Mechanisms of Homeostasis and Adaptations

These flashcards cover the mechanisms of homeostasis, the nervous and endocrine systems, human glandular functions, endotherm adaptations, and water conservation in plants (xerophytes).

What is the role of the internal coordination systems (Nervous and Endocrine systems) in maintaining homeostasis?

To coordinate and create pathways of communication for the negative feedback systems through nerves or hormones to keep the body within tolerance limits.

How do transport speeds differ between the Nervous and Endocrine systems?

Nerve impulses transport quickly along nerves to specific locations, while hormones are chemical substances transferred through the bloodstream at a much slower rate.

What are interceptors?

Receptors within the body that detect internal stimuli related to homeostasis.

Match the receptor type to its specific function: Thermoreceptors, Chemoreceptors, and Osmoreceptors.

Thermoreceptors detect changes in temperature; Chemoreceptors detect chemical concentrations like $pH$, $CO_2$, and oxygen in blood vessels; Osmoreceptors detect changes in osmotic pressure in the hypothalamus.

What constitutes the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)?

The CNS consists of the brain and spinal cord, while the PNS consists of other nerves that carry information to and from the CNS.

Describe the structure and function of the components of a neuron: Cell Body, Dendrites, and Axon.

The Cell Body contains the nucleus and organelles (grey matter); Dendrites receive impulses and conduct them toward the cell body; the Axon conducts messages away from the cell body (white matter) and often has a myelin sheath for insulation.

How are Sensory, Motor, and Interneurons distinct in their function?

Sensory neurons carry impulses from the PNS to the CNS; Motor neurons transfer messages from the CNS to effectors (muscles/glands); Interneurons act as 'middle men' linking sensory and motor neurons within the CNS.

What occurs during the 'Action Potential' of a nerve impulse?

It involves an electrochemical change in the electrical potential of the cell membrane caused by the movement of ions like $Na^+$, $K^+$, and $Cl^-$ across the membrane.

Describe the state of a neuron membrane 'at rest.'

The membrane is polarized, with more negatively charged ions inside the cell than outside, and ion channels are generally closed.

How do neurotransmitters facilitate the transmission of impulses at a synapse?

The action potential triggers the release of neurotransmitters from synaptic vesicles into the synaptic gap, where they move to receptors on the next neuron's dendrites to initiate a new action potential.

What is the primary function of the Hypothalamus in homeostasis?

It serves as the main link between the Nervous and Endocrine systems, regulating activities like heart rate and body temperature, and directing the pituitary gland's hormone secretions.

What are the two main functions of the spinal cord?

It serves as a conduction pathway for nerve impulses between receptors and the brain, and it coordinates reflex actions.

How does the Pituitary Gland regulate water concentration?

The hypothalamus stimulates the posterior pituitary to release Anti-diuretic hormone (ADH), which causes the kidney tubules to reabsorb more water when body levels are too low.

What hormone does the Thyroid gland produce to regulate body temperature?

It produces thyroxine, which increases metabolic rate to release energy and provide heat when body temperature drops.

How does the Parathyroid gland respond to low calcium levels in the blood?

It secretes parathyroid hormone (PTH), which causes bones to release calcium and kidneys to reabsorb more calcium.

What are the functions of Cortisol and Aldosterone secreted by the Adrenal cortex?

Cortisol regulates stress management and energy conversion; Aldosterone increases reabsorption of $Na^+$ and decreases reabsorption of $K^+$ in the kidneys to regulate blood pressure and volume.

How do the alpha and beta cells in the Islets of Langerhans regulate blood glucose?

Beta cells produce insulin to lower high glucose levels (converting it to glycogen/fat); Alpha cells produce glucagon to increase low glucose levels (breaking down glycogen/fat).

Define 'Endotherm' and provide the three types of adaptations they use for thermoregulation.

An endotherm generates its own body heat through internal metabolism; it uses Behavioural (actions), Structural (physical traits), and Physiological (body functions) adaptations.

Give an example of a structural adaptation for thermoregulation in Fairy Penguins.

Feathers provide an insulating layer to reduce heat loss, and their small surface-area-to-volume ratio (common in cold climates) helps conserve heat.

What is the difference between Vasodilation and Vasoconstriction in physiological thermoregulation?

Vasodilation increases blood flow to the skin surface to increase heat release, while vasoconstriction reduces blood flow to conserve heat.

What are the two main functions of transpiration in plants?

1. Lifting water and dissolved ions from roots to the top of the plant (transpiration stream). 2. Evaporative cooling to regulate temperature.

List three structural adaptations Xerophytes use to reduce water loss.

1. Waxy or leathery cuticles to prevent evaporation. 2. White hairs to reflect sunlight and reduce surface temperature. 3. Reduced leaf size or leaf shedding to minimize the number of stomata.

How do succulents survive dry periods?

They possess stems and leaves that swell to retain moisture when it is available, which is then used during dry periods.

How does the orientation of leaves assist some plants in water conservation?

By hanging vertically or changing orientation, leaves ensure stomata are not exposed to direct sunlight, reducing the rate of transpiration.