Animal Structure and Function

Animal Structure and Function

• Anatomy is the study of an organism's structure.
• Physiology explores the functions of these structures.
• Anatomical adaptations enable specific physiological processes.
• Animal body plans depend on habitat and lifestyle, and are shaped by evolution.
• Physical laws constrain animal size and shape.
• Aquatic animals can achieve larger sizes due to water's buoyant support.
• Living cells require an aqueous medium for exchanging nutrients and wastes.
• Substances move across plasma membranes passively or actively.
• Animal size dictates necessary physiological adaptations.
• Single-celled organisms facilitate diffusion, as their entire surface contacts the environment.
• Hydra use aqueous environments to circulate fluids in and out of the mouth.
• Every cell in a simple animal can directly exchange solutes with its environment.
• Large animals use specialized organs for molecular exchange.
  • The digestive system takes up nutrients.
  • The respiratory system facilitates gas exchange.
  • The excretory system disposes of waste products.
• Fine convoluted surfaces increase surface area, enhancing solute exchange efficiency.

Types of Tissue

• Epithelial tissue consists of tightly packed cells that act as barriers, protecting against injury, microbial attack, and fluid loss.
• Columnar epithelia line the intestines, secrete materials, absorb nutrients, and are often ciliated.
• Stratified columnar epithelia line the inner surface of the urethra.
• Cuboidal cells are specialized secretory cells found in kidney tubules and glands.
• Pseudo-stratified ciliated columnar epithelia line tubes and remove debris with cilia.
• Stratified squamous epithelia rapidly divide, pushing older cells to the surface for replacement.
• Simple squamous epithelia are thin and leaky, lining blood capillaries and lung air sacs, where gas exchange occurs.
• Connective tissue binds and supports other tissues.
• It's composed of loosely organized cells in an extracellular matrix containing hydrophilic macromolecules.
• Fibers, often made of collagen, can be elastic, rigid, or linear.
• Loose connective tissue binds epithelia to other tissues, acts as packing, and holds organs in place.
• Fibroblasts secrete protein fibers.
• Macrophages are immune cells that engulf microbes.
• Fibrous connective tissues are dense and contain many collagen-rich fibers arranged in parallel bundles for maximizing strength.
• They are found in tendons and ligaments.
• Bone forms the skeleton and supports most vertebrates.
  • Bone is made of osteoblasts (specialized cells) and collagen.
  • Bones contain a marrow cavity.
  • Bone marrow creates red and white blood cells, using collagen and hydroxyapatite.
• Blood consists of cells and plasma.
  • White blood cells are part of the immune system.
  • Red blood cells carry gases.
  • Platelets are important for blood clotting.
• Adipose tissue is specialized loose connective tissue that stores fat, insulates the body, and stores metabolic fuel.
• Cartilage has collagenous fibers in a protein/carbohydrate matrix.
• It's strong, flexible, hydrophilic, and found at the ends of bones and in structures like the larynx and cervix.
• Eroded cartilage in bones can impede mobility and cause pain.
• Nervous tissue senses stimuli and transmits signals throughout the body using many receptors.
• Neurons send signals via nerve impulses, which are electrical and can signal other nerves or effector cells.
• Neurons release neurotransmitters affecting behavior in post-synaptic cells.
• Complex neural interactions control brain functions.
• Muscle tissue contracts following neural stimulation.
  • Contraction requires ATP hydrolysis.
• Skeletal and cardiac muscle contain myofibrils made of myosin and actin.
• Muscles can either be striated, or smooth
  • Skeletal muscles are attached to bones by tendons, support voluntary movement, and are innervated
  • Smooth musclse are slow and controlled by nerves
  • Cardiac Muscles are branched from cell to cell, and in contact with each other, which allows for quick coordination during heart beats

Tissues, Organs, and Organ Systems

• Tissues are organized into functional units called organs.
• Organs are arranged into layers.
• The stomach has four main layers:
  • The mucosal epithelium lines the lumen, secreting mucus and digestive juices. The mucus has a high pH to protect against the acidity of hydrochloric acid and pepsin.
    • The submucosa is a layer of connective tissue with nerves and blood vessels.
    • The muscularis is a layer of smooth muscle that allows stomach contraction.
    • The serosa is a layer of connective and epithelial tissue encapsulating the organ.
• Organs are suspended by connective tissue sheets called mesenteries, surrounded by fluids.
• Organs work together in organ systems to carry out major body functions in mammals.
• Each system has interrelated organs working to ensure survival.

Regulation of the Internal Environment

• Animals maintain internal conditions within set limits despite external fluctuations.
  • Regulated factors include pH, temperature, and blood glucose.
• Maintaining parameters within limits is called homeostasis.
• It involves balancing external conditions with regulatory mechanisms, though change is important in some cases.
• Regular cyclical changes, like menstrual cycles, involve hormone concentration changes.
• Feedback circuits are crucial for homeostasis.
  • A homeostatic system must include a sensor, controller, and effector.
  • An example is a central heating system. The thermostat is the control center and sensor, while the heater is the effector.
• The human body temperature is 37 degrees Celsius and is regulated by feedback circuits.
• The hypothalamus in the brain acts as a sensor and control center to maintain this.
  • If temperature is high, nerve impulses increase sweating and surface blood flow.
  • If temperature is low, signals stop sweat glands, reduce peripheral blood flow, and induce shivering.

Regulatory Systems and Chemical Signaling

• Regulatory systems coordinate organ systems and maintain homeostasis.
• Two major systems involved:
  • The endocrine system releases hormones into the blood.
  • The nervous system uses neurons to send signals.
• Positive or negative feedback mechanisms regulate these systems, for example, the regulation of the temperature
• Temperature regulation is a common form of feedback.
• Positive feedback exists, for example, during contraction.
• Chemical signaling involves two major systems of cell communication: the nervous and endocrine systems.
• The nervous system is high-speed, short-term communication via nerve cells.
• The endocrine system is slower-acting, longer-term communication.
• Target cells respond to chemicals (neurotransmitters or hormones).
• These target cells have specific proteins called receptors that bind to neurotransmitters or hormones.
• Binding stimulates cellular activity changes via signal transduction.
• Change in conformation happens through the signal transduction process, such as a change in shape
• Endocrine and nervous systems are related.
• Endocrine glands contain neurosecretory cells related to neurons.
• Some chemicals can have both nervous and endocrine function (e.g., adrenaline).
• Interaction between the two systems maintains homeostasis using positive and negative feedback.

Biological Control Pathways

• Endocrine signaling happens through endocrine glands that release hormones into interstitial glands and capillaries, interacting with cells containing hormone receptors.
• Paracrine signaling works similarly, but hormones do not enter the blood and instead work in short distances.
• Autocrine signaling: a signaling cell responds to its own signal.
  • Is particularly important within the immune cell system.
• Synaptic signaling occurs when a neuron sends out neurotransmitters from its synaptic nerve terminal, which binds to the receptor of the plasma membrane.
  • Distance between sender and receiver is very small
  • It is a very rapid transfer of 100microseconds
• Neuroendocrine signaling occurs when neurosecretory cells form synapses with capillaries and send hormones into capillary, which diffuse to cells.
• Hormones secreted by can affect many or few tissues in the vertebrate endocrine system.
• Some hormones have effects on other endocrine glands and are known as trophic hormones.
  • The hypothalamus links to the pituitary gland - also called the Hypothalamic pituitary system
    • There are also Sex hormones which effect most of the cells of the body
• The hypothalamus controls hormone release from the pituitary gland and is central to physiological coordination.
• Hormones vary in size, chemical nature, and physical characteristics.
  • Some are amino acid-based or proteins, while others are lipids.
• There are four main classes of hormones: water-soluble (hydrophilic) like polypeptides (insulin), amines (epinephrine) and lipid-soluble (hydrophobic) like steroids (cortisol) and amines (thyroxine).

Mechanisms of Chemical Signalling

• Many hormones bind to cell surface receptors leading to cell activities which happen very rapidly
• Many water-soluble hormones cause changes in gene expression.
• Some hormones affect cellular activity by binding to nuclear receptors.
• A hormone can have many effects, varying by cell type, and cells can have different signal transduction pathways for the same chemical.
• Major endocrine glands include the Pineal gland which secrets melotonine
• Hypothalmus / Pituitary Glands
• Thyroid Gland
• Thymus
• Pancreas
• Adrenal Glands
• Kidneys
• Testes / Ovaries

Regulation and Other Hormones

• Hormones are also regulated by feedback, for examples digestion = low pH in duodenum stimulates secretin release
  • HCO3 signals the pancreas in a negative feedback loop
• Blood calcium regulation is important for nervous system and muscle contraction.
• Parathyroid glands on the thyroid gland's surface secrete parathyroid hormone, increasing blood calcium.
• Calcitonin reduces blood calcium and is produced by parafollicular cells in the thyroid gland with which the hormones are antagonistic
• The body cannot live without parathyroid glands
• Blood glucose is regulated by antagonistic hormones.
  • The pancreas has endocrine and exocrine functions.
• It releases hormones, insulin and glucagon, into the endocrine system, among others like Bicarbonate
• The islets of Langerhans secrete glucagon (alpha cells) and insulin (beta cells) which helps with limits
• Insulin lowers blood glucose by stimulating the uptake of glucose into glycogen.
• In Type 1 diabetes, beta cells are destroyed by antibodies and require thorugh injection
• Type 2 diabetes is characterized by reduced cellular responsiveness to insulin and can be managed with exercise and dietary control.
• The adrenal glands, located on top of the kidneys, deal with short and long term stress responses

Adrenal Glands, Hormones and Sex Hormones

• Adrenals are found on top of the kidneys with their main function being dealing with both long and short term stress

• Consist of cells from neutral crest

• Medulla = secretes adrenaline and nor-adrenaline to initiate fight or flight response

• Cortex = secretes 2 which results in stimulation of good or bad stress

• Catecholamine hormones are controlled by nerves that release acetylcholine -The effect of catecholamine release allows for increase of of basel metabolic, and breaks down glycogen to release glucose and stimulate fat breakdown

• Corticosteroids

  • are a response to stress in a produced adrenal cortex
  • Is controlled by endocrine signalling from anterior pitituary, and releases ACTH under the control of the hypothalamus
  • Affects metabolism - glucogenic

• Mineralocorticoids regulate salt and water balance, blood volume, and blood pressure.

• Aldosterone regulates blood pressure and salt regulation.

• The Renin-angiotensin system helps regulate blood pressure

• Sex Hormones are steroids and are structurally related to corticosteroids

• Are produces in gonads such as testes and ovaries or structurally related steroids

• Testosterone in males, is produced by testes

  • Regulated via the inhibin

Sex Determination & Introduction & Overview of Nervous System

• Sperm count that is high - secreted, to reduce gonadotropin release from AP, but if it is low it goes up
• Sex hormones and reprodutive cycle is done in 2 phasis
  • Follicular phase =
  • Luteal phase =
• Human reprodutive structures can become testes (CY embroyos)
  • It determined by SRY gene (Sry induced expression of SOX9 - regulatory transcription factor) -The nervous system works hand in hand with endocrine and immune systems to maintain homeostasis, via ELECTRICAL impulses
• Has 3 main functions and is HIGHLY COMPLEX
• Sensory input through sensory receptors
• The information is sent to CNS
• Motor output gets sent from CNS to effector cells

Information processing & Neuron Structure

• Nerves travel between CNS systems back and forth.
  • Nerves with connections to the CNS are called IN to CNS
  • The connections away from CNS are called EFF out of CNS

• Information processing - Neural circuits is something deadly neurotoxins are capable of doing that impacts the processing circuit

• For example cone snails, can detect prey as the siphon detects and sends a signal to the brain, which triggeres release of toxin

• Neuron Structure has the following features:

• Has nucleous and other organelles and dentrites

  • Covered in projections called dendrites which send high electricaly messages
  • Axons = sends signals out with a hillock that allows conduction
  • Covered in myelin sheath for quick conduction
  • Synaptical ends which allow transfer through cell signalling, with the cell termed presynaptic and responsive cell termed post-synaptic
  • Calcium gates allow neutrons transfer as well

• Nerve cells have varied structuture

  • Have peripheral endings that detech specific stimuli
  • Some have complex dentrites
  • MOTOR neurons are complex yet rapid

Supporting Cells in Nervous Systems

• Contains Glial cells

  • that are responsible for supporting roles such as
  • Astrocytes which form structural and regulative roles with capillaries to form barrier. also tightly regulatate movement of bloos

• Nerves are electrically-excititable cells with membranes that are ALTERED that are caused by MOVEMENT

• The movement has specilialisied ion channels

• Cell membranes lead to the following

  • K+ is main cantion inside cell (Na+ oustide)
  • Chloride outsidd
  • Ion and channel pumps play a role too

Nerve impulses

• Na+K+ ATPase moves Na+ out of cell and K+ into cell which then all allows K+ channel outflow with Na infux
• This can lead to change asymmetries across the membrane. and create a resting membrane with potential
• Unexcited state - resting potential with specialized ion channels
• Different from not gated

• Voltage gated ions allow the neuron to be stimulated by nerotrasnmitter and allow change in membrane potential

• Hyperpolarization and depolarization
• AT dendrite nerotrasmitters simulate changes in the same membrane potential, through channels
  • Hyper decrease = less positive
  • Depo increase = more positive

Graded potential is linked to strength of the signals and creates channles :depolarization leads to actiom potentials with the amount channels to be opene 10 all or nothing the axon is triggered to spread Action potentials then close, leading to polarization

Action Potentials

Voltage gated, sodium and pottasium channels are responsibke for -K+ single voltage sensitive ( resting state, depolarization) - Na + 2 gate voltage sensitive, closed but depolarizes

• Potential has
• Closed gates of 70 mv Stimui graded voltage charges allow Na move or change AP is fully move ions in remian closed opening slowly as potential for cells

How action potentials signify signal strength?

All or none, know the nervous system will fire frequent stimulation

• Propagation Of Nerve Impulses- will spread away • Myelination Of Neurons- providing innovation on cell with vated ion channels at gags

• increases speed

• Synapes to the cell

• Are were commutionication is had
• Can be bwtwwem
• Electrical synapse are propgated and couplred and secrete
  • Cell membrane are receptive
  • Regulte cells depending on ions, Requires cell interations can recuieve info and are excitablilt

Action Potential (continuation)

• Cell electrical calls or inhibited -Graduated protential by multiple, which allows for trigger point too
  • AP has chemicals from Pre synap, cells release
• Main types include •ACTH •Biogenic amines •amino acids •neuropeptides

Circulation and Gas Exchange:

Arteries and Veins have layer and 3 layers outer allowing layers Inner allowing to flow easily

capillaries thin layed to get changes

Artery vs vein - vein less, pressure lower blood back is prevent with viens Veins travel up and follow to haertt decrease and capillaries, and dampered Capiliaries are for supplies

Circulation & Exchange

• Each tissue has many capillaries that supply nutrients and takeaway waste products In some oragns is it constant

• Depends or relies and is connected with muscles which increase musclse for it to go,

• Artterioles allow a smaller flow of arteirs channels to maintain fnuction

capilaries- allows exchanges water and pressures exchange depends concentration water balance 4-8 leters a day interstiral fulud drains lymph the 56 blood in water solvent, ions osmostis protens water

Leukocyes Erythrocytes

Red blood And Blood Production

Small cells 8 microenters Produced to in bone maerrros 02 binding proteins

• plateletes samelr All cell in bone mrarows stem , split, etc repplich blood cell

blood clot seals cell Plateles control actinos Causes form etc

Gas Exchange:

Molecular uptakes

Q2 is needed for atp

structure determines on eniviromnet simple cells can excahgne what'd needed Animals in squmaios neeed grills Animaos use ljnggss

suspenden in water for gil invertrates over body ventatlion can help echnoderms througb eskelto

• Annelids through structres, but need structres in eskotel Watr over strcutreis Gil-

Fish gills

water pumped and flow flimenta lamella blood is oppoosite maximizes excahnfes Gil cap are loaded and water is high

Insects: air tubes branch small branch touch cells

• diffusion lines end
  • Air sacs for O2
• more insect need 02 flow

lungs restricted system connected . for air and gas transfer with cappiralies least amount with O2, water ,

3D system: high eptithiel,.

moisture and air allows dissolved

• phaynx to lungs through and trachea, then small here alvecoli for gas transfer

Respiratory Systems (summary)

• Dissolves on wet system

• Birds breath more

• No alveoili but 2 breath. lungs inhalation thoractic results to lungs

• tudalv

• volume, but means
• • monitor

levels to breath arterial system

• CO2 drive excahnges lower than alvieroal 02 with blood in 0

Respiratory Pigments & Immunity

• Qy not super high to active tissuees to prevent extra hreats

• haemoglobins use 2

• Immunity -

Innate Immunity - and defencess and is rapid

• Acquired Immunity - specific and has memory

Pathogens & TLRs

• Invertebrate and cell is in Phogyctiosisis and amops

• hemoyctie activitiy for foreign and digest

• and cell will kill and proctect

• pathogens reongition =

• they have compeents not
• inmuke cells that protect activitieiees

Cells lysozyme or surface, and TLR. immune