Animal Physiology and Morphology Quiz

Animal Form and Function

• Animal morphology and physiology are adaptations allowing survival and reproduction in specific environments. These adaptations are heritable traits.
• Physical laws (e.g., mechanical strength, diffusion, heat exchange) restrict adaptations and sometimes lead to convergent evolution.
• Body size affects animal function, specifically the surface area to volume ratio (SA:volume).
• Increasing complexity in large, multicellular animals creates design constraints on body form and function.
• Specialisation of cells, tissues, and organs/organ systems is evident in complex animals.
• Transport systems (e.g., circulatory, digestive) are a vital part of animal function.
• Control/coordination mechanisms (hormonal, electrical) are used to maintain homeostasis.
• Homeostasis is maintained via negative feedback.
• Thermoregulation is an example of form, function, and behaviour integrating to maintain homeostasis.

Galapagos Finches

• Finches' beaks show adaptations related to the size of seeds they eat.
• Small beaks are ideal for eating small seeds.
• Medium beaks are suited to medium-sized seeds.
• Large beaks are suited for large seeds.
• Some finches have beaks for eating insects or nectar.

Seemingly Bizarre Animals

• Seemingly bizarre animals reflect adaptations to their environments. This is demonstrated with examples from 1970s and 1990s and the Burgess Shale fauna (500 million years ago) and the Census of Marine Life (2010).

Material Exchange in Animals

• All animals exchange materials (nutrients, gases, wastes, heat) with their environment.
• Small organisms have large surface area relative to volume/mass, enabling efficient exchange.
• Diffusion distance between the environment and cells is reduced in small organisms, leading to better exchange.
• Larger multicellular organisms require specialized structures (e.g., respiratory systems) for efficient material exchange.

Surface Area-to-Volume Ratio

• Body size significantly influences how animals function.
• Volume increases faster than surface area as size increases. This impacts the rate at which resources are obtained or used.
• Larger animals generally have lower mass-specific metabolic rates per unit of mass compared to smaller animals.

Complex Organisms and Exchange

• Complex, multicellular organisms need other solutions for material exchange and have specialized transport systems and specialized body fluids (e.g., interstitial, blood) allowing contact across different areas in the organism.
• These solutions include specialized surfaces that increase surface area (e.g., folded or branched structures).

Hierarchical Organization

• Cells are organized into tissues, tissues into organs, and organs into organ systems.
• There are four main tissue types: connective, epithelial, nervous, and muscle tissue.
• Connective tissue is further subdivided into various types including loose, dense, and fluid connective tissue.

Other Tissue Types

• Epithelial tissue forms coverings and linings.
• Nervous tissue is involved in transmitting signals.
• Muscle tissue is responsible for movement. Muscle cells are also characterized in three types: skeletal, cardiac, and smooth.

Coordination and Control

• Complex body plans are coordinated by the endocrine and nervous systems.
• The endocrine system uses hormones that travel throughout the body to elicit a response. Responses can be very slow and long term.
• The nervous system uses action potentials to transmit signals rapidly. The responses are fast and short term.
• Both systems work together and involve feedback regulation to control a wide range of functions and activities within the body across diverse types of cells, organs, and tissues.

Different Hormone Families

• Different hormone families (peptides, amino acid derivatives, steroids) have unique structures and functions.
• Lipid solubility of the hormones determines how they interact with target cells.

Lipid Solubility and Hormone Function

• Lipid solubility significantly affects a hormone's function, influencing synthesis, storage, transport, and mode of cellular action.
• Different mechanisms exist for protein/monoamine hormones compared to steroid/thyroid hormones. Protein and monoamine hormones act on receptors on the cell surface. Steroid hormones often act inside the cell through their receptors and result in changes in gene expression.

Endocrine Networks

• Endocrine systems function via networks (axes), facilitating communication and coordination.
• Examples include the hypothalamic-pituitary-thyroid axis.

Feedback Regulation

• Neuroendocrine systems are regulated by feedback loops.
• Negative feedback is the most common type, maintaining constant hormone levels.
• Positive feedback is less common and associated with rapid events like birth and ovulation.

Hormonal Regulation of Reproduction

• Hormones (e.g., GnRH, estrogen, progesterone) regulate female vertebrate reproduction and gonad function.
• Sensory input (e.g., day length, food) can regulate these processes via the hypothalamus, pituitary and gonads.

Hypothalamus and Pituitary

• The hypothalamus and pituitary work together to regulate peripheral endocrine organs.
• Hormones released by the hypothalamus regulate the release of hormones from the anterior pituitary and posterior pituitary. These hormones control several important functions like reproduction, stress response, and growth.

Neuroendocrine Regulation of Stress

• The hypothalamic-pituitary-adrenal (HPA) axis regulates the stress response.
• Short-term stress responses involve adrenaline/epinephrine.
• Long-term stress involves cortisol.

Insect Metamorphosis

• Neuroendocrine and endocrine control regulate metamorphosis in insects.
• The brain, neurosecretory cells, corpora cardiaca, and corpora allata release various hormones that drive different stages of development. These hormones are particularly essential in regulating the process of metamorphosis, which involves significant changes in physical structure, during an insect's life cycle.

Nervous System Signaling

• The nervous system uses electrical signals called action potentials to convey information.
• Action potentials are rapid, transient changes in membrane potential.
• The signal travels down the axon and can trigger a response in another neuron or effector cell.

Neuron Structure and Organization

• Neurons have cell bodies, dendrites, axons, and synaptic terminals.
• Information flows from dendrites to the cell body to the axon, ending at the synaptic terminals for signaling to another cell.
• Information flows through electrical signals from one end of the neuron to the other, but the transmission between neurons is different, with a chemical synapse that involves neurotransmitters.

Action Potentials

• Action potentials are changes in membrane potential restricted to a single point on the membrane. The voltage-gated channels open and close sequentially driving the changes.
• The action potential propagates down the membrane and can travel along the axon.
• The speed of propagation in the axon depends on the diameter of the axon. The speed can often be increased by special insulation present called the myelin sheath.
• The direction is often one way, due to refractory periods of voltage gated ion channels.

Neuron Communication

• Neurons communicate through chemical synapses using neurotransmitters.
• Neurotransmitters are released into the synaptic cleft, binding to receptors on the postsynaptic neuron.
• The strength of the potential in the postsynaptic neuron is a graded response proportional to the signal strength of the incoming action potential from the presynaptic neuron.

Vertebrate Nervous System

• The vertebrate nervous system is divided into central and peripheral nervous systems.
• Sensory neurons transmit information from the environment/muscles to the CNS.
• Interneurons in the CNS integrate this information.
• Motor neurons send information from the CNS to muscles, glands or other organs.

Vertebrate PNS Organization

• The vertebrate PNS is further organized into somatic and autonomic divisions.
• Somatic division is responsible for voluntary movement.
• Autonomic division regulates involuntary processes like heart rate, digestion etc. This division is further subdivided into sympathetic and parasympathetic branches which have opposite effects, and control the body's reaction to a situation.

The Nerve Stimulus-Muscle Reaction Mechanisms

• Action potentials are propagated down the motor neuron and release neurotransmitter (acetylcholine).
• The neurotransmitter stimulates muscle contraction via the movement of intracellular calcium ions .
• This triggers muscle contractions according to the sliding filament model.

Test your knowledge on the relationship between animal morphology and physiology, particularly concerning adaptations. This quiz delves into physical laws, cell specialization, thermoregulation, and the role of body size in animal function.