that they have multiple nuclei. this is because during the development of skeletal myocytes, multiple cells fuse together to form one large cell. multiple nuclei are retained to maintain adequate control over the cell, which can grow to be very long. skeletal muscle is involved in body movements. it typically attaches bone to bone, but it can also attach bone to the skin. for ex, the muscles in the face attach the bones in the face to the outer skin. skeletal muscle is involved in both voluntary and involuntary movement produced by skeletal muscles. the nuclei of skeletal myocytes are placed peripherally in the cell, like adipose loose connective tissue proper. in this case, the nuclei are pushed to the side of the cell by the protein fibers that cause the striated appearance. -cardiac muscle- cardiac myocytes, or cardiac muscle cells, are striated and have only one nucleus. they are also shorter and more branched than skeletal myocytes. the cellular junctions between cardiac myocytes contain intercalated discs, which have many gap junctions and desmosomes (anchoring junctions). these intercalated discs are high in protein (as proteins are involved in forming cellular junctions), so they stain dark in histological images. gap junctions- between cardiac myocytes allow for electrical and metabolic coupling by facilitating the movement of nutrients and ions between cardiac muscle cells. desmosomes- (anchoring junctions)- between myoctyes allow the cardiac muscle to resist tearing. when your heart fills up with blood, the muscle must be able to stretch without pulling apart. desmosomes ensure that this is the case. -smooth muscle- smooth myoctes or smooth muscle cells are not striated. smooth muscle consists of cells that arrange into sheets. these cells are spindle shaped and have nuclei in the center. their major function is to proper things along internal passageways. for ex, smooth muscle moves food along the digestive tract, urine out of the bladder, and babies out of the uterus. dont confuse w stratified squamous epithelial tissue. although smooth muscles may appear to be tightly packed, flattened, and elongated like stratified squamous epithelial cells, you can distinguish the two because smooth muscle will not have free apical surface or a basement membrane, but stratified squamous epithelial tissue will. another key feature of smooth muscle cells is that they have cigar-shaped nuclei, which can be very long. *when deciding whether an image is of epithelium or something else, always look for a free apical surface

connective tissue- blood-red blood cell

consists of red blood cells (erythrocytes) and white blood cells (leukocytes) in a fluid matrix called plasma. it exists within blood vessels. only need to know what a red blood cell looks like. a red blood cell also called an erythrocyte has a bioconcave shape, meaning that it has a dimple on both sides. (donut whose center is not completely hollowed out). the bioconcave shape of a red blood cell increases its surface area, which is important because red blood cells carry oxygen. the shape also allows the red blood cell to fold so that it can get through extremely narrow capillaries without causing a blockage. interestingly, red blood cells travel through the thinnest capillaries in single-file fashion. red blood cells carry hemoglobin which is responsible for transporting oxygen. much like the keratin in skin cells, the hemoglobin in red blood cells essentially takes the cells over and kills them. this is not a problem however, because the body continuously produces new red blood cells in the bone marrow.

integumentary system- the skin

consists of two layers: the epidermis and the dermis. the epidermis (which consists of epithelial tissue) is superficial to the dermis (which consists of connective tissue). the skin is a dry membrane and all lining and covering membranes consist of epithelial tissue on top of connective tissue. hypodermis not technically part of the skin. this subcutaneous layer of connective tissue lies deep to the dermis and primarily consists of adipose cells. skin consists of the epidermis and dermis not hypodermis.

dorsal body cavity

contains the cranial cavity and vertebral/spinal cavity

Membrane proteins (two types) - integral proteins

cross into the hydrophobic portion of the bilayer. When an integral protein completely crosses the entire membrane, it is called a transmembrane protein. The majority of the functioning proteins in the plasma membrane are transmembrane proteins

fluid mosaic model

current working theory of cell membrane structure. States that a cell membranes is not a rigid structure, but rather a fluid "mosaic" of phospholipids and embedded proteins. A cross section of a membrane might look like this: (proteins float in a sea of phospholipids)

integumentary system- the skin- the epidermis- thick skin- stratum granulosum

derives its name from the fact that it has a number of darkly staining granules. this is a much thinner layer than the stratum spinosum, usually consisting of between just a handful of layers of flattened keratinocytes. two important features in this layer are as follows: -keratohyalin- a protein that turns tonofilaments into keratin, essentially killing the cell. keratohyalin stains dark -lamellar granules- waterproof the skin by secreting a lipid-rich substance that seeps into the extracellular space and "fills in the cracks" *cells at the basal layer of this stratum are alive and cells at the apical layer of this stratum are dead. you will see nuclei in the cells at the basal layer but not at the apical layer

oblique plane

diagonal angle

tissue response to injury

different types of tissues have different regenerative capacities: -good regenerators- include epithelium and bone tissue, which have a high mitotic rate. ex, scrapes, broken bones -poor regenerators- include skeletal muscle and cartilage. these tissues have limited regeneration capacity for various reasons. cartilage has poor regeneration because it has poor blood supply. (pierced ears). although skeletal muscle has very good blood supply, it doesnt regenerate well. -almost no regeneration- cardiac muscle and nervous tissue have almost no capacity for regeneration. if you damage this tissue, its gone forever.

abdominopelvic cavity

divided into the abdominal cavity (contains the liver, kidneys, and stomach) and the pelvic cavity (contains the pelvis, rectum, and some reproductive organs)

three types of cell junctions- tight junctions

do not form channels between cells; rather, they link the outsides of cells together so that the extracellular fluid cannot pass between them. for this reason, you should think of tight junctions as a fluid barrier. like gap junctions, tight junctions result from the fusion of transmembrane proteins on adjacent cells.

classification of epithelia

epithelial can be described based on two dimensions: -number of layers of cells- epithelial tissue is called simple epithelium if it consists of just one layer of cells and stratified epithelium if it consists of multiple layers of cells. -shape of the cells on the apical surface- the shape of the cells on the apical surface can be squamous, cuboidal, or columnar *classification based on the shape of the cell is the shape at the apical surface, shape at basal surface does'nt matter

shape of epithelial cells- squamous

epithelial is called squamous if it is flat, thin, and squished. (the word squamous means scale or scale-like, like a snake scale). squamous cells are arranged like floor tiles, and they form thin epithelium that allows for the rapid passage of substances. they look like fried egg under a microscope. this kind of epithelial tissue may sometimes also be involved in secretion.

shape of epithelial cells- columnar

epithelial tissue is called columnar if it is much taller than it is wide. typically the nucleus of a columnar cell is farther down, toward the basement membrane. columnar epithelial cells are typically used for secretion or absorption.

shape of epithelial cells- cuboidal

epithelial tissue is called cuboidal if it is the same size all around, in a cube or hexagonal shape. cuboidal epithelial tissue functions in secretion and absorption. (the nucleus will be as close to the middle of the cell as possible)

three types of cell junctions- gap junctions

form channels between adjacent cells. they are found in avascular cells (such as the cornea or lens) and in electrically excitable cells (such as cardiac muscle cells). transmembrane proteins on two cells fuse together to form a channel called a connexon through which cytoplasm and nutrients it contains can be exchanged. this allows for metabolic coupling (as one cell can get its nutrients from another) and electrical excitability (as the movement of ions from one cell to another can allow a depolarization to spread). *gap junctions are the ones responsible for the movement of materials between cells

thoracic cavity

formed by the ribs, chest muscles, sternum, vertebral column, and diaphragm. Divided into 3 compartments, the left and right pleural cavities (protect the lungs) and the mediastinum (pericardial cavity, which surrounds the heart)

cytoplasm (3 component)- inclusions

found in some, but not all cells. they are temporary structures that usually store nutrients, such as fat or glycogen. not all cells have the capacity to store fat or glycogen, so not all cells have inclusions

organelles- lysosomes

lysosomes are sacs of hydrolytic enzymes that break down large molecules and thus act as the site of intracellular digestion. different lysosomes have different specific enzymes targeted at certain biomolecules, including polysaccharides, proteins, fats, and nucleic acids. lysosomes typically have a pH of about 5. *lysosomes digest

epithelial tissue

found on the body's surfaces and lining the body's hollow organs. ex: skin, which covers the outside of the body, the lining of the mouth, the serous membrane that lines the ventral body cavity, all glands in the body. epithelial tissue serves three principal functions: -selective barrier- epithelial tissue regulates the movement of materials between the body and the environment. for ex you dont well up w eater when you take a bath because the epithelial cells in the skin prohibit water from flowing into the body. likewise, you dont shrivel up in the sun because the skin protects against evaporation. the skin is much more permeable to hand lotion, however, so you can hydrate dry, flaky hands by rubbing lotion on them -secretion- epithelial tissues make up all of the glands in the body. the glands are responsible for secretion of materials such as saliva and hormones -protection- epithelial tissue protects the body's surfaces against the environment. for ex. the epithelial tissue in the skin protects the underlying connective tissue from harm. epithelial tissue consists of cells arranged in sheets. sheets can be one cell thick, or they can consist of multiple layers. special features of epithelial tissue -a free surface- epithelial tissue always has a free surface, meaning that one surface is always exposed to an area of no cells, such as the outside of the body, a duct, or the lumen of a hollow organ. this is because epithelial cells cover, line, or secrete, so they must be exposed to an opening. -cellularity- epithelial cells are packed tightly together, leaving little room for an extracellular matrix. therefore, epithelial tissue is primarily made up of cells. -avascularity- there are no blood vessels in epithelial tissue, meaning that epithelial tissue has no direct blood supply. as a result, the tissue has to receive nutrients from other cells and tissues through cell junctions. -nervous innervation- nerve endings usually run together with arteries and veins. however, epithelial tissue is an exception. even though epithelial tissue has no arteries or veins, it does have nerve endings. this is why you definitely feel it if you scratch your skin, but you wont bleed unless the cut reaches down to the underlying layer of connective tissue (which does have blood vessels) -regeneration- epithelial tissue is constantly exposed to harsh environments, so it has to be continuously regenerated. new cells are continuously being created through mitosis, and old cells are continuously being sloughed off. for ex, we continuously loose and replenish our skin. the surface of your body has a lot of dead skin cells -polarity of cellular components- the top of epithelial tissue is different from the bottom. the top surface, called the apical surface, is the free surface that faces the lumen, duct, body cavity, or body surface. the bottom surface, called the basal surface, adheres to a basement membrane, a thin, double layer that lies outside the cells and serves as a point of attachment (described as a slime or goo, the top part of which is secreted by the epithelial cells and the bottom part of which is secreted by the underlying tissue. *the basement membrane is extracellular, it is not inside of the cell. epithelial tissue is alive, for the most part, even though they dont have a direct supply of blood. this is because epithelial cells receive nutrients from other cells. *epithelial cells are alive, even though they are avascular. *the tissue that lies directly below epithelial tissue is almost always connective tissue.

ventral body cavity

includes the thoracic cavity and abdominopelvic cavity, separated by the diaphragm

epithelial cells- simple squamous epithelial tissue

is a single layer of flat epithelial cells. this flat, thin layer of cells is useful for allowing the rapid passage of materials through diffusion and filtration. this tissue is also responsible for the production of fluid in the serous membrane. can be found in the air sacs of lungs. tightly packed cells w little extracellular matrix. there are two special kings of simple squamous epithelia -endothelium-the simple squamous epithelial layer that lines the blood vessels and heart, essentially forming one continuous hollow space -mesothelium-forms the serous membranes, including the pleura (around the lungs), pericardium (around the heart), and peritoneum (around the organs in the abdominal cavity)

cytoplasm (3 component)- cytosol

is the intracellular fluid which consists of a combination of water and dissolved material. the cytosol is mostly (75% to 90%) water and it makes up approx. 55% of the cell's volume. many chemical reactions occur in the cytosol.

integumentary system- the skin- the epidermis- thick skin- stratum lucidum

is the layer that is present in thick skin but not thin skin. this relatively thin layer stains clear, which is where it gets its name

integumentary system- the skin- the epidermis- thick skin- stratum corneum

is the most superficial layer of the epidermis, which consists of 25 to 30 layers of flattened keratinocytes. these cells are all dead by the time they reach the stratum corneum. they are continously shed and replaced with keratinocytes from the layers beneath. dead cells from the stratum corneum are continuously being shed and replaced by cells from below. epidermis completely replaces itself every three to five weeks.

connective tissue fibers- collagen fibers

large, thick, strong fibers that provide tensile strength and withstand pulling forces. they are the strongest, widest, and most abundant type of fiber in connective tissue. these fibers are made up of many different fibrils wound around each other like a rope.

mucous membranes

line cavities that are open to the outside environment, consist of cells that secrete mucus

connective tissue fibers- elastic fibers

long fibers with intermediate diameter, though they often branch off and form networks that make them stronger. their primary function is to allow the tissue to recoil, like a rubber band. the body consists of many elastic tissues, including the skin and the lungs.

integumentary system- the skin- the epidermis- thick skin- stratum spinosum

much thicker layer of eight to ten layers of keratinocytes of various shapes and sizes. these cells begin to produce tonofilaments, which are precursors to keratin filaments. stratum spinosa gets its name because its keratinocytes look spiny under a microscope when this tissue is cultured. the spiny appearance results bc the cells naturally shrink in culture, but the desmosomes remain intact, so they tend to poke out of the cells. large cell in stratum spinosum is a langerhans cell, a dendritic cell whose function is to phagocytose bacteria and other antigens that make their way into this layer of the skin.

epithelial cells- stratified cuboidal epithelial tissue

multiple layers of cells who apical layer consists of cube-shaped or hexagon-shaped cells. the tissue (which is relatively rare in the body) often forms the duct portion of large glands, and it almost always has layers that are two cells thick.

epithelial cells- stratified columnar epithelial tissue

multiple layers of cells whose apical layer consists of cells that are taller than they are wide. this tissue is rare in the human body. often serves as a transitional tissue that exists between two other tissue types. most prevalent place is the male urethra.

nervous tissue

nervous tissue can be found in the brain, spinal cord, and nerves (only axons and neuroglia are found in nerves, however). nervous tissue consists of two types of cells -neurons- the basic kind of nervous cell. the cell body is called a soma. this is where the nucleus and most of the organelles are found. off of the soma are a number of projections, including a single axon (which carries electrical information away from the soma) and many dendrites (which bring electrical information to the soma) you can think of the dendrites as the cell's "sensory feelers" -neuroglia- sometimes called glial cells, support cells for the neurons. they are typically very small, so you can usually only see their nuclei in images at a magnification that shows neurons as well.

integumentary system- the skin- the hypodermis

not part of the skin. it is a subcutaneous layer of connective tissue that primarily consist of adipose tissue. it contains blood vessels, lymphatic vessels, and nerves that extend into the dermis. the adipose tissue protects these and other underlying structures. it also stores energy and insulates the rest of the body.

three types of endocytosis- receptor-mediated endocytosis

occurs when a chemical (called a ligand) binds to receptors on the cell membrane specific to that ligand, triggering the formation of a vesicle. this type of endocytosis is highly specific to certain kinds of molecules

ipsilateral/contralateral

on the same side/on opposite sides

organelles- golgi apparatus

part of the cell that receives the products of the endoplasmic reticulum, modifies them, sorts them, and ships the modified products either to the rest of the cell or outside the cell via transport vesicles. for example, the golgi apparatus processes proteins by adding carbohydrates to them. secretory cells--that is, cells that secrete things--tend to have a high concentration of golgi apparati. the golgi apparatus consists of three to ten cisternae, membranous sacs thought to have evolved from the endoplasmic reticulum. it has two sides a cis side and a trans side. cis is latin for same side. the cis side is the receiving side of the golgi body, where vesicles that have budded off from the endoplasmic reticulum fuse with the golgi body. trans is latin for opposite side. it is the side that sends vesicles to their destination organelles. vesicles emerging from the trans side of the golgi apparatus include lysosomes. vesicles can either fuse with the plasma membrane to exocytose particles, be incorporated into the plasma membrane, or fuse with lysosomes.

Membrane proteins (two types) - peripheral proteins

peripheral proteins are only loosely associated with he hydrophilic end of the integral protein. They are not embedded into the hydrophobic core of the lipid bilayer.

cell membrane

phospholipid bilayer with proteins embedded in one or both halves. Our body's exchanges occur across cell membranes, because cell membranes are what separate the living cell from its nonliving environment. Plasma membranes are selectively permeable, meaning some substances pass through them more easily than others.

Membrane lipids come in three varieties: phospholipids

phospholipids- account for approx. 75% of membrane lipids. These constituents are amphipathic, meaning they are hydrophilic (dissolve in water) in some portions and hydrophobic (repels water) in others phospholipids naturally arrange in a bilayer organization, in which the fatty acid tails associate with one another and the polar heads face the aqueous environments--either inside or outside the cell. The bilayers formed by phospholipids is important because it assists in the fusion of membranes during phagocytosis. You can think of the bilayer as a little lipid droplet that encases the entire cell.

3 basic components of a cell

plasma membrane, cytoplasm, and a nucleus

accessory organs (epithelial derivatives)- nails

plates of tightly packed, dead, hard, keratinized epidermal cells. they are similar in many ways to the keratinocytes that make up the hair, but they are packed together in a way that makes them harder. they form a solid covering of the dorsal portion of the tips of the toes and fingers--that is, the distal portion of the digits. the major components of the nail are: -nail body-also sometimes called the nail plate is the outside portion of the nail, which protects the underlying nail matrix -nail bed- the skin on which the nail plate rests -nail matrix-the part of the nail bed lying beneath the nail. it produces new cells that eventually become the nail plate -nail root-the portion of the nail that extends under the skin -lunula- the semilunar, light region of nail near the base. it is whitish (rather than pink) because it contains nail matrix cells and thickened epidermal cells that prevent the reddish color of the underlying blood supply from showing through -eponychium- or cuticle is the skin at the base of the nail that closes off the skin fold at the junction of the skin and the nail -free edge- the portion of the nail body that extends over the tip of the digit. this the part you cut -lateral nail fold- is the region where the cuticle fold itself under the nail

4 types of tissue- nervous tissue

primarily used for control. it senses what is going on in the internal and external environment, and it initiates an appropriate response.

4 types of tissue- epithelial tissue

primarily used for covering and lining. specifically it covers the body surfaces and lines the body's hollow organs, cavities, and ducts. it also forms glands, such a the salivary glands, which secrete saliva

4 types of tissue- muscle tissue

primarily used for movement. for example cardiac muscle moves blood, and smooth muscle moves other things, such as urine, feces, food, and babies. muscle tissue--specifically, skeletal muscle tissue- also plays a role in thermoregulation, as it generates body heat.

4 types of tissue- connective tissue

primarily used for support. it binds, protects, and supports organs. it also plays a role in fat storage and in immunity. examples of connective tissue include fat cells, cartilage, bone tissue, and blood

connective tissue

primarily used for support. most diverse and abundant type of tissue in the body. some special characteristics are: -few cells-connective tissue consists of a small number of cells and a lot of extracellular matrix. in fact, in most cases there is more extracellular matrix than cells. (epithelial has packed cells and little extracellular matrix). the composition of the extracellular matrix determines the particular properties of the connective tissue. for ex, bone is solid, blood is liquid, and the other types of connective tissue are gel-like substances (somewhere in between solid and liquid) -originate from mesenchyme- all connective tissues originate from embryonic cells called mesenchyme. the mesenchyme then differentiates into different kinds of cells, which ultimately become different connective tissue types. -fibroblasts become fibrocytes, which make up connective tissue proper -chondroblasts become chondrocytes, which make up cartilage. -osteobalsts become osterocytes which make up bone -hematopoietic stem cells become blood cells, which make up the blood -lots of fibers- the extracellular matrix of connective tissue typically consists of many fibers, which are non-living components produced by cells and ground substance. the consistency of the ground substance depends on its components. for ex, the ground substance of bone tissue has lots of crystallized minerals that make it hard, while the ground substance of blood has a lot of liquid and no crystallized minerals

two types of glands- endocrine glands

produce secretions called hormones that are directly released into the extracellular fluid and enter the blood without the need for a duct. the hormones are dumped into the interstitial fluid and enter the blood through capillaries. they then flow throughout the body until they reach their effector organs, which may be far away from where the hormone was originally secreted

two types of glands- exocrine glands

produce secretions that flow either directly onto body surfaces or into cavities. whereas hormones can act on far-away effector organs, secretions from exocrine glands tend to act locally, on nearby effector organs. for ex, oil glands are embedded into the skin. they secrete oil that dumps into a pore and acts loyally, not on far-away organs. for example an oil gland in the right forearm does not supply oil for the forehead. exocrine glands can be divided into two types: -multicellular exocrine -glands consist of multiple cells. the secretory cells produce a product which is exocytosed into a duct. the product then builds up in the duct, until it reaches the surface epithelium and is released into the free area. -unicellular exocrine glands- consist of just one cell. the only unicellular exocrine learned is the goblet cell (is an epithelial cell), which produces mucus

cell's plasma membrane's 3 main functions

protection- protects the cell from bacteria and other pathogens that may try to invade it communication- receptors in the plasma membrane play a role in cell communication. Ex. a chemical messenger may bind to a protein receptor on the membrane of a hormone-releasing cell, triggering a signal transduction pathway that leads to the release of a hormone regulation-cells are open systems that must obtain nutrients and dispose of wastes. Cells use a number of mechanisms, including passive transport and active transport, to move materials in and out.

meninges

protective issue that lines the cranial and vertebral cavity

glands

refer to epithelial cells that make and create a product--usually an aqueous secretion that contains proteins. ex of products of glands include milk, bile, digestive enzymes, mucus, hormones, sweat, and oils. these secretions are produced inside the epithelial cells and then exocytosed to the outside environments.

tissue

refers to a group of cells that live and work together for a common function. there are four types of tissue: epithelial tissue, connective tissue, muscle tissue, and nervous tissue

cytoplasm

refers to everything within the cell membrane except for the nucleus or nucleoid region. the cytoplasm consists of three major components: cytosol, organelles, and inclusions

Membrane transport (3 methods) - passive transport

refers to the diffusion of a substance across a biological membrane. Passive transport occurs automatically without the need for energy input. Three methods of passive transport include simple diffusion, facilitated diffusion and osmosis simple diffusion- type of passive transport in which solutes move across the membrane from areas of high concentration to areas of low concentration. simple diffusion does not require energy input; it is driven by a concentration gradient. Only small, lipid-soluble molecules can pass through the plasma membrane. large molecules. ions (such as potassium, sodium, chloride, calcium and magnesium) and charged particles cannot pass through the cell membrane through simple diffusion. facilitated diffusion- refers to the passive movement of molecules down a concentration gradient using a transport protein. facilitated diffusion is passive because it does not require energy input; the molecules still move because of the concentration gradient. it is facilitated in the sense that it could not occur without a membrane protein osmosis- a special kind of passive transport that specifically refers to the movement of water from areas of high water concentration (or low solute concentration) to low water concentration (or high solute concentration). water can pass directly through the plasma membrane in some instances, but most osmosis occurs with the help of transport proteins called aquaporins.

Membrane transport (3 methods) - active transport

refers to the movement of a substance across a biological membrane against its concentration gradient with the help of energy input and specific transport proteins (proteins often called ion pumps). the difference between active transport and passive transport is that active transport requires energy input, often in the form of ATP *pumps always require energy

exocytosis

refers to the movement of large molecules from within the cell into its environment. this involves the movement of vesicles created by the golgi apparatus to the plasma membrane, where they fuse with the membrane and dump their contents. many secretory cells use exocytosis to export their products to the outside world. for example, neurons secrete chemical messengers called neurotransmitters via vesicles. in endocytosis vesicles are produced from the plasma membrane so endocytosis reduces the surface area of the plasma membrane, while exocytosis restores the surface area when the vacuoles fuse with the plasma membrane, thus adding to the plasma membrane. the cell can also embed a protein into its lipid bilayer by producing and embedding a vacuole with an embedded protein and sending it to fuse with the cell membrane. receptors can also be added to the plasma membrane in this manner.

endocytosis

refers to the movement of large molecules into the cell from its environment. this involves taking in extracellular materials by forming vesicles that break off into the cytoplasm. there are three types of endocytosis: phagocytosis, pinocytosis, receptor-mediated endocytosis

location of ribosomes- mitochondria

ribosomes look like little black dots under a microscope

peritoneum

serous membrane associated with the abdominal organ or abdominal viscera

pericardium

serous membrane associated with the heart

accessory organs (epithelial derivatives)- hair

several accessory organs derive from epithelial tissue and are found embedded in the skin. these include hair, nails, and oil and sweat glands. -hair- hairs are elongated columns of dead, keratinized, epidermal cells (keratinocytes) that emerge from the skin of mammals are held together by extracellular proteins. the following are the major structures of a hair: -hair shaft- the hair shaft is the portion visible on the skin's surface -hair root- the hair root is the portion that penetrates the skin and lies below the skin's surface -hair follicle- the sheath surrounding the hair root in the skin it has two layers: the external root sheath- is the direct, downward continuation of the epidermis--an extension of the stratum basale. at the most superficial layers, it contains all four layers traditionally found in hairy skin. however, as it extends deep toward the bulb, the number of layers decreases until only the stratum basale is left. at the bulb, the external root sheath produces hair matrix cells, much like the stratum basale produces new keratinocytes. the internal root sheath- is produced by the external root sheath. it lies in the space between the external root sheath and the hair root, and it is deep to the external root sheath in the hair. -bulb- found at the base of the hair follicle -papilla- is the indentation in the bulb that consists of connective tissue, capillaries, and nerve tissue. these capillaries deliver substances that stimulate hair growth and supply necessary nutrients to the growing hair. -arrector pili muscle-is a small, smooth muscle that attaches to the hair follicle. a contraction of this follicle causes the hair to become erect producing "goose bumps" in humans (the fact that it is a type of smooth muscle means that we cant control its movement, ex: goosebumps). although goose bumps dont serve much of a function in humans, they do serve important functions in other animals. it causes fur to stand up making them look larger and more intimidating. causes skin to pucker up and get thicker providing a more insulating barrier. -matrix-is the portion of the hair follicle located near the papilla of the bulb where cells actively divide and produce new hair cells. during differentiation, hair cells produce keratin and absorb melanin from melanocytes. the production of new cells pushed old cells upward and they eventually die. the keratin that these dead cells leave behind eventually contributes to hair growth, and the color of the hair depends on the type and abundance of melanin produced. 99.9% of all oil glands dump into hair follicles hair types like straight, curly and wavy hair are determined by the shape of the hairs themselves. round hairs lead to an overall appearance of straight hair. oval shaped hairs lead to an overall appearance of wavy hair. flat hairs lead to an overall appearance of curly hair.

integumentary system

skin, hair, nails

nucleus

the "brain center" of the cell because it contains the chromosomes, which hold most of the cell's DNA. this information is eventually used by the ribosomes to create proteins. dna replication, rna replication, and transcription all occur within the nucleus, which is usually the cell's largest organelle. the nucleus is the most easily identified of a cell's organelles under a microscope. (living cells nucleus stains very dark). generally spherical and located in the center of the cell. nucleus is enclosed by a nuclear envelope, a double membrane that separates the contents of the nucleus from the cytoplasm. it also has a dense region called a nucleolus, where the ribosomal subunits are made. (nucleolus not enclosed by a membrane). the nuclear envelope has a number of nuclear pores that regulate the flow of materials to the rest of the cell

epithelial tissue - basement membrane

the basal lamina is closest to the basal surface of the epithelial cells; it is secreted by the epithelial cells themselves. the reticular lamina is closest to the underlying tissue (which is usually connective tissue). it is formed by reticular fibers that are secreted by the underlying tissue *the word lamina means layer or sheet the top layer of the basement membrane is the basal lamina, the bottom layer of the basal membrane is the reticular lamina. above the basement membrane is epithelial tissue and below the basement membrane is connective tissue.

integumentary system- the skin- the dermis

the deep layer of the skin, which lies below the epidermis. this is a very tough layer, which primarily consists of connective tissue (mostly connective tissue proper). unlike the epidermis, the dermis is vascular and supplied by many blood vessels. it also has lymphatic vessels and nerves. the dermis is organized into two layers. from deepest to most superficial that are as follows: -reticular dermis- accounts for the bottom 80% of the dermis and consists of dense irregular connective tissue proper -papillary dermis- accounts for the top 20% of the dermis and consists of loose areolar connective tissue proper. the papillary dermis gets its name from the fact that it forms dermal papillae, upward nipple-like projections of the dermis into the stratum basale of the epidermis. (the word papilla means nipple). these projections increase the surface area over which epidermis comes in contact with the dermis. this is important for two reasons: -metabolic coupling- recall that the epidermis is avascular, so it has to get its nutrients and other materials from the dermis. for this reason, it is important that the dermis comes in contact with the epidermis as much as possible, to maximize the number of gap junctions between the cells that form the border between these layers. -strengthening connections- a large amount of surface area is required to ensure that the epidermis and the dermis remain connected to one another, and to ensure that they are as sturdy together as possible.

integumentary system- the skin- the epidermis- thick skin- stratum basale

the deepest layer of the epidermis which consists of a single layer of simple cuboidal keratinocytes, melanocytes, and merkel cells. the keratinocytes in this layer are highly mitotic and produce all of the new cells that replace the cells that are sloughed off at the top of the epidermis. in addition to keratinocytes, this layer consists of two other cell types: -melanocytes- produce melanin, a pigment that we will discuss in greater detail during the next class. once the melanin is produced it is transferred to the keratinocytes. as a result, there is more melanin in a typical keratinocyte than in a typical melanocyte -merkel cells- are sensory cells that are associated with a nerve ending. when they are compressed, they activate the sensory ending of the nerve ending, relaying light touch information. light touch sensors bc it doesnt take much compression to activate them.

location of ribosomes- rough endoplasmic reticulum

the endoplasmic reticulum is a network of membranes extending from the nuclear envelope. the rough endoplasmic reticulum is studded with ribosomes and is a major site of protein synthesis

organelles- centrosome

the microtubule organizing center consisting of two centrioles; it is the place at which microtubules for cilia and flagella are formed. the centrosome also plays an important role in cell division during mitosis. they look like little mini-licorice pieces.

integumentary system- the skin- the epidermis

the most superficial layer of skin, which consists of several layers of epithelial tissue. like all epithelial tissue the epidermis is avascular, meaning that it does not have its own blood supply. it consists of keratinized stratified squamous epithelium with four major kinds of cells: -keratinocytes, cells that produce keratin (account for the vast majority of all cells in the epidermis, greater than 90%) -melanocytes, cells that produce melanin -langerhans cells, a type of phagocytic immune cell -merkel cells, which are involved in sensory perception epidermis consists of either four or five layers, depending on the kind of skin. the two types of skin are: -thin skin- covers most of the body and consists of four epidermal layers. this kind of skin covers areas of the body where there is very little friction or mechanical abrasion. hair is present in this type of skin. -thick skin- covers the feet, fingertips and palm--the areas of the body where friction and mechanical abrasion are common. this kind of skin consists of the four layers present in thin skin plus an additional layer: the stratum lucidum. there are no hair follicles in thick skin *no hair follicles on thick skin bc hair follicles are typically associated w oil glands. thick skin is in areas where we grip things so we want to avoid oily surfaces there.

integumentary system- the skin- the dermis- dermal papillae

the papillary dermis gets its name from the fact that it forms dermal papillae, upward nipple-like projections of the dermis into the stratum basale of the epidermis. (the word papilla means nipple). these projections increase the surface area over which epidermis comes in contact with the dermis. this is important for two reasons: -metabolic coupling- recall that the epidermis is avascular, so it has to get its nutrients and other materials from the dermis. for this reason, it is important that the dermis comes in contact with the epidermis as much as possible, to maximize the number of gap junctions between the cells that form the border between these layers. -strengthening connections- a large amount of surface area is required to ensure that the epidermis and the dermis remain connected to one another, and to ensure that they are as sturdy together as possible.

pleura

the pleura refers to the serous membranes associated with the lungs. Each lung has its own serous membrane.

integumentary system- the skin- cutaneous sensation

the skin has specialized sensors for light touch, pressure/vibration, and pain -light touch- hair, merkel cells, and meisner's corpuscles are highly sensitive sensory receptors that all sense light touch. this is the kind of subtle sensation you feel when an insect lands on the back of your hand or your hair brushes across your face. these types of sensors are placed more superficially in the skin -hair is often surrounded by nerve endings that can sense both pain and light touch. when the hair moves or is plucked out, the nerve endings are activated and sensory information is transmitted to the brain -merkel cells- are found in the stratum basale, the lowest layer of the epidermis. a nervous structure is always associated with merkel cells. when pressure is applied to the merkel cell, a neuron is activated. -meisner's corpuscles- are free nerve endings that have been encapsulated by a jelly-filled structure. when this jelly-filled structure gets "squished" pressure is put on the nerve endings -pressure/vibration- pacinian corpuscles are larger and fewer in number than merkel cells or meisner's corpuscles. they detect vibrations and changes in pressure. located much deeper in the skin than the light touch receptors. as a result it takes more deformation to activate them than the light touch receptors -pain- free nerve endings in the skin relay information about pain. these nerve endings play a role in protection bc pain means something is wrong. free nerve endings are often associated with hair, but they are also scattered throughout the dermis and epidermis. heat, cold, and pain sensors are located in the most superficial layers of the skin. *question mark in the picture is the pacinian corpuscle

the cytoskeleton consists of three kinds of fibers: microtubules

thick, hollow rods with walls made up of subunits called tubulin, a globular protein. they have a more tubular shape than the other fibers. microtubules project outward from the centrosome and give cells support, shape, and pressure resistance, especially when pressed on by adjacent cells. they make up the cilia and flagella, motile projections from the cell, and they assist in either moving the cell itself or moving items along the surface of the cell. whereas microvilli increase the cell's surface area, cilia move objects along the cell's surface by "wiggling." similarly flagella use their whiplike motions to move the entire cell. cilia are motile while microvilli are non motile.

integumentary system- the skin- the structural basis for skin color

three pigments are primarily responsible for determining an individual's skin color: melanin, carotene, and hemoglobin. carotene has an orangish color and hemoglobin has a red color. the actual pigment itself can range in color from black to reddish brown to yellow. Eumelanin (true melanin) gives a person a black or brown color, while phenomelanin gives a person a yellow to red color, particularly in the hair. one's skin, eye, and hair color are usually determined by the balance of pigments--particularly phenomelanin and eumelanin. there are even variations within skin or hair color types. differences in skin color are not due to the number of melanocytes (cells that produce melanin). rather they are due to the amount of melanin that the melanocytes produce and transfer to keratinocytes. individuals with darker hair and skin have melanocytes and transfer to the keratinocytes. individuals with darker hair and skin have melanocytes that produce and transfer more melanin, while individuals with lighter hair and skin have melanocytes that produce and transfer more melanin, while individuals with lighter hair and skin have melanocytes that produce very little melanin. light-skinned people often have skin that appears red or pink. this is because skin without significant amounts of melanin is translucent and the blood supply below is red (due to hemoglobin, a red pigment) two issues relating to skin color and melanin are as follows: -UV radiation and tanning-exposure to ultraviolet radiation, from the sun or from a tanning bed, causes the skin to get darker. this is because UV radiation speeds up the process in which an enzyme called tyrosinase converts tyrosine (an amino acid) to melanin within a melanosome (a specialized organelle within melanocytes where melanin is produced). a tan is only temporary because the darker, melanin-containing keritanocytes are eventually shed from the stratum corneum and replaced with new keritanocytes from below. on average, a person loses a tan after about a month. the only way to maintain a tan is to continuously expose oneself to UV radiation. -Albinism- an inherited, genetic condition in which a person is unable to produce any melanin. this is usually due to a defect in the tyrosinase enzyme. albino individuals usually have pink or red eyes and translucent hair and skin.