Homeostasis and Thermoregulation, Slides of Animal Anatomy and Physiology

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HOMEOSTASIS

37 C

pH of

pH of

0.1% blood

sugar

• Homeostasis – an equilibrium (steady

state) between an organism’s various

physiological functions, and between the

organism and the environment.

• This is a balance in response to

continually changing conditions in both the

internal and external environments

• Homeostasis – an equilibrium (steady

state) between an organism’s various

physiological functions, and between the

organism and the environment.

• This is a balance in response to

continually changing conditions in both the

internal and external environments

Control Systems

• All homeostatic control systems have

three components:

• a monitor  special sensors located in the organs of the body detect changes in homeostasis
• a coordinating centre ,  receives message from sensors and relays information to appropriate regulator (organ/tissue that will act to restore steady state)  brain
• a regulator  restores normal balance  muscles and organs
• All homeostatic control systems have

three components:

• a monitor  special sensors located in the organs of the body detect changes in homeostasis
• a coordinating centre ,  receives message from sensors and relays information to appropriate regulator (organ/tissue that will act to restore steady state)  brain
• a regulator  restores normal balance  muscles and organs

FEEDBACK

SYSTEMS

MAINTAIN

HOMEOSTAS

IS

Components:

**1. Receptors

2. Control** **Center
3. Effectors**

FEEDBACK

SYSTEMS

MAINTAIN

HOMEOSTAS

IS

Components:

**1. Receptors

2. Control** **Center
3. Effectors**

• All animals exhibit some coordination by

chemical signals:

• hormones = produced by the endocrine system convey information between organs of the body
• pheromones = chemical signals used to communicate between different individuals
• neurotransmitters = chemical signals between cells on a localized scale (over short distances; between neurons)
• All animals exhibit some coordination by

chemical signals:

• hormones = produced by the endocrine system convey information between organs of the body
• pheromones = chemical signals used to communicate between different individuals
• neurotransmitters = chemical signals between cells on a localized scale (over short distances; between neurons)

The Endocrine System

• Has several key components:
• Hormones = secreted by endocrine or neurosecretory cells, travel into body fluids to target cells where it elicits a specific response
• Target Cell = cell equipped to respond to the given hormone
• Neurosecretory cells = neuron that receives signals from other nerve cells and responds by releasing hormones into body fluids or into a storage organ from which they are later released.
• Endocrine gland = ductless gland that secretes hormones into the body fluids for distribution through the body
• Note: Exocrine gland = glands that produce a variety of substances (e.g sweat, mucus, digestive enzymes) and deliver their produces via ducts, are NOT part of the endocrine system.
• More on the endocrine system in chapter 8…..
• Has several key components:
• Hormones = secreted by endocrine or neurosecretory cells, travel into body fluids to target cells where it elicits a specific response
• Target Cell = cell equipped to respond to the given hormone
• Neurosecretory cells = neuron that receives signals from other nerve cells and responds by releasing hormones into body fluids or into a storage organ from which they are later released.
• Endocrine gland = ductless gland that secretes hormones into the body fluids for distribution through the body
• Note: Exocrine gland = glands that produce a variety of substances (e.g sweat, mucus, digestive enzymes) and deliver their produces via ducts, are NOT part of the endocrine system.
• More on the endocrine system in chapter 8…..

• Most homeostatic control systems are negative feedback systems. These systems prevent small changes from becoming too large.
• A relationship in which the response is opposite to the stimulus (or impressed change)
• The body is self correcting by the use of negative feedback
• Example: glucose and insulin, thermostat (pg. 336)
• Most homeostatic control systems are negative feedback systems. These systems prevent small changes from becoming too large.
• A relationship in which the response is opposite to the stimulus (or impressed change)
• The body is self correcting by the use of negative feedback
• Example: glucose and insulin, thermostat (pg. 336) high glucose in blood ↑ insulin production

Response No heat produced Room temperature decreases Set point Too hot Set point Heater turned off Room temperature increases Too cold Set point Control center: thermostat Heater turned on Response Heat produced

• Positive Feedback systems: process by

which a small effect is amplified

• A relationship in which the response is

the same as the stimulus

• Leads to instability and possibly death
• Some rare limited examples:

birthing process in humans: childbirth

 hormone oxytocin

• Positive Feedback systems: process by

which a small effect is amplified

• A relationship in which the response is

the same as the stimulus

• Leads to instability and possibly death
• Some rare limited examples:

birthing process in humans: childbirth

 hormone oxytocin

POSITIVE FEEDBACK (reinforces) ►increases an action ►must be turned off by outside event ►decreases an action ►could run away = death POSITIVE FEEDBACK (reinforces) ►increases an action ►must be turned off by outside event ►decreases an action ►could run away = death

• blood loss

• ↓ B.P.
• ↓ heart beat
• ↓ B.P.

• blood clotting

Thermoregulation

• • Thermoregulation: the maintenance of body temperature within a range that enables cells to function efficiently.
  • Ectotherms: (reptiles etc.) rely on air temperature to regulate metabolic rates. Therefore activity is dependent on environment.  adaptations: seeking sun, shade
  • Endotherms: (mammals etc.) maintain constant body temp (37°C) regardless of environment. Respond to changes in environmental temp. by using energy to produce heat
• • Thermoregulation: the maintenance of body temperature within a range that enables cells to function efficiently.
  • Ectotherms: (reptiles etc.) rely on air temperature to regulate metabolic rates. Therefore activity is dependent on environment.  adaptations: seeking sun, shade
  • Endotherms: (mammals etc.) maintain constant body temp (37°C) regardless of environment. Respond to changes in environmental temp. by using energy to produce heat

(^40) River otter (endotherm) Body temperature ( ° C) 30 20 Relationship between body temperature & Environmental temperature Largemouth bass (ectotherm) Ambient (environmental) temperature (°C) 0 10 20 30 40 Body temperature ( ° C) 20 10

B. Balancing Heat Loss and

Gain

• In thermoregulation, physiological and

behavioral adjustments balance heat

loss and heat gain

• 5 general adaptations in animals’

thermoregulation:

• Insulation
• Circulatory adaptations
• Cooling by evaporative heat loss
• Behavioral responses
• Adjusting metabolic heat production
• In thermoregulation, physiological and

behavioral adjustments balance heat

loss and heat gain

• 5 general adaptations in animals’

thermoregulation:

• Insulation
• Circulatory adaptations
• Cooling by evaporative heat loss
• Behavioral responses
• Adjusting metabolic heat production

1. Insulation

• Insulation is a major thermoregulatory adaptation in mammals and birds
• It reduces heat flow between an animal and its environment
• Examples are skin, feathers, fur, and blubber
• In mammals, the integumentary system acts as insulating material
• Insulation is a major thermoregulatory adaptation in mammals and birds
• It reduces heat flow between an animal and its environment
• Examples are skin, feathers, fur, and blubber
• In mammals, the integumentary system acts as insulating material