Chapter 40 (Principles of Animal Form and Function) - Notes PDF

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Chapter 40: Basic Principles of Animal Form and Function All animals: 1) Obtain nutrients and oxygen 2) Produce offsprings 3) Avoid predation/disease Key Concepts • Animal form and function are correlated at all levels of organization • Feedback control maintains the internal environment in many ani...

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Chapter 40: Basic Principles of Animal Form and Function All animals: 1) Obtain nutrients and oxygen 2) Produce offsprings 3) Avoid predation/disease

Key Concepts •

Animal form and function are correlated at all levels of organization

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Feedback control maintains the internal environment in many animals (homeostatic and behavioral processes)

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Homeostatic processes for thermoregulation involve form, function, and behaviour

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Energy requirements are related to animal size, activity, and environment

Overview: Diverse Forms, Common Challenges •

Anatomy is the (defining) biological form of an organism

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Physiology is the study of biological functions an organism performs

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The comparative study of animals reveals form and function are closely correlated

Animal form and function are correlated at all levels of organization •

Size and shape affect the way an animal interacts with its environment and at the meantime environment affect the shape of the animal (streamlined bodies of fish help them to move through water)

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The body plan of an animal is programmed by the genome, itself the product of millions of years of evolution

Evolution of Animal Size and Shape •

Physical laws constrain strength, diffusion, movement, and heat exchange

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

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Properties of water limit possible shapes for fast swimming animals

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Evolutionary convergence reflects different species’ adaptations to a similar environmental challenge - PHYSICAL LAWS CONSTRAIN EVOLUTION

Exchange with the Environment Introduction •

Materials such as nutrients, waste products, and gases must be exchanged across the cell membranes of animal cells (for proper metabolism)

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Rate of exchange is proportional to a cell’s surface area, whereas the amount of exchange material proportional to a cell’s volume

OPPORTUNITY FOR EXCHANGE DEPENDS ON ORGANIZATION OF CELLS IN THE BODY Single celled organisms •

A single-celled protist living in water has sufficient surface area to service its entire volume of cytoplasm and carry out all necessary exchange Multicellular simple organisms

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Multicellular organisms therefore REQUIRE ALL CELLS TO BE IN CONTACT WITH WATER (inside or outside of body)

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Multicellular organisms with a saclike (baglike) body plan have body walls that are only two cells thick (hydra), where inner layer is bathed by water from gastrovascular cavity and outer – by surrounding water

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In flat animals such as tapeworms, most cells are in direct contact with the environment to perform exchange via diffusion; Multicellular complex organisms

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More complex organisms are composed of compact masses of cells with complex internal organization

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Evolutionary adaptations such as specialized, extensively branched or folded structures, enable sufficient exchange with the environment Vertebrates •

In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells. Exchange between the interstitial fluid and circulatory fluid (blood) enables cells throughout the body to obtain nutrients and get rid of wastes

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A complex body plan (external skeleton, developed sensory organs, internal digestive organs) helps animals living in variable environments to maintain a relatively stable internal environment (especially in TERRESTRIAL environments, which are MORE VARIABLE)

Hierarchical Organization of Body Plans •

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

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Tissues make up organs, which together make up organ systems

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Some organs, such as the pancreas, belong to more than one organ system: DIGESTIVE role: pancreas produces enzymes which function in digestion ENDOCRINE role: pancreas regulates blood sugar levels in blood Figure 1Internal exchange surfaces of complex animals.

Organ System

Main Components

Main Functions

Digestive

Mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus

Food processing (ingestion, digestion, absorption, elimination)

Circulatory

Heart, blood vessels, blood

Internal distribution of materials

Respiratory

Lungs, trachea, other breathing tubes

Gas exchange (uptake of oxygen; disposal of carbon dioxide)

Immune and lymphatic

Bone marrow, lymph nodes, thymus, spleen, lymph vessels, white blood cells

Body defence (fighting infections and cancer)

Excretory

Kidneys, ureters, urinary bladder, urethra

Disposal of metabolic wastes; regulation of osmotic balance of Blood

Endocrine

Pituitary, thyroid, pancreas, adrenal, and other hormonesecreting glands

Coordination of body activities (such as digestion and metabolism)

Organ Systems in Mammals Reproductive

Ovaries or testes and associated organs

Reproduction

Nervous

Brain, spinal cord, nerves, sensory organs

Coordination of body activities; detection of stimuli and formulation of responses to them

Integumentary

Skin and its derivatives (such as hair, claws, skin glands)

Protection against mechanical injury, infection, dehydration; thermoregulation

Skeletal

Skeleton (bones, tendons, ligaments, cartilage)

Body support, protection of internal organs, movement

Muscular

Skeletal muscles

Locomotion and other movement

Animal Tissues •

Different tissues have different structures suited to their functions

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Tissues are classified into four main categories: 1.

Epithelial

3.

Muscle

2.

Connective

4.

Nervous

1. Epithelial Tissue •

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

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It contains cells that are closely joined (tight junctions) – function as a barrier against mechanical injury, pathogens and fluid loss

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Epithelia also form active interfaces with the environment (epithelium of nasal cavity is crucial for olfactory system)

The 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) – combination of different structures

Combination of cellular forms and their functions -

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Cuboidal: specialized for secretion; makes up epithelium of kidney tubules and many glands Simple columnar: secretion or absorption; lines the intestines Simple squamous: diffusion; lines blood vessels and the air sucks of the lungs Peudostrafieid columnar: found in mucous membranes that line portions of the respiratory track Stratified squamosal: found on surfaces subject to abrasion (multilayered; REGENERATES QUICKLY); lines outer skin, mouth, anus and vagina

Polarity of epithelial tissues (polarized = having different sides) -

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Apical surface: exposed to fluid or air surface; characterized by specialized elongations which are often accompanied by specialized projections (ie microvilli in intestine) Basal surface: opposite side of epithelium. Attached to basal lamina, a dense mat of extracellular matrix that separates the epithelium form the underlying tissue

2. Connective Tissue •

Connective tissue mainly binds and supports other tissues

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It contains sparsely packed net of cells scattered throughout an extracellular matrix

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The matrix consists of fibres embedded in a liquid, jellylike, or solid foundation

Connective tissue contains cells, including Fibroblasts that secrete the protein of extracellular fibres Macrophages that are involved in the immune system (engulf foreign particles and any cell debris by phagocytosis

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There are 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 (connect connective tissues to other tissues)

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Six major types of connective tissue in vertebrates i.

Loose connective tissue -

ii.

found in skin and throughout the body binds epithelia to underlying tissues and holds organs in place contains all 3 types of fibres

Fibrous connective tissue -

found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints

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collagenous fibres

iii.

Bone -

iv.

Mineralized tissue and forms the skeleton Bone forming cells - osteoblasts deposit matrix of collagen, where calcium, magnesium, phosphate ions (both organic and inorganic components) combine into a hard mineral

Adipose tissue -

v.

stores fat for insulation and fuel specialized loose connective tissues

Blood -

vi.

composed of blood cells (erythrocytes – carry O2), white blood cells (leukocytes – defense) and cell fragments (platelets - blood clotting) in blood plasma plasma is a liquid ECM containing water, salts, dissolved proteins

Cartilage -

is a strong and flexible support material made of collagenous fibres embedded in protein-carbohydrate matrix chondroitin sulphate matrix & collagen secreted by chondrocytes

3. Muscle Tissue •

Muscle tissue is responsible for nearly all types of body movement

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Muscle cells consist of filaments of the proteins actin and myosin, which together enable muscles to contract in response to nerve signals

Muscle tissue is divided in the vertebrate body into three types: -

Skeletal muscle, or striated muscle, responsible for voluntary movement; attached to bones by TENDONS; Skeletal muscle fibres form by the fusion of many cells, resulting in multiple nuclei in each muscle cell or fibre. The arrangement of contractile units, or sarcomeres, along the fibres gives the cells a striped appearance.

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Smooth muscle responsible for involuntary body activities spindle shaped cells

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Cardiac muscle responsible for contraction of the heart striped like skeletal muscles INTERCALATED DISKS (disk like interconnections between fibres) synchronize contractions

4. Nervous Tissue •

Nervous tissue functions in the receipt, processing, and transmission of information

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BRAIN - concentration of nervous tissues; INFORMATION PROCESSING CENTER

Nervous tissue contains -

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Neurons (or nerve cells) – basic units of the nervous system; include cell body (impulse perception) and dendrite (impulse perception), axon (transmits to other neurons muscles or other cells) Glial cells, or glia, that help nourish, insulate, and replenish neurons

Coordination and Control •

Control and coordination within a body depend on the endocrine system and the nervous system Role of endocrine system in coordination and control

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The endocrine system transmits chemical signals called hormones (spread via blood, need receptor) to receptive cells throughout body via blood

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A hormone may affect one or more regions throughout the body (epinephrine release)

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Hormones relatively slow acting, but can have long-lasting effects (since the body needs some time to evacuate hormones from the blood stream)

Role of nervous system in coordination and control •

The nervous system transmits information between specific locations (not as broad as endocrine system)

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communication in nervous system involves both ELECTRICAL and CHEMICAL signals

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The information conveyed depends on a signal’s pathway, not the type of signal

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Nerve signal transmission is very fast Nerve impulses can be received by four types of other cells:

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neurons

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endocrine cells

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muscle cells

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exocrine cells

Endocrine vs Nervous System •

Both required for fine-tuned coordination and control

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However, they DIFFER in several aspects

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1) Duration long-lasting vs instantaneous (nervous)

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2) Speed variable vs fast (nervous)

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3) Transmission via blood vs via neurons

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4)Signal type chemical vs chemical(neurotransmitters)/electrical (changed in voltage)

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5)Response cells must have a receptor vs cells must be connected to an axon

Homeostasis •

Homeostasis is a dynamic equilibrium - Interplay between external factors that tend to change the internal environment and internal control mechanisms that oppose such changes

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Organisms use homeostasis to maintain a “steady state” or internal balance (body temperature, blood pH, and glucose concentration) regardless of external environment

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Primarily via negative feedback (control mechanism that reduces the disturbance)

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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

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The response returns the variable to the set point (any deviation from the set point would be negatively regulated)

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SET POINT examples: pH of blood & interstial fluid maintained within 0.1 pH unit of 7.4; glucose maintained b/w 70-110 mg per 100 mL of blood

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Set point can also be in the form of a NORMAL RANGE (upper and lower limits to variable)

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

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Controls are NOT instantaneous: therefore, changes in internal environment are moderated but not eliminated

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POSITIVE FEEDBACK mechanisms tend to drive processes to completion (ie childbirth)

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In animals and plants, a circadian rhythm governs physiological changes that occur roughly every 24 hours...