Unit 9 - Human physiology

Gas exchange?

The exchange of oxygen and carbon dioxide to and from the blood at the alveoli and respiratory tissue 

What is the role of diffusion in gas exchange?

Gas exchange is facilitated by diffusion allowing air to move across surfaces

Why do large organisms require large surface areas for gas exchange?

Diffusion is slow and organisms need large surface areas to make it more rapid

What are examples of ventilation systems?

• Insects trachea - Tubes from the exoskeleton used for gas exchange

• Fish gills - Remove co2 to water and extract o2

• Internal ventilation systems - The lungs

What are the properties of gas exchange surfaces?

• Permeability - O2 and CO2 can diffuse freely 

• Large surface area - Large total surface area in relation to volume of organism

• Moist - Covered in film of moisture so gasses can dissolve

• Thin tissue layer - The gasses must diffuse a short distance 

Why do concentration gradients needed to be maintained?

Diffusion evens out concentration gradients creating an equilibrium which ends gas exchange

How does cell respiration maintain the concentration gradient?

Oxygen is continuously used and carbon dioxide is continuously produced maintaining concentrations in organisms, O2 low on inside high on outside, CO2 High on inside low on outside

At a tissue level how is a concentration gradient maintained?

Blood flows through the circulatory capillaries constantly keeping a concentration between blood and tissue 

At a organ level how is concentration gradient maintained?

Ventilation moves air/ water actively through the lungs or gas over the respiratory surface maintaining a difference between air in the lungs and blood in the capillaries

The respiratory system?

A network of organs and tissues that enable exchange between the body and the enviroement

What are the locations of gas exchange in humans?

• The upper respiratory tract - nose, mouth, pharynx, larynx

• The lower respiratory tract - Trachea, bronchi, bronchioles

• Lungs - Pair of spongy organs that exchange gases between the blood and air

• Muscles - Diaphragm and intercostals that contract and relax to facilitate breathing

What structure of the lungs make it adapted for maximum gas exchange?

• Alveoli sacs being thin and having large surface areas for greater diffusion

• Surfactant creating moisture that reduced tension and prevent alveoli from sticking together 

• Capillary being thin enough to maintain the concentration of gasses and reduced the distance of diffusion 

• The lower respiratory tract having branching tubes to move air to and from the lung providing ventilation air ways

Ventilation?

The process of actively making air or water move over the respiratory surface

Inspiration?

The volume of the chest cavity increasing and decreasing the pressure in the lungs drawing air from the atmosphere

Expiration?

The volume of the chest cavity decreasing causing the pressure inside the lungs to increase

Outline the process of inspiration?

The diaphragm contracts, moving down, pushing the abdomen out, relaxing it, while the external intercostal muscles pull the rib cage up and out as the internal intercostal muscles relax, increasing volume and decreasing the pressure, allowing air to move from high to low pressure .

Outline the process of expiration?

The diaphragm relaxes into a dome shape while the abdomen contracts pushing the organs upwards, While the external intercostals relax and the internal intercostals contract pulling the rib cage in and down causing the volume to decrease and pressure increases in the lungs moving air pressure in the lungs to lower concentration outside the body

Ventilation rate?

The number of inspiration and expiration cycles per minute

Tidal volume?

The volume of fresh air inhaled or the volume of air exhaled within each ventilation

Inspiratory reserve volume?

The amount of air a person can inhale after normal tidal inhalation 

Expiratory reserve volume?

The amount of air a person can exhale forcefully after normal tidal exhalation

How can one measure tidal volume,vital capactity and insipatory and expiratory reserve volume?

• Spirometer

• Water displacement - Filling a container with water inverting it and blowing into a tube connected to the container displacing water

How are capillaries structures adapted for their function?

• Branching - to increase surface area

• Narrow lumen diameter - good surface area to volume ratio

• Thin vessel wall - The capillary valves one cell thick for exchange

• Fenestration - capillaries have tiny pores that allow larger molecules to pass through speeding up exchange

Compare arteries and veins?

• Wall thickness - Veins have thinner walls than arteries

• Lumen size - Veins’ lumens large diameter, arteries’ lumens are central and hollow

• Elastic fibers - Arteries have more smooth muscle and elastic fibers in their wall compared to veins (arteries = think tunica media) (veins = thin tunica media)

• Muscles - arteries have smooth muscles, veins do not( due to no change in pressure)

• Presence of valves - Veins have valves to prevent backflow, arteries don’t

Occlusion?

A blockage of blood vessels preventing oxygen and nutrients from reaching the cells

Arteries?

Blood vessels that transport high pressure blood away from the heart and branch into smaller vessels

Veins?

Large blood vessels that transport deoxygenated blood to the heart

Capillaries?

The site of exchange of materials between blood and the internal or external environment

Describe the structure and function of the layers of the arteries wall?

• Tunica media - Thick layer containing smooth muscle and elastic fiber transporting a pulse

• Tunica intima - Smooth endothelium to the artery for smooth blood flow with low resistance

• Tunica externa - Outer layer consisting of connecting tissues with collagen fibers to prevent swelling and bursting due to pressure

• Lumen - Hollow pathway that maintains high pressure and velocity of flow

Unit of measure for pulse rate?

Beats per minute

What are two methods for determining heart rate

• Through arteries in the wrist or neck

• Through optical sensors that emit red light into tissue

How do veins maintain flow of blood?

• Pocket valves that prevent backflow by catching blood and closing valves

• Skeletal muscles that aid in the circulation of blood by squeezing veins walls

• Thin walls for blood flow between the capillaries and veins to be continuous

Coronary arteries?

Arteries that supply blood to the heart branching from the aorta

Coronary occlusion?

Partial or complete obstruction of blood in a coronary artery restricting blood flow to the heart

Causes of coronary occlusion?

• Build-up of plaque (Atherosclerosis)

• Blood clots (thrombosis)

• Travelling blod clots (embolism)

Consequences of coronary occlusion?

• Reduced blood flow

• Fatigue

• Heart attacks

Risk factors for coronary heart disease?

• High blood pressure

• Smoking

• Diabetes

• Obesity

• Old age

Reproduction?

The production of offspring by parents through sexual or asexual methods

Compare asexual and sexual reproduction?

• Parents : Asexual = 1 Sexual = 2

• Meiosis : Asexual = no (mitosis) Sexual = Yes

• Offspring : Asexual = Genetically identical Sexual = Genetically different

• Genetic variation = Asexual = no Sexual = YeS

• Environment : Asexual = Doesn’t respond to environmental changes Sexual: Responds to environmental changes

Outline the role of meiosis in the sexual life cycle?

Meiosis maintains the correct number of chromosomes

Outline the role of fertilization in the sexual life cycle?

Fertilization fuses the two haploid gametes to form a diploid zygote

Sexual reproduction results in……

Genetic variation

Compare male and female gametes?

• Size : Female = large Male = smaller

• Motility : Female = Non motile Male = Motile

• Production rate : Female = Few produced Male = Large numbers produced

• Energy reserves : Female = large energy reserves to support fertalization Male = low energy reserves

Scrotum?

Sac protecting the testes

Testes?

Produce sperm

Epididymis?

Long coiled tube on top of each testies were sperm mature

Vas deferens?

Transports mature sperm to the urethra for ejaculation

Seminal vesicles?

Glands that produce fluid high in fructose

Prostate gland?

Adds alkaline ph to semen to neutralize the acid ph of vagina

Urethra?

Narrow tube that moves urine and semen to the exterior of the body

Penis?

Male external genitalia

Ovaries?

Small oval shaped glands located on either side of the uterus that produce eggs and make hormones

Oviducts?

Tubes that serve as a passage between the ovary and the uterus

Uterus?

Hollow muscular organ that nourishes and develops the fetus

Cervix?

Lower portion of the uterus that connect the uterus to the vagina for mensturation and birth

Vagina?

A muscular canal lined with mucus membranes connecting the uterus and cervix to the outside of the body

Vulva?

All of the structures that make the female external genitalia

Ovarian cycle?

The series of changes in the ovary during which the follicle matures and releases an egg

What are the two main phases of the ovarian cycle?

• The follicular phases

• The luteal phase

Follicle stimulating hormone(FSH)?

Rises in the first 10 days of mensturation cycle stimulating the development of follicles each containing an egg and follicular fluid

Luteinizing hormone (LH)?

Rises to a sharp on day 14 of the cycle stimulating the maturation of the oocyte and ovulation

Estrogen?

Rises to a peak in the second week of the cycle stimulating repair and thickening of the endometrium and increases of FSH receptors

Progesterone?

Rises following ovulation reaching a peak then dropping back to a low level by the end of the menstrual cycle

Describe the negative feedback loop that regulates FSH during the cycle?

Oestradiol lowers the level of FSH and LH being secreted through the hypothalamus. subsequently lowering the level of oestradiol produced

Describe the positive feedback loop that regulate the secretion of LH during the ovarian cycle?

Oestradiol switches from day 12-14 to provide positive feedback to the hypothalamus causing and increase in LH leading to ovulation

Fetalaization?

The fusion of a sperm with an egg to form a zygote

Describe the process of fertalization?

The sperm move from the cervix to the uterus, swimming to the egg, directing their movement to the egg based on temperature (thermotaxis) and chemical gradients (chemotaxis). Sperm digests cells en route through glycophorins to reach the plasma membrane of egg cells. Once a sperm reaches the egg the spems’s plasma membrane binds to the egg cell’s plasma membrane through proteins causing a fusion of membranes (minus the sperm tail and mitochondria). The zona pellucida around the gg hardens preventing entry form other sperm, the sperm and egg zygote remain seperate untile mitosis the both nucelus breakdown.

In vitro fertalization?

Occurs through medically assisted reproduction outside the body in a lab

Outline the process of IVF?

• Downregulation

• FSH injection

• HCG injection

• Egg collection

• Fertilization

• Endometrial preparation

• Embryo transfer

Embryo transfer?

Embryos are placed in the uterus and progesterone is given to ensure the lining is maintained

Endometrial preparation?

Oestradiol and progesterone prescribed to stimulate thickening of endometrium

Fertilization?

Egg is mixed with sample sperm in dish then incubated for 1-2 days

Egg collection?

Surgical procedure using a micro pipette and ultrasound to drain eggs

HCG injection?

Follicles are stimulated to mature when 18mm in diameter

FSH injection?

Injection given for 7-12 days to stimulate follicles to develop (super ovulation more FSH)

Downregulation?

Injections given to stop secretion of FSH and LH