Chapter 27&33

Torpor

Low activity and metabolism for energy conservation.

Topor: characteristic

Enables survival in difficult conditions.

Hibernation:

Long-term torpor for winter cold and food scarcity.

Estivation

Summer torpor for surviving high temperatures and water scarcity.

Daily torpor

Many small mammals and birds use this during the coldest part of the day.

Homeostasis

Maintaining a stable internal environment despite external changes.

Homesostasis: Examples in humans

Constant body temperature, blood pH, and glucose levels.

Which feedback is most important

Negative feedback is key

Negative feedback

return a variable to a normal range

Positive feedback

amplifies changes and doesn't usually maintain homeostasis in animals.

Mechanisms of Homeostasis:

When an internal condition goes out of its normal range (stimulus), it's detected (sensor), causing a reaction (response) that brings it back to normal (set point).

Mechanisms of Homeostasis: order

Stimulus, sensor, response, and set point

two ways the body maintains control

• Blood Sugar (Negative Feedback): Eating raises blood sugar. Insulin lowers it. Low blood sugar stops insulin release. This cycle keeps blood sugar stable.

• Childbirth (Positive Feedback): Baby pushes on cervix, releasing a hormone. The hormone causes contractions, pushing more on the cervix. This intensifies until birth.

Acclimatization

Homeostasis adjusts to external changes.

Acclimatization: Example

High Altitude): Moving to higher altitudes with less oxygen causes the body to increase red blood cells for better oxygen delivery.

Thermoregulation (Homeostatsis)

Maintaining stable internal temperature for enzyme function.

Hypothalamus

Brain region controlling temperature regulation.

Heat Exchange:

Occurs through radiation, convection, conduction, and evaporation.

Integumentary System:

Skin, hair, and sweat glands often involved in mammal heat regulation.

Five Thermoregulation Adaptations:

• Insulation

• Circulatory adaptations

• Evaporative cooling

• Behavioral responses

• Adjusting metabolic heat production

Insulation example

fur/feathers trap air

Circulatory adaptations

Vasodilation: This is the widening of blood vessels, which increases blood flow to the skin. This allows heat to dissipate from the blood to the surrounding environment, cooling the body.

Vasoconstriction: This is the narrowing of blood vessels, which reduces blood flow to the skin. This conserves heat by preventing blood from losing heat to the environment.

Evaporative cooling

Sweating

Behavioral responses and Adjusting metabolic heat production

Honeybees huddle for warmth in cold weather.

Four Main Animal Tissues:

Epithelial

Connective

Muscle

Nervous

Epithelial

Lines surfaces and cavities.

Connective

Supports and connects other tissues.

Muscle:

Enables movement.

Nervous

Transmits electrical signals.

Connective Tissues:Composed of

cells (fibroblasts and others) embedded in a non-cellular gel like ground substance.

Connective Tissues:Contain a

mix of collagen, elastic, or reticular fibers, providing strength and flexibility.

Connective Tissues: function

Connect different tissues and provide structural support.

types of Connective tissues

Loose/areolar tissue, dense connective tissue, adipose tissue, cartilage, bone, blood

Loose Connective location

found beneath the skin, surrounding organs, and filling spaces between tissues.

Fibrous Connective location

irregular: skin regular: tendons and ligaments

Cartilage location

shark skeleton, fetal bones, human ears, intervertebral discs

Bone location

vertebrate skeletons

Adipose location

adipose (fat)

Blood location

blood

skeletal striation

striated

skeletal control

voluntary

skeletal location

skeletal muscles

smooth striation

non-striated

smooth control

involuntary

smooth location

visceral organs

cardiac striations

striated

cardiac control

involuntary

cardiac location

heart

cardiac special characteristic

intercalated discs

intercalated discs

specialized connections between cardiac muscle cells that allow for synchronized contraction.

Epithelial Tissues:

Classified by the number of cell layers (single = simple, multiple = stratified) and cell shape (squamous, cuboidal, columnar, transitional).

Squamous:

Flat, for diffusion (e.g., lung alveoli, capillaries). Also found stratified in skin, mouth, vagina (for protection).

Cuboidal:

Cube-shaped, for secretion and absorption (e.g., glands, renal tubules).

Columnar:

Tall, for absorption and secretion (e.g., digestive tract). Can appear layered (pseudostratified) in the respiratory tract.

Transitional:

Can change shape, allowing stretching (e.g., urinary bladder).

nervous tissue contains

The neuron

neuron

main cell, specialized for receiving and transmitting electrical impulses

Neuron Structure:

Cell body, dendrites, axon, axon terminals

Cell body:

Contains the nucleus.

Dendrites:

Recieves input.

Axon

Transmits impulses.

Axon terminals:

Connect to other nerve cells (synapses)

Supporting Cells (Glia)

Astrocyte, Oligodendrocyte

Astrocyte

Regulates the neuron's chemical environment.

Oligodendrocyte

Insulates the axon for efficient impulse transmission.

what is soma

cell body