Bio 2: Chp 40

Anatomy

Biological structure

Physiology

Biological function

Tissue

Organized specialized cells

Organ

Organized specialized tissue

Organ system

Organized organs

Four main categories of tissues

Epithelial
Connective
Muscle
Nervous

Epithelial

Covers and lines

Apical epithelial surface

Faces the lumen (cavity) or outside

Basal epithelial surface

Attached to underlying tissue

Cuboidal epithelium

Secretion
Found in glands & kidneys

Simple Columnar

Secretion & Absorption
Lines intestines

Simple Squamous

Exchanges material by diffusion
Capillary linings & alveoli

Pseudostratified Columnar

Lines mucous membranes & portions of respiratory tract

Beating cilia sweep film of mucus along surface

Stratified Squamous

Regenerates rapidly
New cells replace sloughed off cells
Surfaces subject to abrasion

Connective tissue

Binds & supports other tissues

Loose connective

Binds epithelia to underlying tissues
Holds organs in place

Cartilage

Strong & flexible support
Composed of chondrocytes
Nose, ears, & IV disks

Fibrous connective

Found in tendons & ligaments
Dense w/ fibers

Adipose tissue

Stores fat
Lage fat droplets

Blood

Composed of cell fragments, plasma, & cells

Cell fragments

Composed of platelets

Plasma

Liquid extracellular matrix
Water, salts, & dissolved proteins

Blood cells

Erythrocytes
Leukocytes

Bone

Mineralized forms skeleton
Osteoblasts
Bone units = osteons

Muscle tissue

Long cells = muscle fibers
Contract in response to nerve signals
Composed of actin & myosin

Skeletal muscle

It is striated muscle
Voluntary muscle
Can only increase size, NOT #

Smooth muscle

No striations
Involuntary movement
Visceral organs
Spindle shaped cells

Cardiac muscle

Heart contractions
Striated, branched
Composed of intercalated disks

Nervous tissue

Senses stimuli
Transmits signals
Contains neurons & glial cells

Neurons

They’re the nerve cell
Composed of cell body, dendrites, & axons

Glial cells

Nourish, insulate, & replenish
Types: oligodendrocytes, Schwann cells, astrocytes

Oligodendrocytes

Myelinate CNS axons

Schwann cells

Myelinate PNS axons

Astrocytes

Diverse functions

Regulator

Have internal control mechanisms that resist changes
Maintains set point

Conformer

Internal condition varies w/ external changes

Homeostasis

Maintain relative constant internal environment regardless of external environment

Mechanisms of homeostasis

Set point
Stimulus
Sensor
Response

Response

Helps return the variable to set point

Negative feedback

Helps return a variable to normal range

Positive feedback

Amplifies a stimulus
DOES NOT MAINTAIN HOMEOSTASIS

Circadian Rhythm

Sleep-wake cycle
Changes every 24 hrs

Acclimatization

Setpoints change to environment

Endothermic

Generate heat by metabolism

Ectothermic

Gain heat from external sources

Radiation

Heat exchanged through emission of EM waves

Evaporation

Heat exchanged from liquid to gas

Convection

Heat exchanged by movement of air/liquid

Conduction

Heat exchanged by direct contact

Insulation: skin, feathers, fur, & blubber

Reduce heat flow b/w animal & its environment

Countercurrent exchange

Transfer heat b/w fluids flowing in opposite directions
In marine animals & birds
Reduces heat loss

Ectothermic behavioral response

Posture themselves to minimize/maximize absorption of solar heat

Thermogenesis

Increasing metabolism to produce heat
Moving/shivering

Nonshivering thermogenesis

Hormones cause mitochondria to increase their metabolic activity

Hypothalamus

Controls thermoregulation in mammals

Bioenergetics

Overall flow and transformation of energy in an animal

Metabolic rate

Amount of energy animal uses in unit of time

How is metabolic rate determined?

Heat loss
O2 consumed or CO2 produced
Measuring energy content of food & energy lost in waste

BMR

Endotherm
Comfortable temp
Higher rates

SMR

Ectotherm
Specific temp
Lower rates

Size & metabolic rate

Proportional to m^3/4 (inverse parabolic curve)
Smaller animals have higher metabolic rates

Torpor

Low activity & decreased metabolism
Saves energy
Avoiding difficult conditions

Hibernation (winter/cold)

Long-term torpor
Food scarcity
Metabolism 20x less

Estivation (summer/hot)

Scarce water

Daily torpor

Small mammals & birds
Adapted to feeding patterns