Bio 1002 form and function

Anatomy

study of biological form of an organism

Physiology

study of biological functions an organism performs

Comparative study of animals reveals

s form and function closely correlated

Animal form and function are correlated at __ levels of organization

all

__ affect the way an animal interacts with its environment

Size and shape

Many different animal body plans have evolved and determined by __

genome

__ constrain strength, diffusion, movement, and heat exchange

Physical laws

As animals increase in size, __ must be proportionately larger to support their mass

skeletons

__ reflects different species’ adaptations to a similar environmental challenge

Evolutionary convergence

Rate of exchange __ to cell’s surface area

proportional

Amount of exchanged material __ to a cell’s volume

proportional

Materials such as__ , __ , __must be exchanged across animal cell membranes

nutrients, waste products, and gases

Internal exchange surfaces of complex animals

Hierarchical Organization of Body Plans

 Most animals composed of specialized cells organized into tissues that have different functions

 Tissues make up organs, which together make up organ systems

 Some organs, such as the pancreas, belong to more than one organ system

Organ Systems in Mammals

Structure and Function in Animal Tissues

 Different tissues have different structures suited to their functions

 Tissues classified into four main categories:

 Epithelial  Connective  Muscle  Nervous

Epithelial Tissue

 Epithelial tissue covers outside of body and lines organs and cavities within body

 Contains cells that are closely joined

 Shape of epithelial cells may be

 cuboidal (like dice)

 columnar (like bricks on end)

 squamous (like floor tiles)

 The arrangement of epithelial cells may be

 simple (single cell layer)

 stratified (multiple tiers of cells)

 pseudostratified (a single layer of cells of varying length)

Connective Tissue

 Connective tissue mainly binds and supports other tissues

 Contains sparsely packed cells scattered throughout extracellular matrix

 Matrix consists of fibres in a liquid, jellylike, or solid foundation

 Three types of connective tissue fibre, all made of protein:

 Collagenous fibres provide strength and flexibility

 Elastic fibres stretch and snap back to their original length

 Reticular fibres join connective tissue to adjacent tissues

 Connective tissue contains cells, including

 Fibroblasts that secrete the protein of extracellular fibres

 Macrophages that are involved in the immune system

Fibroblasts

secrete the protein of extracellular fibres

Macrophages

are involved in the immune system

Connective Tissue in vertebrates

 In vertebrates, the fibres and foundation combine to form six major types of connective tissue:

1. Loose connective tissue binds epithelia to underlying tissues and holds organs in place

2. Cartilage a strong and flexible support material

3. Fibrous connective tissue found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints

4. Adipose tissue stores fat for insulation and fuel

5. Blood composed of blood cells and cell fragments in blood plasma

6. Bone mineralized and forms the skeleton

Muscle Tissue

 Muscle tissue consists of long cells called muscle fibres, which contract in response to nerve signals ‘'

 It is divided in the vertebrate body into three types

1. Skeletal muscle, or striated muscle, responsible for voluntary movement

2. Smooth muscle responsible for involuntary body activities

3. Cardiac muscle responsible for contraction of the heart

Nervous Tissue

 Nervous tissue senses stimuli and transmits signals throughout the animal

 Nervous tissue contains

 Neurons, or nerve cells, that transmit nerve impulses

 Glial cells, or glia, that help nourish, insulate, and replenish neurons

Coordination and Control

 Control and coordination within a body depends on the endocrine system and the nervous system

 Endocrine system transmits chemical signals called hormones to receptive cells throughout body via blood

 A hormone may affect one or more regions throughout body

 Hormones relatively slow acting, but can have long-lasting effects

 Nervous system transmits information between specific locations

 Information conveyed depends on a signal’s pathway, not the type of signal

 Nerve signal transmission very fast

 Nerve impulses can be received by neurons, muscle cells, endocrine cells, and exocrine cells

Animals manage their internal environment by __ or __to the external environment

regulating , conforming

Regulating and Conforming

Animals may regulate some environmental variables while conforming to others

aquatic temperature regulators and aquatic temperature conformers

Regulators

use internal control mechanisms to moderate internal change in face of external, environmental fluctuation

Conformer

allow internal condition to vary with certain external changes

Homeostasis

 maintain a “steady state” or internal balance regardless of external environment

 In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level

 For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response

 The response returns the variable to the set point

Feedback Control in Homeostasis

 Dynamic equilibrium of homeostasis maintained by negative feedback, returns variable to normal range '

 Most homeostatic control systems function by negative feedback, where buildup of end product shuts system off

 Positive feedback amplifies a stimulus and does not usually contribute to homeostasis in animals

Alterations in Homeostasis

 Set points and normal ranges can change with age or show cyclic variation

Homeostasis can adjust to changes in external environment, a process called acclimatization

Human circadian rhythm

 Circadian rhythm governs physiological changes that occur roughly every 24 hours

 Occurs in other animals and plants

Homeostatic processes for thermoregulation involve form, function, and behaviour

Thermoregulation

Endothermic animals generate heat by metabolism

 Birds and mammals are endotherms

 Ectothermic animals gain heat from external sources

 Ectotherms include most invertebrates, fishes, amphibians, and nonavian reptiles

Thermoregulation

is process by which animals maintain an internal temperature within a tolerable range

Endothermic animals

generate heat by metabolism

Ectothermic animals

gain heat from external sources

Endothermy and Ectothermy

 In general, endotherms active at a greater range of external temperatures

 While, ectotherms tolerate greater variation in internal temperature

 Endothermy more energetically expensive than ectothermy

Balancing Heat Loss and Gain

 Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conduction

Heat regulation

 Heat regulation in mammals often involves integumentary system: skin, hair, and nails

 Five adaptations help animals thermoregulate:

 Insulation

 Circulatory adaptations

 Cooling by evaporative heat loss

 Behavioural responses

 Adjusting metabolic heat production

Insulation

 Skin, feathers, fur, and blubber reduce heat flow between animal andenvironment

 Insulation especially important in marine mammals such as whales andwalruses

Circulatory Adaptations

 Regulation of blood flow near body surface significantly affects thermoregulation

 Many endotherms and some ectotherms can alter amount of blood flowing between body core and skin

 In vasodilation, blood flow in skin increases, facilitating heat loss

 In vasoconstriction, blood flow in skin decreases, lowering heat loss

Cooling by Evaporative Heat Loss

 Many types of animals lose heat through evaporation of water from their skin

 Panting increases the cooling effect in birds and many mammals

 Sweating or bathing moistens the skin, helping to cool an animal down

Behavioural Responses

 Both endotherms and ectotherms use behavioural responses to control body temperature

 Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat

Adjusting Metabolic Heat Production

 Thermogenesis is adjustment of metabolic heat production to maintain body temperature

 Thermogenesis increased by muscle activity such as moving or shivering

 Non shivering thermogenesis takes place when hormones cause mitochondria to increase their metabolic activity

Acclimatization in Thermoregulation

 Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes

 When temperatures subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells

The thermostatic function of the hypothalamus in human thermoregulation

Physiological Thermostats and Fever

 Thermoregulation controlled by a region of the brain called the hypothalamus

 The hypothalamus triggers heat loss or heat generating mechanisms

 Fever is the result of a change to the set point for a biological thermostat

Bioenergetics

 Bioenergetics is the overall flow and transformation of energy in an animal

 Determines how much food an animal needs

 Relates to an animal’s size, activity, and environment

Energy Allocation and Use

 After the needs of staying alive met, remaining food molecules can be used in biosynthesis

 Biosynthesis includes

 body growth and repair

 synthesis of storage material such as fat

 production of gametes

Metabolic rate

 Metabolic rate is amount of energy an animal uses in a unit of time

 Metabolic rate can be determined by

 An animal’s heat loss

 The amount of oxygen consumed or carbon dioxide produced

Minimum Metabolic Rate and Thermoregulation

Basal metabolic rate (BMR)

Standard metabolic rate (SMR)

 Both rates assume a nongrowing, fasting, and nonstressed animal

Basal metabolic rate (BMR)

the metabolic rate of an endotherm at rest at a “comfortable” temperature

Standard metabolic rate (SMR)

the metabolic rate of an ectotherm at rest at a specific temperature

Influences on Metabolic Rate

 Ectotherms have much lower metabolic rates than endotherms of a comparable size

 Metabolic rates affected by many other factors. Two of these factors are size and activity

Size and Metabolic Rate

 Metabolic rate proportional to body mass to power of three quarters (m3/4)

 Smaller animals have higher metabolic rates per gram than larger animals

 The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal

 The relationship of metabolic rate to body size in mammals

Torpor

physiological state in which activity low and metabolism decreases

Hibernation

a long-term torpor, an adaptation to winter cold and food scarcity

Torpor and Energy Conservation

 Torpor enables animals to save energy while avoiding difficult and dangerous conditions

 Summer torpor, called estivation, enables animals to survive long periods of high temperatures and scarce water

 Daily torpor exhibited by many small mammals and birds and seems adapted to feeding patterns