Topic 11 Animal physiology

Objectives Expected outcomes

o Required content

Topic 11 Animal physiology

State the function of bones and exoskeletons

Identify the types and structure of synovial joints

Describe the structure of a human elbow

Discuss the roles of antagonistic muscle pairings

Describe the antagonistic muscle pairings in an insect leg

State the key functions of the skeleton

Describe how the skeleton is adapted to carry out its function

Compare endoskeletons with exoskeletons

Identify the location of synovial joints

Sketch and label a diagram of a synovial joint

Discuss problems that are associated with synovial joints

Define antagonistic pairing

Give examples of antagonistic muscle pairings

Discuss the importance of

The bones and exoskeleton serves the role of protecting vital organs and soft tissue, providing levers for movement and anchorage points for muscles. Levers can change the size and direction of a force, they consist of an effort force, pivot (fulcrum) and resultant force.

An exoskeleton is a complex and rigid structure consisting of flexible joints. Exoskeletons in arthropods are made from chitin. Exoskeletons provide greater protection than an endoskeleton, they provide better leverage. However, exoskeletons are heavy and therefore limit size, they do not grow and therefore need to be shed (molted), this leaves the organism venerable until the new exoskeleton hardens.

Locomotion is the movement of an organism from one place to another. Muscles provide the force for this movement. Fish contract their muscle to move their tail from side to side, this movement pushes the fish forward. The fish steer through the movement of their fins. Flying birds contract their wing muscles to flap their wings, the downward motion generates lift and when the wings in a fixed position, the movement of air creates lift.

The point at which two bones meet is called a joint. The bones may be fixed at a joint or may be able to move (articulation). Synovial joints such as the elbow and knee are typical articulated joints. Synovial joints are made up of cartilage which covers the ends of the bones, preventing contact between them, reducing friction and absorbing impact. Synovial fluid to reduce friction further and lubricate the joint. The synovial membrane (joint capsule) which is a tough ligamentous material that holds everything in place and produces the synovial fluid. Furthermore, ligaments hold the bones together preventing dislocation and restricting movement. Tendons attach the muscles to bones. Some synovial joints are referred to as hinge joints- they only allow flexion and extension, other joints such as a ball and socket joint also allow abduction (outward) and adduction (inward) and rotation. When synovial joints are damaged they may result in Osteoarthritis (wear and tear of the joint) and rheumatoid arthritis (inflammation).

Topic 11 Animal physiology

Sketch and annotate typical muscle cell

State the function of myofibrils in muscle fibers

Explain the function of sarcomeres within the myofibrils

Link the sliding of actin and myosin filaments to muscle contraction

Describe muscle contraction

Use animations to visualize muscle contraction

Discuss the importance of ATP hydrolysis and cross

Sketch a diagram of a muscle cell

Recognise muscle cells from microscope images

Explain the function of myofibrils

Define sarcomere

Describe myogenesis and the structure of a sarcomere

Identify and discuss the role of myofilaments

Identify myofilaments and banding from muscle tissue diagrams

Explain how myofilaments slide over each other during muscle contraction

There are a number of different types of muscle that are found in living organisms. These include smooth muscle (radial and longitudinal), cardiac and skeletal muscle. Skeletal muscles are the ones that are attached to the skeleton. When viewed under the microscope we see that they are multinucleated with visible stripes- we say that they are striated.

Many muscle cells fuse together during embryonic development (myogenesis) to form a large muscle fibre.

The surrounding membrane is called the sarcolemma. The muscle fibres contain modified endoplasmic reticulum calle sarcoplasmic reticulum and these store calcium. There are also many mitochondria which produced the ATP needed for muscle contraction.

Myofibrils are elongated threadlike structures that are found within the muscle fibers. They are made up

Topic 11 Animal physiology

11.3 Animal Physiology

Objectives Expected outcomes

o Required content

Topic 11 Animal physiology

Discuss metabolic reactions that are subject to homeostatic control

Discuss how body temperature is controlled

Discuss the underlying issues of finding blood cells, glucose, proteins and drugs in urinary tests

Urinalysis and diabetes in more detail

Link enzyme reactions to homeostasis

Any metabolic reaction that involves enzymes may be subject to homeostatic control. There reactions include:

Protease- pH in the stomach must be maintained around 1.5 for optimal activity Hunger- provides the body with needed substrates and energy eg starch is a substrate for

amylase and is obtained through the consumption of food. Glucose- when in excess this is converted to glycogen by enzymes in hepatocytes Temperature- this needs to be kept at an optimum to prevent enzymes from being

denatured Body temperature needs to be controlled in order to keep metabolic activity at an

optimum. The skin is important in temperature regulation, skin arterioles carry blood to the surface of the skin, if body temperature is high these arterioles will dilate (vasodilation) and allow more blood to reach the surface, and therefore more energy is lost from the body by radiation. The body also loses heat by sweating, the latent heat of vaporization (the energy needed for sweat to evaporate) is an important factor for the removal of heat energy from the body. The hairs on the skin also lay flat and thus reduce insulation and trap less air, this is more evident in animals rather than humans. When too cold the arterioles constrict (vasoconstriction) reducing the volume of blood that reaches the skin, therefore reducing energy loss by radiation and conserving body heat. When too cold nerve signals are also sent to the skin muscles and liver this cause shivering and an increase in metabolic activity. The hairs on the skin also stand on end- this traps a layer of air which acts as insulation. The body temperature is monitored b hypothalamus which activates the temperature regulation mechanism. When body tem returns to normal the mechanisms are switched off- this is an example of negative feedback. Arctic mammals are more adapted to lower temperatures than tropical mammals, they tend to have thicker fur- that is capable of trapping more air for insulation and a thicker layer of insulating fat and this means that they have less reliance on metabolism (BMR) to regulate their temperature.

Urinalysis is a method of testing urine to detect health problems or substance abuse. The analysis can be done using chemical test strips which change colour in the presence of various substances. Glucose in the urine indicates diabetes, protein also indicates diabetes and kidney damage- proteins may indicate glomerular damage if they can pass through the filtration slits, they will not be reabsorbed in the convoluted tubule as they are too large., white blood cells indicate an infection in the urinary tract. Red blood cells may indicate the presence of kidney stones or tumors. Urinalysis can also be used to test for illegal or banned substances and drugs.

Topic 11 Animal physiology

Explain the correlation between the type of nitrogenous waste and the evolutionary history/habitat of an organism

Define osmolarity and osmotic pressure

Explain what is meant by osmoregulator and osmoconformer

Explain how insects carryout osmoregulation and the function of the Malpighian tubule system

Compare the content of blood in both

Explain the meaning of nitrogenous waste

Compare the nitrogenous waste from mammals, fish, reptiles and birds

Link the type of nitrogenous waste to the evolutionary history/ habitat of an organism

Define homeostasis, hyper/iso/hypo-tonic, isosmotic and osmotic pressure

Explain the need for osmoregulation

State the meaning of osmoregulator and osmoconformer

Define and recognize the Malpighian

Nitrogenous waste is toxic and produced by the deamination (degradation) of excess amino acids. Different animals release their nitrogenous waste in various ways. Fish, echinoderms and coelenterate all live in water and therefore excrete this waste as toxic ammonia which is diluted by an abundance of water. Other animals such as mammals use energy to convert the toxic ammonia to a less harmful urea which is soluble and dissolves in the blood, before excreting it. Some animals will use additional energy to convert the waste to nontoxic uric acid, an insoluble compound which does not need to be mixed with water and is released as a paste, this allows the animal to conserve water reducing the weight of the organism this is particularly important for flying animals, these animals include birds, reptiles and insects. Uric acid is particularly useful in bird’s eggs as the insoluble waste released by the developing bird will not be toxic to the organism as it will crystalize. Amphibians will release ammonia in the early stages of life and the urea after metamorphosis. The type of waste that is released is linked to evolutionary history, habitat and environment. There is a tradeoff between the toxicity of the waste and the energy expenditure.

Homeostasis is the maintenance of a constant internal environment within narrow limits- it also involves the monitoring of variables within the body and mechanisms of negative feedback (the corrective process is switched off once the body returns to normal) and often involves the use of hormones from the endocrine system or the nervous system.

Examples include the regulation of body temperature and the control of blood sugar levels. It is essential that organisms are able to do this as it is needed to keep the internal conditions at an optimum for enzyme activity. Body temperature, oxygen levels pH and water content are some of the conditions that need to be kept constant. The maintenance of the water balance in the blood is referred to as osmoregulation.

Osmolarity means the amount of solute (salt) that is present in a liquid. This leads to osmotic pressure- the pressure needed to prevent the movement of water by osmosis. Solutions that have a high osmotic pressure are said to be hyper tonic, low pressure hypotonic and two solutions with equal osmotic pressure are isotonic

An osmoregulator is an organism that controls its solute content keeping it at a constant level. Organisms that do this include terrestrial animals, freshwater animals and bony fish in marine environments. An osmoconformer, will have the same solute content as its environment.

Insects have tiny tubes that branch from the intestinal tract. These are called Malpighian tubules. Insects produce uric acid as a waste product of metabolism, this is toxic and needs

Topic 11 Animal physiology

Sketch a diagram of the kidney tubule and state the function of each part

Explain how substances are reabsorbed in to the blood through the convoluted kidney tubule

State the function of the loop of Henle and explain how a hypertonic solution is maintained in the medulla

Link the length of the loop of Henle to the need to conserve water in animals

State the role

Sketch a diagram of the kidney tubule

Discuss the importance of each component within the kidney tubule

Explain the mechanisms by which substances are reabsorbed in the convoluted tubule

Explain the role played by the loop of Henle

Discuss the importance of maintaining a hypertonic solution in the medulla

Explain why the limited length of the loop of Henle could lead to excessive water loss in humans

State the problems caused by having too little water in the body

State the problems caused by having too much water in the body (hyponatremia)

The kidney nephron is the functional unit of the liver and consists of the following: Glomerulus: this is a cluster of knotted capillaries through which the blood flows through at

very high pressure the differences in diameter between the afferent and efferent arterioles assists with this. This means that fluid from the plasma is forced out of the capillaries at a rate of more than 100 times that of tissue fluid formation. Substances with a mass smaller than 65000 atomic mass units (including glucose and amino acids) will also pass out of the blood through the glomerulus- this is called ultrafiltration. The glomerular filtrate does not contain plasma proteins or blood cells as these are far too large to pass through. In the glomerulus there are small openings (fenestrations) which allow the substances to move through the capillary walls. The basement membranes of the glomerulus have a network of glycoproteins which are negatively charged, these form a mesh that prevents the larger molecules, such as proteins from being filtered. (note the body produces a large amount of glomerular filtrate 180L per day).

Bowman’s capsule- this structure is cupped shaped with a porous inner wall it collects the glomerular filtrate, it is made up of cells called podocytes these cells have extensions (foot projections) which surround and support the glomerulus, they form filtration slits, which allow smaller molecules to be filtered but not larger ones. .

Topic 11 Animal physiology

11.4 Animal Physiology

Objectives Expected outcomes

Required content

Topic 11 Animal physiology

Describe the structure of the human ovary

Describe the processes of spermatogenesis and oogenesis

Explain why spermatogenesis and oogenesis result in different numbers of gametes with different cytoplasm

Identify the key features of the human ovary

Recap the process of meiosis

Describe the process of spermatogenesis

Describe the process of oogenesis

Compare the process of spermatogenesis with that of oogenesis

Draw and label a sperm cell diagram

Draw and label an egg cell diagram

Compare the structure of an egg with that of the sperm

The cortex is the outer part of the ovary, the medulla is the inner part, the stroma is the tissue that is rich in blood vessels.Meiosis is the production of gametes by reduction division. 4 non identical daughter cells are produced during the process. Variation is increased through the random assortment of chromosomes and crossing over during prophase 1. Spermatogenesis is the production of sperm cells and oogenesis

Topic 11 Animal physiology

Compare internal and external fertilization

Define polyspermy and discuss the mechanisms implemented to prevent this

Describe the process and importance of implantation in the endometrium

Describe the role of HCG and progesterone

Describe the role of the placenta during pregnancy

Explain why the placenta needs to secrete estrogen and progesterone

Placenta Describe the

process of positive feedback in relation to

Define internal and external fertilization

Give examples of internal and external fertilization

Compare and contrast internal and external fertilization

Describe the process of fertilization- include the acrosome reaction, fusion of the plasma membranes of the gametes and the cortical reaction

Define polyspermy

Discuss the mechanisms implemented to avoid polyspermy

Discuss the consequences and causes of polyspermy

Describe the

Aquatic animals tend to favor external fertilization, the eggs and sperm are released in to the water in close proximity. Possible problems with this include predation and susceptibility to environmental conditions. Eggs and sperm tend to be released in very large numbers to account for this. Terrestrial animals favor internal fertilization, this prevents the drying out of the gametes, the advantage of this is that the egg and sperm are in close proximity and the developing embryo can be protected.Sperm cells have receptors on their membranes which detect the chemicals that are released by the egg. This allows the sperm to locate the egg. Many sperm many approach the egg at the same time, to prevent multiple sperm entering the egg (polyspermy) the following occurs:The sperm push through the layer of follicle cellsThey encounter a receptor glycoprotein layer of the egg (zona pellucida) The head of the sperm binds to the zona pellucida and releases the enzymes from the acrosomeThe enzymes digest the zona pellucidaProteins on the sperm membrane bind with those on the egg membrane and the membranes fuse, the genetic material from the sperm enters the egg (fertilization). Fertilization activates the egg cell, this cause enzyme containing vesicles (cortical granules) to be released outside of the egg by exocytosis. The enzymes digest the membrane binding sites and harden/thicken the zona pellucida, preventing any further sperm from entering the egg. The male nucleus swells when it enters the ovum and the secondary oocyte completes the second stage of meiosis.Once fertilization has occurred the zygote will start to divide to form a ball of cells, a large ball of cells is called a blastocyst. The blastocyst is moved along the oviducts by the movement of cilia, until it reaches the uterus. At this point the zona pellucida has broken down and energy reserves have been used up. The blastocyst will embed in to the endometrium. The blastocyst develops fingerlike projections which penetrate the wall of the uterus allowing it to obtain nutrients and oxygen from the mother’s blood. This develops in to the placenta. Upon implantation it is essential that the lining of the endometrium is maintained. The embryo releases the hormone human chorionic gonadotropin (HCG) which stimulates the growth and development of the corpus luteum and prevents its degeneration. Thus resulting in the production of progesterone and estrogen. Progesterone will prevent further ovulation, and maintain the endometrium. It also prevents contraction of the uterine wall. The fingerlike fetal projections (placental villi) in contact with the uterus wall will develop into the placenta- the babies blood will flow through capillaries in the placental villi. The placenta is needed to allow the exchange of materials between the maternal and fetal blood. The maternal blood flows through the spaces between the placental villi (inter-villous spaces) the fetal blood vessels are very

Topic 11 Animal physiology