Chap 40

response

(1) In cellular communication, the change in a specific cellular activity brought about by a transduced signal from outside the cell. (2) In feedback regulation, a physiological activity triggered by a change in a variable.

bioenergetics

(1) The overall flow and transformation of energy in an organism. (2) The study of how energy flows through organisms.

Ectotherms

(e.g., most invertebrates, fishes, amphibians, and non-bird reptiles) use environmental energy and behavioral adaptations to regulate body temperature.

Non-cellular components made by the cells

(i.e., bone and cartilage).

Energy Sources and Allocation (see fig 40.19)

- Animals harvest chemical energy from food - Energy containing molecules are broken down to make ATP - Once energetic needs are met remaining molecules are used in biosynthesis

Other Behavioral Responses

- Basking in the sun and moving into the shade - Maintaining a certain posture (see fig 40.15)

Balancing Heat Loss and Gain Insulation reduces the flow of heat between an animal and its environment. This includes:

- Feathers - Fur/hair - Blubber - Skin

Quantifying Energy Use (see fig 40.20)

- Metabolic rate is the amount of energy an animal uses in a unit of time. - This can be measured by monitoring the amount of oxygen consumed and/or the amount of carbon dioxide produced by an organism

Modes of Heat Exchange (see fig 40.12

- Radiation - Evaporation - Convection - Conduction

Control and Coordination

-Animals need to coordinate activities among organs

>>>Epithelial tissue

-Cells form continuous sheets called membranes -Membranes cover the body and line all body cavities -The main function of the epithelial tissue is to form a barrier and the cells are closely joined -Because of this the epithelial tissue has no blood vessels -The tissues are either nourished by diffusion from capillaries beneath it or is continuously lost and replaced by cell division -There are many types of epithelial tissue

>>>Muscle tissue

-Composed of long cells called muscle fibers capable of contracting in response to nerve signals. The cells have actin and myosin fibrous proteins which are used for the contractive process. -There are three types of muscle, skeletal (also called striated), smooth, and cardiac Skeletal muscles - unbranched fibers - Striated - voluntary movement - attached to bones Cardiac muscles - branched fibers - striated - involuntary Smooth muscles - spindle-shaped cells - unstriated - found in the digestive tract, arteries, and bladder - contraction of many internal organs

>>>Connective tissue

-Functions mainly to bind and support other tissues. -Composed of sparsely packed cells scattered throughout an extracellular matrix -Includes the layer beneath the skin called the Loose connective tissue, Fibrous connective tissue, Cartilage, Bone, Adipose, Blood and Lymph. -The connective tissue is surrounded by large quantities of extracellular substances (between the living cells) that are secreted from the connective tissue.

>>>Nervous tissue

-Sense stimuli and transmits signals throughout the animal. -Composed of cells called neurons that are specialized to generate and conduct electrical signals. -also contains support cells called gila cells - primarily located in the brain and spinal collum -A neuron has four major parts: Dendrites - receive signals Cell body - maintains and repairs the cell Axon - conducts an electrical signal to a target cell Synaptic terminals - transmits the signal to target cell at a region called the synapse

Childbirth

1) Early in labor, uterus starts to contract, 2) This starts to force baby's head into cervix, 3) This stretches the cervix and causes the receptors signal for further contractions. 4) Usually once the process begins it continues until the baby is pushed out.

Counter current exchange (see fig 40.13)

A countercurrent exchange system traps heat in the body core, thus reducing heat loss from the extremities, particularly when they are immersed in cold water or in contact with ice or snow. In essence, heat in the arterial blood emerging from the body core is transferred directly to the returning venous blood instead of being lost to the environment.

negative feedback

A form of regulation in which accumulation of an end product of a process slows the process; in physiology, a primary mechanism of homeostasis, whereby a change in a variable triggers a response that counteracts the initial change.

positive feedback

A form of regulation in which an end product of a process speeds up that process; in physiology, a control mechanism in which a change in a variable triggers a response that reinforces or amplifies the change.

organ system

A group of organs that work together in performing vital body functions.

hibernation

A long-term physiological state in which metabolism decreases, the heart and respiratory system slow down, and body temperature is maintained at a lower level than normal.

circadian rhythm

A physiological cycle of about 24 hours that persists even in the absence of external cues.

torpor

A physiological state in which activity is low and metabolism decreases.

organ

A specialized center of body function composed of several different types of tissues.

types of epithelial tissue

All types of epithelia consist of cells that line a surface, are tightly packed, are situated on top of a basal lamina, and form an active and protective interface with the external environment.

conformer

An animal for which an internal condition conforms to (changes in accordance with) changes in an environmental variable.

regulator

An animal for which mechanisms of homeostasis moderate internal changes in a particular variable in the face of external fluctuation of that variable.

tissue

An integrated group of cells with a common structure, function, or both.

**Types of connective tissue

Bone - Collagen fibers in calcium salts -rigid part of the skeleton -support Loose connective tissue -loose weave of fibers -wide spread packing material -Holds organs in place Fibrous connective tissue -consists of parallel fibers -found in tendons and ligaments - connects bones and muscles Cartilage -consists of a rubbery colaginous matrix -found in flexible parts of the skeleton -support Blood -liquid plasma matrix -transport gasses nutrients and waste material Adipose tissue -storage, insulation and padding

It is a common misconception that ectotherms are "cold-blooded" and endotherms are "warm-blooded."

Ectotherms do not necessarily have low body temperatures. On the contrary, when sitting in the sun, many ectothermic lizards have higher body temperatures than mammals. Thus, the terms cold-blooded and warm-blooded are misleading and are avoided in scientific communication.

Two systems are responsible for the control/ responce to stimuli:

Endocrine - slow response, but long lasting - hormon activated - well adapted for coordinating gradual changes that affect the entire body, such as growth, development, reproduction, metabolic processes, and digestion Nervous - quick response, but short lived - electrical impulse - well suited for directing immediate and rapid responses to the environment, such as reflexes and other rapid movements.

There are four general types of tissue (see 40.5):

Epithelial Connective Muscle Nerve

Cooling by Evaporative Heat Loss

Evaporation from a surface causes heat loss - Sweating - Panting - Bathing

Mechanisms of Homeostasis

Homeostatic control systems have three functional components: - Receptor - Control center - Effector

nervous system

In animals, the fast-acting internal system of communication involving sensory receptors, networks of nerve cells, and connections to muscles and glands that respond to nerve signals; functions in concert with the endocrine system to effect internal regulation and maintain homeostasis.

endocrine system

In animals, the internal system of communication involving hormones, the ductless glands that secrete hormones, and the molecular receptors on or in target cells that respond to hormones; functions in concert with the nervous system to effect internal regulation and maintain homeostasis.

stimulus

In feedback regulation, a fluctuation in a variable that triggers a response.

set point

In homeostasis in animals, a value maintained for a particular variable, such as body temperature or solute concentration.

sensor

In homeostasis, a receptor that detects a stimulus.

hormone

In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the organism, changing the target cells' functioning. -The signaling molecules that are broadcast throughout the body by the endocrine system

Positive feedback

Intensifies the original change when the need exists. Drives events to a conclusion -Biological examples: Childbirth. -Real life example: classic snowball effect.

Exchange in Complex Animals (see fig 40.4)

Large, complex animals have highly folded or branched internal surfaces -This increases surface area -Cell in these surfaces are specialized for exchanging materials

standard metabolic rate (smr)

Metabolic rate of a resting, fasting, and nonstressed ectotherm at a particular temperature.

Internal exchange surfaces of complex animals.

Most animals have surfaces that are specialized for exchanging chemicals with the surroundings. -These exchange surfaces are usually internal but are connected to the environment via openings on the body surface (the mouth, for example). -The exchange surfaces are finely branched or folded, giving them a very large area. -The digestive, respiratory, and excretory systems all have such exchange surfaces. -The circulatory system carries chemicals transported across these surfaces throughout the body.

There are two basic forms of feedback mechanisms involved in regulation:

Negative feedback Positive feedback

acclimatization

Physiological adjustment to a change in an environmental factor. - change in homeostasis - a temporary change during an animal's lifetime, should not be confused with adaptation

ectothermic

Referring to organisms for which external sources provide most of the heat for temperature regulation.

endothermic

Referring to organisms that are warmed by heat generated by their own metabolism. This heat usually maintains a relatively stable body temperature higher than that of the external environment.

Negative feedback (see fig 40.8)

Response to change is to counteract the change resulting in a return to the original condition. "Negative" because it negates the initial change.

Exchange in Simple Organisms (see fig. 40.3)

Single-celled organisms - Exchange material by diffusion - Entire plasma membrane is exposed to medium Multicellular organisms with a sac body plan - Body wall is only 2 cell-layers thick - Exchange is by diffusion

Suppose the animals at a zoo were resting comfortably and remained at rest while the nighttime air temperature dropped. If the temperature change were sufficient to cause a change in metabolic rate, what changes would you expect for an alligator and a lion?

The alligator's body temperature would decrease along with the air temperature. Its metabolic rate would therefore also decrease as chemical reactions slowed. In contrast, the lion's body temperature would not change. Its metabolic rate would increase as it shivered and produced heat to keep its body temperature constant.

countercurrent exchange

The exchange of a substance or heat between two fluids flowing in opposite directions. For example, blood in a fish gill flows in the opposite direction of water passing over the gill, maximizing diffusion of oxygen into and carbon dioxide out of the blood.

interstitial fluid

The fluid filling the spaces between cells in most animals.

Which animal must eat a larger proportion of its weight in food each day: a house cat or an African lion caged in a zoo? Explain.

The house cat; smaller animals have a higher metabolic rate per unit body mass and a greater demand for food per unit body mass.

thermoregulation

The maintenance of internal body temperature within a tolerable range.

basal metabolic rate (bmr)

The metabolic rate of a resting, fasting, and nonstressed endotherm at a comfortable temperature.

If a mouse and a small lizard of the same mass (both at rest) were placed in experimental chambers under identical environmental conditions, which animal would consume oxygen at a higher rate? Explain.

The mouse would consume oxygen at a higher rate because it is an endotherm, so its basal metabolic rate is higher than the ectothermic lizard's standard metabolic rate.

integumentary system

The outer covering of a mammal's body, including skin, hair, and nails, claws, or hooves.

physiology

The processes and functions of an organism.

homeostasis

The steady-state physiological condition of the body. -maintaining a variable, such as body temperature or solute concentration, at or near a particular value, or set point

anatomy

The structure of an organism.

metabolic rate

The total amount of energy an animal uses in a unit of time.

hypothalamus

The ventral part of the vertebrate forebrain; functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing factors that regulate the anterior pituitary. - the sensors responsible for thermoregulation are concentrated in

-Homeostasis

This "maintenance of an internal environment" is a dynamic process which require continual regulation (and energy)

Circulatory adaptations

Vasodilation - blood flow to the skin increases, facilitating heat loss Vasoconstriction - blood flow to the skin decreases, lowering heat loss

What mode of heat exchange is involved in "wind chill," when moving air feels colder than still air at the same temperature? Explain.

Wind chill" involves heat loss through convection, as the moving air contributes to heat loss from the skin surface.

Animals with radial symmetry are ____________________, and animals with bilateral symmetry are ____________________.

a. diploblastic/triploblastic

Basic Principles of Animal Form and Function Animal form and function are correlated at

all levels of organization.

Conformer -

allows internal conditions to vary with certain external changes

Each animal cell must have access to

an aqueous environment. Simple two-layered sacs and flat shapes maximize exposure to the surrounding medium. More complex body plans have highly folded internal surfaces specialized for exchanging materials.

The internal environment is made up of ___. The exchange of ____occurs with cells here

cells and interstitial fluid that fills spaces between cells. The exchange of material occurs with cells here.

The basic scheme of organization involves

cells organized into tissues organized into organs organized into organ systems.

Tissue is Composed of

cells with similar structure and function

Maintaining the internal environment can be achieved by

conforming and/or regulating (see fig 40.7).

Most of the exchange surfaces of multicellular animals are lined with _____.

epithelial tissue

One of the characteristics of life is that organisms

establish and maintain an internal environment.

Homeostatic processes for thermoregulation involve

form, function, and behavior.

One way of regulating is the process of

homeostasis.

These components are used

in feedback system to control and maintains the internal environment.

Homeostasis maintains

internal variables within an acceptable range or effects a return to the acceptable range as soon as possible.

Compared with a smaller cell, a larger cell of the same shape has _____.

less surface area per unit of volume

From the descriptions of ectotherms and endotherms, it might seem that all ectotherms are poikilothermic and all endotherms are homeothermic. In fact, there is

no fixed relationship between the source of heat and the stability of body temperature.

In some mammals, endocrine signals released in response to cold cause mitochondria to increase their metabolic activity and produce heat instead of ATP. This process, called

nonshivering thermogenesis

An animal whose body temperature varies with its environment is called a ___. In contrast, a ___ has a relatively constant body temperature.

poikilotherm (from the Greek poikilos, varied) homeotherm For example, the largemouth bass is a poikilotherm, and the river otter is a homeotherm

Physical laws, especially physics of exchanging materials with environment, limits

range of animal forms.

Connective tissues typically have _____.

relatively few cells and a large amount of extracellular matrix

Energy requirements are related to animal

size, activity, and environment

Food moves along the digestive tract as the result of contractions by _____.

smooth muscle

Bioenergetics:

the flow of energy through an animal

Organ Systems Organ systems carry out

the major body functions of most animals (see table 40.1)

The river otter's body temperature is largely independent of that of the surrounding water, whereas the largemouth bass's body warms or cools when the water temperature changes. We can convey these two trends by labeling

the otter a regulator and the bass a conformer with regard to body temperature.

In negative feedback what does the effector effect?

the variable the sensor is sensing

An emergent property belongs to

the whole of something but not its parts. - a bicycle can be used for transportation, but its parts, such as the pedals, wheels, gears, or frame, cannot. Transportation is thus an emergent property of the assembled bicycle.

brown fat

tissue in the neck of some mammals between their shoulders that is specialized for rapid heat production

Endotherms (e.g., birds and mammals)

use metabolic heat to regulate body temperature (see fig 40.16)

Regulator -

uses internal control mechanisms to moderate internal change in the face of internal and/or external fluctuation.