lec 1 cell/tissue

one major theme in physiology is that ___ and ___ are related

form and function

(form is anatomy, function is physiology)

example with hippos. how have hippos made their own natural sunscreen?

-nickname: blood sweat (but doesnt contain either)

-made of highly ACIDIC compounds that ABSORB UV

-comes out pores red, fades to brown

whats the only mammal that is a poikilotherm and what that mean. how can they go 18 minutes without oxygen

poikilotherm=animal whose internal temperature varies (changes w their surroundings)

-naked mole rat

-can go 18 minutes without oxygen by going into a “suspended animation” or slowed metabolism state, which reduces their bodies’ energy demands

-switches from a GLUCOSE-based metabolic system (require O2 to release energy) to a FRUCTOSE-based metabolic system (dont need O2 so continue to create energy needed for cells in vital organs)

why is it that naked mole rats dont develop cancer?

-have increased high molecular weight HYALURONAN (polysaccharide) (have 5 times more hyaluronan than humans)

-this accumulates in extracellular matrix but involved in stimulating intracellular pathways that INDUCE p16

-researchers found destroying this polymer in naked mole rats allow cancer to spread as they normally would (suggest hyaluronan could be crucial to keep disease going)

example with horned lizard. in what 3 ways do they defend themselves?

1. first defense: CAMOUFLAGE

2. puff bodies up to twice their normal size

3. squirt TOXIC BLOOD from eyes

how does the horned lizard squirt toxic blood out its eyes?

1. contract muscles near eyes (reduce blood flow out head = build up blood PRESSURE)

2. when pressure strong enough, blood vessesls around eyes RUPTURE = shoot blood up to 5 feet (and they can control direction)

whats a structure in sharks/surgeon/rays/lungfishes that increases nutrient absorbtion and how?

SPIRAL VALVE - internally twisted to increase surface area of intestine = increase nutrient absorption

whats the name of the internal fold of intestine in bivalve mollusks, starfish, lampreys, annelids

typhlosole

whats a typhlosole

internal fold of intestine

whats the name for organisms with only one cell vs organisms with many cells

unicellular vs multicellular organisms

2 or more tissues make up ______ which together make up ____

organs

organ system

why are cells so small? and The rate of material exchange in and out of cell is a function of its _____

-small cells have high surface area to volume ratio = allow more stuff to move in/out of cell

-the rate of material exchange in/out of cell is a function of its surface area.

what are 3 effective ways for structures to have a high surface area-to-volume ratio?

1. Flattening

2. Folding

3. Branching

describe what flattening is and its benefits and some examples with animals and plants

flattening - thin/broad surface maximized exposed surface to enviro relative to volume (surf area increase without greatly increasing volume)

ex. fish gills have Lamellae (flat) that increase O2 intake

ex. Alveoli (thin-walled and flat) facilitatte efficient gas exchange

ex. Leaves (broad and flat) capture more sunlight for photosynthesis

describe folding method and its benefits and some examples

surfaces fold into complex shapes to pack more surface area in given volume

-ex. mammal small intestine has FOLDS like villi and microvilli for increase nutrient exchange

-ex. mitochondrial CRISTAE are folded to increase surf area for atp prod

-ex. brain cortex folds increase surf area for neurons = enhance processing capacity

describe branching and some examples

-structures grow into intricate networks with fine extensions

ex. CAPILLARIES (small blood vessels) are highly branched to increase O2 delivery to tissues)

ex. DENDRITES and AXONS of neurons have branching structures to transmit and receive signals over large distances

ex. PLANT ROOTS branched to increase water/nutrient uptake from soil

4 basic types of tissue? what 2 things are they defined by?

-tissues are difined by morphology and function

Epithelial

Connective

Muscle

Nervous

what parts of body do epithelial tissues cover? whats the functioin? (2)

-epithelial tissue (tightly packed cells) cover OUTSIDE OF BODY and LINES the ORGANS/CAVITIES (lumens) IN BODY

-create PROTECTION and involved in diffusion of ions/molecules

describe and draw the 3 shapes of epithelial cells. what does each shape cell line in the body?

1. Squamous (thin/flat smell with small central nucleus)

-lines wall of blood vessels and bowman’s capsule

2. Cuboidal (cube-shape with central nucleus)

-lines tubules in mammal kidney

3. Columnar (rectangular with nucleus near base (bottom))

-form inner lining of some digestive organs (stomach/colon/small intestine) and lines anus, eyelids, most of respiratory tract

-absorb material from digestive tract

describe the 3 layers of epithelial cells. draw out table with each combo of layer and shape. what shape can pseudostratified be?

simple = one layer

stratified = two or more layers

pseudostratified = simple (one layer) epithelia that appears stratified

-can only be columnar

what makes pseudostratified epithelial appear stratifiesd? what happened?

-sometimes cells become so crowded that the nuclei become displaced and form several rows (appears stratified)

what is apical vs basal surface on epithelial cells?

apical side: face outside (exposed)

basal side: bottom side (attached to tissue)

what is basal lamina and reticular lamina? which is each secreted by?

basal lamina: mixture of glycoproteins and collagen. attachment site for epithelium, seperating it from underlyinh connective tissue

-secreted by EPITHELIAL CELLS

reticular lamina: secreted by underlying connective tissue. forms basement membrane that holds it all tgt.

what 2 components make up the basement membrane

basal lamina (secreted by epithelium above it, made of collagen and glycoproteins) and reticular lamina (secreted by connective tissue beneath it)

what is a cell junction in epithelial cells

cell junction: intercellular connection between cell membranes of adjoining cells (cells touching)

what are the 3 types of cell junctions in epithelial cells? briefly describe them (like what they do)

1. Tight junction - SEPARATE cells into APICAL and BASAL compartments (prevent leakage of molecules between cells)

2. Gap junction - intercellular passage between membranes of adjacent cells (to facilitate/help small molecules and ions move between neighbouring cytoplasms)

-remember gap junction is a COMMUNICATING junction made of connexons

3. Anchoring junction - common on LATERAL and BASAL surfaces of cells (provide strong/flexible connections by mechanically attaching cells to their neighbours or to the extracellular matrix)

-4 types: desmosomes, hemidesmosomes, focal adhesions, adherons

-remember: tight junction prevent leakage (apical top and basal bottom), gap junction as bridge between membranes, anchoring junction as strong connector (lateral + basal surfaces, side and bottom)

what is the most abundant tissue type in body?

connective tissue

what two things makes up the connective tissue?

cells

extracellular matrix

what 2 things make up the extracellular matrix? so technically what THREE things make up connective tissue?

ground substance (non-living gel, high in water)

protein fibers

so connective tissue is cells, ground substance, protein fibers

what are responsible for MAKING the extracellular matrix?

Fibroblasts

what are mesenchymal cells?

stem cells (starter cells) that can differentiate (develop) into any type of connective tissue cell

what are the 3 types of connective tissue FIBERS? which is most abundant? briefly describe each shape

1. Collagen fibers (MOST ABUNDANT) -long, THICK, wavy, very strong (high tensile strength, resistant to stretching/tearing)

2. Reticular fibers - THINNER and BRANCHED (mesh-like networks=structural support)

3. Elastic fibers - THINNER and LONG and BRANCHED and strong (can be stretched 150% of original length)

5 types of connective tissue (in vertebrates) and which is most common

Loose (ex. adipose) (MOST COMMON)

Fibrous (or dense)

Bone

Blood

Cartilage

think: LFBBC

what does loose connective tissue do (2 main functions) ? what is more abundant in its ECM (extracellular matrix)? what kinds of cells it contain? what is is composed of?

-BINDS epithelia to underlying tissue AND HOLDS ORGANS IN PLACE

-in its ECM, more ground substance than protein fibers

-contains all resident cells (mesenchymal cells, macrophage, adipocyte, fibroblast) with fibroblasts being most abundant

-composed of PROTEIN FIBERS (loosely scattered in extracellula matrix)

where are fibrous (dense) connective tissue found? whats its ECM like? what cells it contains?

-found in tendons and ligaments

-fibrous ECM has lots of COLLAGEN FIBERS and less ground tissue than that in loose tissue (allows for high strength+restistant to stretching)

-like loose tissue, contains all resident cells with fibroblast most abundant

what is unique about the bone, and that makes it have lots of protection and rigid support?

the bone’s ground substance is MINERALIZED

what protein fiber is most abundant in the bone? what cells it contains

-in bone, collagen most abundant (reticular fibers are in red marrow)

-has all resident cells (like loose and fibrous) BUT within the MARROW TISSUE (not in mineralized matrix)

-also:

-osteoblasts (cells that form bone)

-osteocytes (mature bone cells trapped in mineralized matrix)

-osteoclasts (break down/reabsorb bone)

what are the bone-forming cells called? what do they produce

OSTEROBLASTS produce CALCIUM PHOSPHATE (in form of HYDROXYAPATITE crystals), responsible for mineralization of bone

bone is a fluid connective tissue. whats its main function? what cells it contain? what does its ECM contain?

-transports GASES NUTRIENTS WASTES thru body

-contains most resident cells: mesenchymal cells, macrophage, fibrocytes (precursors to fibroblasts)

-also:

-Erythrocytes (red blood cells)

-Leukocytes (white blood cells)

-Thrombocytes (platelets)

-ECM of blood DOESNT HAVE PROTEIN FIBERS but ground substance is PLASMA (consists of water, electrolytes, nutrients, hormones, salts, various dissolved proteins)

which connective tissue is strong and flexible and acts as shock absorbercar

cartilage

what cells in cartilage? describe its ecm

CARTILAGE has most resident cells: macrophage, mesenchymal cells, fibroblasts

-COLLAGEN most abundant protein fiber (just like bone) and NO reticular fibers

-may contain elastic fibers (depends on type of cartilage)

what is responsible for the distinctive appearance of cartilage?

due to polysaccharides called chondroitin sulfates, which BIND with GROUND SUBSTANCE proteins to form PROTEOGLYCANS

-chondroitin sulfates is secreted by chondrocytes (which also secretes collagen fibers)

what makes the skeletons of sharks, rays, and skates so flexible and lightweight, and why is this beneficial

-their skeletons are mostly made of COLLAGEN (and collagen makes up cartilage)

-cartilage is less dense than bone, so cartilage provides SUPPORT without the weight of bone, so skeleton is lightweight/flexible, and the animals can be more energy-efficient and buoyant in water (ability to float)

how does muscle tissue respond to stimulation?

by contracting to provide MOVEMENT
-contraction is caused by sliding ACTIN and MYOSIN filaments

3 types of muscle?

skeletal

cardiac

smooth

describe the structure of each type of muscle and does each have uni or multinucleated cells

skeletal - SINGLE, LONG, cylindar, obvious striations (lines). multinucleate

cardiac - BRANCHED, striations, intercalated discs (gap junctions -provide electrical coupling between heart cells). uninucleate

smooth - SINGLE, fusiform (spindle shape), NO striations. uninucleate

do each of the 3 muscles have voluntary or involuntary control?mono or multinucleated? striated?intercalated discs? cell shape?

skeletal: voluntary, multi, striated (obv), long cylinder

cardiac: involuntary, mono, striated, intercalated discs, branched

smooth: involuntary, mono, spindle-shaped (fusiform)

what does the nervous tissue do when it senses stimuli

transmits electrochemical signals in FORM OF NERVE IMPULSES that COMMUNICATE between diff regions of animal

what 2 things do nervous tissue contain

neurons (aka nerve cells) that transmit nerve impulses

glial cells (aka glia) that help nourish, insulate, replenish neruons (aka support + protection for neurons)

what are the 2 distinct types of projections from cell body of neurons? where is the nucleus located in neuron

in neuron, nucleus in cell body

projections: short branched DENDRITES (transmit signals from adjacent cells to cell body) and long AXONS (carry signals from cell body to other cells)